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: part of the cerebral cortex 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: part of the cerebral cortex 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: part of the cerebral cortex 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
range of reaction: asserts our genes set the boundaries within which we can operate, and our environment interacts with the genes to determine where in that range we will fall
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: part of cerebral cortex 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