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Cognitive Neuroscience > Chapter Three > Flashcards

Chapter Three Flashcards

1
Q

Representations:

A

properties of the world that are manifested in cognitive systems (mental) and neural systems (neural)

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2
Q

Single-cell recordings:

A

measure the responsiveness of a neuron to a given stimulus (in terms of AP/sec)

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3
Q

Electroencephalography (EEG):

A

measurements of the electrical signal generated by the brain through electrodes placed on different points on the scalp

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4
Q

What characteristic makes EEG methods highly useful?

A

changes are conducted instantaneously making it useful when measuring relative timing of cognitive events and neural activity

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5
Q

Event-related potentials:

A

The average amount of change in voltage at the scalp that is linked to the timing of a particular cognitive events

EX: stimulus, response

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6
Q

Reaction time:

A

the time taken between the onset of a stimulus/event and the production of a behavioral response (button press)

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7
Q

Functional imaging methods (fMRI) have better temporal/spatial resolution than temporal/spatial resolution.

A

spatial; temporal

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8
Q

Lesion methods tend to rely on measuring […] than […].

A

error rates; time-based processes

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9
Q

The AP is directly measured in the method of […].

A

single/multi cell recording

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10
Q

How can single-cell recording be obtained?

Why is it impossible to measure AP from a single neuron noninvasively?

A

electrode implanted intra or extracellularly

signal is too weak and the noise from other neurons is too high

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11
Q

Multi-cell recordings:

A

electrical activity (AP/sec) of many individually recorded neurons recorded at one or more electrodes

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12
Q

Grandmother cell:

A

hypothetical neuron that just responds to one particular stimulus

EX: the sight of one’s grandmother

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13
Q

What are the three different types of representation that may be found at the neural level?

A
  1. local: all information about a stimulus/event is carried in one of the neurons (grandmother cell)
  2. fully distributed: all information about a stimulus/event is carried in all the neurons of a given population
  3. sparse: a distributed representation in which a small proportion of the neurons carry information about a stimulus/event
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14
Q

Rate coding:

A

the informational content of a neurons may be related to the number of AP per second

given stimulus/event is associated with a change (typically increase) in the rate of neural firing

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15
Q

Temporal coding:

A

synchrony of firing may be used by a population of neurons to code the same stimulus or event

given stimulus/events is associated with greater sychronization of firing across different neurons

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16
Q

Both multi and single-cell recordings representation of information dependson what type of coding?

Why?

A

sparse distributed coding

  1. conserves energy
  2. high memory capacity
  3. protect against losing information if synapses or neurons die
  4. generalize/categorize (deja vu)
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17
Q

Th physiological bases of the EEG signal originates in the […] current rather than the axonal currents.

A

postsynaptic dendritic (passive)

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18
Q

In order for an electrical signal to be detectable at the scalp, what basic requirements need to be met?

Based on these requirements, what region is the most optimal space for EEG recording?

A
  1. whole population of neurons must be active in synchrony to generate a large enough electrical field
  2. population must be aligned in a parallel orientation so they can summate together (not cancel out)

cerebral cortex

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19
Q

EEG: The greater the electrical activity of neurons…

A

the greater the voltage change at the scalp

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20
Q

To gain an EEG measure one needs to compare the …

A

voltage between two or more different sites

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21
Q

What are some types of reference sites for EEG voltage comparisons?

A
  1. nasal
  2. mastoid bone behind ear
  3. average of all electrodes
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22
Q

Electrode placement labeling:

A

right side = even numbers
left side = odd numbers

midline = z

frontal = f
parietal = p
occipital = o
temporal = t
central = c

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23
Q

What are the limitations of ERPs?

A

Poor spatial resolution– don’t know the source of the signal we only know scalp distributions

  1. electrical signal is filtered/distorted by body tissue
  2. summed postsynaptic potentials; ERP loses identity of individual neurons/layers
  3. cannot distinguish IPSPs and EPSPs; polarity at the scalp depends on the location and the type of PSP
  4. inverse problem; have the output but that could be created through a variety of combinations

Incomplete measure of the brain

  1. ERP generated by synchronous firing of open field neurons
  2. ERPs are blind to close sources and asynchronous firing
  3. Electrical fields in sulci cancel out
  4. Distant and small activity will cancle out
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24
Q

The most common use of EEG in cognitive neuroscience is the method known as […].

A

ERP

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25
Q

How do you get an enhanced signal-to-noise ratio?

A

when different EEG waves are averaged relative to the presentation of a stimulus (a tone)

more trials = more observable ERP

26
Q

Polarity significance in EEG recordings:

What does polarity depend on?

A

NONE: can’t infer which is excitation or inhibition so N and P peaks mean nothing

spatial arrangement/summation of dipoles of the neurons that are giving rise to the signal at that particular moment in time

27
Q

The EEG signal tends to oscillate at different rates aka …

Alpha waves reflect oscillations in the […] range.

Beta waves reflect oscillations in the […] range.

Gamma waves reflect oscillations in the […] range.

Theta waves reflect oscillations in the […] range.

Delta waves reflect oscillations in the […] range.

A

frequency bands

7-14 Hz

15-30 Hz

30-100 Hz

4-7 Hz

28
Q

Increases in the alpha band have been linked to […].

What specifically happens to the waves in this range?

A

increased attention OR filtering out of irrelevant information

the neurons become more synchronized in their electrical activity, especially at the 7-14 Hx range

29
Q

Increases in the gamma band have been linked to […].

A

binding or grouping: a perceptual integration of parts into wholes (IMPORTANT FOR OBJECT RECOGNITION)

30
Q

Mental chronometry:

A

study of the time-course of information processing in the human nervous system

31
Q

Additive factors method:

What is the strength of this method?

A

general method for dividing reaction times into different stages

one could take an unknown factor (sleep deprivation, Parkinson’s, reading ability) and determine whether this has an additive effect or interactive effect

32
Q

Use the additive factors method to develop the general steps for 4+2

A

visual recognition (2 and 4)

computing the sum (addition)

producing a response (6)

33
Q

Stenberg’s experiment involved a
working memory task in which participants were given an array of one, two or four digits to hold in mind (e.g., 5, 9, 3, 2). They were then shown a single probe digit (e.g., 9) and asked to press one of two buttons (labeled “yes” and “no”) to indicate whether this item had been in the previous array.

Sternberg proposed the task could be divided into a number of separate stages:

A
  1. encoding
  2. comparing
  3. deciding
  4. responding
34
Q

If different factors from different stages of the additive factors method were affected, this would be termed as a […].

If only one processing stage of the additive factors method were affected, this would be called […].

A

additive effects

interactive effect

35
Q

Difference between reactive time and ERP waveform

A

RT is a single measure that is assumed to reflect different stages/components

ERP consists of a series of waves that vary continuously through time

36
Q

ERP:

Early peaks in a task may reflect…

Later peaks…

A

Early– perceptual encoding

Later– comparison stage

37
Q

What are some aspects of ERP waveforms that can correspond with different cognitive stages of processing?

A
  1. early vs later peaks
  2. amplitude of those peaks vary
  3. effect of a new variable on earlier or later peaks
38
Q

N170:

How is this component affected?

A

an ERP component/deflection linked to perceiving facial structure (NP at 170 ms)

affected by perceptual changes to image

39
Q

N250:

How is this component affected?

A

ERP component that reflects face recognition and identity processing

affected by familiarity; not affected by view changes (like N170)

SPECIFIC FACE NOT SPECIFIC IMAGE

40
Q

Later, positive-going components of facial recognition/processing:

How is this component affected?

A

ERP component for person recognition (faces and names)

affected by both faces and names

are also sensitive to the repetition
and familiarity of specific person identities, and
the effects generalize to names as well as faces

41
Q

Associative priming:

A

reaction times are faster to stimulus X after being presented to stimulus Y if X and Y have previously been associated together (if they tend to co-occur)

42
Q

Exogenous components:

Another name for this is…

A

components that appear to depend on the physical properties of a stimulus (sensory, modality, size, intensity)

evoked potentials

43
Q

Endogenous components:

A

appear to depend on properties of the task (what the participant is required to do with the stimulus)

44
Q

Why is the spatial of ERP methods poor?

A

inverse problem

45
Q

Inverse problem:

A

the difficulty of locating the source of electrical activity from measurements taken at the scalp

KNOWN: electrical potential at the scalp

UNKNOWN: number, location, and magnitude of the electrical sources

46
Q

How could one attempt to solve the inverse problem?

A

dipole modeling

or use a fMRI to collect data at the same time as the EEG/ERP

47
Q

Dipole modeling:

A

an attempt to solve the inverse problem

involves assuming how many dipoles (regions of electrical activity) contribute to the signal recorded at the scalp

48
Q

ERP components: Early negatives

What are they? What can they tell us?

A

between period 100-300

the attention effect: a larger response to stimuli when the subject’s attention is directed to some of the stimulus features than when the subject attention is directed elsewhere.

49
Q

ERP components: Mismatch negativity (MNN)

What are they? What can they tell us?

A

onset latency: 50 msec
peak latency: 100-200 msec

brain response to violations of a rule

50
Q

Advantages of ERP technique

A

DIRECT MEASURE OF BRAIN
ACTIVITY
* Non-invasive
* Continuous data over time
* Excellent temporal resolution
(milliseconds)
* No response required
* Time-lock brain activity to any
stimulus or response event
* Multidimensional measures of
activity in space and time
* Easy, fast, and cheap to use

51
Q

-INFERENCES IN ERP DATA-

Difference in topography implies …

A

different neural sources: qualitative difference

The opposite is not always true; the same distribution does not always equal the same sources because of the inverse problem

52
Q

-INFERENCES IN ERP DATA-

A difference in the start of component (onset): the brain has…

A

detected a difference at least by that point – but maybe earlier and not
detected

53
Q

-INFERENCES IN ERP DATA-

Difference in latency on the same component implies …

A

same process but with different time course

54
Q

-INFERENCES IN ERP DATA-

Difference in amplitude implies …

A

increase in neural activity…but from the same or new sources unknown

55
Q

-INFERENCES IN ERP DATA-

NO difference in ERP does not mean …

A

no difference in brain activity; it is an incomplete measure of neural activity

56
Q

What is the benefit of an ECoG implant?

A
  1. removes sources of electrical interference or
    filtering.
  2. Result is cleaner signal that is better localizable than scalp EEG
57
Q

ECoG is often used preoperatively to…

A

localize the source of epileptic seizures.

58
Q

A change in ERP always means …

A

there was a change in neural
activity

59
Q

How can an ERP change?

A
  1. time
  2. amplitude
  3. polarity
  4. distribution across scalp
60
Q

What are the three uses of ERP as a tool:

A
  • How does the brain respond to different stimuli?
  • When in time does the brain respond to a stimulus?
  • Dependent Measure as a Psychological too

Cognitive Neuroscience (3 decks)

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