Psychology Vocab

Acetylcholine (ACh)

a neurotransmitter that controls muscle contractions

Action potential

the electrical impulse that provides the basis for the conduction of a neural impulse along an axon of a neuron

Afferent neurons

neurons that transmit messages from sensory receptors to the spinal cord and brain; also called sensory neurons

All-or-none principle

the fact that a neuron fires an impulse of the same strength whenever its action potential is triggered

Amygdala

a part of the limbic system that facilitates stereotypical aggressive responses

Aphasia

a disruption in the ability to understand or produce language

Autonomic nervous system (ANS)

the division of the peripheral nervous system that regulates glands and activities such as heartbeat, respiration, digestion, and dilation of the pupils

Axon

a long, thin part of a neuron that transmits impulses to other neurons from axon terminals

Broca’s aphasia

a language disorder characterized by slow, laborious speech

Central nervous system (CNS)

the brain and spinal cord

Cerebellum

a part of the hindbrain involved in muscle coordination and balance

Cerebral cortex

the wrinkled surface area (gray matter) of the cerebrum

Cerebrum

the large mass of the forebrain, consisting of two hemispheres

Chromosome

a microscopic rod-shaped body in the cell nucleus carrying genes that transmit hereditary traits

Computerized axial tomography (CAT or CT)

a method of brain imaging that generates a three-dimensional image of the brain

Corpus callosum

a thick fiber bundle that connects the hemispheres of the cortex

Dendrites

root-like structures that receive impulses from other neurons

Depolarize

to reduce the resting potential of a cell membrane toward zero

Dizygotic (DZ) twins

twins that develop from two fertilized ova; also called fraternal twins

DNA

the substance that forms the basic material of chromosomes, containing the genetic code

Dopamine

a neurotransmitter involved in pleasure, movement, and learning; linked to Parkinson’s disease and schizophrenia

Down syndrome

a condition caused by an extra chromosome on the 21st pair, characterized by mental deficiency

Efferent neurons

neurons that transmit messages from the brain or spinal cord to muscles and glands; also called motor neurons

Electroencephalograph (EEG)

a method of detecting brain waves by measuring current between electrodes on the scalp

Endocrine system

the system of glands that secrete hormones into the bloodstream

Endorphins

inhibitory neurotransmitters similar to morphine in their effects

Epilepsy

temporary disturbances of brain functions involving sudden neural discharges

Evolutionary psychology

the study of how adaptation and natural selection relate to mental processes and behavior

Functional MRI (fMRI)

a form of MRI that observes the brain in real time by taking repeated scans

Gamma-aminobutyric acid (GABA)

an inhibitory neurotransmitter that helps calm anxiety

Gene

a basic unit of heredity found at a specific point on a chromosome

Genetics

the area of biology focusing on heredity

Genotype

one’s genetic makeup based on nucleotide sequencing

Gland

an organ that secretes chemical substances such as hormones

Glial cells

cells that support neurons by removing waste and insulating them

Gray matter

neurons and neural segments involved in spinal reflexes

Heredity

the transmission of traits from parent to offspring via genes

Hippocampus

a brain structure involved in memory formation

Hormones

substances secreted by endocrine glands that regulate body functions

Hypothalamus

a bundle of nuclei involved in body temperature, motivation, and emotion

Instinct

a stereotyped behavior pattern triggered by a specific stimulus

Limbic system

a group of structures involved in memory, motivation, and emotion

Magnetic resonance imaging (MRI)

an imaging method that reveals brain activity by measuring blood flow

Medulla

a hindbrain area involved in regulating heartbeat and respiration

Monozygotic (MZ) twins

twins from a single fertilized ovum; also called identical twins

Motor cortex

the section of cortex linked to muscular responses throughout the body

Mutation

a sudden variation in an inheritable characteristic

Myelin

a fatty substance that insulates axons, facilitating neural impulse transmission

Natural selection

the concept that adaptive genetic variations enable survival and reproduction

Nature

the inborn character of an organism

Nerves

bundles of ax