6 Executive Function Notes

EXECUTIVE FUNCTION

1. Frontal lobe lesion and the Supervisory Attentional System (humunculus)

e.g, Phineas Gage

1. Patients with F lesion cannot switch between rules Milner (1963) Wisconsin Card Sorting Test (WCST) patients with frontal lobe injury carried on sorting the cards according to the old rules, while patients withT/P/OF lesions did not. However, WCST can tap into other cognitive processes (inhibition inhibit previous set etc.)

2. Patients with F lesion perform badly on combined tasks rather than individual: Shallice & Burgess (1991) – 6ET: they fail to disengage from one task and move to another (which is necessary for completing a task in a limited amount of time)

3. Shallice & Norman (1980) SAS explains routine vs. non-routine situations by schemas which compete by inhibition and contention scheduling. Eg, explains utilization behaviour (the hammer, nail, and picture example - Lhermitte).

2. An ‘army of idiots’ perform the control ascribed to the humunculus (convergences and divergences between behavioural and neuropsy)

   1. Behavioural data: Miyake (2000) argue that we have 3 basic executive functions: shifting, updating, inhibition based on data coming from patients with F lesions who performed 9 tasks (Task Switching etc) Factor Analysis

   2. Neuropsychological data: Stuss (2007) mPFC is energising (but monitoring & task setting correspond to Miyake) [Counting Stroop Task]

   3. Neuroimaging data:

Carter (1998) ACC (ↄmPFC) is involved in “error detection” AX-CPT task

Bush (1998) ACC is involved in “conflict detection” Counting Stroop Task

Grinband et al (2008) gives a potential resolution to the inconsistency: They found that ACC activation is linked to time on task, arguing that there is a possible role for ACC in evaluating effort associated with a choice (ACC is sensitive to the amount of effort involved in task performance) – fits more in with the “energizing” idea, but ACC resolves action selection during situations involving conflicting sensory infoerrors, conflict detection

Can you decode cognitive functions by looking at patters of activation in the Left Lat. PFC and Right Lat. PFC?

Left Lat PFC + P: Kim meta-analysis (2012), Bode (2009) – activation in P before lat PFC partial support for the idea that left lateral PFC involved in task setting/ switching. Neuroimaging studies reveal a more distributed system including right lat PFC and inf P.

Aaron (2003) role of Right Lat PFC in inhibition, but might be due to a role in attention & partly due to e role in response control. Dodds (2011) revealed a role in integrating of bottom-up, sensory information with top-down, response-related information to facilitate flexible, goal-directed behaviour, so it might play a more general role in response control.

Attentional account may resolve the apparent discrepancy with the neuropsychological ‘monitoring’ account (Stuss, 2007): Monitoring for behaviourally relevant stimuli and adjusting behaviour based on that information. Connectivity with other brain regions suggests dual role in attention and action is plausible: Right inf PFC is connected to sensory processing regions and motor control regions, so it might act as an interface between attention and response control.

3. The Unity of Executive functions – The Multiple Demand System Neurons have adaptive coding properties: They adapt to code relevant information for what is the most behaviourally task relevant and events that are in attentional focus.

Freedman et al. (2001) dynamic flexible change in the properties of a neuron from one task to another

Stokes (2013) PFC neurons adapt their properties within a single trial to represent different types of information

Goal neglect patients are unable to follow tasks and organize behaviour, so the attentional episodes fall apart.

4. The role of other regions in cognitive control

   1. frontopolar cortex (BA10) gateway function, controlling the ability to switch between internal and external information

   2. orbitofrontal cortex role in emotion and decision making: integrates information about reward, shaping voluntary actions in a way that you undertake those actions more in the future to obtain reward.

   3. basal ganglia Parkinson Disease reveals gating role of basal ganglia in motor control and executive function: (they have a problem in attentional switch task (shift from colour to shape) Basal ganglia enables preparing/updating motor plans +WM representations, goal representations from PFC, acting like a switch.

Goal-oriented behaviour (i.e., behaviours that allow us to interact with others in a purposive manner), and adaptive behaviour (depending on the changes in the environment) has been attributed to ‘executive control’ (=functions that allow people to adjust behaviour according to higher-order goals and plans).

These functions are critical in everyday life, as they allow us, for example, to resist temptations, overcome habits, or replace actions when required (e.g. when you are driving a car and a pedestrian unexpectedly crosses the street).

1. Frontal lobe injury and the Supervisory Attentional System

Phineas Gage: a metal rod penetrated his frontal lobe, but he survived. Deficits: personality and higher functions (controlling + organizing behaviour to act in a socially appropriate way). Abilities: communicate etc.

a) Patients with F lesion cannot switch between rules: Milner (1963) asked patients with a variety of different lesions: DLPFC (dorsolateral PFC), T/P/OF to perform Wisconsin Card Sorting Test (WCST), which involved deducing the correct sorting criterion (colour/shape/number) based on feedback and to flexibly switch sorting rules when feedback indicated that the sorting criterion has changed). Patients with F lesions carried on sorting the cards according to the old rules when the rules were changed couldn’t switch between the rules.

*However, WCST can tap into inhibition (inhibit the previous set), attention (attend to the relevant information), WM (remember the...

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