Brains, Biology, and Behavior

signal sent by a neuron once inputs exceed a threshold

substance that excites or stimulates

principle that the strength of a neural response does not depend on the strength of the stimulus. Neurons either fire or do not fire in response to stimulation; there are no gradations.

substance that inhibits or suppresses

area of the cerebral cortex that interprets inputs from multiple sources, decides how to respond, and puts the decision into action

brain and spinal cord

structure that contains DNA, the genetic material that is passed from one generation to the next

3-D visual image of the brain constructed by using X-rays to detect differences in tissue density

organic molecule containing coded instructions for the life processes of an organism

recording of the brain's electrical activity made by placing electrodes on the scalp

body system that consists of different glands used to produce hormones that regulate body functions

study of heritable changes in the expression of genes that are caused by the environment

brain imaging technique that uses a strong magnetic field and radio waves to identify which areas of the brain are active while a person engages in a cognitive task

unit of heritable material that codes for a particular trait

type of cell that makes up most of the brain tissue, responsible for providing nutrients to neurons and removing debris

proportion of phenotypic variance attributable to genetic variance

chemical secreted by an endocrine gland that triggers a response from a particular type of cell or tissue

brain region involved in motivation, emotion, learning, and memory

imaging technique that uses a strong magnetic field and radio waves to produce a detailed image of the brain or other body parts

mechanism of evolution in which individuals that are better adapted to their environment survive and reproduce more successfully than less well adapted individuals do

process by which new neurons are formed in the brain

cell in the nervous tissue that transmits electrical and chemical signals throughout the body

hormone released into the gap between the axon of a neuron and another neuron's dendrites

system of neurons outside the brain and spinal cord that transmits messages throughout the body

observable characteristics of an organism that result from genetic and environmental influences

ability of brain circuitry to change as a function of experience

technique for mapping brain activity by measuring blood flow to brain regions experiencing heightened neural activity

period after a neuron fires during which it cannot fire again

difference in the voltage between the inside and outside of a neuron

space found between two nerve cells, across which neurotransmitters travel