Neural Mechanisms of Motion Perception and Brain Structure

Introduction

• Precision throwing: Uniquely human ability; visual motion is a shared ability among animals
• Observations about stop motion: Difficulty discerning emotion due to loss of subtle facial micro-expressions and the importance of motion in lip reading
• Importance of motion in daily life: Helps avoid predators, cross streets safely, etc.
• Thought question: How would you code a system to detect motion in a video?

Importance of Motion Processing in the Brain

• Speculation: Do we have special brain machinery for processing motion?
• Practical scenario: Living in a strobe-like world would be difficult due to the importance of motion in daily activities
• Future topic: Case study of a woman with motion perception issues

Neuroanatomy Basics

• Human Brain Components: Overview
  • 100 billion neurons
  • Neuron structure: Cell body, axon, dendrites, and potentially myelin sheath
  • Synapses: High quantity critical for brain function
  • Energy efficiency: Brain runs on ~20 watts vs IBM's Watson's 20,000 watts
  • Cortex: Outer sheet folded around the brain, size of a large pizza

Components of the Brain

• Brain Stem: Relays information, primitive but essential for life (breathing, consciousness, temperature regulation)
• Cerebellum: Motor coordination, debatable role in cognition, connected with many cognitive tasks
• Subcortical Regions: Thalamus, hippocampus, amygdala, and more

Specific Structures

• Thalamus: Grand central station; relays sensory info to the cortex but also involved in high-level cognitive computations
• Hippocampus: Long-term episodic memory and navigation (famous case: HM, Lonnie Sue Johnson)
• Amygdala: Emotion, especially fear; patient SM case study

Additional Brain Details

• White Matter: Bundles of axons connecting brain regions, vital for understanding brain function
• Cortex Organization: Mapping primary sensory regions (visual, auditory, somatosensory, gustatory)
  • Maps: Visual space, touch space, auditory frequency

Visual Cortex and Perception

• Receptive Fields: Concept of neurons responding to specific visual fields
• Retinotopy: Mapping of visual space in the visual cortex
• Functional MRI: Identifying areas like MT in humans by comparing responses to moving vs stationary dots
• Direction Selectivity: Neurons respond to specific motion directions; demonstrated through after-effects (psychophysical techniques)

Functional and Structural Differentiation in the Cortex

• Visual Area MT: Evidence for distinct function, connectivity, and histological differences
  • Direction-selective neurons
  • Human MT response to motion, motion aftereffect demonstration
  • Damage to MT: Case study of patient with akinetopsia (motion blindness)
  • Distinct connectivity and structural characteristics

Conclusion

• Key points: Understanding of primary sensory cortex, structure-function relationships, importance of connectivity
• Upcoming Topics: Further exploration of neural basis of perception, cortical mappings, and computational aspects.