Overview
This lecture introduces the basics of the brain's structure and function, emphasizing the localization of brain functions and the relationship between biological and psychological processes.
Early Theories of Brain Function
- Franz Joseph Gall developed phrenology, linking personality to skull bumps, which was later debunked.
- Gall correctly proposed that specific brain areas control specific behaviors (localization of function).
The Brain and Nervous System
- The central nervous system (CNS) consists of the brain and spinal cord, acting as the body's command center.
- The peripheral nervous system gathers sensory information and reports it to the CNS.
Case Study: Phineas Gage
- Phineas Gage survived a severe brain injury but experienced significant personality changes, highlighting brain-mind linkage.
- His case demonstrates how physical brain changes can affect psychological traits, but is often simplified in textbooks.
Brain Structure and Function
- The "old brain" handles basic functions and includes the brainstem, medulla (automatic functions like heart rate), pons (coordinates movement), thalamus (sensory relay), and reticular formation (arousal).
- The cerebellum controls voluntary movement, non-verbal learning, time perception, and is impaired by alcohol.
- The limbic system (amygdala, hypothalamus, hippocampus) controls emotion, motivation, memory, and reward.
- The hypothalamus also regulates body functions and the endocrine system.
- Hippocampus is crucial for learning and forming new memories.
Cerebrum and Cortex
- The cerebrum (two hemispheres) is 85% of brain weight, enabling thinking, speaking, perception.
- Corpus callosum connects hemispheres; certain functions are lateralized but both sides work closely together.
- The cerebral cortex consists of four lobes: frontal (personality, planning), parietal (touch, body position), occipital (vision), temporal (hearing, speech).
- Motor cortex (in frontal lobe) controls movement; somatosensory cortex (in parietal lobe) processes sensations.
- Association areas handle complex processes like thinking and memory integration.
Debunking Myths
- The idea that we use only 10% of our brains is false; most regions are active even during simple tasks.
- Left/right brain dominance is a pop psychology myth; both hemispheres are deeply interconnected.
Key Terms & Definitions
- Phrenology — Disproven theory linking skull shape to personality.
- Localization of function — Idea that specific brain areas control specific behaviors.
- Central Nervous System (CNS) — Brain and spinal cord; body’s command center.
- Peripheral Nervous System — Nerves outside CNS; gather sensory information.
- Limbic System — Brain region for emotion, motivation, and memory (amygdala, hypothalamus, hippocampus).
- Cerebral Cortex — Brain’s outer layer; involved in higher mental functions.
- Motor cortex — Controls voluntary movement.
- Somatosensory cortex — Processes touch and body sensations.
- Association areas — Brain regions involved in higher-level processing and integration.
Action Items / Next Steps
- Review the functions and major parts of the brain.
- Prepare for next week’s lesson on sensation and perception.