Unit #1 Biological Basis of Behaviour

Action potential

A neural impulse; a brief electrical charge that travels down an axon. (p. 41)

Adrenal gland

A pair of endocrine glands that sits just above the kidneys and secretes hormones (epinephrine and norepinephrine) that help arouse the body in times of stress. (p. 49)

Agonist

A molecule that increases a neurotransmitter's action. (p. 44)

All-or-nothing

A neuron's reaction of either firing (with a full-strength response) or not firing. (p. 41)

Amygdala

Two lima-bean-sized neural clusters in the limbic system; linked to emotion. (p. 56)

Antagonist

A molecule that inhibits or blocks a neurotransmitter's action. (p. 44)

Autonomic nervous system

The part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms. (p. 46)

Axon

The segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands. (p. 40)

Behavioural genetics

The study of the relative power and limits of genetic and environmental influences on behavior. (pp. 9, 69)

Biological psychology

The scientific study of the links between biological (genetic, neural, hormonal) and psychological processes. Some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists. (p. 38)

Brainstem

The central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions. (p. 55)

Cerebellum

The hindbrain's "little brain" at the rear of the brainstem; functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory. (p. 55)

Cerebral cortex

The intricate fabric of interconnected neural cells covering the forebrain's cerebral hemispheres; the body's ultimate control and information-processing center. (p. 59)

Chromosomes

Threadlike structures made of DNA molecules that contain the genes. (p. 70)

CNS

The brain and spinal cord. (p. 45)

CT scan

A computerized imaging technique that uses X-ray images taken from different angles to create detailed cross-sectional images of the brain or other body structures.

Dendrites

A neuron's often bushy, branching extensions that receive and integrate messages, conducting impulses toward the cell body. (p. 40)

DNA

A complex molecule containing the genetic information that makes up the chromosomes. (p. 70)

Endocrine system

The body's "slow" chemical communication system; a set of glands and fat tissue that secrete hormones into the bloodstream. (p. 48)

Endorphins

"Morphine within"—natural, opiate-like neurotransmitters linked to pain control and to pleasure. (p. 44)

Environment

Every nongenetic influence, from prenatal nutrition to our experiences of the people and things around us. (p. 69)

Epigenetic

The study of the molecular mechanisms by which environments can influence genetic expression (without a DNA change). (pp. 74, 476)

Evolutionary psychology

The study of the evolution of behavior and the mind, using principles of natural selection. (pp. 9, 75)

fMRI scan

A technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function as well as structure. (p. 52)

Fraternal twins

Individuals who developed from separate fertilized eggs. They are genetically no closer than ordinary siblings, but they shared a prenatal environment. (p. 71)

Frontal lobe

The portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgments. (p. 59)

Genes

The biochemical units of heredity that make up the chromosomes; small segments of DNA capable of synthesizing proteins. (p. 70)

Genome

The complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes. (p. 70)

Glial cell

Cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory. (p. 40)

Heritability

The proportion of variation among individuals in a group that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied (p. 319)

Hormones

Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues. (p. 48)

Hypothalamus

A limbic system neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward. (p. 57)

Identical twins

Individuals who developed from a single fertilized egg that split in two, creating two genetically identical organisms. (p. 71)

Interactions

The interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity). (p. 73)

Interneurons

Neurons within the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs. (p. 46)

Lesion

Tissue destruction. Brain lesions occur naturally (disease or trauma), in surgery, or experimentally (using electrodes to destroy brain cells). (p. 51)

Limbic system

Neural system located mostly in the forebrain—below the cerebral hemispheres—that includes the amygdala, hypothalamus, and hippocampus; associated with emotions and drives. (p. 56)

Medulla

The hindbrain structure that is the brainstem's base; controls heartbeat and breathing. (p. 55)

Molecular genetics

The study of the molecular structure and function of genes, including how genes influence behavior.

Motor (efferent) neurons

Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands. (p. 46)

MRI scan

A technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. MRI scans show brain anatomy. (p. 51)

Mutation

A random error in gene replication that leads to a change. (p. 76)

Myelin sheath

A fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one node to the next. (p. 40)

Natural selection

The principle that the inherited traits that better enable an organism to survive and reproduce in a particular environment will (in competition with other trait variations) most likely be passed on to subsequent generations. (pp. 8, 75)

Nerves

Bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sensory organs. (p. 46)

Nervous system

The body's speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems. (p. 45)

Neuron

A nerve cell; the basic building block of the nervous system. (p. 39)

Neurotransmitter

Chemical messengers that cross the synaptic gap between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse. (p. 42)

Occipital lobe

The portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields. (p. 59)

Parasympathetic nervous system

The division of the autonomic nervous system that calms the body, conserving its energy. (p. 46)

Parietal lobe

The portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position. (p. 59)

PET scan

A technique for detecting brain activity that displays where a radioactive form of glucose goes while the brain performs a given task. (p. 51)

Pituitary gland

The endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands. (p. 49)

PNS

The sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body. (p. 45)

Reflex

A simple, automatic response to a sensory stimulus, such as the knee-jerk reflex. (pp. 48, 168)

Refractory period

In neural processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state. (p. 41)

Reuptake

A neurotransmitter's reabsorption by the sending neuron. (p. 42)

Sensory (afferent) neurons

Neurons that carry incoming information from the body's tissues and sensory receptors to the brain and spinal cord. (p. 46)

Somatic nervous system

The division of the peripheral nervous system that controls the body's skeletal muscles. Also called the skeletal nervous system. (p. 46)

Sympathetic nervous system

The division of the autonomic nervous system that arouses the body, mobilizing its energy. (p. 46)

Thalamus

The forebrain's sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla. (p. 55)

Threshold

The level of stimulation required to trigger a neural impulse. (p. 41)

Franz Gall

Developed phrenology, the now-discredited theory that bumps on the skull could reveal a person's personality and mental abilities. His work helped introduce the idea that different areas of the brain have different functions.

Paul Broca

Discovered Broca's area in the left frontal lobe, which is involved in speech production. Damage to this area can cause difficulty speaking, known as Broca's aphasia.

Carl Wernicke

Identified Wernicke's area, usually located in the left temporal lobe, which is important for understanding language. Damage to this area can cause difficulty understanding language, even when speech remains fluent.

Roger Sperry

Conducted split-brain research on patients whose corpus callosum had been severed. His experiments demonstrated that the brain's left and right hemispheres have specialized functions.

Michael Gazzaniga

Worked with Roger Sperry on split-brain research. Demonstrated how the two hemispheres process information differently and identified the left hemisphere's tendency to create explanations for behaviour, known as the left-brain interpreter.

Charles Darwin

Developed the theory of evolution by natural selection, explaining how inherited traits that improve survival and reproduction become more common across generations. His work laid the foundation for evolutionary psychology.