Brain & Cognition 2 🧠Flashcards
(153 cards)
1
Q
the perception-action cycle
A
high level sensory cortex (hierarchical processing) -> meaningful features from the environment. -> motor outputs in reverse hierarchy,
2
Q
overt orienting and attending
A
Moving your eyes, body, ears, nose, etc in the direction of a relevant stimulus (what the superior colliculus does).// •Eye & orienting movements
•Colliculus Superior: saccadic eye movements, orienting
•Pulvinar: attention shifts
•Frontal Eye Fields
3
Q
covert attention
A
Shifting your attention towards something, without any external, overt signs, i.e. while maintaining fixation. This mechanism has evolved particularly in social animals, in which direction of gaze often has strong meaning (threat, aggression, sexual attraction)// •Pulvinar, FEF •Ventral Frontal cortex •Dorsolateral PreFrontalcortex •Superior Parietal Lobe (SPL) •Temporo-Parietal Junction (TPJ)
4
Q
cocktail party effect
A
One may pretend to listen to someone in front of you, while actually focusing on what is said in another conversation.
5
Q
attentional capture
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while listening to the person in front of you, your attention may be suddenly captured by someone saying your name in another conversation:
6
Q
top down attention
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when subjects are instructedto focus their attention on some locationof the visual field (such as in the Posner cueing task). The behavioral effect typically is that reaction times to presented targets are faster at the attended location.10
7
Q
bottom-up attention
A
a suddenly appearing stimulus will automatically ‘capture’ attention. Shorter reaction time to primed location. This happens even when subjects know the cue (prime) is mostly invalid (which shows captureis ‘automatic’ and not top down).
8
Q
inhibition of return
A
when the temporal interval between prime and target > 300 ms.Now, reaction time is longerfor the cued location. The subject starts to actively suppress attention to the location of the (mostly invalid) cue.
9
Q
object based attention
A
Instead of focusing on a particular location, attention can also focus on a particular object/ Attention can be directed towards objects that overlap in space.
10
Q
feature based attention
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shorter reaction times to objects with features
11
Q
a potential label for assembly coding
A
Neurons of each assembly fire action potentials in synchrony. Assembly A and B code for different objects. The brain ‘knows’ which parts belong together because those that belong to an assembly fire action potentials in synchronyCross-correlation function reveals synchrony
12
Q
feature integration theory
A
Features (like orientation or color) are detected in parallel across the visual field•Yet only at the location where attention is focused, these features are integrated•Can only occur for one or a few items at a time because of capacity limit of attention
13
Q
crowding
A
inability to identify objects when surrounded by other objects (in peripheral vision)
14
Q
biased competition model of attentional selectiong
A
- High level neurons have large receptive fields
- Multiple stimuli withinthe RF causes the response to be the average of the responses to poor (house) and optimal (face) stimuli that are obtained when these are presented in isolation: face detection (in this case) is hampered by the competing house stimulus
- Attention can biasthe competition, so that the response (here between 150-300ms) is what it would have been when the stimulus was presented alone.
- This resolves the competition, and allows for optimal subsequent processing, detection, reaction etc
15
Q
things that cause attention
A
•Increase in fire rate and synchrony of attended locations, features and objects•(therefore) Feature binding and faster responses•A resolving of competition between responses falling with the same receptive field, hence better discrimination, less crowding
16
Q
change blindness
A
the inability to notice changes that would be perfectly obvious once attention is directed to them
17
Q
early vs late selection
A
1.At what moment during processing?2.At what level of processing in the visual hierarchy (V1, V4, higher?)3.In what pathways does selection occur (dorsal vs ventral)?
18
Q
inattentional blindness
A
the inability to memorize and report salient stimuli (such as gorillas) when attention is diverted to some other task-relevant stimulus
19
Q
early selection
A
Unattended words are not distinguished from non-words >
20
Q
attentional blink
A
the inability to memorize and report a stimulus (T2) that is presented briefly after (up to ~500 ms) a stimulus (T1) that has tobe reported or memorized
21
Q
late selection
A
Missed (unseen) T2 houses nevertheless evoke selective activation of the PPA (difference between red and blue). This activation is only amplified (green) when the target is seen
22
Q
neglect
A
- No (conscious) percept of contralateral stimuli, that is not caused by a primary sensory deficit (hemianopsia) or a motor deficit (hemiparesis)
- Ignoring of contralateral stimuli•Slower reaction to contralateral stimuli
- Ignoring the ‘contralateral’ half of objects
- Much less eye, head or arm movements (exploration) towards contralateral side
23
Q
allesthesia
A
stimuli are perceived at incorrect locations
24
Q
extinction
A
- Typically end stage of neglect/ milder versionof neglect
•when both ipsi-and contralateralstimuli are present, only the ipsilateral stimuli are perceived
25
object based neglect
patients not so much ignore the left side of their visual space, but the left side of objects, regardless of their position in space. Only recognize and copy right sides.
26
balint syndrome
Very few eye movements: ‘gaze paralysis’. Note how the patient cannot follow the object the doctor is waving in front of her
27
simultanagnosia
inability to see more than one (part of) object at a time. Note how patient is focused on corner of bed.// inability to understand the spatial relationship between objects, and to see more than one object at a time, not seeing the big picture
28
unconscious priming
faster categorization of words when preceded by an unseen (extinguished) object of the same category. Yet unable to pick the unseen stimulus
29
3 guises of consciousness
state, device, sensation
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polysomnography
simultaneous recording of EEG (brain) , EMG (muscle tone) and EOG (eye movements)
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awake
Low amplitude, high frequency EEG•Saccadic eye movements•Muscle tone (high EMG)
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asleep
•High amplitude, low frequency EEG•No saccadic eye movements (drifts)•Low muscle tone (low EMG), paralysis
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rem sleep
Low amplitude, high frequency EEG•Saccadic eye movements•Low muscle tone (low EMG), paralysis
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sleep paralysis
muscle tone stays flat because of muscle paralysis, yet person awake EEG and EOG like awake
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narcolepsy
sudden rem sleep onset
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sleep violence
rem sleep without muscle paralysis: violent movements acting out dreams
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brain stem reticular system activating system & medial reticular formation
•Set of nuclei in the brain stem•Send fibersto the cortex with modulatory neurotransmitters
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reticular activating system
is critical for maintaining the conscious state
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brainstem reticular formation
critical for maintaining the conscious state//
| projects to the cortex, either directly, or via the intralaminar nuclei of the thalamus
40
Effects of electrical stimulation of Medial Reticular Formation (MRF) in anesthetized cats
1. More high frequency EEG (gamma) relative to low frequency EEG (delta)2.Firing rates variable3.Oscillations go up, more high frequency oscillations4.Synchrony goes up
- cat wakes up
41
thalamus
gates the info from the senses to the cortex
42
brain stem mrf
modulates the thalamic gating from arousal to sleep, allows or shuts down the inputs from the senses
43
utilization behaviour
The tendency to grasp common objects when presented, and perform the function commonly associated with the object.
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imitation behaviour/mimicry
The tendency to imitate the gestures, actions, sentences of the person in front of you.
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cortical
parietal, temporal, occipital lobe
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subcortical
thalamus, basal ganglia, cerebellum, amygdala, hippocampus, brainstem nuclei
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frontal
pre-motor, motor cortex
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contra-lateral frontal lobe
pre-frontal, pre-motor, motor cortex
49
how does the pfc enable flexibility of reponses
1. Workingmemory, so that longer stimulus response contingencies are possible, delayed responses
2. inhibting direct response
3. adding value to choice options, and updating these values on the basis of experience
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different PFC neurons may encode object identity or location
Different strength of delay activity depending on identity (‘what’) of object (left neuron), Different strength of delay activity depending on location (‘where’) of object (right neuron)
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internal value
generalized and automatic VALUE system It assigns value to items we are confronted with, dictates our choices., The PCC (posterior cingulate cortex), Hippocampus, VS (ventralStriatum/ nucleus Accumbens), ventromedialPFC
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reward pathway in the brain
vmPFC, signals value for broad range of choices, including moral value, nucleus accumbent, signals value and motivation, dopamine releasing neurons in VTA signal reward or reward prediction
53
what would be needed for the PFC to perform a function of picking up the phone
reciprocal connections with sensory and motor cortex, neurons encoding rules between input and output, inputs from reward systems (dopamine), rapid learning of such rules, neurons encoding abstract concepts like 'being at home' , keeping info 'on line (WM) because stimulus-response contingencies may span time
54
choices are determined by
a combination of low-and high-level versions of ‘greed’, ‘fear’, and ‘herd’ behavior•There is not one system that is ‘boss’, or in control. You are the combination of all these ‘drives
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readiness potential
The actual movement is preceded by the subjective intent to actwith ~250 ms, But this subjective intent to act is itself precededby ~500 –1000 msof neural activity of the motor cortex (Cz): Our conscious intent to act is in fact the result of an unconscious process. Free will is an illusion
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choice blindness
motivations do not lead our choices
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post hoc rationalization
Subjects give motivations for ‘their’ choice(which was not their original choice) that vary from confabulation to motivations that pertain to the forced choice instead of the original one
58
Gazzaniga's split brain experiments : the brain interpreter
The left hemisphere puts all information together into a final narrative, a story about the motivations and goals of our actions and thoughts
59
whole body rubber hand illusion
•Subjects (PS) sees himself (VF) in VR goggles•He is stroked on the back in sync with the dummy that is filmed (PF)•After a while, het feels an ‘out of body experience’ towards the VF copy•This does not happen when stroking is out of sync, or with non-corporeal objects
60
corpus callosum
connects two hemispheres to work together and connects the cortex to the two hemispheres. Connections between homotopicareas, also some between heterotopic areas•Together with Anterior Commisure(not always cut in surgery)•Posterior Commisureconnects subcortical nuclei
61
the WADA test
each hemisphere is temporarily anesthetized using amobarbital (or sodium amytal, etc).In most people, anesthesia of the left hemisphere results in aphasia, the inability to speak or comprehend languageBut some people have right hemisphere dominance for language, others bilateral language capabilities
62
split brain patients
The left hemisphere is dominant / necessary for language and speech
Stimuli that are only represented in the right hemisphere cannot be verbally reported
When the posterior part of the callosum is sectioned, higher order, abstract information about the stimulus can be reported, not the stimulus itself (middle panel)
63
right hemisphere better at
recognizing faces , In order to find this difference, it is required that no ‘verbal’ descriptions of faces can be made (e.g. blonde vs brunette), FFA also more prominent
- sees the big picture (the whole)
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left hemisphere
doing semantic categorisation/analysi, seeks patterns and sequences in events
65
hemianopsia
patients with unilateral lesions to V1. lesions to striate cortex (V1) result in cortical blindness. patients insist they see nothing, have no visual sensation whatsoever, are not aware of anything happening on that side.
66
blindsight
most likely mediated via the projections of the optic tract to the superior colliculus, which projects to the dorsal stream areas, like MT and parietal cortex.// fairly low visual acuity and lower precision. some have argued that they are mediated by Y type mango cellular LGN pathways conveying only low spatial frequency information. color task present themes challenges to blindsight patients while they are best at localisation, motion and other properties carried by the dorsal pathways
67
signal detection theory
stimulus A versus B (or absent vs present) generate different internal representations, that are noisy, and distributed as Gaussians. The observer sets an internal criterion. If the signal exceeds the criterion, the observers says A, if it is below, he says B (or Y/N). HIT = saying A when there is A, MISS= saying B when there is A. CR = saying B when B, FA = saying A when B. By manipulating criterion, Hits and FA’s will change. Plotting FA’s vs Hits gives a RecieverOperaterCurve. The d’ is the discriminability of the two stimuli
68
continuous flash suppression
the stimulus in one eye is strongly masked by a high contrast, colorful, rapidly changing (moving) image in the other eye. This renders the stimulus invisible.
69
subjective invisibility
report of complete unawareness (1 on Perceptual Awareness Scale) , generally more ‘lenient’. There is often still above chance discrimination on subjectively invisible trials
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objective invisibility
chance level performance on YN task: d’ = 0, suffers from the problem ‘what to ask’.
71
bistable stimuli
Stimulus remains constant, yet conscious percept switches spontaneously
72
characteristics of binocular rivalry
Presenting two different stimuli to the two eyes (stationary for minutes) results in spontaneous switches of perceiving the one (say left eye) stimulus, then the other (right eye), then the first again, etc. Dominance lasts several seconds, but may vary in length from switch to switch. Dominance length has a characteristic frequency distribution, that is the same in man(green) and monkey
73
bistable stimulus, rotating random dot sphere
This spontaneously alternates between seeing clockwise (CW) or counter clockwise (CCW) movement. What is seen by the subject can be decoded from motion sensitive and parietal areas involved in 3D perception
74
global neuronal workspace theory
GNWT distinguishes three modes of processing a stimulus may undergo
1. Subliminal, evoking only a weak and not very ‘deep’ activation of cortex
2. Preconscious, higher strength and deeper activation, yet because of the absence of attention, it does not reach the ‘Global Workspace’
3. Conscious, because attended, signals reach the Global Workspace, and hence can be broadcast to other modules of the brain, enabling ‘access’
75
attentional blink paradigm
GNWT is supported by paradigms that contrast neural signals for stimuli that are reportedas ‘seen’ versus stimuli that are reported as ‘not seen’.
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higher order thought theory
HOTT distinguishes first order(FO) representations from higher order (HO) representationsThe FO representations reside in sensory cortex, memory regions, arousal circuits, reward circuits, proprioception, etc. These FO representations need to be re-represented by higher order regions in frontalcortex. These re-representation are ‘thoughts’ aboutthe FO representation.Many varieties of these ‘thoughts’ and their functions (and many varieties of HOTT)
77
measuring metacognition
How sure are you that the answer you gave at the detection task is right? The (often speeded) detection / discrimination task is followed by a question where subjects rate their confidenceof the answer. This can be either high /low or 1/2/3/4 etc. Or a post decision wagering (how much do you bet on being right).
78
integrated information theory
The main tenets of IITcan be presented as a set of phenomenological axioms, ontological postulates, and identities...// integrated information required info being exclusive (differentiated, specialized, selective, specific ) yet also being integrated (the sum being more than the parts)
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axioms
self-evident truths about consciousness –the only truths that, with Descartes, cannot be doubted and do not need proof (experience exists, it is irreducible etc.)...
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central axioms
intrinsic existence, , information, composition, exclusion
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intrinsic existence
each experience is real, and it exist from its own intrinsic perpectic independent of external observers
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information
each experience is the particular way it is (composed of a specific set of specific phenomoonenlogical distinctions ) thereby differing from other possible experiences (differentiation)
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composition
structured, each experience is composed of phenomenological distinctions, elementary or higher order with exists within it
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exclusion
consciousness is definite, in content of spatiotemporal grain, each experience has the set of phenomenal distinctions it has, not less or more, and flows at the speed it does not faster or slower
85
recurrent processing theory
RPT takes the distinction between feedforwardand recurrent (re-entrant) processing as fundamental to understanding consciousness. It is the neural definitionof consciousness. In doing so, it makes a distinction between attention and consciousness, and between phenomenal and access consciousness.
86
unconscious inhibition
they had to withold their response when the annulus was preceded by a NO-GO cue (square). The cues were either visible or masked so that they were invisible (chance performance on detection, a). InvisibleNO-GO cues slowed down responses to the annulus (b,c)
87
orientation
v1, v2, v3, v4
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direction of motion
v1, v3, MT, MST
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depth
v1, v3, MT
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color
v1, v2, v4
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more complex shapes
TE(faces), Ent (identities), temporal lobe (houses)
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perceptual interference
information/cues that are no longer independent of each other; perceived brightness, perceived color, color constant, many other illusions
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perceptual inference
Information that is inferred from the visual input, going beyond what is ‘physically’ there •Illusory contours
•Ambiguous stimuli
•Many other illusions
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incremental gestalt grouping
The binding / grouping of distant features and elementsfor which no specific and dedicated systems exist, requiring short or long distance (horizontal) interactions between similar neuronsGestalt rules of perceptual organization
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perceptual organiztion
The combination of high and low level features, and from distant locations in the visual field into organized surfaces, objects, scenes
96
visibility manipulations
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Anesthesia
Blindsight
Masking, Dichoptic masking
CFS, Rivalry
Objective vs Subjective thresholds
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attentional manipulations
Neglect
Attentional Blink
Change Blindness
Inattentional Blindness
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functionalist conclusion
Conscious visual experience arises with perceptual organization / binding / grouping / integration
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physicalist conclusion
Conscious visual experience arises with the transition from feedforward to recurrent visual processing
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attention invokes capacity limit
you can only attend to one or a few items at a time. Yet you seem to seemany more. Somewhere, there is a bottleneck for attention (early or late)
101
overflow argument
you see more than you can attend, cognitively access, or report
102
functionalist theories
They associate consciousness with particular functions:
•GNWT: access, attention, working memory, report
•HOTT: higher order thoughts, metacognition
•RPT: perceptual organization, binding
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structuralist theories
they associate consciousness with architecture
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dualism
mind and body are different entities, different substances, with different rpoperties
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interactionism
mental and interact, e.g. via the pineal gland according to Descartes
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epiphenomenalism
Physical events cause mental events, but mental events have no effect on physical (brain) events
•E.g. Libetexperiments
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monism
Mind and body are the same entities, you can ‘translate’ one into the other
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idealism, solipsism
There is only the mental, the physical is a mental imagination (as in the Matrix)
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physicalism, materialism
There is only the physical
| •View most neuroscientists have
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reductive materialism
all mental phenomena can be reduced to physical (e.g. brain) processes
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eliminative materialism
Our notion of mental phenomena is flawed, they do not exist
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behaviourism
Disregard all the mental, only look at behavior
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functionalism
mental phenomena can be realized in different physical structures (brains, computers, aliens), as long as they are analogously related to each other, to the external world, and to behavior
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Chalmers easy prol=blems
Still very difficult (maybe requiring decades of science) but we can sort of see the solution lying ahead
ex: •The integration of information by a cognitive system
•The ability of a system to access its own internal states
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the hard problem; qualia
The way things look, feel, sound etc.The private, intrinsic, ineffable, and directly apprehensible phenomena of consciousness. For example ‘yellow’ or ‘pain’:
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explanatory gap
explaining the function does not explain the experience
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philosophical zombies
These are functionally identical to normal humans, except they have no Qualia, no experience.
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Mary the super color scientist
She has no color experiences (e.g. she lives in a colorless world), yet knows everything there is to knowabout color processing, rods and cones, the brain etc. Now she leaves her seclusion, and suddenly, for the first time, sees, experiencescolor. Will she not have learned something new? > E.G.
119
inverted spectrum thought experiment
How can we ever know that what I see and report as red, is in someone else’s mind the same color? Maybe they experience my green, where I experience red. We all call these colors ‘red’, and assigns this color to apples, lights, tomatoes etc, but how do we know we experience the same?
120
dual aspect theory of information
where info automatically is accompanied by experience (like matter is also energy)
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biological chauvinism
is there a missing piece in AI systems that would make them conscious?? does it need to be implemented biologically?
122
the plant nervous system
Cells of the root apex transmit signals via action potentials. These occur in synchronous bursts, where activity spreads over the root with speeds of ~100 –200 mm/s. Spread of activity depends on Ca+, and Ca+ channels (blocked by Gd3-) Glutamate increases activity, Glu-receptor antagonist DNQX blocked
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panpsychism
the idea that everything that processes information (humans, animals, plants, bacteria, robots, thermostats), or even anyhting at all (rocksandair) has some sort of mental ‘life’. Or even is conscious.
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p consciousness
raw experience (seeing hearing)
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a consciousness
about reflecting on the experience (knowing, reporting, cognition)
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granger causality
an analysis of the direction of neural signal flow
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premotor theory of attention
attention is just the preparation for an overt shift (eye movement or action)
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amodal completion of bilateral stimuli
changes to left hemifield circles (which are in the extinguished visual field) are not detected when indecente (red circle) yet are detected (green circle) when part of an illusory figure (= inner displays)
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behaviourally extinction and neglect
seem to cause a deficit in selection at relatively late levels, because we see unconscious recognition of objects, semantic priming, and modaal completion. neural signals on the other hand seem not to survive far beyond V1, suggesting early selection. Still unclear therefor what the level of processing is of neglected stimuli
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eeg consists of very selective signals
they are coming from synchronous synaptic currents on the apical dendrites of cortical pyramidal neurons. action potentials or activity from other neurons or from deep structures and nuclei is not visible in the eeg
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thalamic gating by the mrf
sensory information (eye, ear) is transferred to sensory cortex PC via thalamic relay cells (th relay). reticular nucleus of the thalamus (ThR/nRt) inhibits this transfer (decrease of sensation). MRF inhibits this inhibition, it causes stronger input from senses to cortex
132
thalamo cortical oscillations
cortex, thalamus and RNT form a reverberatory circuit that generates different rhythms. slow rhythms prevent sensory inputs from periphery to reach cortex. these slow oscillations are disrupter by MRF stimulation (so that the activity goes back to high freqs and signals can get through)
133
brain death : somatosensory evoked potential
record response of spinal cord, Brian stem, and cortex to electrical stimulation of the wrist. absence of response beyond p13/n13 is sign of brain death (but make sure noise level is not making N20 invisible). presence of N20 is indicating cortical response and 'good' prognosis.
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burst suppression EEG
flat EEG interspersed with high voltage bursts of EEG activity
135
locked in syndrome
trauma or occlusion of basilar artery at the level of the pons, which leaves cranial nerves below nV and the corticospinal and bulbar tracts damaged. : no movements upper face eyes or eyelids. smell, vision hearing and sensations remain present
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persistent vegetative state
anoxic or traumatic brain injury. often following coma (if not death) also called unresponsive wakefulness syndrome
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inhibition netwrok
ability to rapidly abort planned or already ongoing acctions. right lateralised fronoparietal most porimently the right inferior frontal cortex/gyrus
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valuation system
posterior cingulate cortex
hippocampus
ventral striatum/nucleus accumbus
ventromedial PFC
139
where do valuation systems get the values from?
reward pathway in the brain
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ventral tegmental area
nucleus accumens (ventral striatum)
ventro-medial prefrontal cortex
dopaime
reward pathway in the brain
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reward prediction error hypothesis
via associative learning the reward/dopamine signal can shift from the reward itself to the associated stimulus. the dopamine signal is not about the reward itself, but about the difference between the expected reward and the actual reward
141
vmPFC ventromedial prefrontal cortex
signals value for broad range of choices, including moral value// allows for more flexibility of responses by adding the possibility to delay responses (WM), inhibit responses or add value to the response options. these values are obtained via associative learning or conditioning. finally, the learned responses are incorporated into lower levels and become 'routine'
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nucleus accumbens (ventral striatum)
signals value and emotion
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VTA ventral tegmental area
dopamine releasing neurons as signal reward or reward prediction
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inferior temporal cortex
show category selectivity. yet these neurons are overall much less categorical than neurons in PFC
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brain regions positively correlated with behaviour change
mPFC and precuneus
146
spatial summation across midline
faster reaction to two stimuli in blind and intact hemifield than to one stimulus in intact hemifield
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metacontrast masking
controls of target and mask overlap.
148
global ignition
manifests itself typically at a latency of 300-400 ms after stimulus onset
149
seen vs unseen dichotomy
only N3, P3a, P3b frontal correlates with this. frontal activity is the neural correlate of what subjects report seeing.
150
attention in recurring processing theory
attention is fully dependent of the feedforward/recurrent dimension. it equals depth of processing. some stimuli may penetrate deeper into the visual hierarchy than others, for ex depending on their relative strength (neural state) or on reactivation hofneurons and pathways (biased state). this selection may influence both feedforward nd recurrent processing
151
horse race model
cortical activity has to rise to a certain threshold to initiate a saccade. stronger responses reach threshold faster
152
role of attention
filtering unwanted information so that the attended info can be properly processed and detected or recognised
increase resolution of v4 cells.
153
attention causes
increase in fire rate and synchrony of attended locations, features and objects
therefore feature binding and faster responses
a resolving of competition between responses falling with the same receptive field, hence better discrimination, less crowding
