Lecture Notes on Motion Processing and Neuroanatomy

Introduction to Motion Processing

• Importance of understanding animal movement to avoid predators or catch prey.
• Unique human ability: Precision throwing, not found in other animals.
• Visual motion perception is shared across many animals.

Observations on Emotion and Lip Reading

• Difficulty in discerning emotions through static facial expressions in stop-motion.
• Importance of micro-expressions: fleeting expressions can convey complex emotions.
• Suggestion for a future demo: Poor audio quality would enhance reliance on lip reading and might highlight challenges in communication.

Biological and Ecological Importance of Motion

• Motion detection is vital for safety and survival (e.g., crossing streets safely).
• Speculation on the brain's special machinery for processing motion due to its biological significance.

Overview of Upcoming Content

• Next lecture will involve a demonstration of brain dissection by a renowned neuroscientist.

Neuroanatomy Basics

Human Brain Overview

• Average human brain contains approximately 100 billion neurons.
• Neurons consist of:
  • Cell body with nucleus.
  • Dendrites (input processes).
  • Axon (output process, often with a myelin sheath for faster signal conduction).
• Brain operates on just 20 watts of power (comparatively efficient).

Major Components of the Brain

1. Cortex
   • Folded outer layer, approx. the size of a large pizza.
   • Focus of most course content.
2. Brain Stem
   • Connects spinal cord to the brain, regulates basic bodily functions (breathing, consciousness).
3. Cerebellum
   • Involved in motor coordination; debated role in cognition.
4. Limbic System
   • Includes critical structures such as the hippocampus and amygdala.
5. White Matter
   • Composed of myelinated axons connecting different brain regions.

Key Brain Structures

Thalamus

• Acts as a relay station for most sensory information before reaching the cortex.
• Involved in cognitive computations and information gating.
• Most sensory modalities (except olfactory) pass through the thalamus.

Hippocampus

• Key for forming long-term episodic memory and navigation.
• Case study: H.M. lost the ability to form new memories after hippocampus removal.
• Lonnie Sue Johnson: severe memory loss due to viral infection, highlighting the hippocampus's role in memory.

Amygdala

• Crucial for emotion processing, especially fear.
• Patient SM: lost ability to recognize and experience fear post-amygdala loss.

White Matter

• Makes up 45% of the brain; essential for understanding cortex connectivity.
• Connectivity fingerprints help define different cortical regions.

Cortex Overview

Primary Sensory Regions

• Visual, auditory, somatosensory cortices; each has distinct maps.
• Concept of receptive fields in visual cortex explained:
  • Neurons fire in response to stimuli in specific visual fields.
  • Retinotopy: adjacent parts of the visual field correspond to adjacent parts of the cortex.

Research Methods in Visual Cortex

• Studies using deoxyglucose to map receptive fields in animal studies.
• Human studies using fMRI to identify motion-sensitive areas in the brain.

Visual Area MT

• Specialized in motion processing.
• Evidence of distinct function, connectivity, and physical differences from neighboring areas.
• Studies demonstrate direction selectivity in neurons; implications for understanding motion perception.

Summary and Key Takeaways

• Motion processing is critical for survival; it requires specialized brain regions.
• The brain's complex structure supports various cognitive functions.
• Understanding the brain's organization is essential for comprehending perception.