Module Three Flashcards
(178 cards)
1
Q
What is the key difference between measurement and manipulation techniques in cognitive neuroscience?
A
Measurement techniques record brain activity to show co-occurrence with cognitive processes, while manipulation techniques disrupt brain function to test causal roles of regions.
2
Q
Why can’t measurement techniques prove that a brain region is necessary for a function?
A
Because they are correlational, showing only that region activity co-occurs with the function, not that it is required for it.
3
Q
What is the primary purpose of manipulation techniques?
A
To establish causal roles of brain regions by altering their function and observing resulting behavioral changes.
4
Q
How do measurement and manipulation approaches complement each other?
A
Measurement identifies candidate brain–behavior associations; manipulation confirms causal roles, and together they strengthen inferences about neural mechanisms.
5
Q
Which measurement technique provides millisecond temporal resolution and cellular spatial precision?
A
Single-unit recording (electrophysiology).
6
Q
Which measurement techniques have intermediate temporal resolution (seconds to minutes) and spatial resolution (millimeters to centimeters)?
A
PET and fMRI.
7
Q
Which techniques are considered low in temporal resolution (minutes to days)?
A
Pharmacological methods and lesion studies.
8
Q
Which techniques offer high spatial resolution at the level of individual neurons?
A
Intracranial electrodes used in invasive neurophysiology (e.g., single-unit recording).
9
Q
What spatial resolution do EEG and MEG typically provide?
A
Low spatial resolution on the order of centimeters to whole-brain measurements.
10
Q
Why is no single method sufficient to capture all spatial, temporal, and causal aspects of brain function?
A
Because each technique has trade-offs in resolution, invasiveness, and causal inference, so converging evidence from multiple approaches is needed.
11
Q
What does single-unit recording measure and how precise is it?
A
It measures action potentials (spikes) from individual neurons with millisecond temporal precision and cellular-level spatial precision.
12
Q
What is the fundamental principle underlying single-unit recording?
A
Action potentials are voltage deflections when a neuron’s membrane potential exceeds a threshold (~+50 mV), each with a stereotyped amplitude and waveform.
13
Q
What technology is used to place electrodes for single-unit recordings?
A
Insulated microelectrodes inserted via craniotomy, positioned using microdrives and stereotaxic coordinates.
14
Q
Why are spike-sorting algorithms necessary in single-unit recording?
A
Because recorded signals may reflect multiple neurons, and spike sorting separates individual neuron activity from multiunit recordings.
15
Q
What are the typical durations and outputs of single-unit recording sessions?
A
Sessions last minutes to hours, yielding raw spike trains over time and summary firing rates (e.g., peristimulus time histograms) across hundreds of trials.
16
Q
What are two main advantages of single-unit recording?
A
It directly captures individual-neuron spikes and provides ground-truth data for neural circuit models.
17
Q
What are two main limitations of single-unit recording?
A
It is highly invasive (craniotomy plus electrode insertion) and samples only a small number of cells at a time.
18
Q
How does EEG measure brain activity and with what temporal resolution?
A
EEG detects synchronized postsynaptic potentials as voltage fluctuations on the scalp, providing millisecond-level temporal resolution but low spatial precision.
19
Q
What are Event-Related Potentials (ERPs)?
A
ERPs are tiny, time-locked voltage shifts uncovered by averaging EEG traces around repeated stimuli, reflecting successive processing stages (perception, attention, etc.).
20
Q
What hardware is involved in EEG signal acquisition?
A
Electrode arrays (from 2 to >128 channels), conductive disks connected by light wires, amplifiers sampling at 250–1000 Hz, and filters to reduce noise.
21
Q
Why is spatial source localization difficult in EEG?
A
Because the inverse problem arises from volume conduction and scalp blurring, making it ambiguous to pinpoint underlying neural generators.
22
Q
What are two main advantages of EEG?
A
Non-invasive, safe for repeated human studies, and provides millisecond temporal resolution of sequential processing stages.
23
Q
What are two main limitations of EEG?
A
Poor spatial precision and lengthy setup to achieve low-impedance contacts.
24
Q
How does MEG detect brain activity and what advantage does it have over EEG?
A
MEG tracks nano-weak magnetic fields from synchronized dendritic currents, providing millisecond temporal resolution and better spatial localization than EEG because magnetic fields are less distorted by the skull.
25
What equipment is required for MEG recording?
SQUID sensors (cryogenically cooled), magnetic shielding rooms to block external noise, and source-modeling algorithms for localization.
26
What are the primary advantages of MEG?
Non-invasive whole-brain coverage with millisecond temporal and centimeter spatial precision, and superior source localization compared to EEG.
27
What are the main limitations of MEG?
High cost and facility requirements ($2–3M+), dependence on shielded rooms, poor detection of radial sources, and remaining inverse problem ambiguity.
28
How does PET create functional brain images, and what does it measure?
PET uses radioactive tracers bound to metabolically relevant molecules; decay emits positrons that collide with electrons producing gamma rays detected in coincidence to map tracer distribution, reflecting regional blood flow, metabolism, or receptor binding.
29
What infrastructure is required to produce PET tracers?
An on-site cyclotron to generate short-lived radionuclides, radiochemistry facilities to synthesize tracer compounds, and scintillation detector rings in the PET scanner.
30
Why does PET have poor temporal resolution?
Because it integrates metabolic signals over minutes per block, preventing isolation of rapid or event-specific neural responses.
31
What are two main advantages of PET?
Chemical specificity through custom tracers (e.g., FDG for glucose metabolism, PiB for amyloid) and whole-brain coverage with moderate spatial resolution (~1 cm).
32
What are two main limitations of PET?
Invasiveness due to radioactive tracer injections and high cost/logistical complexity limiting scan frequency and sample size.
33
How does fMRI measure neural activity and what is the BOLD signal?
fMRI measures blood oxygenation changes: neural activation increases oxygenated blood, causing localized T2-weighted signal changes; BOLD contrast arises from paramagnetic deoxyhemoglobin altering MR signal.
34
What are the primary hardware components of an fMRI scanner?
A main magnet, gradient coils, RF coils for excitation/detection, a shielded room, and peripheral equipment for stimulus presentation and participant monitoring.
35
What technological advances have improved fMRI performance?
Parallel imaging with multi-channel RF coils, optimized pulse sequences for faster/sensitive imaging, and hardware/software refinements (rather than simply increasing field strength).
36
What are key advantages of fMRI?
Non-invasive applicability to humans, good spatial resolution (millimeters), decent temporal resolution (seconds), broad accessibility, and analytic flexibility (connectivity, MVPA) with strong research support.
37
What are key limitations of fMRI?
High cost, safety exclusions (e.g., metal implants), noisy/claustrophobic environment, susceptibility to artifacts (motion, physiology), and interpretative challenges like the reverse inference fallacy.
38
What is the main rationale for using brain stimulation techniques in cognitive neuroscience?
To depolarize or hyperpolarize neurons via external currents, generating or inhibiting action potentials to test the causal role of targeted brain regions.
39
Which two non-invasive brain stimulation methods are commonly used in healthy human research?
Transcranial Magnetic Stimulation (TMS) and Transcranial Direct Current Stimulation (tDCS).
40
How does TMS induce neural activation?
A rapidly changing current in a coil generates a transient magnetic field that penetrates the skull, inducing an electric field in underlying neural tissue via electromagnetic induction, triggering action potentials in oriented neurons.
41
What are common coil designs for TMS and how do they differ?
Circular coils produce diffuse stimulation, while figure-eight coils focus stimulation to about 1 cm spatial resolution.
42
How is target localization for TMS typically achieved?
By identifying responsive sites via motor or visual thresholds, neuronavigation using individual MRI/fMRI coordinates, or behavioral effects when stimulating scalp locations.
43
How is TMS intensity determined for each participant?
By measuring the motor threshold—the minimal intensity to evoke a muscle twitch—and setting stimulation as a percentage of that threshold.
44
What is the difference between online and offline rTMS protocols?
Online rTMS is applied during task performance (5–20 Hz) to transiently disrupt activity; offline rTMS (low-frequency 1 Hz or theta-burst) is applied before tasks to create lasting excitability changes (10–30 min).
45
What are two main advantages of TMS?
Non-invasive focal modulation (~1 cm) with millisecond temporal control and flexible protocols for various research goals.
46
What are two main limitations of TMS?
Restricted to cortical targets, potential discomfort/distraction (clicks, scalp sensations), uncertain duration of effects, and rare risk of seizures requiring careful screening.
47
How does tDCS modulate neural excitability?
By applying a weak constant current (1–2 mA) between anodal and cathodal electrodes: anodal stimulation depolarizes (increases excitability), while cathodal hyperpolarizes (decreases excitability).
48
What effects do tDCS after-effects typically have and how long do they last?
After-effects can last up to ~60 minutes, modifying cortical excitability beyond stimulation period.
49
What is tACS and how does it differ from tDCS?
Transcranial Alternating Current Stimulation (tACS) delivers oscillating currents at specific frequencies to influence neural rhythms, whereas tDCS uses direct steady currents.
50
What were the findings of the Fecteau et al. (2007) tDCS study on right dlPFC activity and risk-taking?
Anodal tDCS over right dlPFC reduced risk-taking and increased low-risk choices, suggesting upregulating this area curbs risky behavior, though effects likely involve interhemispheric balance.
51
What is microstimulation in invasive animal studies and why is it used?
Microstimulation uses intracortical electrodes to induce action potentials in localized neuron populations, providing direct causal evidence of site-specific spiking on behavior.
52
How did Olds & Milner (1954) demonstrate the reinforcing effect of septal stimulation in rats?
Rats implanted with electrodes in the septal area pressed a lever to self-administer electrical pulses, indicating septal activation is reinforcing.
53
What is an advantage of microstimulation regarding subject awareness?
Animals do not consciously perceive the electrical current, so behavioral changes arise solely from neural activation without demand or placebo effects.
54
What clinical parallel exists for invasive microstimulation methods?
Deep brain stimulation in humans treats disorders like Parkinson’s disease, depression, and OCD by chronically implanted electrodes delivering electrical pulses.
55
Describe the Romo & Salinas (2001) microstimulation study in macaques and its significance.
Macaques trained to compare vibration frequencies had one vibration replaced by microstimulation in primary somatosensory cortex; animals judged artificial stimulation as equivalent to real tactile input, demonstrating precise neural pattern control of perception.
56
What is optogenetics and how does it improve upon electrical stimulation?
Optogenetics uses light-sensitive proteins expressed in genetically targeted neurons, allowing precise activation or inhibition of specific cell types with millisecond temporal control, surpassing electrical stimulation’s lack of cell-type specificity.
57
What was the key finding of the Tsai et al. (2009) optogenetics study?
Phasic optogenetic stimulation of VTA dopamine neurons in mice induced a preference for a location paired with stimulation, proving that specific neuronal firing drives reward behavior.
58
What is the historical importance of lesion studies in humans?
They provided early causal evidence for brain–behavior relationships, exemplified by Broca’s and Wernicke’s aphasia, by correlating focal damage with specific cognitive deficits.
59
What information is needed to conduct a lesion study in human neuropsychology?
Lesion identification via structural MRI, functional assessments of residual activity, and well-matched control groups on demographic and cognitive variables.
60
What is the difference between single dissociation and double dissociation in lesion studies?
Single dissociation: one patient group is impaired on Task A but not Task B; double dissociation: two patient groups show complementary deficits (Group 1 impaired on A only, Group 2 impaired on B only).
61
What are two main advantages of human lesion studies?
They provide strong causal inference from clinically evident deficits and can reveal unanticipated brain functions relevant for diagnosis and rehabilitation.
62
What are two main limitations of human lesion studies?
Lesions are often diffuse affecting multiple regions, there is no pre-lesion baseline, and reorganization or medications may confound interpretations.
63
Describe the Fellows & Farah (2003) vmPFC lesion study and its conclusion.
Patients with vmPFC or dlPFC lesions performed a reversal-learning card task; vmPFC-lesioned patients struggled after rule reversal, indicating vmPFC is necessary for flexible updating of stimulus-outcome associations.
64
What advantages do experimental lesion models in animals offer?
Precise anatomical control over lesion location, randomized design with matched training, no medication confounds, and reversible options (e.g., cooling) for within-subject comparisons.
65
What are two limitations of animal lesion approaches?
High technical demands (surgery, training, infrastructure) and challenges in generalizing complex human behaviors to animal models.
66
What did the Rudebeck et al. (2006) lesion study in rats demonstrate about OFC and ACC functions?
OFC-lesioned rats became impatient (avoiding delayed rewards), while ACC-lesioned rats became effort-averse (avoiding high-effort rewards), showing OFC controls delay sensitivity and ACC controls effort sensitivity in decision-making.
67
What are network considerations when interpreting effects of brain manipulations?
Manipulations can influence interconnected regions, so attributing behavioral changes to a single site must account for network-level effects.
68
How can sequential combinations of methods enhance understanding of neural mechanisms?
One method (e.g., fMRI) localizes relevant areas, and another (e.g., TMS or EEG) tests causal or timing aspects, providing complementary insight.
69
What is the benefit of multimodal imaging approaches like TMS-fMRI?
They reveal how altering activity in one area affects processing in connected regions, elucidating network dynamics.
70
According to Ruff & Huettel (2013), why is it essential to use convergent evidence from multiple techniques?
Because no single technique can fully capture the mechanistic details of neural function, combining methods yields robust and comprehensive models of cognition and behavior.
71
What is the definition of overt visual attention?
Overt attention involves eye movements (saccades) to bring an object into central (foveal) vision for detailed processing.
72
What is the definition of covert visual attention?
Covert attention enhances processing of peripheral areas without shifting the eyes.
73
What is top-down (voluntary) attention?
Attention directed by goals, knowledge, or expectations, focusing on what matters to the individual (e.g., searching for a friend in a crowd).
74
What is bottom-up (involuntary) attention?
Attention automatically captured by noticeable external stimuli (e.g., reacting to a sudden loud noise or flashing light).
75
What is change blindness and how does it demonstrate the importance of attention?
Change blindness occurs when significant changes in a scene go unnoticed because attention is spread out, demonstrating that without focused attention, large changes in the visual field can be missed.
76
What visual disorder in parietal-lesion patients highlights the role of attention?
Spatial neglect, where damage to parietal areas causes patients to miss stimuli in part of their visual field, showing how attention guides perception.
77
Name three perceptual benefits of covert attention.
(1) Better contrast detection, (2) Sharper spatial detail, (3) Faster reaction times to stimuli at attended locations.
78
How does covert attention improve contrast detection?
By focusing attention on a location, the visual system becomes more sensitive, making it easier to see faint or low-contrast objects at that spot.
79
What effect does covert attention have on spatial detail?
Attention sharpens spatial resolution, improving the ability to notice small differences or fine details in the attended region.
80
Describe the Posner (1980) finding on reaction times and covert attention.
Posner found that reaction times are faster for stimuli appearing at attended locations compared to unattended ones, demonstrating that covert attention speeds processing.
81
What is a receptive field (RF) in visual neuroscience?
A receptive field is the specific area of the visual field to which a neuron responds.
82
In the single-stimulus paradigm, how does attention affect firing rates?
When attention is focused on a stimulus within a neuron’s RF, the neuron’s firing rate increases compared to when attention is directed elsewhere.
83
Which visual areas show modest firing-rate increases under spatial attention?
LGN, V1/V2, V4, and MT/V5, although the magnitude of increase can vary and sometimes be absent.
84
What is the two-stimulus paradigm in spatial attention studies?
A paradigm where two stimuli (preferred and non-preferred) are placed inside the same RF, allowing study of how attention to one stimulus modulates neuron responses.
85
In the two-stimulus paradigm, what happens when attention is directed to the preferred stimulus?
Neuron firing increases, as if only the preferred stimulus were present in the RF.
86
What happens when attention is directed to the non-preferred stimulus in the two-stimulus paradigm?
Firing to the preferred stimulus is suppressed, showing that attention can reduce responses to non-attended stimuli even if they are in the RF.
87
How does feature-based attention modulate neuronal responses?
Neurons tuned to a relevant feature (e.g., color or motion) respond more strongly when that feature is attended, even if the stimulus is outside the spatially attended region.
88
Give an example of feature-based attention in visual cortex.
A V4 neuron preferring red will fire more strongly when searching for a red object, even if that red object is not in its RF.
89
How do spatial and feature-based attention interact in areas like MT and V4?
Both forms of attention produce similar boosts in neuronal activity, suggesting they share common underlying mechanisms.
90
What is the concept of RF shrinkage under attention?
When multiple stimuli occupy a neuron’s RF, attention effectively “shrinks” the RF to focus on the attended stimulus, reducing responses to distractors.
91
What does the response-shift model propose about attention’s effect on contrast–response curves?
That attention acts like adding contrast, shifting the contrast–response curve so the neuron responds to a stimulus as if it were stronger.
92
What does the response-gain model propose about attention’s effect on contrast–response curves?
That attention multiplies the neuron’s response at all contrast levels, boosting firing rates uniformly without changing the contrast threshold.
93
In what situation does the response-shift model better describe attentional effects?
When the attended stimulus is smaller than the attended area, such as focusing on a small dot within a larger region.
94
When is the response-gain model more prominent?
When the attended stimulus is larger than the attended area, such as looking around while riding in a car.
95
What is a normalization-based model of attention?
A unifying framework suggesting that attention modulates how neurons normalize their inputs, either by boosting input signals (input-gain) or reducing the divisive normalization (output-normalization) to increase firing.
96
What is input-gain in normalization models of attention?
Attention boosts the input signals to a neuron before normalization, enhancing its response to the attended stimulus.
97
What is output-normalization in normalization models of attention?
Attention reduces the divisive normalization denominator so that a neuron’s output is less suppressed by competing inputs, resulting in a stronger response.
98
Name one key study supporting input-gain as a mechanism of attention.
Ghose (2009) provided evidence that attention increases neural input signals in visual cortex.
99
Name one key study supporting output-normalization as a mechanism of attention.
Reynolds & Heeger (2009) and Lee & Maunsell (2009) showed that attention reduces output normalization, boosting the neuron's firing rate.
100
What is the local-field potential (LFP)?
The LFP is the combined electrical activity from many nearby neurons, reflecting slow brain signals in a region.
101
How does attention affect LFP coherence in area V4?
Attention increases LFP coherence, meaning neural signals in V4 become more synchronized when attention is directed to that area.
102
What is spike–LFP coupling and how does attention affect it?
Spike–LFP coupling is the synchronization between a neuron’s spikes and the LFP; attention enhances this coupling, improving coordination between individual neurons and their surrounding network.
103
How does attention influence trial-to-trial response variability?
Attention reduces firing-rate variance across trials, making neuron responses more reliable when attention is focused on their RF.
104
What are noise correlations and how does attention affect them?
Noise correlations are correlated firing variability between neuron pairs; attention decreases noise correlations, improving population coding by reducing shared variability.
105
Describe how attention can shift RF centers.
Attention can cause a neuron’s RF center to move toward the attended location, possibly due to changes in center–surround interactions that bias tuning.
106
What is the parietofrontal network’s role in attention?
The parietofrontal network (including LIP, FEF, and SC) controls the allocation of both overt and covert attention through interconnected circuits.
107
What is the lateral intraparietal area (LIP) involved in with respect to attention?
LIP activity reflects the location of covert attention, indicating where attention is directed even without eye movements.
108
What role does the superior colliculus (SC) play in covert attention?
SC neurons respond to covert shifts of attention without eye movements, reflecting target selection in the absence of saccades.
109
How does FEF (frontal eye field) activity relate to covert visual search?
FEF neurons fire in sequences that reflect serial covert scanning of potential targets, with earlier firing when the target is near a neuron’s preferred RF location.
110
What evidence shows inter-areal synchrony during attention?
Increased LFP–LFP synchrony and spike–LFP coupling between parietofrontal areas and visual cortex when attention is directed, indicating enhanced communication.
111
Which brain areas predict saccade targets before eye movements?
LIP, FEF, and SC all show activity that predicts the chosen target immediately before a saccade, demonstrating their role in overt attention.
112
How does microstimulation of FEF affect visual processing in area V4?
Sub-threshold microstimulation of FEF boosts detection performance and makes V4 neurons behave as if spatial attention were directed to the corresponding location.
113
What happens when LIP, FEF, or SC are reversibly inactivated during visual search tasks?
Monkeys exhibit deficits in attention-based search: SC inactivation causes them to ignore cued locations and respond to distractors, indicating an attentional impairment.
114
What is the priority-map hypothesis?
A theoretical map where each spatial location’s activity represents its priority based on both bottom-up salience and top-down relevance, guiding overt and covert attention to the highest-priority location.
115
How does the priority map integrate bottom-up and top-down signals?
By combining sensory-driven salience (e.g., novel stimuli) with goal-driven factors (e.g., task relevance, expected rewards) to compute a priority signal at each location.
116
How does the priority map guide overt attention?
Overt attention (saccadic eye movements) is directed toward the peak of activity on the priority map, corresponding to the most important location.
117
How does the priority map guide covert attention?
Covert attention shifts toward the peak of the priority map without moving the eyes, focusing processing on the highest-priority location.
118
What behavioral phenomena can be predicted by the priority map’s activity?
Saccadic latencies (eye movement speed), covert attention shifts, and choices in decision-making tasks can all be predicted by the priority map’s peaks.
119
Why is the priority-map hypothesis important for clinical applications?
It links neural activity in LIP, FEF, and SC to behavior, providing insights that can inform interventions for patients with spatial attention deficits, such as neglect rehabilitation.
120
Which studies demonstrate the effect of stimulus size on attentional modulation models?
Reynolds & Heeger (2009) showed that for small stimuli, response-shift effects dominate, while for large stimuli, response-gain effects are more prominent.
121
What is an example of bottom-up signals affecting activity in attention control areas?
A sudden flash in the visual field increases LIP activity at the corresponding location, automatically capturing attention.
122
Give an example of a top-down signal affecting the priority map.
Task instructions to search for a red object increase FEF and LIP activity at locations containing red items, prioritizing these locations for attention.
123
How does feature-based attention improve search efficiency?
By globally boosting the representation of items sharing the attended feature (e.g., color), enabling faster detection of the target among distractors.
124
What is the inverse problem in EEG and MEG source localization?
The challenge in determining unique neural sources from scalp-recorded EEG or MEG signals, because multiple source configurations can produce similar measured fields.
125
Why must interpretations of fMRI data beware of the reverse inference fallacy?
Because observing activation in a region does not definitively imply a specific cognitive process, as the same region may be involved in multiple functions.
126
In what way do microstimulation and reversible inactivation provide causal evidence for attention mechanisms?
Microstimulation shows that activating a region can mimic attention effects, while reversible inactivation shows that disabling a region impairs attention, together proving necessity and sufficiency.
127
How does output-normalization explain attention effects when multiple stimuli are in a neuron’s RF?
Attention reduces the normalization pool’s suppressive influence, so the attended stimulus evokes a stronger response despite competing inputs.
128
What role does the superior colliculus play in overt attention?
SC selects targets and initiates saccades by representing highest-priority locations and driving eye movement toward them.
129
How do changes in noise correlations affect population coding under attention?
Reduced noise correlations under attention improve the combined information carried by neuron populations, enhancing discriminability and behavioral accuracy.
130
Explain how RF center shifts under attention might arise from center–surround interactions.
Attention may enhance excitation at the attended location while suppressing surrounding areas, effectively shifting a neuron’s RF center toward that focus.
131
Describe one way in which EEG can be integrated with other methods to study attention.
EEG can be combined with fMRI (EEG-fMRI) to correlate millisecond-level timing (ERPs) with localized BOLD signals, revealing when and where attention-related processes occur.
132
How does tDCS modulate attention-related brain areas?
Anodal tDCS over FEF or parietal areas can increase excitability, enhancing attentional performance, while cathodal tDCS can decrease excitability, impairing attention.
133
What outcome in a visual search task indicates successful covert attention allocation?
Faster detection of target objects or improved discrimination accuracy at attended locations without corresponding eye movements.
134
How do LIP neurons signal both bottom-up salience and top-down relevance?
LIP firing rates increase for novel, salient stimuli (bottom-up) and also for stimuli matching task goals or expected rewards (top-down), reflecting combined priority.
135
What evidence shows that attention improves neural processing at attended locations before any saccade?
In FEF and SC, neurons respond to covert attention shifts, firing in anticipation of a saccade to an attended location even when the eyes remain stationary.
136
Why is reduced trial-to-trial variability important for attention?
It makes neural responses more reliable, reducing noise and allowing downstream neurons to decode attended signals more accurately.
137
How can reversible inactivation of FEF affect visual area V4 activity?
Inactivation of FEF decreases V4 neuron responses to attended stimuli, demonstrating FEF’s top-down influence on sensory processing.
138
What does increased LFP–LFP synchrony between parietofrontal areas and visual cortex suggest about attention?
It indicates enhanced functional connectivity and coordinated processing, reflecting top-down signals modulating sensory areas.
139
How does the priority-map hypothesis explain choice behavior in decision tasks?
By treating potential choice locations as peaks on the priority map, with higher activity predicting faster or more likely selection of those options.
140
Summarize why a unifying normalization-based model is valuable for understanding attention.
By showing that both spatial and feature-based attention can be explained by common mechanisms of input boosting and output normalization, the model accounts for diverse attentional effects with a single framework."In Blankenburg et al. (2010), which network is identified as playing a key role in top-down visuospatial attention?
141
In Blankenburg et al. (2010), what was the primary research question regarding the posterior parietal cortex (PPC)?
Whether stimulation of the PPC directly causes attention-related changes in the visual cortex.
142
In Blankenburg et al. (2010), which technique was used to test causal influence of the PPC on visual areas?
Concurrent TMS–fMRI (transcranial magnetic stimulation with functional MRI).
143
In Blankenburg et al. (2010), what task were participants asked to perform during the experiment?
They viewed two checkerboard streams and reported the number of small targets on the cued side (left, right, or neither).
144
In Blankenburg et al. (2010), where was TMS applied and at what intensities?
TMS was applied to the right PPC at high (effective) and low (control) intensities.
145
In Blankenburg et al. (2010), how did high-intensity TMS to right PPC affect the right visual cortex activity?
It increased the difference in activity between attended and unattended sides in the right visual cortex.
146
In Blankenburg et al. (2010), was there any effect of high-intensity PPC TMS on the left visual cortex?
Yes, a smaller but similar attention-dependent increase in activity was observed in the left visual cortex.
147
In Blankenburg et al. (2010), how did TMS intensity affect participants’ behavioral performance?
TMS intensity did not affect reaction time or accuracy; performance remained the same across high and low TMS.
148
In Blankenburg et al. (2010), which visual areas showed increased activation during active attention compared to neutral?
Early visual and extrastriate areas showed increased activation during active attention versus neutral.
149
In Blankenburg et al. (2010), which parietal region was activated during active attention?
The superior parietal cortex was activated during active attention.
150
In Blankenburg et al. (2010), what was the effect of contralateral attention on visual cortex activation?
Attending left boosted right visual cortex activity, and attending right boosted left visual cortex activity.
151
In Blankenburg et al. (2010), how did high-intensity TMS affect the right fusiform gyrus (V4/Fusiform)?
It enhanced the attention effect (left vs. right attention) in the right fusiform gyrus, but only when attention was engaged.
152
In Blankenburg et al. (2010), what pattern was observed in the left fusiform gyrus under high-intensity TMS?
High-intensity TMS boosted the attention effect (right vs. left attention) in the left fusiform gyrus, absent during neutral.
153
In Blankenburg et al. (2010), what does the state-dependent TMS effect indicate?
That PPC’s influence on visual cortex is active only when participants direct attention, not during neutral attention states.
154
In Blankenburg et al. (2010), what was the key conclusion about PPC’s top-down influence?
High-intensity TMS to right PPC increases attentional modulation in extrastriate visual cortex only during active attention, proving a top-down causal role.
155
In Blankenburg et al. (2010), how do the results align with previous attention network studies?
They support animal and human evidence that PPC is integral to attention networks, showing causal propagation of attention signals.
156
In Blankenburg et al. (2010), why is concurrent TMS–fMRI crucial for understanding attention networks?
It allows direct stimulation of PPC while measuring resulting changes in remote visual areas, revealing causal connectivity.
157
In Blankenburg et al. (2010), what does the absence of TMS effects during neutral tasks suggest?
That PPC-to-visual cortex modulation requires an attentionally engaged state to occur.
158
In Blankenburg et al. (2010), why did the authors include both high and low TMS intensity conditions?
To distinguish specific effects of PPC stimulation on attention from nonspecific TMS effects, using low-intensity as a control.
159
In Blankenburg et al. (2010), what broader implication did the authors highlight regarding causal perturbations?
That top-down causal perturbations from attention control regions propagate to sensory areas only when attention is active."What network is involved in top-down visuospatial attention and includes the PPC in Saygin & Sereno (2008)?
160
In Saygin & Sereno (2008), what was the primary question about the PPC’s role in attention?
Whether the PPC directly causes attentional changes in the visual cortex in humans.
161
In Saygin & Sereno (2008), what technique combines stimulation of one brain area with measurement in others?
Concurrent TMS–fMRI.
162
What was the goal of Saygin & Sereno (2008)?
To test whether stimulating the right PPC with TMS causes attention-related changes in the visual cortex.
163
In Saygin & Sereno (2008), what task did participants perform during the experiment?
They viewed two checkerboard streams and reported the number of small targets on the attended side (left, right, or neither).
164
In Saygin & Sereno (2008), where was TMS applied?
To the right posterior parietal cortex (PPC).
165
In Saygin & Sereno (2008), what were the two TMS intensity conditions used?
High (effective) intensity and low (control) intensity.
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In Saygin & Sereno (2008), what did fMRI measure?
Brain activity in visual and parietal areas during TMS and the attention task.
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In Saygin & Sereno (2008), what was the effect of high-intensity TMS on the right visual cortex?
It increased the difference in activity between attended and unattended sides.
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In Saygin & Sereno (2008), did high-intensity TMS affect the left visual cortex similarly?
Yes, but the effect was smaller than in the right visual cortex.
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In Saygin & Sereno (2008), what does the increased attention effect in visual cortex imply?
That the PPC exerts top-down, attention-dependent modulation on the visual cortex.
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In Saygin & Sereno (2008), what were the behavioral results regarding task performance?
Neutral tasks were faster and more accurate than attention tasks, and TMS did not affect reaction time or accuracy.
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In Saygin & Sereno (2008), which visual areas showed increased activity during active attention versus neutral?
Early visual and extrastriate areas.
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In Saygin & Sereno (2008), which parietal region showed increased activity during active attention?
The superior parietal cortex.
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In Saygin & Sereno (2008), what is meant by 'contralateral attention'?
Attending to one visual hemifield (left or right) boosted activity in the opposite (contralateral) visual cortex.
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In Saygin & Sereno (2008), what happened in the right fusiform gyrus (V4/Fusiform) when high-intensity TMS was applied?
High-intensity TMS enhanced the attention effect (left vs. right attention), but only when attention was directed.
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In Saygin & Sereno (2008), did the left fusiform gyrus show the same TMS × attention interaction?
Yes, high-intensity TMS boosted the attention effect (right vs. left attention) in left fusiform, absent during neutral.
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In Saygin & Sereno (2008), what does 'state-dependent' TMS effect refer to?
That TMS influenced visual cortex only when participants were actively directing attention, not during neutral trials.
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In Saygin & Sereno (2008), what key conclusion was drawn about PPC and visual cortex?
High-intensity TMS to right PPC increases attentional modulation in extrastriate visual cortex only when attention is engaged, demonstrating a top-down causal influence.
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In Saygin & Sereno (2008), how do these findings align with previous research on attention networks?
They support animal and human studies showing PPC’s role in attention, illustrating that causal perturbations propagate top-down during active attention.
