L11_High_Level_Sensory_Perception_Annotated

Lecture Overview

• Lecture Title: High Level Sensory Perception

• Course: PSC 101 - Bio Psych

• Date: February 18th, 2025

Page 2: Introduction

• Engaging the audience to think about visual information processed by their brains.

• Encourage discussion and sharing of answers.

Page 3: Visual Information Processing

• Information processed includes:

  • Color

  • Facial recognition (Face ID)

  • Orientation of objects

  • Edges of objects

Page 4-5: Learning Objectives

• 11.1: Describe representation of complex stimuli via multiple brain regions and parallel processing.

• 11.2: Identify features processed in the dorsal stream ('Where Pathway') and predict experiences from damage.

• 11.3: Identify features processed in the ventral stream ('What Pathway') and predict experiences from damage.

• 11.4: Apply learned concepts about the visual system to other sensory systems.

Page 6: Processing Complex Visual Stimuli

• Focus on:

  • Spatial awareness (Where a face is)

  • Recognition of objects (That this is a face)

  • Processing of abstract features.

• Initial processing not confined to Primary Visual Cortex (V1).

Page 7: Aspects of Vision

• Visual information includes detailed traits:

  • Identity

  • Size

  • Movement

  • Location

Page 8: Complexity of Visual Processing

• The complexity surpasses a single area’s processing capabilities.

• Aspects processed in specific brain areas for swift understanding.

Page 9: Hierarchical Organization

• V1 initiates visual processing before sending details to neighboring areas (V2, V3, V4).

• Distinct aspects of vision processed by respective brain areas.

Page 10: Parallel Visual Processing

• Visual system operates quickly due to parallel processing across different brain regions.

Page 11: Broken-Up Processing

• Each visual aspect processed in specialized areas.

• Higher cognitive areas recombine this information for comprehensive representation.

Pages 12-19: Major Visual Pathways

• Two primary pathways:

  • Dorsal Stream: 'Where Pathway' handles location and movement.

  • Ventral Stream: 'What Pathway' manages object identification.

• Interaction between pathways enables holistic vision representation.

• Damage to MT Area: Results in akinetopsia (motion blindness), where motion is perceived as discrete frames.

Page 20-21: Akinetopsia

• Defined as a subtype of agnosia (unable to perceive objects/actions).

• Retina and V1 functionality is intact; processing ability in MT compromised.

Page 22-23: MST Functionality

• MST (Middle Temporal Area) tracks optic flow: visual perception when moving.

Pages 24-30: Parietal Lobe Functions and Damage

• Location: Upper back of the brain; processes spatial information, attention, and eye movements.

• Damage can lead to hemispatial neglect, where one visual field is neglected.

• Example: Artist who regained painting ability post-stroke demonstrates neuroplasticity.

Pages 31-42: Ventral Stream Details

• Involves recognizing features and identifying objects.

• Fusiform Face Area (FFA) is crucial for face processing, responding strongly to faces.

• Prosopagnosia: Damage leads to inability to recognize faces despite clear visibility of facial features.

Pages 43-59: Grandmother Cell Theory and Recognition

• Initial theory of single cell recognition for complex objects (Grandmother Cell).

• Rejected for inefficiency; shift towards hierarchical coding hypothesis.

• Hierarchical coding breaks objects into foundational components, allowing for flexible recognition.

Page 60-62: Visual Agnosia

• Condition of not recognizing visually identifiable objects; linked to damage in temporal or occipital lobes.

Pages 63-78: Sensory System Overview

• Each sensory system processes different modalities (sight, sound, touch).

• Each system has specialized receptors tuned to its modality, encoded in action potentials.

  • Diagram on common sensory systems:

    • Visual System: Photoreceptors (light).

    • Auditory System: Hair cells (pressure waves).

    • Somatosensory System: Mechanoreceptors (touch).

    • Olfactory System: Chemoreceptors (smell).

    • Gustation System: Chemoreceptors (taste).

• Topographic organization in primary sensory cortex allows efficient processing of sensory information.

• Sensory systems display hierarchical structure with both primary and high-level processing regions.

Learning Objectives Explained

11.1: Describe representation of complex stimuli via multiple brain regions and parallel processing.

• Overview: Complex stimuli such as sights and sounds activate multiple brain areas simultaneously. This representation involves a network of regions collaborating to create a cohesive perceptual experience, rather than one single area handling the entire process.

11.2: Identify features processed in the dorsal stream ('Where Pathway') and predict experiences from damage.

• Details: The dorsal stream is responsible for processing the location and movement of objects in the visual field. Damage to this pathway may lead to difficulties in spatial awareness or the ability to track moving objects. For example, someone with such damage might struggle to catch a ball due to impaired perception of its trajectory.

11.3: Identify features processed in the ventral stream ('What Pathway') and predict experiences from damage.

• Details: The ventral stream focuses on object identification and recognition, processing features such as color and shape. Damage here can lead to conditions like prosopagnosia (difficulty recognizing faces), where individuals may see a face but cannot identify whose face it is.

11.4: Apply learned concepts about the visual system to other sensory systems.

• Application: Understanding how the visual system processes information can serve as a model for other sensory systems, such as auditory or somatosensory systems. Each sensory modality has unique pathways and processing regions, yet many underlying principles of parallel processing and hierarchical organization remain consistent across sensory modalities.