Psy & Brain Science CH. 3

absolute refractory period

The brief period of time following an action potential when the ion channel is unable to respond again.

action potential

The electrical signal that passes along the axon and subsequently causes the release of chemicals from the terminal buttons.

all-or-none principle

The principle that when a neuron fires, it fires with the same potency each time; a neuron either fires or not, although the frequency of firing can vary.

Amygdala

A brain structure that serves a vital role in learning to associate things with emotional responses and in processing emotional information.

autonomic nervous system (ANS)

A component of the peripheral nervous system; it transmits sensory signals and motor signals between the central nervous system and the body‘s glands and internal organs.

Axon

A long, narrow outgrowth of a neuron by which information is conducted from the cell body to the terminal buttons.

basal ganglia

A system of subcortical structures that are important for the planning and production of movement.

brain stem

An extension of the spinal cord; it houses structures that control functions associated with survival, such as heart rate, breathing, swallowing, vomiting, urination, and orgasm.

Broca's area

A small portion of the left frontal region of the brain, crucial for the production of language.

cell body

The site in the neuron where information from thousands of other neurons is collected and integrated.

central nervous system (CNS)

The brain and the spinal cord.

Cerebellum

A large, convoluted protuberance at the back of the brain stem; it is essential for coordinated movement and balance.

cerebral cortex

The outer layer of brain tissue, which forms the convoluted surface of the brain; the site of all thoughts, perceptions, and complex behaviors.

Chromosomes

Structures within the cell body that are made up of DNA, segments of which comprise individual genes.

corpus callosum

a thick band of nerve fibers that connects the two hemispheres of the brain

Dendrites

Branchlike extensions of the neuron that detect information from other neurons.

dizygotic twins

Also called fraternal twins; twin siblings that result from two separately fertilized eggs and therefore are no more similar genetically than nontwin siblings.

dominant gene

A gene that is expressed in the offspring whenever it is present.

electroencephalograph (EEG)

A technique for measuring electrical activity in the brain.

endocrine system

A communication system that uses hormones to influence thoughts, behaviors, and actions.

frontal lobes

Regions of the cerebral cortex—at the front of the brain—important for movement and higher-level psychological processes associated with the prefrontal cortex.

functional magnetic resonance imaging (fMRI)

An imaging technique used to examine changes in the activity of the working human brain by measuring changes in the blood‘s oxygen levels.

gene expression

Whether a particular gene is turned on or off.

Genes

The units of heredity that help determine an organism‘s characteristics.

Genotype

The genetic constitution of an organism, determined at the moment of conception.

Heredity

Transmission of characteristics from parents to offspring through genes.

Heritability

A statistical estimate of the extent to which variation in a trait within a population is due to genetics.

Hippocampus

A brain structure that is associated with the formation of memories.

Hormones

Chemical substances, released from endocrine glands, that travel through the bloodstream to targeted tissues; the tissues are subsequently influenced by the hormones.

Hypothalamus

A brain structure that is involved in the regulation of bodily functions, including body temperature, body rhythms, blood pressure, and blood glucose levels; it also influences our basic motivated behaviors.

Insula

The part of the cerebral cortex lying inside the lateral fissure; important for taste, pain, perception of bodily states, and empathy.

magnetic resonance imaging (MRI)

A method of brain imaging that uses a powerful magnetic field to produce high-quality images of the brain.

monozygotic twins

Also called identical twins; twin siblings that result from one zygote splitting in two and that therefore share the same genes.

myelin sheath

A fatty material, made up of glial cells, that insulates some axons to allow for faster movement of electrical impulses along the axon.

Neurons

The basic units of the nervous system; cells that receive, integrate, and transmit information. They operate through electrical impulses, communicate with other neurons through chemical signals, and form neural networks.

Neurotransmitters

Chemical substances that transmit signals from one neuron to another.

nodes of Ranvier

Small gaps of exposed axon between the segments of myelin sheath, where action potentials take place.

occipital lobes

Regions of the cerebral cortex—at the back of the brain—important for vision.

parasympathetic division

A division of the autonomic nervous system; it returns the body to its resting state.

parietal lobes

Regions of the cerebral cortex—in front of the occipital lobes and behind the frontal lobes—important for the sense of touch and for attention to the environment.

peripheral nervous system (PNS)

All nerve cells in the body that are not part of the central nervous system. The peripheral nervous system includes the somatic and autonomic nervous systems.

Phenotype

Observable physical characteristics, which result from both genetic and environmental influences.

pituitary gland

A gland located at the base of the hypothalamus; it sends hormonal signals to other endocrine glands, controlling their release of hormones.

Plasticity

A property of the brain that allows it to change as a result of experience or injury.

positron emission tomography (PET)

A method of brain imaging that assesses metabolic activity by using a radioactive substance injected into the bloodstream.

prefrontal cortex

The frontmost portion of the frontal lobes, especially prominent in humans; important for attention, working memory, decision making, appropriate social behavior, and personality.

Receptors

In neurons, specialized protein molecules on the postsynaptic membrane; neurotransmitters bind to these molecules after passing across the synapse.

recessive gene

A gene that is expressed only when it is matched with a similar gene from the other parent.

relative refractory period

The brief period of time following action potential when a neuron‘s membrane potential is more negative, or hyperpolarized, making it harder to fire again.

resting membrane potential

The electrical charge of a neuron when it is not active.

Reuptake

The process whereby a neurotransmitter is taken back into the presynaptic terminal buttons, thereby stopping its activity.

somatic nervous system (SNS)

A component of the peripheral nervous system; it transmits sensory signals and motor signals between the central nervous system and the skin, muscles, and joints.

split brain

A condition that occurs when the corpus callosum is surgically cut and the two hemispheres of the brain do not receive information directly from each other.

sympathetic division

A division of the autonomic nervous system; it prepares the body for action.

Synapse

The gap between the terminal buttons of a "sending" neuron and the dendrites of a "receiving" neuron, where chemical communication occurs between the neurons.

temporal lobes

Regions of the cerebral cortex—below the parietal lobes and in front of the occipital lobes—important for processing auditory information, for memory, and for object and face perception.

terminal buttons

At the ends of axons, small nodules that release chemical signals from the neuron into the synapse.

Thalamus

The gateway to the brain; it receives almost all incoming sensory information before that information reaches the cortex.

transcranial magnetic stimulation (TMS):

The use of strong magnets to briefly interrupt normal brain activity as a way to study brain regions.