Biological Basis of Behaviour Week 11c Neural Basis of Attention

NEURAL BASIS OF ATTENTION

INTRODUCTION TO ATTENTION AND NEURAL FUNCTIONING

  • Attention Definition: A cognitive process enhancing information processing.

STUDYING ATTENTION

  • Key Considerations: Spatial and temporal resolution are crucial.

  • Neuroimaging Techniques Used:

    • EEG: Excellent temporal, poor spatial resolution.

    • fMRI & PET: Good spatial, inferior temporal resolution.

EEG, fMRI & PET STUDIES ON ATTENTION

  • Findings: Neurons processing attended stimuli show stronger, higher-amplitude responses, boosting activity in associated brain regions (e.g., V1, superior colliculi, LGN).

CORTICAL SELECTIVITY IN ATTENTION STUDIES

  • Different brain areas activate based on the attended stimulus (e.g., FFA for faces, parahippocampal place area for houses).

ZOOM LENS MODEL OF ATTENTION (SASAKI ET AL., 2000)

  • Theory Overview: Attention acts like a zoom lens with variable spotlight sizes; smaller spotlights offer greater processing power.

  •   Instead of a fixed-size spotlight, the zoom lens model suggests our attention can:

      ⁠◦  Narrow to focus on fine details in a small area.

      ⁠◦  Widen to monitor a larger region with less precision.

  • Findings: V1 activation extent varies with local (smaller area, strong BOLD) versus global stimuli (broader area).

INDIVIDUAL NEURONS AND ATTENTION

  • Research Focus: Primarily on non-human primate visual systems.

  • Neuronal Response: Attention enhances or suppresses neuronal responses, maintaining tuning bandwidth but sharpening tuning functions, or shifting them.

BRAIN AREAS INVOLVED IN ATTENTION CONTROL

SUBCORTICAL AREAS

  • Superior Colliculus (SC): Directs eye movements towards attention targets.

  • Pulvinar Nucleus: Important for orienting, shifting attention, and filtering distractors. Damage impairs contralateral attention; enhanced function improves shifting.

TWO NEURAL NETWORKS IN ATTENTION

DORSAL ATTENTIONAL NETWORK

  • Function: Controls top-down attention; includes Intraparietal Sulcus (IPS/LIP) and Frontal Eye Field (FEF).

  • directs attention voluntarily based on goals or expectations

  • key regions

    • intraparietal sulcus (IPS), focuses attention on specific location or tasks

    • frontal eye field (FEF), controls voluntary eye movements and attention shifts

FRONTAL EYE FIELD (FEF)

  • Role: Essential for top-down, voluntary eye movement control, connected to SC. Damage impairs suppressing unwanted eye movements (Inhibition of Return - IOR).

    • guides eye movements towards things we choose to focus on

    • linked to superior colliculus (SC), helps coordinate eye movements

VENTRAL ATTENTIONAL NETWORK

  • Function: Governs bottom-up attention to novel stimuli; primarily involves the Temporoparietal Junction (TPJ).

  • reacts to unexpected or novel stimuli in the environment

  • key regions

    • temporoparietal junction (TPJ)

    • acts like a circuit breaker

    • redirects attention when something surprising happens

TEMPOROPARIETAL JUNCTION (TPJ)

  • Role: Controls bottom-up attention, acting as a "circuit breaker" for unexpected stimuli. Exhibits strong right-hemisphere lateralization; damage impairs responses to novel inputs.

  • detects new or important stimuli and interrupts ongoing focus

  • lateralisation: stronger in the RH

INTERACTION BETWEEN DORSAL AND VENTRAL SYSTEMS

  • Both systems interact for coordinated attention responses, modulating visual areas and subcortical systems. Strong IPS-TPJ links facilitate swift attention reallocation across modalities.

•  These two systems work together:

  ⁠◦  Dorsal sets and maintains focus.

  ⁠◦  Ventral interrupts and redirects attention when needed.

•  IPS–TPJ connections allow fast switching between tasks or sensory inputs.

NEUROPSYCHOLOGICAL IMPAIRMENTS IN ATTENTION

  • Common Conditions: Hemispatial neglect, anosognosia, extinction, impaired object recognition in unusual views, Balint's syndrome.

HEMISPATIAL NEGLECT

  • Definition: Resulting from right inferior parietal cortex damage, causes neglect of the left side of space/body, not due to visual defects. Patients ignore objects on their left, fail visual imagery or drawing tasks on the left.

  • damage to the right inferior parietal cortex

  • ignores left side space/body

  • symptoms: 

    • failing to notice objects on the left

    • omitting left-side details in drawings or mental imagery

ANOSOGNOSIA

  • Affected individuals lack awareness of their hemispatial neglect.

PRISM EFFECT

  • Concept: Prism glasses shift visual representation, aiding rehabilitation by reducing visual field deficits, even post-removal.

EXTINCTION

  • Definition: A sensitive measure of neglect where two visual stimuli are presented, but only one (typically right-sided) is reported, due to biased visual competition.

OBJECTS IN STRANGE VIEWS

  • Right parietal lesions impair recognition of familiar objects presented in unusual views, a deficit in perceptual classification.

BALINT'S SYNDROME

fucked attention → can’t attend to more than one object. identifies parts but not the whole object.

  • Description: Characterized by bilateral lesions affecting attention regions, leading to oculomotor apraxia, optic ataxia, and simultagnosia.

  • Simultagnosia: Inability to attend to more than one object/feature at once, despite preserved vision, e.g., identifying parts but not the whole object.