Chapter 3. Key Terms

action potential
electrical signal that moves down the neuron’s axon

adrenal gland
sits atop our kidneys and secretes hormones involved in the stress response

agonist
drug that mimics or strengthens the effects of a neurotransmitter

all-or-none
phenomenon that incoming signal from another neuron is either sufficient or insufficient to reach the threshold of excitation

allele
specific version of a gene

amygdala
structure in the limbic system involved in our experience of emotion and tying emotional meaning to our memories

antagonist
drug that blocks or impedes the normal activity of a given neurotransmitter

auditory cortex
strip of cortex in the temporal lobe that is responsible for processing auditory information

autonomic nervous system
controls our internal organs and glands

axon
major extension of the soma

biological perspective
view that psychological disorders like depression and schizophrenia are associated with imbalances in one or more neurotransmitter systems

Broca’s area
region in the left hemisphere that is essential for language production

central nervous system (CNS)
brain and spinal cord

cerebellum
hindbrain structure that controls our balance, coordination, movement, and motor skills, and it is thought to be important in processing some types of memory

cerebral cortex
surface of the brain that is associated with our highest mental capabilities

chromosome
long strand of genetic information

computerized tomography (CT) scan
imaging technique in which a computer coordinates and integrates multiple x-rays of a given area

corpus callosum
thick band of neural fibers connecting the brain’s two hemispheres

dendrite
branch-like extension of the soma that receives incoming signals from other neurons

deoxyribonucleic acid (DNA)
helix-shaped molecule made of nucleotide base pairs

diabetes
disease related to insufficient insulin production

dominant allele
allele whose phenotype will be expressed in an individual that possesses that allele

electroencephalography (EEG)
recording the electrical activity of the brain via electrodes on the scalp

endocrine system
series of glands that produce chemical substances known as hormones

epigenetics
study of gene-environment interactions, such as how the same genotype leads to different phenotypes

fight or flight response
activation of the sympathetic division of the autonomic nervous system, allowing access to energy reserves and heightened sensory capacity so that we might fight off a given threat or run away to safety

forebrain
largest part of the brain, containing the cerebral cortex, the thalamus, and the limbic system, among other structures

fraternal twins
twins who develop from two different eggs fertilized by different sperm, so their genetic material varies the same as in non-twin siblings

frontal lobe
lobe involved in reasoning, motor control, emotion, and language; contains motor cortex

functional magnetic resonance imaging (fMRI)
MRI that shows changes in metabolic activity over time

gene
sequence of DNA that controls or partially controls physical characteristics

genetic environmental correlation
view of gene-environment interaction that asserts our genes affect our environment, and our environment influences the expression of our genes

genotype
genetic makeup of an individual

glial cell
nervous system cell that provides physical and metabolic support to neurons, including neuronal insulation and communication, and nutrient and waste transport

gonad
secretes sexual hormones, which are important for successful reproduction, and mediate both sexual motivation and behavior

gyrus
(plural: gyri) bump or ridge on the cerebral cortex

hemisphere
left or right half of the brain

heterozygous
consisting of two different alleles

hindbrain
division of the brain containing the medulla, pons, and cerebellum

hippocampus
structure in the temporal lobe associated with learning and memory

homeostasis
state of equilibrium—biological conditions, such as body temperature, are maintained at optimal levels

homozygous
consisting of two identical alleles

hormone
chemical messenger released by endocrine glands

hypothalamus
forebrain structure that regulates sexual motivation and behavior and a number of homeostatic processes; serves as an interface between the nervous system and the endocrine system

identical twins
twins that develop from the same sperm and egg

lateralization
concept that each hemisphere of the brain is associated with specialized functions

limbic system
collection of structures involved in processing emotion and memory

longitudinal fissure
deep groove in the brain’s cortex

magnetic resonance imaging (MRI)
magnetic fields used to produce a picture of the tissue being imaged

medulla
hindbrain structure that controls automated processes like breathing, blood pressure, and heart rate

membrane potential
difference in charge across the neuronal membrane

midbrain
division of the brain located between the forebrain and the hindbrain; contains the reticular formation

motor cortex
strip of cortex involved in planning and coordinating movement

mutation
sudden, permanent change in a gene

myelin sheath
fatty substance that insulates axons

neuron
cells in the nervous system that act as interconnected information processors, which are essential for all of the tasks of the nervous system

neuroplasticity
nervous system’s ability to change

neurotransmitter
chemical messenger of the nervous system

Nodes of Ranvier
open spaces that are found in the myelin sheath that encases the axon

occipital lobe
lobe associated with visual processing; contains the primary visual cortex

pancreas
secretes hormones that regulate blood sugar

parasympathetic nervous system
associated with routine, day-to-day operations of the body

parietal lobe
brain lobe involved in processing various sensory and perceptual information; contains the primary somatosensory cortex

peripheral nervous system (PNS)
connects the brain and spinal cord to the muscles, organs and senses in the periphery of the body

phenotype
individual’s inheritable physical characteristics

pituitary gland
secretes a number of key hormones, which regulate fluid levels in the body, and a number of messenger hormones, which direct the activity of other glands in the endocrine system

polygenic
multiple genes affecting a given trait

pons
hindbrain structure that connects the brain and spinal cord; involved in regulating brain activity during sleep

positron emission tomography (PET) scan
involves injecting individuals with a mildly radioactive substance and monitoring changes in blood flow to different regions of the brain

prefrontal cortex
area in the frontal lobe responsible for higher-level cognitive functioning

psychotropic medication
drugs that treat psychiatric symptoms by restoring neurotransmitter balance

receptor
protein on the cell surface where neurotransmitters attach

recessive allele
allele whose phenotype will be expressed only if an individual is homozygous for that allele

resting potential
the state of readiness of a neuron membrane’s potential between signals

reticular formation
midbrain structure important in regulating the sleep/wake cycle, arousal, alertness, and motor activity

reuptake
neurotransmitter is pumped back into the neuron that released it

semipermeable membrane
cell membrane that allows smaller molecules or molecules without an electrical charge to pass through it, while stopping larger or highly charged molecules

soma
cell body

somatic nervous system
relays sensory and motor information to and from the CNS

somatosensory cortex
essential for processing sensory information from across the body, such as touch, temperature, and pain

substantia nigra
midbrain structure where dopamine is produced; involved in control of movement

sulcus
(plural: sulci) depressions or grooves in the cerebral cortex

sympathetic nervous system
involved in stress-related activities and functions

synaptic cleft
small gap between two neurons where communication occurs

synaptic vesicle
storage site for neurotransmitters

temporal lobe
brain lobe associated with hearing, memory, emotion, and some aspects of language; contains primary auditory cortex

terminal button
axon terminal containing synaptic vesicles

thalamus
sensory relay for the brain

theory of evolution by natural selection
states that organisms that are better suited for their environments will survive and reproduce compared to those that are poorly suited for their environments

threshold of excitation
level of charge in the membrane that causes the neuron to become active

thyroid
secretes hormones that regulate growth, metabolism, and appetite

ventral tegmental area (VTA)
midbrain structure where dopamine is produced: associated with mood, reward, and addiction

Wernicke’s area
important for speech comprehension