Midterm Flashcards

1
Q

what is cognitive neuroscience

A

study of psychological processes and how they’re implanted in the brain

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2
Q

3 keys to conducting an fMRI study

A
  1. Design a behavioral task that isolates the psychological processes of interest in the brain
  2. Modify the behavioral task so that it’s suitable for an fMRI study
  3. Analyze the behavioral and fMRI data
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3
Q

ethical considerations of studies

A

informed consent

debriefing (tell purpose of study at the end)

privacy/confidentiality

fraud (making up data)

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4
Q

Four goals of scientific research

A

Describe: observe a behavior, make a prediction

Predict

Determine causes

Explain mechanisms

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5
Q

3 types of studies

A

descriptive: observational, notice patterns in the world and report them

correlative: notice a pattern a between two different variables and try to determine how they’re related

true experiments: random assignment, manipulate a variable

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6
Q

within vs between subject design

A

between: groups receive different treatments

within: each subject receives all treatments (makes it harder for 3rd variable to affect results

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7
Q

within subjects design limitation

A

carry over effects: effects from one experimental condition carry over to the next

timing/order of treatments matter

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8
Q

example of confounds

A

clever hans: cues from experimenters affected horse’s reaction

bigfoot

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9
Q

congruency effect

A

reaction times are faster when the target and distractor are congruent than when they are incongruent

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10
Q

Congruency sequence effect

A

(aka conflict adaptation)

the congruency effect is smaller when the previous trial is incongruent than when congruent

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11
Q

Which process drives the CSE?

A
  • Selection for action (botvinick)
    • shift attention toward the relevant target
  • Response inhibition (ridderinkhof)
    • inhibit the response engendered by the distractor
  • Learning and memory confounds (mayr)
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12
Q

botvinick et al.

A

selection for action (previous theory): ACC focuses attention on stimuli we want to act upon

conflict monitoring (botvinick): ACC activated when conflict is detected, dorsolateral prefrontal cortex (DLPFC) activated, then attention is increased

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13
Q

Mayr et al.

A
  • Mayr et al predicted:
    • CSE happens when target and flanker are repeated
    • No CSE when either target or flanker change
  • Found that conflict adaptation occurred only in repetition trials, contradicting the conflict monitoring model
  • CSE comes back when stimulus is repeated in n-2 to n
  • Reduced ACC activity on iI (vs cI) trials reflects repetition priming not conflict monitoring
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14
Q

selection for action (attention adaptation) triggered by:

A

perceptual expectation (expectations about what comes next)

conflict monitoring

negative affect (almost pressing wrong button makes you frustrated)

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15
Q

cI vs iI trials in botvinick et al.

A

cI trials: higher conflict

iI: high selection for action

cI trials had greated ACC response

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16
Q

learning and memory processes that may influence the CSE include:

A

feature repetitions (mayr et al.)

contingency learning biases (schmidt)

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17
Q

Mayr et al used what kind of task

A

2-AFC flanker task

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18
Q

to avoid feature repetitions, some researchers have…

A

employed tasks w/ larger stimulus sets (ex: ullsperger et al.)

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19
Q

contingency learning confounds/biases

A

Ullsperger: 9-AFC (alternative forced choice)

with larger stimulus sets (to avoid feature repetitions), congruent and incongruent trials are presented equally, even though there are fewer unique congruent stimuli (shown 8x often)

flankers (ex 11 11) appeared w/ congruent target (ex 1) 50% of the time but w/ incongruent targets (22 22, etc.) only 6.25% of the time

lead to CSE

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20
Q

describe both experiments in mayr et al.

A

experiment 1: standard flanker task, but analyzed trials by whether they were a change or repetition

experiment 2: removed repetition by alternating b/w up/down and left/right arrows

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21
Q

what does AFC stand for

what do classic experiments use

mayr et al

ullsperger

A

alternative forced choice

classic: 2-AFC (left/right)
mayr: 4-AFC (right/left/up/down)
ullsperger: 9-AFC (9 possible responses)

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22
Q

how does a contingency learning bias lead to a CSE

A

particpants want to respond fast/accurately, so learn strategy of making response congruent w/ flankers

after congruent trial (strategy worked!), contingency bias increases (faster RT cC trials, slower to cI)

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23
Q

mental rotation confounds

A

Kunde and Wuhr

observed a CSE in a 4-AFC, even in trials w/o exact feature repetition or contigency learning biases)

however, all arrow stimuli were mental rotations of the same arrow stimulus

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24
Q

Prime probe word task (Schmidt and Weissman)

A

avoided feature repetitions, contigency learning, and mental rotation confounds

  • 4-AFC task (left-right vs up-down)
  • Alternated b/w these two tasks every trial (no response repetitions)
  • Presented congruent/incongruent stimuli equally (no contigency learning)
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25
Q

conclusion of schmidt and weissman

A

CSE can be observed independent of confounds

a control process influences the CSE, but does not reveal which one:

selection for action (aka attention adapation) or response inhibition

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26
Q

how does prime probe word task of in class experiment differ from schmidt and weissman?

A

increase time separating the prime (distractor) from the probe (target) from 33 ms to 800 ms

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27
Q

logic of class experiment (increasing time b/w distractor and target)

A

overall congruency effect should vanish

however, subjects may still use their memory of what the previous trial was to predict what the next trial will be

therefore, should observe a CSE even though there is no overall congruency effect

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28
Q

class experiment: selection for action (attention adaptation) theory

A

after an incongruent trial and w/ long time b/w distractor and target, subjects can shift all attention to the target when it appears

if they shift all their attention to the target, there won’t be any attention left to identify the distractor

thus, there should be no congruency effect after incongruent trials

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29
Q

class experiment: response inhibition theory

A

w/ a long time b/w target and distractor, subject inhibit response signaled by the distractor after incongruent trials

if they do, there should be a negative (reverse) congruency effect after incongruent trials (faster on iI than iC)

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30
Q

CSE graph label

A
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31
Q

p value

A

probability that null hypothesis is false

null hypothesis = no significant difference b/w two groups

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32
Q

one tailed t test

A

test if sample mean is larger or smaller than population mean

significant when the difference b/w means are large enough that it’s unlikely to occur by chance

5% in one tail

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33
Q

two tailed t test

A

test if sample mean is larger or smaller than population mean

2.5% in each tail instead

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34
Q

paired (one-sample) t-test

A

two sample means come from the same subjects

compare subjects to themselves

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35
Q

unpaired (two-sample) t-test

A

the two sample means come from different subjects

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36
Q

main effect

A

dependent variable changes based on the independent variable

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37
Q

interaction

A

the effect of one independent variable on the dependent variable varies based on another independent variable

unparallel lines

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38
Q

simple effects

A

limit analysis to one of the independent variables to see the what is driving an interaction

only calculated when an interaction is significant

39
Q

clinical applications of fMRI example

A

pateints with traumatic brain injury (TBI) still had some brain activity when imaged with fMRI

40
Q

basic science and fMRI: movies and brain activity

A

people shown movies while in fMRI

reconstruct movie based on brain activity in the primary visual cortex

41
Q

dogs and fMRI example

A

do dogs have similar brain activity as humans?

using fMRI, found that area of reward in dogs correlates to same area in humans

42
Q

first brain imaging experiment

A

Angelo Mosso

humans lay on seesaw, thought that fi people think hard, blood would rush to head and tip the seesaw

43
Q

Blood Oxygen Level Dependent (BOLD) signal

A

an indirect measure of neural activity

increased neural activity → increased blood flow → flow of oxygenated blood (oxy/deoxyhemoglobin ratio increases) → increased BOLD signal

44
Q

typical BOLD signal looks like what

A

initial undershoot: due to neural area using up oxygen before getting more oxy blood

oxy/deoxy ratio increases

oxy/deoxy ratio goes below baseline (use up oxy blood)

45
Q

what does conducting an fMRI study involve

A

put subject in scanner

have subjects perform cognitive tasks

record the BOLD signal

46
Q

how is BOLD signal recorded

A

multiple horizontal slices taken, then divided into many small cubes (voxels)

high spatial resolution

47
Q

TR

A

time it takes to get a whole set of slides

48
Q

cognitive subtraction

A

2 conditions only differ in one respect, parts of brain that are more active is due to that difference

49
Q

assumption of pure insertion

A

assumption for cognitive subtraction

adding new component to a task doesn’t change the basic processes that were already in the task (can add w/o changing pre-existing processes)

50
Q

interpreting the bold signal

A

increased bold signal does not mean more neurons are firing

means more metabolic activity is occuring, but could be excitatory or inhibitory activity

51
Q

fMRI vs normal MRI

A

MRI (structural MRI): used to study brain anatomy

fMRI (functional): used to study brain function

52
Q

how does structural MRI work

A

normally: magnetic fields of proteins initially random

in scanner: some protons align

radio wave pulse: orients protons and produces signal

eventually protons relax back to original orientation

53
Q

diffusion tensor imaging (DTI)

A

MRI based method for imaging the axon tracts that form the white matter of the brain

DTI measures density and motion of water that travels along myelin-covered axons

water normally diffuses in all directions (isotropic), but diffusion along myelinated axon is limited (anisotropic), so water moves only along length of axon bc myelin creastes lipid boundary that influences water movement

54
Q

sports and head injury research

A

concussions associated w/ chronic traumatic encephalopathy (CTE)

tau protein builds up in brain

problems w/ memory, concentration, depression

55
Q

3 main parts of the brain

A

neocortex, limbic, brainstem/cerebellum

56
Q

Layer 1 of the brain

A

brain stem: breathing, swallowing, bladder, HR

cerebellum: balance, coordination

57
Q

Layer 2:

limbic system

A

amygdala: emotion

hippocampus: memory

cingulate gyrus/cortex: conflict, emotion, pain

58
Q

layer 3: neocortex

A

parietal lobe: touch

frontal lobe: higher order thinking, planning, decisions

temporal lobe: hearing, memory

occipital lobe: vision

59
Q

anatomical directions

A

rostal: toward nose

caudal: back of head

ventral: bottom

dorsal: top

60
Q

parts of cingulate cortex

A
61
Q

Parvizi et al.

A

found that the anterior midcingulate cortex (aMCC) plays an important role eliciting determination and motivation within an individual to face challenges

62
Q

Coleshill et al.

A

studied unilateral hippocampal electrical stimulation in epilepsy patients; found that that stimulation of the left hippocampus produced recognition memory deficits for words, while right hemisphere was associated with face recognition deficits

63
Q

longer neural signal leads to _____ BOLD response

A

taller and longer BOLD response

64
Q

superposition

A

fundamental basis for block design

individual responses summate to yield a large response → large BOLD response

65
Q

how long is ideal for a block

A

10-20 seconds

allows enough time for the BOLD signal to go back to baseline so we can actually see signal

66
Q

pros of block vs event related design

A

block: easier to see overall signal

event related: easier to see shape per trial

67
Q

block design graph: why is there a dip

A

undershoots slightly from initial trials

signal from initial trials go back to baseline and drag the sum signal down

68
Q

owen et al.

A

infer cognitive function in vegetative state

had patients/controls imagine tennis, then imagine navigation (of living room)

tennis and navigation produce different patterns of activity, and patients and controls had similar activation for both tasks

69
Q

faces vs houses experiment

A

fusiform face area (FFA) activated more for faces than houses

parahippocampal place area (PPA) activated more for houses than faces

70
Q

problems of longer blocks

A
  1. sagging caused by undershoots summing together (dip in graph)
  2. lots of noise at low frequences of stimulation, therefore we want a higher frequency (shorter blocks so that noise is a diff frequency than signal)
71
Q

houses and faces experiment: what does alternating showing houses and faces do

A

prevent practice/habituation effects

resulting signal reveals main differences in activity b/w block types

maximizes ability to detect differences in activity at the expense of detecting absolute activity

72
Q

what if we wanted to detect absolute activity with block design?

A

include low-level baseline condition (fixation) b/w our two block types of interest

signal reveals activity for each block type and differences in activty b/w the two block types

73
Q

pros and cons of block designs

A

pros: big signals (summed activation), large signal relative to noise is easier to detect

cons: if subject makes mistake, hard to get rid of just one trial, cant separate activity (male faces vs female faces)

74
Q

slow event related designs

A

present 1 trial every 16-20 seconds to isolate BOLD signal to each stimulus/trial

75
Q

cued stroop task

A

double dissociation:

ACC activated when there is conflict/incongruent

DLPFC activated more by attention (ink color)

76
Q

why would you want to go faster with event-related designs?

A

subjects get bored

77
Q

linearity assumption

A

if things add up, you can go faster

if not, BOLD responses differ depending on whether going fast or slow

degree of sub-linearity referred to as a “refractory effect

78
Q

2 design types of event-related design: rapid unjittered

A

randomized trial order, spacing b/w trials is consistent

can see difference b/w conditions, but not how much it changes relative to baseline since baseline isn’t measured

79
Q

2 design types of event-related design: rapid jittered

A

vary spacing between trials to get more baseline activity measurements

80
Q

wagner et al.: recognition memory

A
  • participants saw 80 word trials in rapid jittered design
  • fixation trials added to create jitter
  • asked if word is abstract or concrete, then did recognition test late
  • results: they could predict which words subjects would remember (words w/ more activity)
81
Q

functional connectivity

A

if activity in two regions is correlated across time, then these regions may be communicating

82
Q

functional connectivity: flanker/ stroop tasks

A

more connectivity b/w ACC and DLPFC in incongruent trials than congruent trials

83
Q

preprocessing of fMRI data

A

gets rid of variability in bold signal that is not due to the task

84
Q

5 parts of preprocessing

A

slice-timing

realignment

coregistration

normalization

smoothing

85
Q

slice timing: different way of collected slices in each TR?

A
  • interleaved: all odd or even slices taken first
  • ascending (1,2,3,4,….): start at bottom of brain
  • descending (24,23,22,…): start at top of brain
86
Q

slice timing: SPM assumes…

A

each scan is instantaneous

87
Q
A

green curve: comes from slice collected latest because it is farther along in the BOLD signal sooner than the blue curve

88
Q

slice timing correction

A

since later slices are shifted left, need to shift slices right to align everything with first slice

89
Q

slice timing only needed if

A

temporal dynapics of BOLD responses are important (event-related designs)

if TR is small enough (< 3 seconds)

90
Q

realignment

A
  • correct for motion of participants’ head during the scan
91
Q

different types of motion

A

pitch, roll yaw

92
Q

normalization

A
  • stretch and warp each participant’s brain to match a template brain
93
Q

smoothing

A

replace the intensity value of a voxel w/ a weighted average of its original value plus the neighboring voxels

94
Q

why do we smooth

A

to increase signal to noise ratio

to increase chance of seeing common activation b/w subjects