AP PSYCHOLOGY UNIT 1 BIOLOGICAL BASES OF BEHAVIOR 2026

This is for the 2025-2026 year!

Unit 0: Research Methods:Cross-Sectional Study

Compares different groups at one point

1.1 Epigenetics

Environment can turn genes on/off without changing DNA sequence.

1.1 Biological Psychology

Links biology (brain, hormones, nervous system) & behavior.

1.1 Evolutionary Psychology

Traits/behaviors survive if they help reproduction/survival.

1.1 Twin Studies

Compare identical vs. fraternal twins to separate genetic vs. environmental effects.

1.2 CNS

Brain + spinal cord

1.2 PNS

Connects CNS to body.

1.2 Somatic NS

Voluntary movement.

1.2 Autonomic NS

Involuntary functions

1.2 Sympathetic NS

"Fight-or-flight"

1.2 Parasympathetic NS

"Rest-and-digest"

1.3 Neuron - Dendrites

Receive messages from other neurons.

1.3 Neuron - Soma (Cell Body)

Processes signals and contains nucleus.

1.3 Neuron - Axon

Sends impulses away from cell body.

1.3 Neuron - Myelin Sheath

Insulates axon

1.3 Neuron - Nodes of Ranvier

Gaps in myelin

1.3 Neuron - Axon Terminals

Release neurotransmitters into synapse.

1.3 Neuron - Synapse

Gap where neurotransmitters cross to next neuron.

1.3 Neurotransmitters

Chemical messengers (ACh, Dopamine, Serotonin, Norepinephrine, GABA, Glutamate, Endorphins).

1.3 Sensory Neurons (Afferent)

Carry info to CNS.

1.3 Motor Neurons (Efferent)

Carry info from CNS to muscles/glands.

1.3 Interneurons

Connect sensory & motor neurons in CNS.

1.3 Neural Firing Process

Resting potential

→ action potential

→ refractory period

→ all-or-none principle.

1.3 Endocrine System

Pituitary (master), adrenal (stress), thyroid (metabolism)

1.3B Psychoactive Drugs

Chemicals that alter perception, mood, or behavior.

1.3B Substance Use Disorder

Pattern of compulsive drug use despite negative consequences.

1.3B Tolerance

Need more of a drug to achieve same effect.

1.3B Withdrawal

Physical and psychological symptoms after stopping a drug.

1.3B Addiction

Compulsive craving and use of a substance.

1.3B Stimulants - Nicotine

Increases energy, alertness, dopamine

1.3B Depressants - Alcohol

Slows CNS, relaxation

1.3B Hallucinogens - LSD

Alters perception, causes hallucinations

1.3B Opioids - Heroin

Pain relief and euphoria

1.4 Neuroplasticity

Brain reorganizes after damage or learning.

1.4 Brain Lesions

Tissue destruction leading to loss of function.

1.4 EEG

Measures electrical activity

1.4 CT Scan

Uses a series of X-ray images taken from different angles to create cross-sectional images

1.4 MRI

a medical procedure that uses strong magnetic fields and radio waves to create detailed images of the body's internal organs, soft tissues, bones, and blood vessels

1.4 fMRI

Blood flow/oxygen- repeats of MRI

1.4 PET Scan

a medical imaging test that uses a small amount of a radioactive tracer, injected into your body

1.4 MEG

a non-invasive neuroimaging technique that measures the magnetic fields produced by the brain's electrical activity

1.4 Hindbrain - Medulla

Controls heartbeat and breathing.

1.4 Hindbrain - Pons

Coordinates sleep, arousal, and movement.

1.4 Hindbrain - Reticular Formation

Controls alertness and attention.

1.4 Hindbrain - Cerebellum

Balance, coordination, procedural memory.

1.4 Limbic System - Hippocampus

Memory formation.

1.4 Limbic System - Hypothalamus

Homeostasis, hunger, thirst, sexual behavior

1.4 Limbic System - Thalamus

Sensory relay (except smell).

1.4 Limbic System - Amygdala

Fear, aggression, emotional memory.

1.4 Limbic System - Pituitary Gland

Master endocrine gland.

1.4 Cerebral Cortex - Frontal Lobe

Planning, judgment, voluntary movement, Broca's area.

1.4 Cerebral Cortex - Parietal Lobe

Sensory information, spatial reasoning.

1.4 Cerebral Cortex - Occipital Lobe

Vision.

1.4 Cerebral Cortex - Temporal Lobe

Hearing, Wernicke's area, memory.

1.4 Language - Broca's Area

Speech production.

1.4 Language - Wernicke's Area

Speech comprehension.

1.4 Corpus Callosum

Connects left and right hemispheres for communication.

1.4 Left Hemisphere

Language, speech, writing, math, logic

1.4 Right Hemisphere

Spatial skills, facial recognition, music, art, emotion

1.5 Sleep - NREM-1

Theta waves, light sleep, hypnagogic sensations.

1.5 Sleep - NREM-2

Theta + spindles + K-complex

1.5 Sleep - NREM-3

Delta waves, deep sleep, body repairs.

1.5 Sleep - REM

Beta waves, vivid dreams, paradoxical sleep, memory consolidation.

1.5 Circadian Rhythm

24-hour biological clock regulating sleep-wake cycles.

1.5 Melatonin

Hormone signaling sleep onset.

1.5 Sleep Disorder - Insomnia

Trouble falling/staying asleep

1.5 Sleep Disorder - Narcolepsy

Sudden sleep attacks

1.5 Sleep Disorder - Sleep Apnea

Breathing stops during sleep

1.5 Sleep Disorder - Somnambulism (Sleepwalking)

Occurs in NREM-3

1.6 Sensation

The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.

1.6 Bottom-up Processing

Begins with sensory receptors and works up to higher levels of processing, analyzing the raw sensory data.

1.6 Top-down Processing

Constructs perceptions from the sensory input by drawing on our experience, expectations, and existing knowledge.

1.6 Transduction

The process of converting one form of energy into another; in sensation, it's the transformation of stimulus energies (sights, sounds, smells) into neural impulses our brain can interpret.

1.6 Absolute Threshold

The minimum stimulation needed to detect a particular stimulus 50\% of the time.

1.6 Signal Detection Theory

Predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise). Assumes there is no single absolute threshold and detection depends partly on a person's experience, expectations, motivation, and alertness.

1.6 Difference Threshold (JND)

The minimum difference between two stimuli required for detection 50\% of the time, also known as the Just Noticeable Difference.

1.6 Weber-Fechner Law

States that for an average person to perceive a difference, two stimuli must differ by a constant minimum percentage (not a constant amount).

1.6 Sensory Adaptation

Diminished sensitivity as a consequence of constant stimulation; our sensory receptors become less responsive to unchanging stimuli.

1.6 Synesthesia

A condition where stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway (e.g., seeing colors when hearing music).

1.6 Vision - Cornea

Bends light into eye.

1.6 Vision - Iris

Controls pupil size, regulates light intake.

1.6 Vision - Pupil

Opening for light entry.

1.6 Vision - Lens

Focuses light on retina

1.6 Vision - Retina

Contains rods and cones.

1.6 Vision - Rods

Low light, black & white vision, peripheral vision.

1.6 Vision - Cones

Color vision, fine detail, concentrated in fovea.

1.6 Vision - Bipolar Cells

Receive signals from rods/cones and transmit to ganglion cells.

1.6 Vision - Ganglion Cells

Axons form optic nerve to brain.

1.6 Vision - Fovea

Central point of sharpest vision.

1.6 Vision - Blind Spot

No photoreceptors where optic nerve exits eye.

1.6 Vision - Feature Detectors

Neurons in occipital lobe responding to edges, angles, movement.

1.6 Vision - Parallel Processing

Brain processes color, motion, form, depth simultaneously.

1.6 Vision - Trichromatic Theory

Cones sensitive to red, green, blue

1.6 Vision - Opponent-Process Theory

Opposing retinal processes (red-green, blue-yellow, black-white)

1.6 Vision - Myopia

Nearsightedness

1.6 Vision - Hyperopia

Farsightedness

1.6 Vision - Presbyopia

Aging lens

1.6 Hearing - Outer Ear

Pinna funnels sound, auditory canal directs to eardrum.

1.6 Hearing - Middle Ear

Tympanic membrane vibrates, ossicles amplify sound.

1.6 Hearing - Inner Ear

Cochlea, basilar membrane, semicircular canals, auditory nerve.