cognitive control - inhibition Flashcards
define inhibiton
controlling ones attention, behaviour, thoughts, and/or emotions to override a strong internal predisposition or external lure
not simple stimulus-response driven, contextual response
define flexibility
changing perspectives or approaches to a problem - flexibly adjusting to new demands, rules, priorities → switching between tasks
large range of behaviours applied to contexts flexibly → experiment participation where you respond to stimuli and follow and adapt to task rules
define multi-tasking
some tasks can be done in parallel if they don’t “collide” → related to attention, can they be done on “auto-pilot”
related to working memory
3 main features of cognitive control
inhibition
flexibility
multi-tasking (working memory)
what is cognition
basis for intelligent behaviour
overrides reflexive, habitual responses in favour of complex often long-term goals
cognitive control of: sensory, memory, and motor system
in prefrontal cortex in mammals
difference between cognitive control and executive function
executive functions = specific components e.g. working memory
cognitive control= less clear separation of distinct subcomponents
both are top-down mental processes (not stimulus-driven bottom-up ones)
requires effort or attention
cognitive control – core/basic abilities and higher-order/insight-related abilities
core/basic abilities = working memory, inhibitory control, flexibility
higher-order/insight-related = object permanence, self-recognition, mental time travel, ToM, tool use, causal reasoning
are different executive functions connected?
role and importance of EFs (7)?
questioned whether they can be entirely separated or work together
unknown if they are hierarchically structured
importance of EFs:
* impaired in mental disorders e.g. addiction, ADHD, OCD, depression, SZ etc
* poor EF associated with obesity, overeating, substance abuse
* idea that goof EF = better quality of life
* better school readiness and success
* job success
* marital harmony
* public safety
multicomponent model of memory
central executive
VSSP, episodic buffer, phonological loop
LTM
cognitive flexibility + task to test this
builds on other executive functions e.g. inhibition of previous perspective and loading new perspective into working memory
Wisconsin card sorting task
* task = draw a card and assign to a category to match colour, number, or symbol of another card
*given feedback on whether it was correct or not based on current rule (unknown to them)
* if correct, draw same category again
* if wrong, try another category
* “correct” category will change without warning so participant has to change behaviour in order to find correct category to match
people with some impairments struggle with this → e.g. frontal lobe damage, SZ, stroke, OCD
challenges studying cognitive flexibility
neurological damage is unique to each patient
studied to identified localised involvement
solving task doesn’t only involve cognitive flexibility but also other aspects of EF
inhibition – selecting appropriate thoughts and actions
strengthen appropriate response and inhibit other inappropriate ones
impulsivity related to deficient inhibitory processes
role of frontal lobe in inhibition
inhibit automatic and habitual behaviour
also basal ganglia does this
shown by neurological studies on frontal lobe damage and utilisation behaviour (e.g. given glasses and see if they put them on correctly)
directed vs competitive inhibition
directed = don’t do behaviour X e.g. stop driving at a red light
competitive = many actions competing and inhibition each other
cognitive control stopping mechanisms
put a brake on inappropriate responses
to mediate goal-directed behaviour and self-control
related constructs to inhibition (2)
self-control
* impaired common in many clinical disorders e.g. OCD, drug-addiction, gambling
* value-based decision making and delay discounting
attention
* similar to aspects of cognitive control → selecting/prioritising some processes over others
* often sensory → therefore more automatic than CC and EF
* other strategic forms may involve different mechanisms than sensory attention
importance of inhibition in wider context (4)
- describes behaviour, decision-making, and cognitive processes
- measuring inhibition is important for some diagnoses
- related to clinical and developmental and neuroscience
- related to AI and robotics
examples of inhibitory control (2)
driving in lots of traffic and phone rings/text message
* default = keep driving
* context = if you’re expecting an important call you are more likely to park or check the message
marshmallow test with kids
* long term or short term gain
2 types of inhibition
behavioural inhibition = stopping actions
cognitive inhibition = stopping mental processes
overlapping brain processes from imaging studies for both of these processes
3 types of behavioural inhibition
deferred gratification → impulsive choice → marshmallow test, linked to delayed gratification
* delay discounting, probability discounting, effort discounting
response inhibition → impulsive action → not answering phone whilst driving
* action postponing (waiting), action restraint/withholding, action cancellation (stopping)
reversal learning → inflexibility, compulsivity → stop understanding of one situation and think of new instead e.g. Wisconsin card sorting task
* discrimination reversal, rule/strategy reversal
cognitive inhibition
difficult to understand and study
control of movement is similar to control of ideas
movements can be described and measured more precisely than ideas → can study principles and mechanisms of cognitive inhibition through studying motor response inhibition
* overriding planned or already initiated actions
inhibition and EF
voluntary inhibition → is it a component of executive control?
current view = EFs require one another so combination or attention, inhibition, and flexibility allows complex behaviours
inhibition and attention together for selection of new goals, shifting of focus, performance monitoring and updating goals
impulsivity, compulsivity, and distractibility can inhibit parts of this process
inhibition and impulsivity
acting quickly can be advantageous but doing this persistently can be risky and maladaptive
impulsivity = deficient inhibitory process
link to addiction, ADHD, mania etc.
response inhibition used to measure impulsivity in lab tasks
although response inhibition only corresponds to some types of impulsivity → not all types
use animal studies of response inhibition for neural mechanisms → quantifiable
reaction time distribution
reaction time = time between onset of stimulus and response
contextual - depending on stimulus type
distribution = positive skew
race model of reaction time
linear function used to represent a trial
faster = steeper line
x = time, y = position (activation of process)
horizontal threshold - faster response crosses this threshold first
slope of process and threshold = model parameters
choose parameter values to fit behavioural data from given participant
average out over many trials
(look at notion for graphs if needed)
neurophysiology of reaction time variability
*recordings of frontal eye fields of monkeys performing reaction time task
* frontal cortex neurons indicate reaction times vary due to rate variability in slope of underlying process
* measuring single neuron in multiple trials
result shown in a line graph of average firing rate:
* time 0 = onset of movement (saccade)
* before onset = neuron sharply increases firing rate
* firing rate when movement begins = threshold for action
no difference in threshold for action
fast trails have difference in slope of firing rate increase to slow trials - fast = steeper slope
reflected in race model
4 behavioural tasks to measure inhibition
stroop task
marshmallow test
go/nogo task
stop-signal task
go/nogo task
participants must respond to a go signal and not to a nogo signal e.g. traffic lights where green is go and red is stop
assignment of go and nogo are arbitrary - depends on task instructions
measure reaction times and number of correct trials
stop-signal tasks
2 trial types:
go → green = clap
stop → green followed by red = don’t clap
random order so stop signal cannot be predicted
different variants of a stop-signal task with different stimuli, responses, and trial types
stop-signal delay
time between go and stop signals → shorter stop-signal delays make stopping easier
short delay (~200ms) = response not yet imminent = easier to inhibit
long delay (~800ms) = closer to action, harder to inhibit response = imminent responses are harder to inhibit
SSRT
stop-signal reaction time
how quickly participant reacts to stop signal → reaction is the inhibition of behavioural response
cannot directly measure as you cannot measure not doing anything → but can estimate it using reaction time models and stop-signal tasks
behavioural data in stop-signal tasks - basic and advanced measures
basic measure:
* reaction time in go trials and failed stop trials
* number of correct or error trials → % correct stops and % failed stops
issue of waiting strategies → never clap = 100% success rate on correct stops so need more info
advanced measures:
* inhibition functions = probability of motor response based on stop signal delay
* stop-signal reaction times
intuition for stop-signal reaction time
cannot directly measure stop signal reaction time but can estimate SSRT:
if stop-signal reaction time is 100ms:
* 100ms is needed to make use of stop-signal
* response within 100ms of stop-signal cannot be stopped
* later than 100ms after signal can be stopped
know this based on reaction time distribution
failed stops
* reaction times in (empirical) failed stop trials are mostly fast → inline with consideration from stop-signal reaction times
SSRT - 3 components of stopping
stimulus detection
action selection
inhibition
SSRT - what type of inhibition do they measure
SSRT - describe how well you can inhibit response
reactive inhibition → speed of reacting to stop signal (not proactive inhibition)
common measure used in psychological studies on neurological and psychiatric conditions
race model of stopping
same model as race model of reaction time - includes a stopping stimulus with the go stimulus
if go reaches threshold first, action is carried out
if not, it is inhibited
repeating across many trials to find average → sometimes go will win and sometimes stop will win
steepness of stop doesn’t changed much between trials but go does vary
* stop fails = steep go processes (fast reaction time)
* stop succeeds = flat go process (slow reaction time)
SSRT = time between stop signal and it crossing the threshold
GoRT = time between go signal and crossing the threshold
* analogous to each other
using stop-signal tasks for modelling
- basis of computational models to provide estimate of SSRT from behavioural data
- mathematical - connects go and stop RTs, stop-signal delays, and stopping performance
- reaction times occur in go and failed stop trials
- SSRTs occur in stop trials, can’t be measured directly, estimated using behavioural data from many trials
- general model → describes behaviour and underlying cognitive and neurobiological processes
- application to different animals
- application to different types of stopping, stimuli, and tasks
- allows us to model inhibition functions – can be compared with patient populations or used in conjunction with imaging – fMRI, EEG
proactive vs reactive inhibition
reactive = quick reaction to stop signal
proactive = adjust behaviour in anticipation of potentially having to inhibit a response - prepared to stop
* visible as a change in GoRT
measure of proactive inhibition in stop-signal tasks
using explicit and implicit cues
explicit:
* given cue to indicate possibility of stop signal occurring or not occurring
* done trial by trial
implicit
* vary probability of stop signals across blocks
* e.g. block 1 has many stops, block 2 has very few stops
* needs to be randomised distribution of stop signals or it becomes predictable
define:
* trial
* block
* session
trial = single presentation of a stimulus-response sequence
block = many trials with specific parameters e.g. more or less stops depending on block
session = consists of one or more block, sessions separated by longer time intervals e.g. days apart
step by step measuring proactive inhibition with stop-signal
2 blocks studied
- average reaction times from go trials in block #1
- do the same for block #2
- calculate proactive inhibition score -> mean(RTblock#2) - mean(RTblock#1)
comparing speed of response to go trials are when there are more or less stop trials present
* more stops = slower response to “go” due to proactive inhibition trying to predict stop signals
counterbalance order of block sequence to account for order effects
proactive adjustment hypothesis
people adjust the response threshold when they predict stop signals – balance stopping and going
fast responses are harder to inhibit so they wait more to go in trials due to predicting potential stops
impaired stopping - parkinsons
death of DAergic neurons → therefore levodopa for treatment to increase DA
severe motor and cognitive symptoms
stop-signal tasks compare reaction times in patients with Parkinson’s
longer SSRT in patients compared to control
* no significant differences between those on or not on levodopa medication - so not DA related?
what causes impaired stopping - 3 examples
longer SSRTs than control for:
* alcohol dependence
* methamphetamine abuse
* cocaine abuse
