Chapter 3: Biology and Behavior

Transcranial Magnetic Stimulation (TMS)

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

Functional Magnetic Resonance Imaging (fMRI)

An imaging technique used to examine changes in the activity of the working human Brian by measuring changes in the blood’s oxygen levels

Magnetic Resonance Imaging (MRI)

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

Positron Emission Tomography (PET)

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

Electroencephalograph (EEG)

A device that measures electrical activity in the brain

Broca’s Area

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

Endorphins

Neurotransmitters involved in natural pain reduction and reward

Glutamate

The primary excitatory transmitter in the nervous system

GABA

Gamma-aminobutyric acid; the primary inhibitory transmitter in the nervous system

Dopamine

A monoamine neurotransmitter involved in motivation, reward, and motor control over voluntary movement

Serotonin

A monoamine neurotransmitter important for a wide range of psychological activity, including emotional states, impulse control, and dreaming

Norepinephrine

A monoamine neurotransmitter involved in states of arousal and attention

Epinephrine

A monoamine neurotransmitter responsible for bursts of energy after an event that is exciting or threatening

Acetylcholine

The neurotransmitter responsible for motor control at the junction between nerves and muscles; it is also involved in mental processes such as learning, memory, sleeping, and dreaming

Reuptake

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

Receptors

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

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

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

Action Potential

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

Resting Membrane Potential

The electrical charge of a neuron when it is not active

Synapse

The gap between the axon of a “sending” neuron and the dendrites of a “receiving” neuron; the site at which chemical communication occurs between neurons

Terminal Buttons

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

Axon

A long narrow outgrowth of a neuron by which information is transmitted to other neurons

Cell Body

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

Dendrites

Branchlike extensions of the neuron that detect information from other neurons

Interneurons

One of the three types of neurons; these neurons communicate within local or short-distance circuits

Motor Neurons

One of the three types of neurons; these neurons direct muscles to contract or relax, thereby producing movement

Sensory Neurons

One of the three types of neurons; these neurons detect information. from the physical world and pass that information to the brain

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

Central Nervous System (CNS)

The brain and the spinal cord

Neurons

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

Genotype

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

Phenotype

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

Heritability

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

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

Monozygotic Twins

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

Recessive Gene

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

Dominant Gene

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

Pituitary Gland

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

Hormones

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

Endocrine System

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

Plasticity

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

Gene Expression

Whether a particular gene is turned on or off

Chromosomes

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

Genes

The units of heredity that help determine the characteristics of an organism

All-or-None Principle

Neurons either fire or don’t, but will always fire at the same strength

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

Cerebellum

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

Thalamus

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

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

Hippocampus

A brain structure that is associated with the formation of memories

Amygdala

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

Basal Ganglia

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

Occipital Lobes

Regions of the cerebral – at the back of the brain – important for vision

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

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

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

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

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

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

Corpus Callosum

A massive bridge of millions of axons that connects the hemispheres and allows information to flow between them

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

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 glans and internal organs

Sympathetic Division

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

Parasympathetic Division

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

Gonads

The main endocrine glands involved in sexual behavior: in males, the testes; in females, the ovaries