410 midterm 2 Flashcards
1
Q
What is neurotheology?
A
Neurotheology is the scientific study of the neural correlates of religious or spiritual beliefs, experiences, and practices. It is also called spiritual neuroscience or neuroscience of religion.
2
Q
What are the two main topics discussed in neurotheology?
A
- whether a fundamental belief shared by many has a neural basis (similar to other processes such as perception)
1. The role of the limbic system in mental experiences.
2. Scientific methodology and inference in studying religious experiences.
3
Q
What is the limbic system?
A
The limbic system is a cluster of cortical and subcortical structures that support a range of automatic and controlled functions, linking visceral states and emotions to cognition and behavior.
4
Q
Is the limbic system a single, unified structure?
A
No, it is a cluster of areas rather than a single system, and its definition has evolved over time.
5
Q
How did different researchers define the limbic system?
A
Willis: Included cortical regions around the brainstem.
Papez: Focused on structures around the corpus callosum, mammillary body, and thalamus.
Broca: Linked it to olfactory structures in the mammalian brain.
6
Q
What are the three distinct but overlapping networks in the limbic system?
A
- Hippocampal-diencephalic & parahippocampal-retrosplenial (Yellow Network) → Memory & spatial orientation.
- Temporo-amygdala-orbitofrontal (Green Network) → Behavioral inhibition, memory for temporally complex visual information, olfactory-gustatory-visceral functions, multimodal sensory integration, object-reward association, outcome monitoring.
- Dorsomedial default network (Blue Network; mostly cortical) → Self-reflection, pain perception, attention, mentalizing, empathy, response selection, autobiographical memory, person perception, mind wandering.
7
Q
What disorders are associated with the hippocampal-diencephalic and parahippocampal-retrosplenial networks?
A
Amnesias, Korsakoff’s syndrome, Mild Cognitive Impairment (MCI), Alzheimer’s, Balint syndrome.
8
Q
What disorders are associated with the temporo-amygdala-orbitofrontal network?
A
Alzheimer’s, Kluver-Bucy syndrome, psychopathy, temporal lobe epilepsy (TLE), Geschwind syndrome, semantic dementia.
9
Q
What disorders are associated with the dorsomedial default network?
A
Depression, autism, Alzheimer’s, anxiety, schizophrenia, OCD, ADHD, mild cognitive impairment.
10
Q
What is the role of the temporal lobe in linking cognitive and emotional functions?
A
The temporal lobe is responsible for linking thoughts, behaviors, and emotions.
11
Q
What is temporal lobe epilepsy (TLE)?
A
TLE is a form of epilepsy resulting from seizures within the temporal lobe, regardless of the specific location or underlying cause.
12
Q
What is mesial temporal lobe epilepsy (MTLE), and how does it differ from TLE?
A
MTLE (or limbic epilepsy) is a subtype of TLE where seizures originate in the hippocampus or amygdala (mesial = medial). It is not a single disorder but a cluster of syndromes with various causes and pathologies.
13
Q
What are common clinical features of TLE/MTLE?
A
- Auras (indescribable rising abdominal sensations).
- Sudden fear or anxiety.
- Déjà vu or a sense of familiarity.
- Less common: olfactory/gustatory hallucinations.
- Arrest of behaviour (e.g., lip-smacking, chewing).
- Convulsions are uncommon.
- Amnesia post-seizure (lasting minutes to hours).
- Seizures occur in specific brain regions and produce specific behavioral outcomes
14
Q
Why did Gloor et al. (1982) conduct intracranial EEG recordings on TLE patients?
A
Patients had intractable epilepsy with unclear seizure foci, requiring invasive EEG monitoring to identify spontaneous seizure origins.
15
Q
How was the Gloor et al. (1982) experiment conducted?
A
- Intracerebral EEG was recorded continuously for 5 weeks to identify spontaneous seizures
- On one day, electrodes were stimulated with an electric current.
- Patients verbally reported experiences during stimulation.
16
Q
Front: What were the key experiential phenomena reported by patients?
A
- Visual hallucinations (illusions, elementary and complex), not auditory or olfactory
- Déjà vu, memory recall, fear, emotional distress.
- Sensations of presence (rare).
- Thirst, floating sensations.
- Experiences clustered around visual hallucinations, memory, and fear.
17
Q
What did Patient 4 experience during a spontaneous seizure in Gloor et al. (1982)?
A
- Déjà vu, illusion of precognition, a “weird feeling.”
- Stopped speaking and showed posturing.
- Different EEG frequencies were linked to specific experiences in different parts of the temporal lobe.
18
Q
What brain structures were most associated with experiential phenomena in TLE (Gloor et al., 1982)?
A
Amygdala, hippocampus, parahippocampus, and temporal neocortex.
19
Q
Front: What religious experiences did patients describe in Ramachandran’s video?
A
- Following seizures:
- Feelings of being God, omnipresence.
- Extreme emotional highs and lows.
- Religious/spiritual thoughts triggered by seizures (even in non-religious patients).
- Sense of understanding the world on a cosmic level.
- Feeling of floating, detachment from reality, heightened sensitivity to world suffering.
- Religious/spiritual feelings resulted from seizure onset despite a lack of religiosity beforehand
20
Q
Front: How do TLE patients often describe their religious/spiritual experiences?
A
They report “feelings of God” or “sensed presence,” experiences of omnipresence, and deep philosophical thoughts, as seen in Ramachandran’s research.
21
Q
Front: How might the temporal lobe explain mystical or religious experiences?
A
- The temporal lobe processes emotions and assigns salience to stimuli.
- Seizures cause hyperconnectivity between sensory input and the amygdala.
- This leads to increased emotional significance of all stimuli, making everything seem deeply meaningful.
- This might explain mystical or religious experiences.
- Activity in the temporal lobe may be conducive to religious experience
22
Q
Front: What evolutionary explanation is suggested for widespread religious beliefs?
A
Since religion provides stability in society, it may have evolved as a socially adaptive mechanism.
23
Q
Front: What is Persinger’s “God Helmet” experiment and how does it related to Rama’s MTLE hypotheses?
A
- A device that applies weak electromagnetic fields across the temporal lobes to induce religious or sensed presence experiences.
- Participants are placed in a silent room and blindfolded
- These experiments were designed to test the “hardwired circuitry” hypothesis (ie. eliciting these feelings in all humans)
24
Q
Front: What experiences did participants report when wearing the God Helmet?
A
- Fear, tingling, rushes of energy.
- Sensed presence lurking behind them (this was associated with the right temporal lobe specifically)
- Clammy hands, burping, malaise.
- 80% of participants sensed “something.”
25
What was the key finding in Persinger et al. about the right temporal lobe?
Stimulation of the right temporal lobe was most associated with feelings of sensed presence.
26
How did Persinger explain spontaneous hallucinations in a patient who was having disrupted sleep?
* The patient’s bedside clock emitted electromagnetic fields at the same frequency used in the experiment.
* Those electromagnetic fields were overlapping with the patient's brain (and the person's brain was 'sensitive')
* Removing the clock stopped the hallucinations.
27
Front: What real-world phenomena might be explained by Persinger’s findings?
* Ghost sightings near the Northern Lights (linked to electromagnetic fields).
* Global increases in geomagnetic fields correlated with more seizures.
28
Front: How did Richard Dawkins respond to the God Helmet?
* Reported some tingling and twitching but no sensed presence (those could just be due to being relaxed in an isolation room)
* He scored low on the temporal lobe sensitivity questionnaire.
* This suggests individual differences in susceptibility to religious experiences (does one's brain support these types of experiences?)
29
Front: What criticism exists about Persinger’s research?
* His findings are difficult to replicate.
* This casts doubt on the "hardwired circuitry" hypothesis for religious experiences.
30
Front: If religious experiences were "hardwired," how could we test this?
* We should be able to induce religious or sensed presence feelings in all humans, not just TLE patients.
* God Helmet experiments (Persinger)
31
Front: What studies attempted to test the "Hardwired Circuitry" hypothesis?
TMS (Transcranial Magnetic Stimulation) studies.
Persinger & Granqvist experiments.
32
Front: How was the 'heightened connections' hypothesis tested?
* Galvanic Skin Response (GSR) should be elevated to all stimuli for TLE patients vs. control
* TLE patients vs. controls viewed neutral, unpleasant, and pleasant images.
* TLE patients had higher GSR responses to all stimuli.
* baseline GSR between groups was equal
33
Front: What was a methodological issue in the GSR study?
* Control group was hospital employees and students.
* Their GSR did not respond to unpleasant stimuli (e.g., burned man).
* This questions the validity of the findings, though the heightened GSR effect remained.
34
What is developmental prosopagnosia (DP)?
DP is a neurological condition where individuals have lifelong difficulty recognizing faces, despite normal vision and intelligence. It is not caused by brain injury but is present from early development.
35
How common is DP?
DP has a similar prevalence to autism, affecting approximately 2-2.5% of the population.
36
Front: Why is early identification of DP important?
Identifying DP in childhood allows for better treatment and coping strategies compared to diagnosis in adulthood.
37
What are Rama's possible explanations for MTLE being linked to religiosity?
1. God really exists
2. Patients seek tranquility in religious feelings given their medical condition
3. Heightened connections between sensory systems and the amygdala so that every objects becomes emotionally salient = sense of "special"
4. Humans have hard-wired circuitry for the purpose of religious experiences which have evolved with human culture.
38
What characterizes mystical experiences, and how do they function according to Persinger et al.?
Mystical experiences involve an altered state of consciousness, characterized by an expansiveness of space or time and an enhanced meaningfulness related to the self. They are generally positive and help reduce anxiety related to self-dissolution (death).
39
What are the two forms of mystical experiences (Persinger)
1) The experience of another Sentient Being near the experient. 2) Perceived localization of the self in a different frame of reference, at significantly different times or distances.
40
How do the left and right hemispheres differ in their roles during wakefulness and dreaming?
The left hemisphere dominates wakefulness with sequential verbal processing and categorical organization, while the right hemisphere dominates dreaming with spatial imagery organized by emotional meaning.
41
What are the primary functions of the left and right hemispheres (Persinger et al.)
The left hemisphere is primarily responsible for sequential linguistic processes, while the right hemisphere handles spatial, affective, and vigilance-related functions.
The right hemisphere can perform syntax at the level of a six-year-old and semantics of a pre-adolescent. The left hemisphere has some visual-spatial processing ability, but neither can fully substitute the other.
42
What are the two types of associative learning, and how are they optimized?
1) Sequential/serial learning, optimized for hearing. 2) Simultaneous/parallel learning, optimized for visual processing.
43
How are experiences and their organization mapped onto different brain regions (Persinger)?
Experiences are processed in caudal cerebral regions, while their organization in relation to expectations, social norms, and morality occurs in the prefrontal regions.
44
What is the right hemispheric equivalent of the ‘sense of self’?
It is dominated by affect, spatial references, and minimal verbal imagery. When weak magnetic fields are applied to the right hemisphere, people report a ‘sensed presence’ beyond the self but personally significant.
45
What is the hypothesis linking the ‘sensed presence’ to brain function?
The sensed presence might be the left hemisphere becoming aware of the right hemisphere’s self, which could be the neurological basis for gods and deities.
46
What gender differences exist in mystical experiences?
Women report sensed presences, vestibular sensations, fear, out-of-body experiences, and feeling of being ‘in another place’ more frequently than men. This may be linked to greater EEG coherence between the temporoparietal regions in women.
47
What is the vectorial hemisphericity hypothesis?
This hypothesis states that for one hemisphere’s processes to intrude into the other, either the active hemisphere must be hyperactivated, or the passive hemisphere must be hypoactivated.
48
What structures interconnect the two hemispheres, and how many neurons cross over?
The Anterior Commissure and Corpus Callosum interconnect the hemispheres, but only a small proportion of neurons directly cross via these routes.
49
How does the vectorial hemisphericity hypothesis relate to psychological depression?
Depression might involve diminished left temporal lobe activity, allowing intrusion of right hemispheric equivalents, leading to personality transformations.
50
What conditions promote hemispheric intercalation?
Life-threatening distress, epilepsy (especially temporal lobe epilepsy), and minor closed head injuries can promote intercalation between left and right hemispheric processes.
51
How do the locations of sensed presences relate to emotion and gender perception?
Left-side presences are usually unpleasant; right-side presences are more positive and may involve hearing a voice. The perceived gender of the presence is typically the opposite of the experient’s.
52
What brain regions are critical for mystical states?
* The temporal lobes, particularly the right hemisphere. The hippocampal-amygdaloid region is especially important.
* Electrical stimulation of the amygdala produces complex mental states, including déjà vu, Nirvana-like pleasantness, fear, and out-of-body-like experiences.
* Disrupting activity in the right temporoparietal junction reduces the role of beliefs in moral judgments, suggesting a link between right temporoparietal activity and moral cognition.
* Activation in the STS resulted in dreamy states in epileptic patients
* cortical and mesiobasal temporal lobe structure stimulation = expected visceral sensations, déjà vu and the incorporation of memories into current contexts
53
According to Persinger et al., what role do magnetic fields play in inducing mystical experiences?
Weak magnetic fields interact with electromagnetic substrates mediating consciousness. Specific configurations can induce out-of-body experiences and sensed presences.
54
What experimental conditions increase the likelihood of mystical experiences?
Sensory deprivation, sitting in an acoustic chamber, being blindfolded, and exposure to dim red light increase the probability of sensed presences when exposed to appropriate magnetic fields.
55
What effect does electrical stimulation of the right inferior parietal region have on movement perception?
It triggers strong intention and desire to move the homunculus-related portion of the contralateral body. With increased stimulation, patients believe they have actually performed the movements, even though they haven’t.
56
What is associated with the sensed presence during an epileptic aura with religious overtones?
Bilateral hypoperfusion within the temporal lobes.
57
Which brain regions show increased activation during religious recitation?
The frontal-parietal pathways, including the dorsolateral prefrontal, dorsomedial frontal, and medial parietal cortices.
58
How do temporal and frontal lobe functions contribute to religious experiences?
The temporal lobe is involved in religious experiences, while frontal alterations may increase religious interests as a personality trait, influencing religious-related vocations.
59
How do weak magnetic fields interact with the electromagnetic substrates of consciousness?
They mediate consciousness and mystical states (e.g., sensed presence, out-of-body experiences) through field-to-field interactions rather than direct current induction.
60
What EEG patterns are associated with out-of-body experiences and the sensed presence?
Greater theta activity convergence between the left temporal and right prefrontal region is linked to sensed presence, while bilateral stimulation enhances right-to-left temporal coherence, associated with out-of-body experiences.
61
What type of magnetic field patterns are most effective (Persinger)?
* Irregular-shaped patterns with intrinsic burst-firing and frequency modulation, rather than sine waves.
* 64 solenoids distributed evenly around the head
* 3ms duration most effective
* takes 15 minutes for the EEG to change under magnetic exposure
62
How does expectancy influence sensed presence?
* expectancy determines the verbal label that the person gives, and those verbal labels are reconstructed as memories after the experience
* so it's important that participants be blinded (and double-blind also important)
63
What was the aim of the Granqvist paper?
* The study aimed to replicate and extend previous research using a double-blind protocol. It also assessed personality traits indicative of suggestibility to determine if they predict the experience of a sensed presence and related phenomena.
* Undergraduates were blinded and not informed about the sham condition; they were told they would be exposed to weak magnetic fields comparable to cell phones while exploring feeling states.
64
Mechanism of Weak Complex Magnetic Fields
* Weak magnetic fields are likely too weak to induce currents strong enough to depolarize neurons, making their mechanism of action unclear. However, the waveform of the field has been suggested to be crucial.
* They may disrupt electromagnetic activity between hemispheres, causing right hemispheric activity to intrude into left hemisphere awareness, potentially leading to a sense of a non-self presence.
65
What indirect evidence suggests a link between temporal lobe activity and paranormal experiences?
Studies show that individuals with partial epileptic signs (e.g., sensory enhancement, affective dissociation) report more paranormal and mystical experiences, including sensed presence. However, this remains correlational.
66
What methodological weaknesses exist in Persinger’s studies?
* Lack of clear randomization and blinding procedures, raising concerns that experiences may be artifactual due to expectancy effects or differential experimenter interactions.
* EXIT scale was constructed inductively and has unknown reliability and construct validity.
67
What is Tellegen’s Absorption Scale, and why is it relevant?
* It is a widely used measure of suggestibility, assessing openness to self-altering experiences. It predicts hypnotic susceptibility and has been linked to paranormal and mystical experiences.
* absorption correlates with scores on the Temporal Lobe Signs Inventory (TLSI), which assesses complex partial epileptic signs.
* personality traits of High absorption, a new-age lifestyle orientation, and signs of anomalous temporal lobe activity associated with mystical and somatosensory experiences—together explaining 10–25% of variance in outcomes.
68
What is the Temporal Lobe Signs Inventory (TLSI) used for?
It assesses psychological experiences indicative of temporal lobe activity, including déjà vu, paranormal experiences, formed visual hallucinations, unusual smells, and stereotyped thinking.
69
What does the EXIT Scale measure?
It captures somatosensory sensations that may follow weak magnetic field exposure, including dizziness, sensed presence, tingling, vibrations, odd smells/tastes, and emotional states.
70
What were the effects of weak complex magnetic fields on reported experiences in Granqvist et al.?
* No statistically significant effects were found on any outcome measures, contradicting previous claims.
* Higher temporal lobe signs, absorption, and new-age orientation were associated with higher EXIT and mysticism scores, but these effects were independent of magnetic field exposure.
* did not find evidence that weak magnetic fields induced the sensed presence of a sentient being, mystical experiences, or other somatosensory effects.
71
If magnetic fields did not cause the effects in Persinger’s studies, what alternative explanations exist?
* Highly suggestible participants may have responded to experimenter effects, expectancy biases, or the priming effects of filling out pre-test questionnaires on anomalous experiences.
* Individuals high in openness to unusual experiences may simply have more unusual experiences when placed in a sensory deprivation context.
72
What does research suggest about the neurophysiological basis of religious experiences?
* Rather than temporo-limbic emotional processes, religious experiences may be more related to attentional and higher cognitive functions associated with prefrontal cortical activation.
* magnetic fields closer to those used in TMS might induce effects, but religious experiences are likely complex and involve multiple motivational, cognitive, and environmental factors.
73
What is change blindness?
Change blindness occurs when we fail to notice changes in our environment because we are not paying attention to them. This affects our subjective experience by causing us to miss significant alterations.
74
How does an attentional set affect change blindness?
If our attentional set is focused on a particular feature (e.g., all red cards on a red background), we may miss even large changes because they do not stand out as expected alterations.
75
What role do transients play in detecting change?
Transients (sudden visual changes, like a person changing their shirt) typically cue attention. However, a mask can remove these transients, making it harder to detect changes without environmental support.
76
What is William James’ definition of attention?
"Taking possession of the mind, in clear/vivid form, of one out of what seem several simultaneously possible objects or trains of thought... It implies withdrawal from some things in order to deal effectively with others." This contrasts attention with distraction.
77
What does Pashler say about defining attention?
Pashler (1998) argues that "no one knows what attention is, and… there may not even be an 'it' there to be known about," emphasizing the challenge of defining attention as a single mechanism.
78
How do researchers study attention?
Attention is studied in different components, such as spatial attention, selective attention, and inattention, rather than as a whole mechanism.
79
What are the different states of arousal in attention?
Awake:
1. Inattentive: Drowsy, relaxed.
2. Attentive: Focusing on specific information (e.g., exam material).
3. Automatic: Unexpected events (e.g., fire alarm) capture attention reflexively.
Asleep: Attention persists in sleep (e.g., dreams), but is difficult to study due to lack of reportability.
80
What is the flanker task?
A test that measures how peripheral distractions affect target judgments. Participants identify arrow directions while ignoring surrounding distractions.
81
What is the Stroop task?
A test where people must name the color of a word, which is easier when congruent (word matches color) and harder when incongruent (word and color differ).
82
What is the visual search task?
A task that measures how quickly a target is found among distractors. Simple targets (one feature) are easy to find, while conjunction targets (multiple features) are harder.
83
what is the attentional network task (ANT)?
* merging flanker + cuing
* adding visual noise to the target
84
what is a hierarchical processing task?
* navon figures congruent and incongruent conditions
85
What are the two types of attention in Posner’s model?
Voluntary (goal-driven): Slow to engage (300-500ms), long-lasting. Example: Studying.
Involuntary (stimulus-driven): Fast to engage, short-lived. Example: A phone ringing.
86
What does Posner's cuing task tap into?
* when attentional cue (arrow) tells us that the target will be here 80% of the time, the other 20% of the time, the target is in the unattended location
* faster response to the attended target
* very little difference between cued and uncued when time is short, response time decreases as cue-target time increases, but response time is roughly the same for uncued even as cue-target time increases
* when cue is in the periphery (instead of central) AND the cue is irrelevant to the target (50% correct), so any benefit to this location is automatic attention benefit
* crossover interaction: in early cue-target time (0-300ms), there are response time benefits to the target location
* in later cue-target times (300-1000ms), there is an inhibition response time effect
87
What is inhibition of return?
In automatic attention, after an initial benefit of attending to a stimulus, attention shifts away over time, making it harder to return to the same location.
88
What brain networks are involved in attention?
Dorsolateral frontoparietal (blue network; frontal eye fields, inferior parietal sulcus, visual areas): Voluntary attention, bilateral representation, controls attention orienting,
Ventrolateral frontoparietal (orange network; ventral frontal cortex, temporoparietal junction, middle frontal gyrus, FEF): Reflexive attention, responds to behaviourally relevant stimuli, lateralized to right hemisphere
89
What is the role of the middle frontal gyrus (MFG) in attention?
The MFG acts as a "circuit breaker," switching between voluntary and reflexive attention based on task demands.
90
What is the relationship between mind-wandering and attention?
* dorsolateral frontoparietal network (attention) and default mode network (inattention) operate in opposition
* Mind-wandering (inattention) opposes attention, engaging the default mode network (DMN), which is active when attention lapses.
* for short periods of time, you can do both (and this activated the overlapping areas)
91
what processes is attention involved in?
* sensory processing/perception: change blindness, visual searches
* action/motor control: behaviours, movements
* awareness (experience of life—if we don’t attend to them, we don’t experience them)
* memory (how is material that we pay attention to remembered—better or worse? differently?)
* social communication: informational cues given to people about other people, what are other people attending to, etc.
92
What are the key properties of attention?
1. Selective: Filters information, allowing focus on only a subset of inputs.
2. Limited Capacity: Can only process a small amount of information at once.
* dual tasks reduce performance due to the switch cost (because of both these properties)
93
What are early and late selection theories of attention?
* Early selection: Filtering occurs before semantic processing (e.g., ignored sounds in a dichotic listening task).
* early filter at the perception stage—what isn’t attended to in the perceptual stage doesn’t move on to cognitive systems, no semantics, so no behaviour
* Late selection: All stimuli are processed perceptually, but only meaningful information is consciously attended to.
* late filter at the semantic analysis stage—all stimuli are processed perceptually until analyzed for their meanings, then only those that are semantically processed go on to be experienced and influence behaviour
94
Which attentional filter theory is correct?
* both
* cocktail party effect: dichotic listening task playing different messages into different ears
* people cannot report what is happening in the ignored stream (no comprehension) which supports the early filter theory
* BUT personally relevant and survival relevant information (names, children crying) can break through the early filter to be processed semantically
95
what are switch costs?
* limited capacity property: limited set of items one can pay attention to at the same time (usually we can only do one thing at once)
* we cannot perform dual tasks without costs (reading and copying words, driving and talking on the cell phone,)
* there appears to be a single pool for available attentional resources (cannot be divided, we can switch but there are always switch costs (we can try to minimize these, but there are always costs))
96
Sana et al., 2013 Computers and Education study
* people are better at remembering information when we write rather than type (we need to reformulate information to write it down succinctly)
* group 1 used a laptop as they normally would (researchers could track what people were doing on the laptop), group 2 could not use a laptop
* group 1 (multi-tasking group) had 10% less memory for class content
* E2: laptop users were placed in front of non-laptop users = the people who didn’t have the laptop were distracted by the people who were using the laptop in front of them (less retention for class content attributed to distraction by laptop use in front of them)
* so attention cannot be held on two things at once
97
What is hemispatial neglect?
* A condition where patients ignore one side of space, usually due to right parietal damage (may be seen due to damage to either hemisphere). It affects multiple sensory modalities and is not due to visual deficits.
* Tests include:
Line cancellation: Patients fail to mark items on the neglected side.
Line bisection: Patients bisect lines too far to the right.
Object copying/drawing: Patients omit the left side of images.
* brain damage associated with neglect correspond with brain areas involved in attention (frontoparietal network of attention)
98
What is extinction in hemispatial neglect?
A phenomenon where patients can detect contralesional stimuli only when presented alone, but fail to notice them when an ipsilesional stimulus is also present.
99
theoretical accounts of neglect
* sensory deficit: patients do not respond to contralesional stimuli/sensations because they are functionally blind (this isn't the case because patients can perceive stimuli)
* motor deficit: patients have deficits in initiating motor actions towards the contralesional space (patients do tend to have a sluggish left side)
* representational deficit (most correct): neglect is not externally mediated, but affects mental representations
* Bizzi et al.: neglected space depended on a mental vantage point (so it has to do with the representation, not a sensory deficit)
100
What is Balint’s syndrome?
* A rare neurological condition caused by bilateral damage to the occipital and parietal lobes, leading to severe visuospatial deficits, impaired eye movement control, and difficulty perceiving multiple objects simultaneously.
* patients’ experience of space disappears, can only see/engage with one object at a time, cannot locate the object that they report seeing, cannot report whether it’s moving toward or awar from them
1. Simultanagnosia: Inability to perceive multiple objects at once.
2. Optic apraxia: Difficulty shifting gaze to new objects.
3. Optic ataxia: Problems coordinating visually guided movements.
* these three symptoms may occur at the same time, but don't have to
* No formal imaging criteria, but bilateral parieto-occipital atrophy on CT/MRI and decreased cerebral perfusion on SPECT scans are suggestive.
101
What is the complete form of Balint’s Syndrome?
The full syndrome occurs when there is involvement of:
Bilateral posterolateral occipital lobes (visual association area)
Parieto-occipital junction
Posterior aspects of both parietal lobes
102
What is the most common cause (and other causes) of Balint’s Syndrome?
* Bilateral watershed infarctions due to sudden hypotension, leading to damage in the parieto-occipital regions.
* Traumatic brain injury (TBI)
* Pre-eclampsia
* Embolic stroke
* Infections
* Posterior cortical atrophy (PCA): A progressive dementia with predominant visual-spatial deficits that eventually leads to full dementia.
* Atypical Alzheimer’s disease: Rare cases affect posterior brain regions, impacting visual processing.
103
Ghoneim et al. case study
* patient saw numbers and letters reversed, couldn’t perform tasks requiring complex visual orientation (e.g., pouring water from a kettle), unable to navigate spaces despite recognizing objects and knowing where to go, repeatedly fell due to poor visual-spatial awareness
* Failed to copy a complex figure, Showed no organization in performing visual-motor tasks, Struggled with forming movements to visual stimuli, simultanagnosia
* patient could not read (skipping letters/words)
* Bilateral posterior parietal and occipital atrophy, more on the right side
* Moderate to marked decreased perfusion in the same areas (right > left)
* No perfusion abnormalities in temporal or frontal lobes, ruling out Alzheimer’s disease
* The disease course was nonprogressive (no change 4yrs later)
* NO APPARENT CAUSE
104
How much does the brain grow from birth to teenage years?
* The brain undergoes a fourfold increase in volume, leading to improvements in cognition and perception as different brain regions become specialized.
* Development is the process of becoming biologically mature, involving changes in brain structures, pathways, emotions, behaviors, and cognition as a function of age.
105
Why is brain development important to study?
1. Understand the relationship between anatomical and functional changes.
2. Examine how social interaction, cognition, and behavior develop.
3. Identify atypical development in neurological disorders.
106
What are some key anatomical changes around birth?
Most neurons have migrated to their respective locations.
Subcortical structures are largely intact.
107
What is synaptogenesis?
The formation of new synapses (connections between neurons) in the brain. It increases synaptic density (the number of synapses per unit of brain tissue).
108
How does synaptogenesis vary by brain region?
Occurs until around age 2 (varies by region).
Primary visual (V1) and auditory (A1) cortices peak around 1 year and decline.
Prefrontal cortex (PFC) peaks later (~3.5 years), with prolonged synaptogenesis.
109
What happens after peak synaptic density?
Synaptic pruning eliminates excess synapses (~60% decrease), making the brain more efficient by refining connections.
110
How does grey matter change between childhood and adulthood?
grey-matter maturation: Grey matter volume decreases as the brain becomes more efficient.
This loss starts in sensory/motor areas, then spreads to parietal, occipital, temporal, and prefrontal cortex (PFC) last.
111
How does cognitive development progress in early childhood?
* Rapid development in: Language acquisition, Object recognition, Motor actions
* 3 models for how anatomical changes facilitate cognitive development
1. maturational model
2. skill learning model
3. interactive specialization model
112
What does the maturational model propose?
A brain region matures, enabling a new behavioral ability (like a light switch turning on). Development is sequential and stage-like.
113
Johnson (1990) visual pursuit study and the maturational model
Newborns: Saccadic (jerky) eye pursuit, lagging behind objects.
2 months: Smooth pursuit but still lags.
3+ months: Anticipatory saccades (predictive eye movements).
* passive viewing task
* condition 1: predictable (slides alternate between left and right (if the baby has anticipatory saccades, they should be visible in this condition)
* condition 2: unpredictable (slides don’t follow a pattern), unable to make anticipatory saccades
* anticipatory saccades only in the predictable condition
* sticky gaze in 1 month old babies mimics adults with Balint syndrome (parietal damage), so 1 mo old babies have immature parietal cortices
* 2 month old babies no longer have sticky gaze issues because their parietal cortex has matured
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Assumptions of the maturational model
1. Mature = adult-like function (otherwise immature).
2. Development is one-off (once a region matures, it stays functional).
3. Intrinsic, genetic, biological factors drive development.
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What does the skill-learning model propose?
* Brain activation in infants is similar to adults learning a new skill. Activation shifts from frontal (learning phase) to posterior (expert phase).
* infants with frontal damage show long-lasting deficits in visual orienting tasks, while infants with damage in other brain areas do not
* this model assumes the involvement of experience (not just nature, also nurture)
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How does the skill-learning model explain eye movement planning?
* ERP study time-locked to eye saccades
* Adults: Eye movements planned in the posterior parietal cortex (pre-saccadic spike potential 8-20ms before the saccade)
* the SP is posterior, in the parietal cortex, represents eye movement planning
* 12-month-olds: Some posterior SP activation (learning phase).
* 6-month-olds: No SP, but some FEF activation (early learning).
*
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What does the interactive specialization model propose?
* Brain regions start with broad, overlapping functions.
* Over time, regions compete and specialize for specific tasks.
* Specialization is driven by experience and environmental factors (reorganization can occur at different ages, not linear)
* Emphasizes networks: collaboration between brain regions (work together to produce function)
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How does the interactive specialization model explain face processing?
* task: passive viewing of natural and manufactured faces
* Younger children: More activation in the left middle temporal cortex (among other regions) for faces.
* Older children: Some areas increase specialization, others decrease (face specialization index for middle temporal decreases, so is becoming responsible for something else)
* Adults: Fusiform face area (FFA) becomes highly specialized for face processing.
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What evidence supports the interactive specialization model?
Progressive changes: Some brain areas increase specialization.
Regressive changes: Other areas lose specialization.
Challenges the maturational model (development isn’t a one-time event; the maturational model doesn't allow for regressive changes).
Emphasizes network collaboration—multiple regions interact to support behavior.
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What are the key differences between the three models of brain development?
Maturational: Regions mature → new abilities emerge, Sequential, stage-like development
Skill-Learning: Infants learn like adults acquiring skills, Frontal to posterior shift in activation
Interactive Specialization: Regions start broadly, then specialize, Progressive & regressive changes, network collaboration
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What are the two perspectives on how the adult functionally specialized brain develops?
Functional specialization arises through intrinsic genetic and molecular mechanisms, with experience only fine-tuning the system.
Functional brain development involves a prolonged specialization process shaped by postnatal experience.
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What are two contrasting views on infant cognitive development?
Infants are born with ‘innate modules’ and ‘core knowledge’ about the physical and social world.
Many behavioral changes during infancy result from general mechanisms of learning and plasticity.
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What does the developmental model predict regarding species with delayed development?
* The more delayed the development, the larger the relative volume of later-developing structures, such as the cerebral and frontal cortex.
* allows for extended postnatal interaction with the environment, shaping brain circuitry.
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How is developmental neuroanatomy studied?
postmortem analysis, developmental PET, and MRI (mostly on children with suspected clinical problems).
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What are key findings from PET scans of infants?
* At under 5 weeks, glucose uptake is highest in the sensorimotor cortex, thalamus, brainstem, and cerebellar vermis.
* By 3 months, activity rises in parietal, temporal, occipital cortices, basal ganglia, and cerebellar cortex.
* The frontal cortex and dorsolateral occipital cortex mature around 6–8 months.
* By the end of the first year, the brain shows adult-like resting activity.
* Resting brain metabolism peaks at 4–5 years (150% of adult levels in some areas).
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How does myelination progress postnatally?
* Most fibers myelinate postnatally, allowing structural MRI studies.
* By 2 years, brain structures resemble adult forms; by 3 years, major fiber tracts are visible.
* After rapid gray matter growth up to 4 years, a slight decline occurs due to pruning.
* White matter increases through adolescence, especially in frontal regions.
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What methods are used to test infant cognition and perception?
Habituation: Infants get bored with repeated stimuli; looking longer at new stimuli suggests perception of novelty.
Preferential looking: Measures time spent looking at different stimuli.
Heart and sucking rate monitoring: Measures interest and recognition.
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What object-processing abilities do infants have?
* During the first year, infants understand object solidity, object permanence, and gravity.
* Until 9 months, infants struggle to reach for occluded objects or detect changes when objects move behind an occluder.
* They may not be surprised if two distinct objects move as one.
* By 4 months, they perceive the two ends of a moving rod as continuous behind an occluder and expect objects to be solid.
* Infants possess innate principles of object perception, such as solidity and spatiotemporal continuity.
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Q: What are two extreme views on how infants develop social processing skills?
1. Infants have prespecified modules for processing socially relevant information.
2. Social brain development results from early social interactions shaping experience-sensitive circuits.
* Middle ground: Infants are born with biases toward social stimuli, which shape learning and plasticity.
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What early social behaviors do infants display?
Preferential looking at face-like stimuli (possibly for bonding and neural specialization).
By 3 months, they follow gaze direction and respond to interactive objects.
By 12 months, they interpret adult actions in terms of goals or intentions.
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What evidence supports the maturational view from the reading?
Early behaviors rely on subcortical structures, later replaced by cortical control.
Parietal cortex maturation at 2–3 months allows disengagement from stimuli.
Frontal cortex maturation at 4–6 months enables inhibition of reflexive saccades.
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What are limitations of the maturational view?
It cannot fully explain dynamic changes in cortical activation or the role of postnatal experience.
Studies of pre-term vs. full-term infants suggest postnatal environment plays a critical role.
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What evidence supports the importance of early experience (sensitive periods)?
Infants with congenital cataracts show persistent deficits in face processing even after early treatment.
Rapid visual acuity improvements post-surgery suggest a ‘triggered’ neural development process.
this supports the skill-learning model: need input to trigger the development of these circuits
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What is spina bifida?
A congenital condition where the spinal column fails to fuse completely, leaving nerve tissue exposed.
The majority of individuals with spina bifida also suffer from hydrocephalus.
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What is hydrocephalus?
A disturbance in the circulation of cerebrospinal fluid (CSF) through the brain's ventricles.
Causes back pressure that can enlarge the ventricles, compressing the brain against the cranium.
In young children with malleable skulls, this can lead to a grossly enlarged head.
Prolonged pressure results in brain matter loss.
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What are the four categories of ventricular expansion in hydrocephalus according to Lorber?
1. Minimally enlarged ventricles.
2. Ventricles filling 50-70% of the cranium.
3. Ventricles filling 70-90% of the cranium.
4. Severe cases: Ventricles fill 95% of the cranium. This group makes up less than 10% of the total sample. Many are severely disabled, yet half have IQs greater than 100.
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What does Lorber suggest about brain function and the cortex?
Neurologists have long assumed the cortex is responsible for all higher functions.
Lorber suggests deep brain structures may perform many functions typically attributed to the cortex.
He compares the cortex to a "reference library" that is consulted as needed.
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How do rat brain lesions inform our understanding of hydrocephalus?
Large surgical brain lesions cause severe dysfunction.
However, gradual damage over time leads to minimal dysfunction.
This suggests the human brain can adapt to a slow reduction in available neural structures, as seen in hydrocephalus.
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What are the effects of asymmetrical hydrocephalus?
In cases where only one side of the brain is affected, a minority of patients show contralateral paralysis or spasticity.
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How does hydrocephalus primarily affect brain tissue?
* Principally a disease of white matter.
* Enlarging ventricles stretch and disrupt white matter fibers.
* Axons and their myelin sheaths break down.
* Gray matter is remarkably spared, though prolonged hydrocephalus eventually causes some gray matter loss.
* This sparing may explain why some hydrocephalus patients retain function.
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How does the brain recover following the implantation of a shunt?
Releasing fluid pressure allows the brain to rebound.
Stretched fibers shorten, reducing ventricular space.
Scar tissue forms from glial cells.
Challenges the neurobiological idea that central nervous system cells cannot repair themselves.
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Does the brain function in a disjointed left vs. right manner as pop psychology suggests?
* No, the idea originates from misinterpretations of split-brain studies, leading to pseudoscience.
* No scientific evidence supports the idea that humans rely on only one hemisphere for processing.
* Both hemispheres work together as a unified system, not as isolated modules.
* While they process information with subtle differences in processing styles, they do not function as "spares" for each other.
* The split-brain patient data only applies to individuals with severed corpus callosum (CC), not typical brains.
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Why is the left-right brain myth problematic in applied settings like education?
* It has led to misguided educational approaches, such as tailoring instruction based on "hemisphere dominance."
* This influences how people perceive themselves, despite no correlation with actual performance.
* Featured in This Idea Must Die: Scientific Ideas That Are Blocking Progress.
* Misinterprets Gazzaniga's split-brain studies, falsely suggesting that all people have a "dominant hemisphere."
* In reality, for those with an intact CC, both hemispheres work together at all times
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Where does most of our knowledge about hemispheric specialization come from?
* Primarily from a single patient, J.W., studied by Michael Gazzaniga.
* Split-brain research has its roots in Roger Sperry’s work on animals.
* Early findings showed that when the CC was severed, the two hemispheres had no knowledge of each other’s learning.
* Later applied to humans, confirming independent processing in disconnected hemispheres.
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How do the left and right hemispheres communicate?
* Via the corpus callosum (CC), the largest white matter fiber bundle (200 million axons).
* Most connections are homotopic (linking corresponding regions across hemispheres). Posterior: Connects visual areas, Midline: Connects motor areas, Anterior: Connects frontal areas.
* Heterotopic connections link non-corresponding areas across hemispheres.
* Ipsilateral connections stay within the same hemisphere.
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How are some brain functions lateralized?
* Each hemisphere processes sensory and motor information from the opposite side (contralateral representation).
* SUBCORTICAL structures are NOT LATERALIZED
* Some functions, like language, are highly lateralized:
* Left hemisphere (LH): Language processing.
* Right hemisphere (RH): Higher lateralization for face processing.
* Both hemispheres contain similar architecture for V1 (visual cortex), indicating shared processing capacities.
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How is language represented in the brain?
* Uses Broca’s and Wernicke’s areas for speech production and comprehension.
* Usually lateralized to the left hemisphere, but individual variability exists.
* Some individuals have bilateral representation of language.
* Grammatical functions are more left-lateralized, while contextual and other processing involves the right hemisphere.
* both hemispheres show the word superiority effect (recognize words faster when they're in words vs. non-words)
* RH cannot understand verbs, pluralizations, possessive or active-passive verb differences
* but some patients’ RH can correctly judge sentences as ‘grammatical’ vs. ‘non-grammatical’
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Why have lateralized specialization?
1. speech is lateralized to enable speed of processing as transcortical projections and transfer take time
2. advantages in having nonidentical forms of representation between the hemispheres, with each having certain advantages for tasks and both hemisphere containing essential machinery for computation
3. efficiency in processing due to limited cortical real-estate?
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Are there structural differences between LH and RH that explain their functional specializations?
* we haven’t found any large differences anatomically to indicate specialization (areas specialized for different functions look anatomically similar)
* Sylvian fissure (planum temporale): Larger in 65% of right-handers according to postmortem analysis (not neuroimaging), but 95%+ of people have language in LH, showing it is not a strong predictor.
* Micro-anatomy differences:
1. Cortical column spacing in LH’s Wernicke’s area is wider, allowing more connections.
2. Larger pyramidal cells in LH, suggesting structural specialization for language.
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What happens when the corpus callosum is severed?
* Split-brain syndrome: Hemispheres function semi-independently.
* Language-dominant hemisphere (usually LH) speaks.
* Sensory, motor, and visual functions remain within their respective hemispheres.
* Used as a treatment for severe epilepsy when no other options remain.
* quite successful, as seizures become localized to one hemisphere and then often fully subside within weeks of the operation
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Roger Sperry's CC studies
* original work on perceptual learning in cats with severed CC
* found that each hemisphere had no idea what the other learned when CC was severed
* later developed tests of hemispheric function on humans with Michael Gazzaniga (his graduate student)
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methodological issues with split-brain patients
only a few suitable for experimental investigations due to:
* most patients aren’t neurologically intact prior and after operation (long history of seizures)
* most show abnormal performance on standard neurological tests, tests of language, and intellectual function
* only a few patients have an ability to comprehend and/or train RH for simple language commands, so testing usually confined to visual stimuli due to good experimental control afforded by lateralized hemispheric projections in the visual areas
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How do split-brain patients behave differently in lab studies?
* LVF (Right Hemisphere) → Left Hand Response (Nonverbal).
* RVF (Left Hemisphere) → Right Hand Response + Speech.
* When shown a word in LVF, patients cannot verbally report it but can draw it with the left hand.
* JW (split-brain patient) confabulates explanations when his left hand (RH) performs an action.
* present a word to LVF + complete CC split = info goes to RH = person cannot verbally report what they saw “I didn’t see anything”
* present a word to LVF + partial CC split = info to RH = incomplete report of what they say, like images
* very important to control for eye movements to keep images stabilized on the retina so that info doesn't get presented to both hemispheres
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most famous split-brain patients/studies
* JW had a full CC resection, but couldn't be scanned using fMRI due to anxiety and seizures
* VP has a partial resection, but still does not integrate visual information, which is transmitted by the posterior part of the CC
* JW unable to verbally report info in LVF, but able to draw it with left hand, and confabulates when left hand points to an image that the left hemisphere didn't see
* letter priming task: identify “H” primed with either “t” (incompatible) or “h” compatible
* JW did a lateralized version of this task: showed priming in RVF (LH) but not LVF (RH), ie. faster for compatible only in LVF
* JW also impaired in judging word meaning categories (furniture being superordinate to chair) and in judging antonyms (love-hate)
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How is visual processing lateralized?
* RH is specialized for processing of faces (but VJ had face processing in LH)
* LH is better at recognizing the self
* face morph spectrum between JW and Gazzaniga —is it me or is it Gazzaniga?
* self-recognition bias in LH (starts recognizing self at 40-50% morph)
* familiar other recognition bias in RH (only starts recognizing self at 70% morph)
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Is attention lateralized?
* Attention is not strongly lateralized; JW could pay attention using both hemispheres.
* but only with RH when cued by faces
* RH follows gaze direction, LH does not.
* When cueing is social (faces), RH dominates.
* When cueing is non-social (arrows), both hemispheres perform equally.
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What is the Left Hemisphere Interpreter Hypothesis?
* speaking LH constructs a narrative of the information it perceives and ‘interprets’ our reality and provides a narrative of experiences (we contextualize things, interpret circumstances and feelings)
* Gazzaniga suggests that the LH interpreter is a basis for our conscious experiences
* JW draws a telephone with the left hand = LH doesn’t know why, so it makes up a story
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How do we test the LH interpreter hypothesis in split-brain patients?
* decision making experiments: arrow indicated visual field of target, either LVF or RVF (80% upper, 20% lower), participants asked to guess where the target will be presented (upper or lower)
* frequency matching: try to guess on each trial correctly where the square will appear (we don’t do this well, we usually get it at chance levels (50%))
* maximizing: choosing upper 100% of the time (this would allow us to get 80% correct)
* for JW: RH eventually learns to maximize (goes above the line), LH doesn’t learn to maximize, keeps frequency matching
* for VP: RH maximizing from the start, LH frequency matching the whole time = not the best possible outcomes
* so interpreting as narratives doesn’t always lead to best outcomes
* RH maximizes, LH frequency matches, even though this is not the optimal response (LH looking for patterns and causal interpretations)
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What was observed in a case of callosal agenesis in the laboratory?
* Callosal agenesis is a birth defect where the corpus callosum is completely or partially absent.
* Despite this structural anomaly, the individual exhibited no obvious cognitive or behavioral deficits.
* Raises questions about neural plasticity and alternative interhemispheric communication pathways.
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How did W.J.’s right hemisphere respond to visual stimuli after callosotomy?
* A picture flashed to the left of fixation was transmitted exclusively to the right hemisphere.
* Since the right hemisphere lacks language production, W.J. was unable to verbally report what he saw.
* The severed corpus callosum prevented communication between hemispheres.
* Demonstrated the independence of each hemisphere when disconnected.
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How do split-brain patients respond to visual stimuli in different visual fields?
1. When a circle appears in the right visual field:
The right hand (controlled by the left hemisphere) points to it.
The left hemisphere can verbally describe it.
2. When a circle appears in the left visual field:
The left hand (controlled by the right hemisphere) points to it.
The right hemisphere perceives it but cannot verbally report it.
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What additional insights did further split-brain studies provide?
* Confirmed the original findings across multiple patients.
* Showed that not just the visual system, but also the somatosensory and motor systems, were functionally split.
* More strikingly, cognitive and perceptual systems were also divided between hemispheres.
* Despite these divisions, patients maintained a subjective sense of psychological unity.
* Highlighted the brain’s parallel and distributed organization.
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The operation of callosotomy might create a person with the ultimate split personality, but early studies suggested no observable split in consciousness or personality. Why?
Consciousness may be housed entirely in one hemisphere.
Consciousness could be tied to language, which is lateralized.
The hemispheres may divide labor so that consciousness shifts depending on task demands.
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What does the split-brain surgery involve?
Severing all or part of the corpus callosum, the major fiber tract connecting the cerebral hemispheres.
Sometimes includes severing additional forebrain commissures.
The corpus callosum contains ~200 million axons from layer 2/3 pyramidal neurons.
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Why are split-brain patients ideal for studying hemispheric independence, yet not always suitable for behavioral studies?
Theoretically ideal due to full separation of hemispheres.
Practically limited because: Many have only partial callosotomies + Most have long histories of severe epilepsy and cognitive impairments
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What did early split-brain studies confirm about hemispheric specialization?
Language is usually lateralized to the left hemisphere.
Right hemisphere excels in spatial processing.
Right hemisphere processing is more literal, while left hemisphere is more constructive.
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Are all perceptual processes superior in the right hemisphere?
* No, asymmetries depend on stimuli and task type.
* Example: Two patients discriminated objects equally well, but the right hemisphere was better at spatial location discrimination.
* Right hemisphere excels in: Line orientation and vernier acuity + Amodal completion (visual grouping), while modal completion is equal in both hemispheres.
* Left hemisphere was indifferent to color cues in line motion perception; right hemisphere showed strong effects.
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what is the 'right hemisphere interpreter' (Wolford)?
* lateralization of visual grouping to the right hem
* in JW: left hemisphere indifferent to the manipulation of the magnitude of the gap in temporality that would affect whether we interpret events as being causally related, but the RH was correctly affected by this temporal gap
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What are the differences in spatial cognition between the hemispheres?
Right hemisphere is superior in mental rotation.
Left hemisphere excels at perspective-taking (imagining oneself in a different spatial perspective).
Neuroimaging confirms parietal and frontal activations in both hemispheres but with different emphases.
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How does hemispheric specialization affect attention?
Right hemisphere (but not left) showed faster response to targets aligned with eye gaze direction.
Effect disappeared with inverted faces, suggesting lateralized cortical processing.
Gaze cueing is tied to the hemisphere specialized for face processing (typically right hemisphere).
So, for higher-order processes like attention, specialization appears driven by stimulus properties
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How does hemispheric specialization affect memory encoding and retrieval?
Encoding is more lateralized than retrieval
Left prefrontal cortex dominant in episodic encoding, particularly for verbal material.
Right prefrontal cortex more involved in encoding nonverbal stimuli (faces, textures).
Split-brain patients show little episodic memory impairment, implying material-specific rather than process-specific encoding/retrieval (ie. encoding processes available in both hemispheres)
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How does self-referential processing differ between hemispheres?
Self-relevant processing enhances memory beyond semantic processing.
Medial prefrontal cortex is more active during self-referential judgments.
Split-brain study found: Right hemisphere more likely to recognize others in face morphs + Left hemisphere biased toward recognizing self.
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How might the left hemisphere interpreter be linked to the perception of self?
* Consciousness, the self, and the LH interpreter intimately connected.
* Two-stage signal detection model
* Left hemisphere has a general bias toward saying "yes" to recognition tasks.
* Split-brain patients show deference to the specialized hemisphere for certain tasks, so that responses from the unfavoured hemisphere seem random
* example: patient may believe that face recognition is the responsibility of the right hemisphere and may not try very hard on faces presented to the left.
* [When the probability guessing paradigm was to guess whether a face would have facial hair or not] the patient frequency matched with the right hemisphere and responded randomly with the left hemisphere. Our interpretation was as above. Faces were seen as the purview of the right hemisphere, so only that hemisphere took the task seriously.
* but for most other stimuli that are seen as being the purview of LH, the RH doesn't try = inconsistent and random responses
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What is the two-stage signal detection model?
* Subjects first decide to respond (should I bother trying), and once they have decided to respond, the traditional signal detection model would apply.
* unwillingness to respond could present as not trying when you need to respond (50/50 responses or perseveration on a response, for instance)
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How does hemispheric specialization relate to consciousness and awareness of deficits?
Modular specialization extends to awareness of one's own deficits.
When a hemisphere assumes responsibility for a task, it also assumes awareness of that task.
Some responses from the "unfavored" hemisphere may reflect an unwillingness to try rather than true incompetence.
Consciousness may be modular and tied to the regions performing specific cognitive tasks.
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What is the connection between temporal lobe epilepsy and religious experiences (Rama)
Temporal lobe epilepsy patients often report intense spiritual experiences.
The left temporal lobe is particularly implicated.
Even when not having seizures, these individuals may show an increased focus on religious and moral concerns.
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Why are religious hallucinations commonly associated with temporal lobe activity?
Religious and moral concepts may be deeply embedded in the neural architecture of the temporal lobes.
This suggests that mystical experiences have a specific neurological basis rather than being purely cultural or psychological.
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Explain Rama's perspective on our experience of emotions.
* mediated by back-and-forth connections with the frontal lobes
* outward expression of emotions depends on the hypothalamus, which has 3 main outputs
1. hypothalamic nuclei send hormonal and neural signals to the pituitary gland, which is often described as the "conductor" of the endocrine system (those hormones affect the entire body)
2. hypothalamus sends commands to the autonomic nervous system, which controls various vegetative or bodily functions, including the production of tears, saliva and sweat and the control of blood pressure, heart rate, body temperature, respiration, bladder function, defecation and so on
3. 4 Fs (the actual behaviour)
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Temporal lobe personality (Rama)
* repeated electrical bursts inside the patient's brain (the frequent passage of massive volleys of nerve impulses within the limbic system) permanently "facilitate" certain pathways or may even open new channels
* heightened emotions and see cosmic significance in trivial events, humorless, full of self-importance, and maintain elaborate diaries that record quotidian events in elaborate detail (hypergraphia), loss of libido and a preoccupation with sexual rituals
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Evolutionary psychology perspective on religion (Rama)
* many human traits and propensities, even ones we might ordinarily be tempted to attribute to "culture," may have been specifically chosen by the guiding hand of natural selection because of their adaptive value (but not genetically predetermined)
* human tendency to seek authority figures—giving rise to an organized priesthood, the participation in rituals, chanting and dancing, sacrificial rites and adherence to a moral code—encourages conformist behavior and contributes to the stability of one's own social group
* those conformist traits multiply with evolution, while people without them are ostracized and
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Rama's GSR testing of 'heightened connections' hypothesis
* heightened response mainly to religious images and words, and blunted response to other, normally arousing stimuli
* eliminates the 'heightened connections' hypothesis
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3 components of Darwinism (Rama)
1. constant struggle for existence
2. random variations in body type that arise from the random shuffling of genes that takes place during cell division
3. fortuitous combinations of genes that cause individuals to be slightly better adapted to a given local environment tend to multiply and propagate within a population since they increase the survival and reproduction of those individuals
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Savant syndrome (Rama)
* General intelligence evolved, the argument goes, so that one can do the myriad things that humans enjoy and that help them survive. But once this intelligence was in place, you could use it for all sorts of other things, like calculus, music, etc.
* savant: mental capacity or general intelligence is abysmally low, yet who have islands of astonishing talent
* refutation of the argument that specialized talents are merely clever deployments of general intelligence
* one part of the brain may for some obscure reason receive a greater than average input or some other equivalent impetus to become denser and larger—a huge angular gyrus = better math ability
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hemineglect brain circuits according to Rama
* reticular activating system activates the entire cerebral cortex, leading to arousal and wakefulness, or a small portion of the cortex, leading to selective attention
* limbic system for emotional behaviour and emotional salience and values of the external world
* frontal lobes for abstract processes: judgment, foresight, planning
* three areas connected in a positive feedback loop that takes a stimulus from the outside world, extracts its salient features and then bounces it from region to region, before eventually figuring out what it is and how to respond to it.
* when that loop is interrupted = hemineglect
* RH has a broad searchlight for both halves of visual field, while LH is confined to RVF (so if LH fails, the RH can take over, but if RH fails, LH cannot)
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mirror agnosia or looking glass syndrome (Rama)
* hemineglect patient (Ellen) tried to reach for an object that was being reflected from the left side as though it was inside the mirror, even checking behind it as though it was hiding
* because of her neglect: "Since the reflection is in the mirror, the object must be on my left. But the left does not exist on my planet—therefore, the object must be inside the mirror."
* not a consequence, but accompanies neglect: right parietal lobe is damaged, patients have all kinds of difficulties with spatial tasks (and mirrors take a lot of spatial processing to understand)
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anosognosia
* the tendency to ignore or sometimes even to deny the fact that one's left arm or leg is paralyzed, despite being mentally lucid in all other respects
* vision is fine, yet the patient insists that their paralyzed body parts are working perfectly, confabulate (almost hallucinate) that they are working as expected, and rationalize reasons that they are not producing the movement required
* somatoparaphrenia—the denial of ownership of one's own body parts
187
Rama explanations for anosognosia
* Freudian: patient simply doesn't want to confront the unpleasantness of his or her paralysis (problem: difference in magnitude of psychological defense mechanisms between patients with anosognosia and what is seen in normal people, problem: asymmetry of this syndrome because denial associated with RH damage, not LH)
* consequence of neglect (problem: neglect and denial can occur independently, problem: why denial usually persists even when the patient's attention is drawn to the paralysis)
* division of labor between our two cerebral hemispheres and in our need to create a sense of coherence and continuity in our lives
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Anosognosia Rama favoured explanation
* LH sifts through information to build a coherent and consistent belief system
* when confronted with information that threatens this worldview, LH either ignores it or tries to squeeze it into your existing framework (this is the basis of Freudian defense mechanisms)
* RH is the “Devil’s advocate” (explains why defense mechanisms are so exaggerated in stroke/denial patients) because at a certain threshold of unbelievability, it forces LH to revise its belief system
* What is damaged in these patients is the manner in which the brain deals with a discrepancy in sensory inputs concerning the body image; it's not critical whether the discrepancy arises from the left or right side of the body
* able to locate the center in the brain that monitors discrepancies; it is a small region of the right hemisphere that receives information from the right parietal lobe
* denial type/severity depends on the brain region that is damaged
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Freudian defense mechanisms (Rama)
* denial, rationalization (and confabulation), humor
* repression: patient will sometimes admit with repeated questioning that she is in fact paralyzed, only to revert soon afterward to denial—apparently "repressing" the memory of the confession she made just a few minutes earlier
* reaction formation: a subconscious attempt to disguise something that is threatening to your self-esteem by asserting the opposite ("I tried with both my hands")
* projection: to avoid confronting a malady or disability, we conveniently attribute it to someone else
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cold water in vestibular system experiment (Rama)
* cold water acted as a "truth serum" that brought her repressed memories about her paralysis to the surface
* admitted she was paralyzed
* after it wears off, patient denies their earlier admission of paralysis
1. connections from the vestibular nerve projecting to the vestibular cortex in the right parietal lobe as well as to other parts of the right hemisphere. Activation of these circuits in the right hemisphere makes the patient pay attention to the left side and notice that her left arm is lying lifeless
2. During these dreams we are often confronted with unpleasant, disturbing facts about ourselves. Thus in both the cold − water state and REM sleep there are noticeable eye movements and unpleasant, forbidden memories come to the surface. Stimulation of vestibular system activates same REM sleep circuit (patients should dream that they are paralyzed)
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can you "cure" his denial by simply tampering with the structure of his beliefs? (Rama)
* experimental epistemology
* [fake injection to ‘paralyze’ the left arm] Apparently my mock injection had worked, for she was now able to accept the fact that her left arm was indeed paralyzed. [this experiment doesn’t work on the non-paralyzed right arm]
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anosognosia and anorexia
* Is the disorder of appetite (linked to feeding and satiety centers in the hypothalamus) primary, or does the body image distortion cause the appetite problem?
* certain parts of the limbic system such as the insular cortex are connected to the hypothalamic "appetite" centers and also to parts of the parietal lobes concerned with body image
* intellectual beliefs about whether you are too fat or thin, your perception of your body image and your appetite are all more closely linked in your brain than you realize—so that a distortion of one of these systems can lead to a pervasive disturbance in the others as well
