Neuropsychology PSYC-3220 Executive Function PDF

Neuropsychology PSYC-3220 Executive Function & Higher-Order Thinking Sebastien Paquette - 2024 Today: Executive Function and Higher-Order Thinking Executive Function: Executive function refers to skills you use to manage everyday tasks like making plans, solving problems and ad...

Neuropsychology PSYC-3220 Executive Function & Higher-Order Thinking Sebastien Paquette - 2024 Today: Executive Function and Higher-Order Thinking Executive Function: Executive function refers to skills you use to manage everyday tasks like making plans, solving problems and adapting to new situations. These skills develop during your lifetime, often declining as you get older.  Think What do you think is the purpose(s) of the human brain evolving executive functioning skills? The Human Lateral Prefrontal Cortex FIGURE 11.2 (from Badre and D’Esposito, 2009)  Theoretical Perspectives of Executive Function Regardless of theoretical perspective, controlling behaviour toward a goal is a signature aspect of executive function. The frontal lobe plays a prominent role. Executive function, also known as cognitive control, is a process by which one guides or controls one’s thoughts (and actions). Control is a central idea in executive function.  Controlled vs. Automatic Processes Shallice (1982) suggested a two-component system: 1. Contention scheduling: a cognitive system that enables automatic processing that has been learned over time. 2. Supervisory attentional system: the cognitive system required to effortfully direct attention and guide action through decision processes.  Executive Function and Frontal Lobe Damage Frontal lobe damage disables the supervisory attentional system, leaving actions to be governed by contention scheduling. A person will appear disinhibited and unable to control behaviour or urges, including those in the social realm. Their behaviour can sometimes be triggered by environmental stimuli (environmental dependency syndrome). They often repeat the same action (or thought) over and over again (perseveration). Environmental Dependency Syndrome FIGURE 11.1  Controlled Behavior Stuss and Benson (1986) suggest the frontal lobes are important in regulating behaviour in nonroutine situations or where behaviour must be carefully constrained. Their model links the degree of control to particular neural substrates hierarchically: At the lowest level, sensory information and simple tasks are automatically processed by posterior brain regions with little daily variation. The next level of control is associated with the executive functions of the frontal lobe. (sensory information adjusted to reach a goal). Highest level – involves self-reflection and metacognition. (relationship of the self and the environment – how to act in the world).  Goal-Centered Processing Executive control allows one to guide behaviour toward a goal. Some models (based on A.I. work) suggest the brain computes subgoals to reach a goal. Emphasizes the role of PFC in creating a hierarchical goal list. Other models suggest the PFC sends biased signals to other brain regions depending on the current goal and context. Emphasizes the role of PFC in maintaining the task goal.  Multifactor Models The unity and diversity model has three components: 1. The ability to main task goals, especially in the face of distraction 1. The ability that allows switching from task to task 2. Allowing the system to reset information in working memory to move to the next subgoal Another model suggests three types of executive abilities: 1. Initiating and sustaining a response (medial frontal regions). 2. Task-setting (left lateral regions) 3. Monitoring (right lateral regions)  Goal-Directed Behaviors Guiding behavior toward a goal is multifaceted Losing any facet of goal-oriented behaviour can derail the entire plan Completing a task involves several skills: Staying on task Sequencing information Modifying strategies Using knowledge in your plans Monitoring actions  Think Using the skills needed for goal-directed behaviour (see previous slide), describe a scenario where you go to the store to buy something to eat or drink.  Executive Dysfunction and Psychological Inertia Executive dysfunction can cause psychological inertia. It is hard to start an action, but once engaged, it is equally hard to stop. Damage to medial frontal regions, including the supplementary motor area and anterior cingulate Evidence suggests that regions of the medial prefrontal cortex determine how much “effort” will be exerted to reach a goal.  Executive Dysfunction and Psychological Inertia GREEN CIRCLE: ANTERIOR CINGULATE/Pre-SMA Regions of the anterior cingulate involved in calculating the degree of effort required to obtain an outcome FIGURE 11.3  Frontal Lobe and Inhibition Some theories argue for a special mechanism of inhibitory control that relies on regions of the right inferior frontal cortex. These regions are involved in overriding or inhibiting responses (especially when they are well-learned) and aborting or terminating responses. Other theories argue that inhibitory control is just an example of when one must maintain a task set under difficult conditions or when there are competing demands.  Go/No-Go Task The person responds by pushing a button when certain visual stimuli appear (Go trials) and withholds response to other stimuli (No-Go trials). Response inhibition is difficult when the No-Go trials are relatively rare because Go responses are expected. In neuroimaging studies, withholding a response has consistently been found to engage a right-sided network of regions, including the right middle and inferior frontal cortex, the pre-SMA, and the parietal cortex.  Stop-Signal Task The person must respond as quickly as possible to a stimulus on the screen. However, in a minority of trials, very shortly (e.g., one-quarter of a second) after the stimulus is presented, another signal (e.g., auditory tone) occurs. This tone indicates that the response should be aborted. This task activates an extensive network of brain regions, spanning (dorso)lateral prefrontal cortex, the anterior cingulate, SMA, pre-SMA, insula, and parietal regions.  Inhibition Lateral PFC may also play a role in inhibitory control. Studies of patients and neuroimaging studies indicate that inhibition is associated with increased demands on cognitive control and working memory, activities supported by the lateral prefrontal cortex. From this perspective, response inhibition may be a specific example of a more general function: interference resolution.  Creation and Maintenance of a Goal A basic prerequisite for meeting a goal is the ability to stay on task, which is disrupted in patients with frontal lobe damage. The creation and maintenance of a goal or plan relies on many regions of the PFC, the dorsolateral prefrontal cortex being prominent among them. The ability to sequence items appears to rely on the DLPFC Many regions, including the dorsolateral, inferior, and medial prefrontal regions, support set-shifting.  Sequencing and Planning To reach a goal, one must determine what steps to take and in what order to take them. Requires knowing what comes before and what comes after Neurons in PFC can distinguish between those tasks that have just been accomplished versus those tasks that are about to be performed Dorsolateral prefrontal regions may be important in these tasks because they support executive processes that act on information being maintained in working memory Self-Ordered Pointing Task This task reveals deficits in sequencing. Deficits on this task are observed after frontal lobe damage, most notably lateral damage. These regions are also active in neurologically intact individuals when they must make a recency judgement.  Self-Ordered Pointing Task FIGURE 11.5  Choosing a Sequencing Strategy Another important aspect of sequencing behaviour is the ability to choose which sequence or strategy best allows a goal to be attained. Patients with frontal lobe damage are less likely to report that they use strategies, One task used to assess strategy is the Tower of London. Tower of London Task (from Newman et al., 2003) FIGURE 11.6  Try.. Who wants to try the Tower of London Task?  Sequencing and Planning Some research suggests that each hemisphere plays somewhat of a complementary role in planning and sequencing. The left hemisphere is more involved in creating subgoals The right hemisphere is more involved in considering the relationships between those subgoals. Integrating these two modes of planning is also essential. The degree of interhemispheric white matter connecting the left and right prefrontal regions predicts how well people perform on the task.  Task-Switching The path to a goal is not always a simple linear progression Often, some unexpected twists and turns require task-switching The classic neuropsychological test used to examine task- switching is the Wisconsin Card Sorting Test (WCST) Neurologically intact people adjust their responses accordingly People with executive dysfunction perseverate  Wisconsin Card Sorting Test FIGURE 11.7  Task-Switching and the Brain A variety of brain areas are activated during performance of the WCST, including: DLPFC, ventrolateral prefrontal cortex, the inferior parietal lobe, temporoparietal association cortex, and the basal ganglia. Task-switching is likely directed by an executive control system independent of the systems that perform each task. Task-Switching and the Brain Patients with left frontal lobe damage have a specific deficit in task-switching. Conversely, increasing activity over the left DLPFC via transcranial direct current stimulation can augment task- switching abilities. Meta-analyses of brain imaging studies also implicate the inferior frontal junction in task-switching. Task-Switching and the Brain The location of the inferior frontal junction has been shown to play a prominent role in switching between two tasks FIGURE 11.8  Another skill: Self-Monitoring and Evaluation Not surprisingly, the ability to evaluate one’s behaviour is affected by frontal lobe lesions. Metacognitive awareness is disrupted in patients with left or right frontal lesions. Frontal damage, especially right frontal damage, impairs the ability to detect errors and modify ongoing behaviours to take corrective action. Error-Related Negativity (ERN) It occurs approximately 100 ms after an error. Amplitude increases under conditions in which response accuracy is emphasized. The larger the error, the larger the amplitude of the ERN. Various converging evidence suggests that the ERN component arises from the rostral regions of the anterior cingulate. Error-Related Negativity FIGURE 11.10 (Taylor et al., 2007).  Self-Monitoring and Evaluation We have a particular set of brain mechanisms that helps to monitor our performance and detect errors. One initial suggestion was that the anterior cingulate detects that an error has been made. However, other evidence suggests that an ERN can still be detected even when a person is unaware of an error. Hence, the ERN is just providing a relatively undifferentiated signal that something is amiss. Self-Monitoring and Evaluation Instead, awareness of an error is indexed by another component, the error positivity (Pe), which frequently follows the ERN by about 200–300 ms. The source of this component remains unclear, but it may be generated in the insula, a brain region associated with interoception, the ability to sense the body's physiological condition. Error Positivity (from Hoonakker et al., 2016) FIGURE 11.11  Medial PFC and Errors The exact computation the medial prefrontal regions perform to detect and correct errors is currently a source of debate. One viewpoint is that the medial PFC monitors for conflict. Other theories argue that the medial PFC determines whether exerting control is worth the effort and cost in a given situation. Still, others argue that it calculates the difference between an action's expected and actual outcome, whether positive or negative. Self-Monitoring and Evaluation Different regions of the cingulate may be involved in the prediction of the outcome of an action as compared to the evaluation of the outcome. Differences among people influence error monitoring and evaluation systems in the brain: Anxious people show an increased ERN Individuals with ADHD show decreases in the ERN and Pe.  Higher-Order Thinking Executive function is often conceptualized to include a set of abilities known as higher-order thinking. This term describes more complicated aspects of thought: Being able to think in an abstract and conceptual manner The ability to deduce rules or regularity and The ability to be flexible and respond to novelty.  Higher-Order Thinking One deficit exhibited by patients with executive dysfunction is an inability to process material in an abstract manner. When reading metaphorical sentences, activity is greater in many areas of the prefrontal cortex compared to reading literal sentences. Another way to examine the issue of abstract thinking is to investigate analogical reasoning. Non-Verbal Analogical Reasoning Problems FIGURE 11.12  Reasoning and the Brain Various regions are activated during analogical reasoning, regardless of whether verbal or visuospatial problems are solved. These include the frontopolar and dorsolateral prefrontal regions, anterior insula, and parietal cortex. Distinct areas in the frontopolar cortex activate for visuospatial analogies as compared to semantic analogies. This pattern suggests common mechanisms for such reasoning and more specific regions that vary with problem type (i.e., spatial, verbal).  Reasoning and the Brain A rostrolateral (frontopolar) region in the left hemisphere that has been implicated in reasoning FIGURE 11.13 (Hobeika et al., 2016)  Making Rules and Inferences Several PFC regions, along with their interactions with the posterior cortex, are required to use rules to guide actions. Ventrolateral PFC is needed to retrieve knowledge of rules. DLPFC is involved in selecting or influencing how rules should be used to guide responding either directly or because it holds rules in working memory. Some theorists suggest that in certain situations, problem-solving is better without the PFC, as it allows for enhanced creativity by not following rules. Making Rules and Inferences Stimuli used to demonstrate the role of the prefrontal cortex in a nonverbal inference task FIGURE 11.15  Response to Novelty Novelty is an event, situation, or action with a low probability of occurring given a particular context. The ventral attentional system is proposed to allow novel stimuli to capture attention. Electrophysiological studies also implicate frontal regions as playing an important role when a novel stimulus captures attention.  Response to Novelty *P3a *NOVEL – red line Evidence for the role of prefrontal regions in novelty. *P3b *RARE – blue line line FIGURE 11.17 (from Polich, 2007) *P3a: earlier and more frontal  Cognitive Flexibility People with executive dysfunction have trouble being cognitively flexible, which means they have trouble evaluating situations in various ways and/or producing various behaviours. Flexibility is required in novel situations and when a new reaction must be made to an old situation. The orbitofrontal cortex is implicated in helping with flexible behaviour (e.g., reversal learning) The frontopolar cortex helps reorient potential task goals toward novel situations or opportunities.  Judgment and Decision Making Executive dysfunction compromises judgment and decision-making abilities, and research has shown: The frontopolar cortex is important for abandoning the current strategy and trying a new one Medial orbitofrontal regions calculate present vs. future rewards Research uses the delay discounting paradigm (intertemporal choice task) DLPFC is engaged when an individual must overcome the temptation to take an immediate reward Working Memory and Executive Function The DLPFC may play a central role in executive function because it supports working memory: Working memory needed: To keep a goal in mind To understand timing and relationships between items and events. To create and follow rules, make inferences, and/or understand the relationships between items in the world  Lateral PFC Organization for Executive Function Model 1: A nested hierarchy of control from caudal to rostral regions of the frontal cortex Posterior influenced by immediate aspects of a situation Anterior affected by the larger context. Model 2: A hierarchy based on the nature of representations competing for control over action selection. Posterior selects actions based on concrete dimensions Anterior selects actions based on abstract dimensions  Lateral PFC Organization for Executive Function Conceptual models of organization FIGURE 11.18 (from Badre, 2008)  Medial and Lateral PFC FIGURE 11.19 Conceptualization of how lateral and medial PFC regions exert executive control via a cascade of control, from stimulus input to response output.  Reflection How could you explain to someone not taking this course why working memory and executive functioning are related?