Cognitive Control

Cognitive Control: the intentional selection of actions, thoughts and emotions in accordance with current goals, context and task demands, as well as the concomitant suppression of those which are inappropriate

• Necessarily requires voluntary, goal-directed behaviour, but this is not the whole story

  • Simultaneous, competing goals

  • Interference from involuntary behaviours

  • Not limited to physical action

  • Sophisticated representation of environmental ‘rules of engagement’

• Comprises a range of processes we collectively refer to as executive functions

Executive Functions

• Working memory

• Choice and decision-making

• Planning

• Behavioural inhibition

• Resolving response conflict

• Task-switching

• Examples

  • Being patient and responding calmly when you’re frustrated

  • Staying focused on your study while resisting the urge to check social media

  • Keeping in mind you need to stop by supermarket on the way home

  • Preparing multiple elements of a complicated dish at once

  • Negotiating a good deal with the used car salesperson

  • Pulling attention away from your crocheting project in time to rescue your child about to leap from the dining table

Measuring and Modelling Cognitive Control

• Many tasks have been developed to assess cognitive control, they share the same common features:

  • ‘Rules’ dictate which instrumental contingencies hold in the presence of particular cues

  • Hold ‘rule’ in mind to disambiguate target cues that are associated with multiple outcomes

  • Apply these complex contingencies to determine the correct response

  • Exert control to make the correct action while inhibiting correct actions

• Examples of cognitive control tasks:

  • Stroop task

  • Continuous Performance Task (CPT)

  • Wisconsin Card Sorting Task

  • N-Back task

Stroop Task

• Rule: Name the colour or read the word

• Ambiguous cues: Colour words written in coloured ink

• Apply rule: Produce the appropriate colour name or word

• Conflict: for the ‘name the colour’ rule you must inhibit prepotent tendency to read words (fluent readers)

Modelling Cognitive Control

• Applied to Green in Red Font - Parallel Distributed Processing

• Presentation of this stimulus activates red colour pathway and the green word input activate pathway leading to response green

  • This is parallel activation

  • Word pathways should dominate - they are naturally stronger (hence why in bold)

Neural Substrates of Cognitive Control: The Prefrontal Cortext

• From patients with frontal lobe damage and fMRI studies, PFC is involved in:

  • Inhibiting inappropriate (but previously relevant) responses

  • Directing attention towards relevant over irrelevant stimuli (especially in unstable environments)

  • Flexibly adapting the ‘rules’ by which behavioural responding is governed

  • Manipulating information in working memory

  • Overcoming conflicting choices

• Neurons in the PFC are selectively activated to apply a ‘rule’ for responding

• Animals were trained on two tasks that were very similar

  • Difference was whether a rule was required to discriminate responding

  • Visual cue told them the rule for a future task they would have to respond

PFC in Cognitive Control (lecture 4)

• ‘Cue’ units: represent information about sensory inputs, motivational state, etc

• ‘Response’ units: represent possible behavioural response output

• ‘Hidden’ units: represent intervening stages of processing between input and output

• PFC can act via hidden units tot bias particular input-output pathways according to task demands

Further Localisation

• Dorsolateral PFC:

  • Important for holding in mind the ‘rule’

• Anterior Cingulate:

  • Important for executing response

• fMRI data is correlational data, so need to directly manipulate activity in PFC in cognitive-control tasks

Do animals use executive functions?

• Rats are capable of selective attention, behavioural inhibition, and task-switching

  • Impaired by lesions to the PFC

A rodent Stroop task?

• Rats receive training with conditional cues, which are then combined at test to create congruent and incongruent compound cues

• Correct responding can only determined by using contextual cues from the environment in which the compound occurs

• They are trained with auditory cue where they learn that they have to press left/right lever depending on context

• The conflict is introduced at test; they are presented with audio-visual compounds of the stimulus they received at training

• The animal has to use contextual cues to figure out which lever to click

• These elements activate pathways to opposing responses

• To bias processing in one of the opposing pathways - it needs to activate the relevant contextual units

Translational Potential

• Rats acquire both biconditional discrimination tasks to an equivalent degree

• Performance at test reveals contextual control of responding to incongruent cues

Response conflict in the PFC

• Pretraining lesions to the mPFC:

  • Do not impact learning of independent biconditional discriminations

  • Do not impact correct responding on congruent trials at test

  • Do impair correct responding on incongruent trials at test

• Rat mPFC is critical for resolving response conflict in a cognitive control task

Regional Selectivity: Anterior Cingulate

• ACC implicated in task performance (as opposed to preparation) from fMRI

• Pretraining lesions to the ACC:

  • Do not impact learning of independent biconditional discriminations

  • Do not impact correct responding on congruent trials at test

  • Do impair correct responding on incongruent trials at test - but only early in the stimulus presentation

• Rat ACC is critical for detection of response conflict

Prelimbic vs. Infralimbic

• DLPFC (PL): Implicated in the application of a ‘rule’ for responding

• Inactivation of PL:

  • Does not impact correct responding on congruent trials at test

  • Does impair correct responding on incongruent trials at test

• Inactivation of IL:

  • Does not impair correct responding on congruent or incongruent trials at test

• Rat PL cortex critical for being able to apply ‘rule’ information to resolve response conflict

• Verifies the correlational studies results

• Laid groundwork for theoretical ideas of how the sub-regions of PFC may coordinate to create cognitive control

Cognitive Control and Psychopathology

• Impairments in cognitive control can look like:

  • Issues with selective attention

  • Impulsivity/poor decision-making

  • Inability to maintain focus on a task

  • Lacking ability to flexibly adjust behaviour in accordance with task demands

• Some psychological disorders that feature impairments in cognitive control (’executive dysfunction’) include:

  • Dementia

  • ADHD

  • Schizophrenia

  • Addiction

Schizophrenia

• Disorder that causes significant impairment in the way reality is perceived

• Characterised by:

  • Positive symptoms: delusions, hallucinations (psychosis)

  • Negative symptoms: apathy, anhedonia, blunted affect

  • Cognitive symptoms: speed of processing, verbal fluency, memory, concentration, working memory, cognitive flexibility, behavioural inhibition

• Animal model:

  • Acute or chronic administration of drugs known to induce psychotic symptoms (e.g., ketamine; PCP) also produce many of the cognitive impairments seen in schizophrenia

• Acute ketamine administration impairs ability to use contextual cues to disambiguate responding in situations of response conflict

• Chronic PCP administration produces lasting changes in ability to use contextual cues to disambiguate responding in situations of response conflict

Addiction

• Addiction or substance abuse disorder, involves a pattern of drug use that causes significant distress or impairment and often includes:

  • The taking of escalating doses

  • Unsuccessful efforts to cut down/stop

  • Experience of craving, tolerance, and/or withdrawal

  • Continued use despite adverse consequences

• Chronic methamphetamine use is associated with:

  • Psychotic-like symptoms (delusions, hallucinations)

  • Impairments in problem-solving, inhibitory control, and decision making

• Animal model: Chronic methamphetamine exposure produces cognitive control deficits that persist after the drug has been discontinued

• The methamphetamine impaired performance in incongruent in trials

• Cognitive impairments in chronic methamphetamine use thought to be related to oxidative stress

  • Administration of antioxidants may ameliorate these deficits

  • Not a properly controlled experiments (it was not counter-balanced) - but still a promising indicator

Summary

• Cognitive control describes the intentional selection of actions, thoughts, and emotions in accordance with current goals, context and task demands, as well as the suppression of those which are inappropriate

  • Can be measured using tasks that require individuals to hold a ‘rule’ in mind in order to disambiguate target cues associated with multiple outcomes or responses (e.g., Stroop)

  • We can understand how this might work using the framework of a parallel distributed process model

  • Human case studies, fMRI, and neural recording investigations have identified the PFC as critical for cognitive control processes

• Using a rodent model of cognitive control we have been able to:

  • Provide experimental evidence that the PFC is causally involve in cognitive control processes

  • Aid in identifying functional disassociations between subregions of the PFC

    • Infralimbic/ventromedial PFC = promotes responding based on ‘weight of evidence’ from simple associative structures

    • Prelimbic/dorsolateral PFC = facilitates use of contextual/’rule’ information to provide flexible top-down modulation of behaviour

    • Anterior cingulate cortex = important for detecting response conflict