AP Psych Unit 1: Biological Bases of Behavior

absolute threshold

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

accomodation

In vision, the process by which the lens of the eye shifts to focus on a particular object.

action potential

A brief electrical charge that travels down the axon of a neuron, generated by the movement of positively charged atoms in and out of channels in the neuron's membrane.

addiction

A complex condition characterized by compulsive drug use or behaviors despite harmful consequences.

agonist

A drug or chemical that enhances the activity of neurotransmitters.

all-or-none response

The principle that a neuron either fires completely or does not fire at all.

alpha waves

The relatively slow brain waves associated with relaxation and wakefulness.

amygdala

A limbic system structure involved in processing emotions, particularly fear and aggression.

antagonist

A drug or chemical that inhibits or blocks the action of neurotransmitters.

association areas

Areas of the cerebral cortex that are not involved in primary motor or sensory functions but are involved in higher mental functions such as learning, remembering, thinking, and speaking.

audition

The sense of hearing.

autonomic nervous system

The part of the peripheral nervous system that controls involuntary functions like heart rate, digestion, and glandular secretion.

axon

The extension of a neuron through which neural impulses are sent.

barbiturates

A class of drugs that depress the activity of the central nervous system, reducing anxiety but impairing memory and judgment.

behavior genetics

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

biological psychology

A branch of psychology concerned with the links between biology and behavior.

biopsychosocial approach

An integrated approach that incorporates biological, psychological, and social-cultural levels of analysis.

blind spot

The point at which the optic nerve leaves the eye, creating a small gap in the field of vision.

blindsight

A condition in which a person can respond to visual stimuli without consciously experiencing them.

bottom-up processing

Analysis that begins with sensory receptors and works up to the brain's integration of sensory information.

brainstem

The oldest part and central core of the brain, responsible for automatic survival functions.

central nervous system

The brain and spinal cord, responsible for processing and coordinating information.

cerebellum

A structure in the hindbrain that helps coordinate voluntary movement and balance.

cerebral cortex

The outer layer of the brain responsible for complex cognitive processes such as thinking, planning, and language.

Charles Darwin

An English naturalist who proposed the theory of evolution by natural selection.

circadian rhythm

The biological clock; regular bodily rhythms that occur on a 24-hour cycle.

cochlea

A coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses.

cochlear implant

A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.

cognitive neuroscience

The interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language).

computed tomography (CT)

A scanning technique using multiple X-rays to construct a 3D image of the brain's structure.

conduction hearing loss

Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.

cones

Photoreceptor cells in the retina that are responsible for color vision and fine detail.

consciousness

Our awareness of ourselves and our environment.

cornea

The transparent outer layer of the eye that covers the pupil and iris and helps focus incoming light.

corpus callosum

The large band of neural fibers connecting the two brain hemispheres and carrying messages between them.

David Hubel

A Canadian neurophysiologist known for his work with Torsten Wiesel on the processing of visual information in the brain.

delta waves

The large, slow brain waves associated with deep sleep.

dendrites

Branchlike extensions of a neuron that receive messages and conduct impulses toward the cell body.

depressants

Drugs that reduce neural activity and slow body functions.

difference threshold

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

dream

A sequence of images, emotions, and thoughts passing through a sleeping person's mind.

dual processing

The idea that information is simultaneously processed on separate conscious and unconscious tracks.

electroencephalogram (EEG)

A recording of the electrical waves sweeping across the brain's surface, measured by electrodes placed on the scalp.

embodied cognition

The theory that cognition is influenced by the body's interactions with the environment.

endocrine system

The body's 'slow' chemical communication system, consisting of glands that secrete hormones into the bloodstream.

endorphins

Neurotransmitters that are natural painkillers produced by the brain.

environment

Every nongenetic influence, from prenatal nutrition to the people and things around us.

epigenetics

The study of environmental influences on gene expression that occur without a DNA change.

Ernst Weber

A German physician credited with the formulation of Weber's law, which describes the relationship between the magnitude of a physical stimulus and the intensity of its perceived sensation.

evolutionary psychology

The study of the evolution of behavior and the mind, using principles of natural selection.

feature detectors

Nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.

fMRI

A technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans.

forebrain

The largest and most prominent part of the brain, including the cerebral cortex and subcortical structures.

fovea

The central focal point in the retina, around which the eye's cones cluster.

fraternal (dizygotic) twins

Twins who develop from separate eggs and are no more similar genetically than non-twin siblings.

frequency

The number of complete wavelengths that pass a point in a given time.

frequency theory

The theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.

frontal lobes

The portion of the cerebral cortex lying just behind the forehead, involved in planning and judgment.

gate-control theory

The theory that the spinal cord contains a neurological 'gate' that blocks pain signals or allows them to pass on to the brain.

genes

The biochemical units of heredity that make up the chromosomes; a segment of DNA capable of synthesizing a protein.

genome

The complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes.

glial cells

Cells in the nervous system that support, nourish, and protect neurons, and play a role in learning and thinking.

gustation

The sense of taste.

Gustav Fechner

A German psychologist known for his work in psychophysics, particularly his development of Weber's law and the concept of the just noticeable difference.

hallucinations

Perceptions that have no direct external cause, arising from disorders such as schizophrenia, sensory deprivation, or drug-induced states.

hallucinogens

Drugs that alter perception and cause hallucinations or profound distortions in a person's perceptions of reality.

heredity

The genetic transmission of characteristics from parents to offspring.

hindbrain

The lower part of the brainstem, comprising the medulla, pons, and cerebellum, responsible for basic life functions.

hippocampus

A neural center located in the limbic system that helps process explicit memories for storage.

hormones

Chemical messengers produced by the endocrine glands and circulated in the bloodstream, regulating the activity of target cells or organs.

hue

The dimension of color that is determined by the wavelength of light; what we know as the color names blue, green, etc.

hypnagogic sensations

Sensations experienced during the transition from wakefulness to sleep, including hallucinations, muscle jerks, and sensations of falling.

hypothalamus

A neural structure lying below the thalamus, regulating bodily functions such as hunger, thirst, body temperature, and sexual behavior, and controlling the pituitary gland.

identical (monozygotic) twins

Twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms.

inner ear

The innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs, involved in balance and hearing.

insomnia

Persistent problems falling asleep or staying asleep.

intensity

The amount of energy in a light or sound wave, which we perceive as brightness or loudness.

interneurons

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

iris

The colored part of the eye that regulates the size of the pupil by controlling the amount of light entering the eye.

kinesthesis

The sense of the body's position and movement of body parts relative to each other.

lens

The transparent structure behind the pupil that changes shape to help focus images on the retina.

lesion

Damage to body tissue, often caused by disease or injury.

limbic system

A set of structures in the brain, including the amygdala, hypothalamus, and hippocampus, involved in emotion, motivation, and memory.

magnetic resonance imaging (MRI)

A technique that uses magnetic fields and radio waves to produce detailed images of the brain's soft tissue.

magnetoencephalography (MEG)

A brain imaging technique that measures magnetic fields generated by neuronal activity in the brain.

medulla

The base of the brainstem, controlling heartbeat and breathing.

Michael Gazzaniga

A pioneering neuroscientist known for his split-brain research, which revealed insights into the functional differences between the brain's hemispheres.

midbrain

A small region of the brainstem involved in auditory and visual processing and regulation of motor movements.

middle ear

The chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea's oval window.

motor (efferent) neurons

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

motor cortex

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

mutation

A random error in gene replication that leads to a change.

myelin

A fatty tissue layer that encases the axons of some neurons, speeding up the neural impulses.

narcolepsy

A sleep disorder characterized by uncontrollable sleep attacks, often triggered by strong emotions.

natural selection

The principle that heritable traits that better enable an organism to survive and reproduce in a particular environment will most likely be passed on to succeeding generations.

nature-nurture issue

The debate over the relative contributions of genetic inheritance and environmental factors to human development.

near-death experience

An altered state of consciousness reported after a close brush with death, often including out-of-body experiences and feelings of peace.

nervous system

The body's speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems.

neurogenesis

The formation of new neurons.

neuron

A nerve cell; the basic building block of the nervous system.