AP Psychology Unit 1: Biological Bases of Behavior and Sensation

Comprehensive vocabulary flashcards covering heredity and genetics, neural anatomy and firing, brain structures and functions, sleep stages and dream theories, and sensory and perceptual processes from Psychology Unit 1.

Nature-nurture issue

The longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors.

Natural selection

The principle that inherited traits that enable a species to survive and reproduce in a particular environment will most likely be passed on to future generations.

Evolutionary psychology

The study of the evolution of behavior and the mind, using principles of natural selection to explore how humans are alike due to shared biology and evolutionary history.

Behavior genetics

The study of the relative power and limits of genetic and environmental influences on individual differences in behavior.

Heritability

The proportion of variation in a trait within a population that can be attributed to genetic differences.

Epigenetics

The study of molecular mechanisms by which environments can influence genetic expression without changing the underlying DNA sequence.

Central nervous system (CNS)

The brain and spinal cord; functions as the body's primary decision maker.

Peripheral nervous system (PNS)

The sensory and motor neurons that connect the central nervous system to the rest of the body.

Interneurons

Neurons located within the brain and spinal cord that communicate internally and process information between sensory inputs and motor outputs.

Sensory (afferent) neurons

Neurons that carry incoming information from sensory receptors and bodily tissues into the brain and spinal cord.

Motor (efferent) neurons

Neurons that carry outgoing instructions from the brain and spinal cord to muscles and glands.

Somatic nervous system (SNS)

The division of the peripheral nervous system that controls voluntary movements of skeletal muscles.

Autonomic nervous system (ANS)

The division of the peripheral nervous system that controls involuntary bodily functions, such as heart rate, digestion, and pupil dilation.

Sympathetic nervous system

The division of the autonomic nervous system that arouses the body and mobilizes energy in stressful situations.

Parasympathetic nervous system

The division of the autonomic nervous system that calms the body and conserves energy.

Dendrites

A neuron's branching extensions that receive and integrate messages, conducting impulses toward the cell body.

Axon

The segmented neuron extension that passes messages through its branches away from the cell body to other neurons, muscles, or glands.

Myelin sheath

A layer of fatty tissue segmentally encasing the axons of some neurons, enabling vastly greater transmission speed of neural impulses.

Action potential

A neural impulse consisting of a brief electrical charge that travels down an axon.

Threshold

The level of stimulation required to trigger a neural impulse, occurring at $-55\,\text{mV}$.

Resting potential

The neuron's stable, negatively charged state when not transmitting an impulse, typically at $-70\,\text{mV}$.

Refractory period

A brief resting pause after a neuron fires during which subsequent action potentials cannot occur until the axon returns to resting potential.

All-or-none response

The neural firing principle stating that once threshold is reached, a neuron fires at full strength or not at all.

Reuptake

The reabsorption of excess neurotransmitter molecules by the sending neuron.

Agonist

A molecule that increases a neurotransmitter's action by increasing release, blocking reuptake, or mimicking its effects at receptor sites.

Antagonist

A molecule that inhibits or blocks a neurotransmitter's action by blocking production or occupying receptor sites without activating them.

Pituitary gland

The endocrine system's master gland regulated by the hypothalamus; releases growth hormone and controls other endocrine glands.

Tolerance

The diminishing effect that occurs with regular use of the same dose of a drug, requiring larger doses to produce the same effect.

Depressants

Psychoactive drugs that reduce central nervous system neural activity and slow bodily functions.

Stimulants

Psychoactive drugs that excite central nervous system neural activity and speed up bodily functions.

Hallucinogens

Psychedelic drugs that distort perceptions and evoke sensory images in the absence of sensory input.

Neuroplasticity

The brain's ability to adapt and change by reorganizing after damage or building new pathways based on experience.

Electroencephalogram (EEG)

A recording of electrical activity across the brain's surface measured using electrodes placed on the scalp.

PET scan

A brain-imaging technique that displays brain activity by tracking where a radioactive tracer of glucose is consumed while performing a task.

fMRI

A technique for revealing brain activity by tracking changes in blood flow through successive MRI scans.

Medulla

The base of the brainstem in the hindbrain that controls vital autonomic functions such as heartbeat and breathing.

Thalamus

The forebrain's sensory relay station that directs messages for all senses (except smell) to corresponding areas in the cerebral cortex.

Reticular formation

A nerve network extending through the brainstem into the thalamus that filters incoming sensory information and controls arousal.

Cerebellum

The hindbrain's 'little brain' responsible for processing sensory input, coordinating movement and balance, and enabling nonverbal learning and memory.

Amygdala

Two neural clusters in the limbic system involved in processing emotions, particularly fear and aggression.

Hippocampus

A limbic system neural center that helps process explicit (conscious) memories of facts and events for storage.

Hypothalamus

A limbic structure lying below the thalamus that regulates homeostasis (hunger, thirst, body temperature) and governs the endocrine system via the pituitary gland.

Motor cortex

An area at the rear of the frontal lobes that controls voluntary muscle movements.

Somatosensory cortex

An area at the front of the parietal lobes that registers and processes bodily sensations of touch, temperature, and movement.

Broca's area

A region in the frontal lobe responsible for directing muscle movements involved in speech production.

Wernicke's area

A region in the temporal lobe responsible for language comprehension.

Corpus callosum

The large band of neural fibers connecting the two cerebral hemispheres that carries messages between them.

Dual processing

The principle that information is often simultaneously processed on separate conscious (deliberate) and unconscious (automatic) tracks.

Circadian rhythm

The internal biological clock that coordinates bodily rhythms, such as temperature and wakefulness, on an approximately $24\text{-hour}$ cycle.

REM sleep

A recurring sleep stage characterized by rapid eye movements, vivid dreams, and relaxed voluntary muscles; also called paradoxical sleep.

Alpha waves

The relatively slow brain waves characteristic of a relaxed, awake state.

Delta waves

Large, slow brain waves associated with deep Stage $3$ (NREM-$3$) sleep.

Suprachiasmatic nucleus (SCN)

A pair of cell clusters in the hypothalamus that controls circadian rhythms by regulating melatonin production by the pineal gland in response to light.

Activation-synthesis theory

The dream theory suggesting that dreams are the brain's attempt to synthesize and create a story out of random neural activity.

Transduction

The process by which sensory receptors convert physical energy from the environment into neural signals that the brain can interpret.

Absolute threshold

The minimum stimulus intensity required to detect a stimulus $50\%$ of the time.

Difference threshold

The minimum difference between two stimuli required for detection $50\%$ of the time; also known as the just noticeable difference (JND).

Weber's Law

The principle that two stimuli must differ by a constant minimum percentage or proportion rather than a constant amount to be perceived as different.

Sensory adaptation

Diminished sensitivity to an unchanging, constant stimulus following prolonged exposure.

Rods

Retinal photoreceptors that detect black, white, and gray; necessary for peripheral and twilight vision.

Cones

Retinal photoreceptors concentrated near the fovea that function in daylight and detect fine detail and color.

Opponent-process theory

The theory that color vision is mediated by opposing retinal pairs (red vs. green, blue vs. yellow, black vs. white), which explains afterimages.

Cochlea

A coiled, bony, fluid-filled tube in the inner ear where sound vibrations move fluid to trigger neural impulses in hair cells.

Sensorineural hearing loss

Hearing loss caused by damage to the cochlea's hair cell receptors or to the auditory nerve; also termed nerve deafness.

Conduction hearing loss

Hearing loss caused by damage to the mechanical structures (eardrum or middle ear ossicles) that transmit sound to the cochlea.

Gate-control theory

The theory that a neurological gate in the spinal cord regulates the transmission of pain signals to the brain by opening via small nerve fibers and closing via large fibers.

Kinesthesis

The sensory system responsible for sensing the position and movement of individual body parts.

Vestibular sense

The sensory system responsible for body balance and movement, detected by semicircular canals and vestibular sacs in the inner ear.