Psychology: Themes and Variations Chapter 3 Vocab

Action potential

A brief shift in a neuron's electrical charge that travels along an axon.

Agonist

A chemical that mimics the action of a neurotransmitter.

Antagonist

A chemical that opposes the action of a neurotransmitter.

Electroencephalograph (EEG)

A device that monitors the electrical activity of the brain over time by means of recording electrodes attached to the surface of the scalp.

Pituitary gland

A gland that releases a great variety of hormones that fan out around the body, stimulating actions in the other endocrine glands.

Synapse

A junction where information is transmitted from one neuron to another.

Critical period

A limited time span in the development of an organism when it is optimal for certain capacities to emerge because the organism is especially responsive to certain experiences.

Axon

A long, thin fiber that transmits signals away from the soma to other neurons or to muscles or glands.

Limbic system

A loosely connected network of structures located roughly along the border between the cerebral cortex and deeper subcortical areas.

Synaptic cleft

A microscopic gap between the terminal button of one neuron and the cell membrane of another neuron.

Inhibitory PSP

A negative voltage shift that decreases the likelihood that the postsynaptic neuron will fire action potentials.

Resting potential

A neuron's stable, negative charge when the cell is inactive.

Transcranial magnetic stimulation (TMS)

A new technique that permits scientists to temporarily enhance or depress activity in a specific area of the brain.

Genotype

A person's genetic makeup.

Excitatory PSP

A positive voltage shift that increases the likelihood that the postsynaptic neuron will fire action potentials.

Reuptake

A process in which neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane.

Zygote

A single cell formed by the union of a sperm and an egg.

Hypothalamus

A structure found near the base of the forebrain that is involved in the regulation of basic biological needs.

Thalamus

A structure in the forebrain through which all sensory information (except smell) must pass to get to the cerebral cortex.

Postsynaptic potential (PSP)

A voltage change at a receptor site on a postsynaptic cell membrane.

Peripheral nervous system

All the nerves that lie outside the brain and the spinal cord.

Adaption

An inherited characteristic that increased in a population (through natural selection) because it helped solve a problem of survival or reproduction during the time it emerged.

Behavioral genetics

An interdisciplinary field that studies the influence of genetic factors on behavioral traits.

Afferent nerve fibers

Axons that carry information inward to the central nervous system from the periphery of the body.

Efferent nerve fibers

Axons that carry information outward from the central nervous system to the periphery of the body.

Nerves

Bundles of neuron fibers (axons) that are routed together in the peripheral nervous system.

Polygenic traits

Characteristics that are influenced by more than one pair of genes.

Neurotransmitters

Chemicals that transmit information from one neuron to another.

Genes

DNA segments that serve as the key functional units in hereditary transmission.

Lesioning

Destroying a part of the brain.

Endocrine system

Glands that secrete chemicals into the bloodstream that help control bodily functioning.

Natural selection

Heritable characteristics that provide a survival or reproductive advantage are more likely than alternative characteristics to be passed on to subsequent generations and thus come to be "selected" over time.

Neurons

Individual cells in the nervous system that receive, integrate, and transmit information.

Myelin sheath

Insulating material that encases some axons.

Endorphins

Internally produced chemicals that resemble opiates in structure and effects.

Autonomic nervous system (ANS)

Nerves that connect to the heart, blood vessels, smooth muscles, and glands.

Somatic nervous system

Nerves that connect to voluntary skeletal muscles and to sensory receptors.

Cerebrospinal fluid (CSF)

Nourishes the brain and provides a protective cushion for it.

Electrical stimulation of the brain (ESB)

Sending a weak electrical current into a brain structure to stimulate (activate) it.

Terminal buttons

Small knobs that secrete chemicals called neurotransmitters.

Chromosones

Strands of DNA (deoxyribonucleic acid) molecules that carry genetic information.

Twin studies

Studies in which researchers assess hereditary influence by comparing the resemblance of identical twins and fraternal twins with respect to a trait.

Family studies

Studies in which researchers assess hereditary influence by examining blood relatives to see how much they resemble one another on a specific trait.

Adoption studies

Studies that assess hereditary influence by examining the resemblance between adopted children and both their biological parents and their adoptive parents.

Central nervous system (CNS)

The brain and the spinal cord.

Parasympathetic division

The branch of the autonomic nervous system that generally conserves bodily resources.

Sympathetic division

The branch of the autonomic nervous system that mobilizes the body's resources for emergencies.

Split-brain surgery

The bundle of fibers that connects the cerebral hemispheres (the corpus callosum) is cut to reduce the severity of epileptic seizures.

Soma

The cell body, contains the cell nucleus and much of the chemical machinery common to most cells.

Hindbrain

The cerebellum and two structures found in the lower part of the brainstem: the medulla and the pons.

Hormones

The chemical substances released by the endocrine glands.

Cerebral cortex

The convoluted outer layer of the cerebrum.

Dominant gene

The gene that is expressed when paired genes are different.

Recessive gene

The gene that is masked when paired genes are different.

Forebrain

The largest and most complex region of the brain, encompassing a variety of structures, including the thalamus, hypothalamus, limbic system, and cerebrum.

Absolute refractory period

The minimum length of time after an action potential during which another action potential cannot begin.

Dendrites

The parts of a neuron that are specialized to receive information.

Genetic mapping

The process of determining the location and chemical sequence of specific genes on specific chromosomes.

Fitness

The reproductive success (number of descendants) of an individual organism relative to the average reproductive success in the population.

Cerebral hemispheres

The right and left halves of the cerebrum.

Midbrain

The segment of the brainstem that lies between the hindbrain and the forebrain.

Corpus callosum

The structure that connects the two cerebral hemispheres.

Inclusive fitness

The sum of an individual's own reproductive success plus the effects the organism has on the reproductive success of related others.

Heterozygous condition

The two genes in a specific pair are different.

Homozygous condition

The two genes in a specific pair are the same.

Phenotype

The ways in which a person's genotype is manifested in observable characteristics.

Identical (monozygotic) twins

Twins that emerge from one zygote that splits for unknown reasons.

Fraternal (dizygotic) twins

Twins that result when two eggs are fertilized simultaneously by different sperm cells, forming two separate zygotes.

Perceptual asymmetries

left-right imbalances between the cerebral hemispheres in the speed of visual or auditory processing.