Biopsychology and the Biological Bases of Behavior

Cells and Neural Communication

• Glial cells: Provide physical and metabolic support, insulation, and communication for neurons.
• Neurons: Interconnected information processors comprised of the cell body (soma), dendrites, axon, myelin sheath, and terminal buttons.
• Synapse: The space between neurons where chemical communication occurs.
• Neurotransmitters: Chemical messengers that bind to specific receptors on the post-synaptic neuron.
• Resting Potential: State where $Na^+$ is higher outside the cell and $K^+$ is higher inside; extracellular fluid is positive while intracellular fluid is negative.
• Action Potential: Dramatic electrical change across the membrane; threshold of excitation is $-55\,mV$, peaking at $+30\,mV$.
• Reuptake: Moving a neurotransmitter from the synapse back into the axon terminal.

Psychoactive Drugs

• Agonists: Mimic a neurotransmitter at the receptor site to strengthen its effects.
• Antagonists: Block the normal activity of a neurotransmitter at the receptor.

The Nervous System

• Central Nervous System (CNS): Consists of the brain and spinal cord.
• Peripheral Nervous System (PNS): Divided into the somatic (sensory/motor) and autonomic systems.
• Autonomic Nervous System: Includes the sympathetic (fight or flight) and parasympathetic (normal/relaxed) divisions.

The Endocrine System

• Hormones: Chemical substances produced by glands that regulate behaviors such as aggression and mating.
• Key Glands: Hypothalamus, Pituitary gland, Thyroid, Adrenal glands, Pancreas, and Gonads.
• Behavioral Endocrinology: The study of psychology and the endocrine system.

Brain Structure and Function

• Lateralization: Hemisphere specialization; the corpus callosum allows inter-hemispheric communication.
• Plasticity: The brain's ability to change, adapt, and reorganize.
• Forebrain Lobes:
    - Frontal: Motor cortex, prefrontal cortex, and Broca’s area (language production).
    - Parietal: Somatosensory cortex (topographically organized).
    - Temporal: Auditory cortex and Wernicke’s area (speech comprehension); memory and emotion.
    - Occipital: Primary visual cortex (retinotopically organized).
• Limbic System: Includes the Amygdala (emotion), Hippocampus (learning/memory), and Hypothalamus (homeostasis/sexual motivation).
• Thalamus: Relay center for sensory processing.
• Midbrain: Contains the substantia nigra, ventral tegmental area (VTA) (dopamine/movement), and reticular formation (sleep/wake cycle).
• Hindbrain: Includes the medulla (autonomic processes), pons (connects brain/spinal cord), and cerebellum (balance/coordination).

Genetics and Environment

• Mutation: Sudden, permanent change in a gene.
• Range of Reaction: Genes set limits on potential; environment determines how much is achieved.
• Epigenetics: Study of how chemical compounds and proteins turn genes on or off without altering the DNA sequence.

Questions & Discussion

• Practice Question: Imagine you are on an airplane preparing to jump out for your first-ever experience skydiving. Which nervous systems would be involved, and in what way? How would your endocrine system react? What role would the forebrain, midbrain, and hindbrain play in your skydiving experience?
• Quick Review Questions:
    - What are the basic structures of a neuron and the function of each structure?
    - How do messages travel through the neuron?
    - What is the role of the nervous system and endocrine systems?
    - What are the parts of the brain?
    - How do nature, nurture, and epigenetics influence personality and behavior?