Attention and Executive Function

Attention & Executive Function

What is Attention?

Attention involves several psychological constructs:

  • Arousal: General state of readiness or alertness, influenced by factors like sleep, interest, and energy levels.

  • Vigilance: Ability to maintain focus on specific information over time; it varies across tasks and individuals.

  • Selective Attention: The process of choosing which information to focus on, given the constant flood of sensory input. Information not focused on is processed more slowly and with less detail.

Types of Attention

  • Overt Attention: Attending to something by looking at it directly.

  • Covert Attention: Attending to something mentally without moving the eyes.

Shifting Attention

  • Endogenous Attention: Intentionally (consciously) shifting attention from one thing to another (top-down process).

  • Exogenous Attention: When a stimulus automatically captures our attention (bottom-up attentional control).

Posner Cueing Paradigm

The Posner cueing paradigm is used to study voluntary and involuntary shifts in attention. In this task, participants focus their eyes on a central point, and an arrow indicates where a stimulus might appear. This tests endogenous control.

  • Endogenous Control: Participants intentionally redirect their attention based on the cue.

  • Exogenous Control: An irrelevant stimulus involuntarily captures attention.

Visual Search

  • Pop Out: Easily finding a single distinct feature.

  • Conjunction Search: More resource-intensive, requiring a combination of features to distinguish an object.

How We Discard Unattended Information

Inattentional and Change Blindness

  • Inattentional Blindness: Failure to notice obvious things in plain sight when attention is occupied elsewhere.

  • Change Blindness: Failure to notice obvious changes to the environment.

Information Processing

When we attend to something, information flows through increasing complexity:

  1. Rudimentary Processing: Edge and color detection.

  2. Complex Processing: Whole object descriptions and memory matching.

  3. Higher-Order Executive Functions: Decision-making.

Theories of Attentional Filtering

  • Early Selection Theory: Unattended information is filtered out early in the processing sequence, before much processing occurs. Evidence for this comes from the dichotomous listening task, where participants can only remember low-level details (e.g., pitch) about the unattended channel but fail to notice higher-order features (e.g., language).

  • Late Selection Theory: Information is discarded only after relatively late stages of processing. The cocktail party effect, where you can pick out certain words even when not paying attention, supports this theory.

  • Perceptual Load Theory: Attention has a limited capacity, allocated strategically across different information sources. With low-load tasks, spare resources shift to task-irrelevant information. High-load tasks consume most processing power, leaving little leftover.

The Neurocircuitry of Attention

Subcortical Regions

  • Reticular Activating System: Brainstem region crucial for sleep/wake cycles and overall arousal.

  • Superior Colliculus: Midbrain structure that helps direct eyes toward an object of attention.

  • Pulvinar: Located in the posterior thalamus, important for overt and covert attentional shifts.

Cortical Regions

  • Default Mode Network (DMN): Helps tune out the outside world for internally-directed cognitive processes like daydreaming. Includes prefrontal cortex (PFC) and posterior cingulate cortex (PCC). Less active when paying attention to external stimuli.

  • Dorsal Attentional Network (DAN): Responsible for endogenous (voluntary, top-down) shifts in attention, especially in goal-directed behavior. Includes the intraparietal sulcus (IPS) and the frontal eye fields (FEF).

  • Ventral Attentional Network (VAN): Responsible for exogenous (bottom-up) shifts in attention, particularly when responding to novel or salient stimuli. Includes the temporoparietal junction (TPJ) and the ventral frontal cortex (VFC).

Executive Function

Executive functions are processes that allow us to plan and achieve goals, maintain or shift focus, and prevent impulsive or inappropriate actions. Key areas are the dorsolateral prefrontal cortex (DLPFC) and orbitofrontal cortex (OFC).

Core Processes

  • Task Switching: Shifting between activities.

  • Sequencing: Breaking down tasks into ordered steps.

  • Inhibitory Control: Suppressing unhelpful thoughts or actions.

Inhibitory Control

Inhibitory control is the ability to suppress thoughts or behaviors that are often automatic.

Stroop Task

The Stroop task demonstrates inhibitory control. Participants name the color of ink a word is printed in, while ignoring the word itself. Incongruent stimuli (e.g., the word "RED" printed in blue ink) result in slower, more error-prone responses compared to congruent stimuli (e.g., the word "RED" printed in red ink).

J.R. Stroop, 1935

  • Congruent Stimulus: Stimuli match, leading to faster, more accurate responses.

  • Incongruent Stimulus: Stimuli conflict, leading to slower, more error-prone responses.

The anterior cingulate cortex (ACC) is implicated in control during Stroop task performance.

Pardo et al., 1990; Carter et al., 1995; Bush et al., 1998

STOP-Change Task

The stop-change task assesses inhibitory control in rodents.

  • GO: Rat presses lever on the side where the cue light appears for a sucrose reward.

  • STOP: A second cue light appears unexpectedly, signaling the rat to inhibit the initial response and move in the opposite direction.

Rats are more accurate and faster on GO trials than STOP trials. ACC neurons fire strongly during correct STOP trials.

Bryden et al., (2018) Cerebral Cortex

Nucleus accumbens neurons fire more strongly after correct trials.

Ashton et al., (2024) J. Neurosci

Attention Deficit Hyperactivity Disorder (ADHD)

ADHD is a complex condition characterized by difficulties with attention, hyperactivity, and impulsivity. Prevalence is around 5.3%, with boys diagnosed more often than girls (12.9% vs 5.6%).

Etiology

  • Genetics: Strong genetic component with heritability estimates between 70-80%. Research has identified at least 12 genome-wide risk loci.

  • Prenatal/Perinatal Factors: Prematurity, low birthweight, and intrauterine exposure to tobacco, stress, and poor nutrition.

Mechanisms

  • Default Mode Network (DMN): Decreased connectivity within the DMN in individuals with ADHD.

Fair et al., 2010; Biol Psychiatry

  • Frontal Circuitry: Reductions in ACC volume in adults with ADHD.

Makris et al., 2010; Journal of Attentional Disorders

Individuals with ADHD have difficulty performing tasks like the Stroop Task.

King et al., 2007; Behavioral and Brain Functions

Pharmacological Treatment

  • Stimulants (1st order):

    • Methylphenidate (Ritalin): Blocks dopamine and norepinephrine transporters, increasing catecholamine transmission. First prescribed in the 1930s.

    • Amphetamine (Adderall): Blocks dopamine and norepinephrine transporters and promotes dopamine release.

  • Non-Stimulants (2nd order): alter norepinephrine levels and are often prescribed when stimulant use causes unwanted side-effects or as an adjuvant to a stimulant prescription.

    • Atomoxetine (Strattera)

    • Guanfacine (Tenex)

    • Clonidine (Catapres)

Pharmacological approaches always need to be individualized and calibrated to an individual’s symptoms.

Non-Pharmacological Treatment

Neonatal frontal cortex lesions in rats recapitulate overactivity associated with ADHD, an effect which is reduced when rats undergo “play intervention”. Common ADHD treatments reduce playfulness, which could exacerbate symptoms of ADHD.

Panksepp et al., 2003; Vanderschuren et al., 2008