8 - cognitive control and inhibition

Question 1

what is cognition?

Answer 1

• basis for ‘intelligent’ behaviour
• overrides reflexive, habitual responses in favour of complex, long-term goals
• key neural structure in mammals: prefrontal cortex

Question 2

what is the difference between cognitive control and executive function?

Answer 2

often used interchangeably

executive functions used for more specific components e.g. working memory

cognitive control has less clear separation of distinct subcomponents

Question 3

features of cognitive control/executive functions

Answer 3

• top-down mental processes
• requires effort or attention
• core (e.g. WM) vs high-order (e.g. ToM) abilities

Question 4

what is working memory?

Answer 4

holding information in mind and mentally working with it

Question 5

what is cognitive flexibility?

Answer 5

changing perspectives or approaches to a problem, flexibly adjusting to new demands, rules, or priorities

requires or builds on other executive functions

measure using Wisconsin card sorting task

Question 6

what is Wisconsin card sorting test?

Answer 6

measures cognitive flexibility

cards with different symbols and colours

participant presented with card, they have to decide which category of cards it fits into

receive feedback on whether it was correct or wrong

correct category changes at some point, participant has to adapt

key measure is perseveration errors (number of times participant kept choosing ‘old’ category)

Question 7

what are current challenges with the Wisconsin card sorting test?

Answer 7

• neurological damage is unique in each patient
• studies attempt to identify more localised involvement
• solving task doesn’t only involve cognitive flexibility

Question 8

what is inhibition?

Answer 8

controlling one’s attention, behaviour, thoughts and/or emotions to override a strong internal predisposition or external lure

some say simply strengthen specific thoughts and actions

others say we strengthen some and inhibit alternative actions and thoughts

Question 9

how do response times effect inhibition?

Answer 9

shorter response time = impulsive, incorrect responses

longer response time = thoughtful, correct responses

successful inhibition is suppressing prepotent response, waiting for correct response to come

Question 10

what is the key function of the frontal lobe?

Answer 10

to inhibit automatic and habitual behaviour

• seen in neurological studies on frontal lobe damage
• seen in utilisation behaviours (give object to patient with use, they use it even if they don’t need it)

Question 11

what is the difference between directed and competitive inhibition?

Answer 11

directed - explicitly told not to do something

competitive - many actions competing and inhibiting one another

Question 12

what are the core executive functions?

Answer 12

working memory
inhibitory control
cognitive flexibility

generally relate and connect each other in different ways, cannot be separated

Question 13

what is behavioural inhibition?

Answer 13

stopping physical actions

Question 14

what is cognitive inhibition?

Answer 14

stopping mental processes

inhibiting memories, thoughts, perceptions, emotions

Question 15

what are types of behavioural inhibition?

Answer 15

deferred gratification (stop impulsive choice)

response inhibition (stop impulsive action)

reversal learning (allows for flexibility)

Question 16

what is reaction time?

Answer 16

time between onset of stimulus and onset of response

varies across individuals and repetitions

Question 17

what drives variability of reaction time?

Answer 17

the slope of the process

Question 18

what is the neurophysiology of reaction time variability?

Answer 18

neurons in frontal cortex indicate that reaction times vary due to rate variability in slope of underlying process

before movement onset neuron sharply increases firing rate

difference is in the slope of the firing rate (process)

Question 19

how is inhibition measured?

Answer 19

using behavioural tasks
e.g. go/NoGo task, stop-signal task

Question 20

what is a Go / NoGo task?

Answer 20

participant needs to respond to some stimuli (Go stimuli), but not to others (NoGo stimuli)

measure reaction times and number of correct Go and NoGo trials

Question 21

what are limitations of the Go/NoGo task?

Answer 21

easy task

general in terms of inhibition, not specific

Question 22

what is the stop-signal task?

Answer 22

participants receive a go signal - “go” trial

occasionally receive a stop signal where they should refrain from responding - “stop” trial

key parameter is stop-signal delay (time between go and stop signal)

Question 23

how does stop-signal delay effect response?

Answer 23

short delay is easier to inhibit because response not yet imminent

long delay is harder to inhibit because response is imminent

Question 24

what is measured in the stop-signal task?

Answer 24

reaction times (of go trials and failed stop trials)

number of correct/error trials (% of correct and failed stops)

but never claps = 100% success rate on correct stops

can be used to calculate stop-signal reaction time (SSRT)

Question 25

what is stop-signal reaction time a measure of?

Answer 25

reactive inhibition - how quickly participants can react to stop signal

includes all 3 components of stopping: stimulus detection, action selection, inhibition

Question 26

what is the stop-signal reaction time?

Answer 26

the time it takes for an individual to successfully stop a planned action after stop signal is presented

Question 27

what is the race model of stopping?

Answer 27

stopping can be modelled as a race between two processes:
- one representing response (“go process”)
- another representing inhibition (“stop process”)

process that reaches threshold first determines behaviour

Question 28

how is the stop-signal reaction time estimated?

Answer 28

using “go” reaction time and stop-signal delay

Question 29

what is reactive inhibition?

Answer 29

the ability to quickly react to the stop-signal

Question 30

what is proactive inhibition?

Answer 30

the ability to adjust behaviour in anticipation of potentially having to inhibit a response

we can prepare to stop by exerting proactive control

Question 31

how is proactive inhibition measured?

Answer 31

change in reaction time in Go trials

using stop-signal task, provide information on the probability of the stop-signal

Question 32

what are clinical examples of impaired stopping?

Answer 32

Parkinson’s disease
Alcohol dependence
methamphetamine abuse
cocaine abuse

all see longer SSRTs

Question 33

what happens in Parkinson’s disease?

Answer 33

• death of dopaminergic neurons
• severe motor symptoms
• longer SSRT