Overview
This lecture introduces biological psychology, focusing on the relationship between brain structures, biological processes (such as neurons, neurotransmitters, and hormones), and psychological functions.
History and Foundations of Biological Psychology
- Early thinkers like Aristotle believed the mind resided in the heart, but Hippocrates correctly identified the brain as its location.
- Phrenology was a historical but incorrect attempt to link skull bumps to traits.
- Biological psychology studies how genetics, hormones, neurotransmitters, and brain structure affect psychological processes.
Brain Structure and Neuroplasticity
- The brain changes throughout life, shaped by both genetics and experiences, a process known as neuroplasticity.
- Examples: London taxi drivers have enlarged hippocampi for spatial memory; pianists have larger auditory cortices.
Neurons: Types and Structure
- Neurons are the basic cells of the nervous system, transmitting information.
- Three types: sensory (afferent), motor (efferent), and interneurons.
- Main parts: cell body (soma), dendrites (receive signals), axon (sends signals), myelin sheath (insulates and speeds transmission).
- Myelination continues into early adulthood; its breakdown can cause diseases like multiple sclerosis.
- Nerves are bundles of axons; glial cells support neurons, provide nutrients, produce myelin, clean waste, and aid communication.
Neuronal Communication
- Neurons communicate via an electrochemical process: electrical (action potential) within, chemical (neurotransmitters) between.
- Neuron firing requires a minimum threshold; response is all-or-nothing.
- Synapse is the gap where neurotransmitters cross from one neuron to another.
Common Neurotransmitters
- Acetylcholine: enables muscle action, learning, and memory; deficit causes paralysis.
- Dopamine: movement, learning, pleasure; low in Parkinson’s, high in schizophrenia.
- Serotonin: mood, hunger, sleep; low levels linked to depression; SSRIs block reuptake to increase serotonin.
- GABA: major inhibitory neurotransmitter; low levels linked to seizures and insomnia.
- Glutamate: major excitatory neurotransmitter; excess can cause migraines or seizures.
- Endorphins: natural painkillers producing feelings of pleasure.
Nervous System Organization
- Central Nervous System (CNS): brain and spinal cord.
- Peripheral Nervous System (PNS): connects CNS to body; divided into somatic (voluntary muscles) and autonomic (involuntary functions).
- Autonomic splits into sympathetic (arouses, fight/flight) and parasympathetic (calms, conserves energy) divisions.
Endocrine System
- Glands secrete hormones into the bloodstream for slower, longer-lasting effects.
- Adrenal glands release adrenaline for fight/flight.
- Pituitary gland (master gland) controls growth, social bonding (oxytocin), and directs other glands (e.g., stimulates cortisol release).
Cerebral Cortex and Brain Lobes
- Cerebrum covers two hemispheres; cortex is the wrinkled outer layer for higher functions.
- Cortex lobes: frontal (speaking, planning, judgments), parietal (touch, body position), occipital (vision), temporal (hearing).
- Most functions require collaboration between multiple lobes.
Key Terms & Definitions
- Neuroplasticity — the brain’s ability to reorganize and form new connections.
- Neuron — a cell transmitting nerve impulses.
- Synapse — junction between neurons where neurotransmitters cross.
- Neurotransmitter — chemical messenger between neurons.
- Myelin sheath — fatty tissue insulating neuron axons.
- Glial cells — support and nourish neurons.
- Central Nervous System (CNS) — brain and spinal cord.
- Peripheral Nervous System (PNS) — all nerves outside CNS.
- Autonomic Nervous System — controls involuntary body functions.
- Sympathetic Division — arouses body for action.
- Parasympathetic Division — calms body to conserve energy.
- Endocrine System — glands that secrete hormones.
- Pituitary gland — master hormone gland.
Action Items / Next Steps
- Complete the homework assignment covering additional brain structures.
- Review diagrams of neurons and brain lobes for visual understanding.