Biopsychology: Genetics, Neural Systems, and Brain Functions

Biopsychology

Examines how biological processes—genes, cells, brain structures, and hormones—influence behavior, thoughts, and emotions.

Genotype

Genetic makeup (DNA).

Phenotype

Observable characteristics (influenced by both genes and environment).

Gene-Environment Interaction

Genes set potential; environment influences expression.

Alleles

Different versions of a gene (dominant/recessive).

Polygenic traits

Most traits (e.g., height, skin color) are influenced by multiple genes.

Mutations

Permanent DNA changes; can be harmful or beneficial depending on environment.

Race and Genetics

Race is a weak biological construct; more variation within racial groups than between them.

Genetic-Environmental Correlation

Genes influence environment (e.g., athletic parents → sports exposure).

Epigenetics

Same genotype can lead to different phenotypes due to environmental influences.

Schizophrenia Study

High genetic risk + disturbed environment = highest likelihood of developing schizophrenia.

Neurons

Information processors.

Glial Cells

Support, protect, and insulate neurons (≈1:1 ratio with neurons).

Soma

Cell body that contains nucleus.

Dendrites

Receive signals from other neurons.

Axon

Sends signals.

Myelin sheath

Insulating layer; increases transmission speed.

Terminal buttons

Contain synaptic vessels which store neurotransmitters.

Synapse

The space between the terminal button of one neuron and the dendrite of another neuron.

Resting Potential

Neuron ready (negative inside, positive outside). Measured at -70 mV.

Action Potential

Electrical signal/impulse triggered once threshold is reached (-55 mV).

Depolarization

Membrane potential becomes less negative making the neuron more likely to fire (excitation).

Hyperpolarization

Membrane potential becomes more negative making the neuron less likely to fire (inhibition).

Threshold of excitation

Level of charge in the membrane that causes the neuron to become active.

Propagation

Signal travels down axon.

Synaptic Transmission

Neurotransmitters released into synaptic cleft.

Reuptake

Moving a neurotransmitter from the synapse back into the axon terminal from which it was released.

Acetylcholine

Muscle action, memory

Dopamine

Mood, sleep, learning

Serotonin

Mood, sleep

Norepinephrine

Alertness

GABA

Inhibition, sleep

Glutamate

Learning, memory

Beta-Endorphin

Pain, pleasure

Agonists

Mimic neurotransmitters (e.g., dopamine agonists for Parkinson's).

Antagonists

Block neurotransmitters (e.g., dopamine antagonists for schizophrenia).

Reuptake Inhibitors

Prolong neurotransmitter action (e.g., SSRIs for depression).

Central Nervous System (CNS)

Brain + Spinal cord.

Peripheral Nervous System (PNS)

Connects CNS to body.

Somatic System

Voluntary movement (afferent = sensory → CNS; efferent = motor → muscles).

Autonomic System

Involuntary control.

Sympathetic

"Fight or flight."

Parasympathetic

"Rest and digest."

Homeostasis

Both divisions balance physiological states to maintain equilibrium.

Neuroplasticity

Brain's ability to reorganize and form new neural connections.

Cerebral Hemispheres

Left: Language, logic, positive emotions; Right: Spatial skills, emotion, negative affect.

Corpus Callosum

Connects hemispheres (split-brain studies reveal specialization).

Cerebral Cortex

Lobes of the Brain.

Frontal Lobe

Reasoning, planning, motor control.

Parietal Lobe

Sensory processing.

Temporal Lobe

Hearing, memory, language comprehension.

Occipital Lobe

Vision, Visual processing.

Thalamus

Sensory relay (except smell), sense are routed before being directed to other areas of the brain for processing.

Limbic System

Emotion & memory.

Amygdala

Emotions, processing fear.

Hippocampus

Memory formation.

Hypothalamus

Regulates homeostasis: hunger, temperature, sexual behavior; links nervous + endocrine systems.

Pituitary Gland

Master gland of the endocrine system.

Medulla

Vital functions (breathing, blood pressure, heartbeat).

Pons

Regulates brain activity during sleep and connects the brain and spinal cord.

Cerebellum

Balance, coordination, movement, motor skill, and muscle memory.