unit 2: biological basis for behavior

Circadian rhythm

Our biological clock; regular bodily rhythms that occur on a 24-hour cycle

Paul Broca

Discovered area in left frontal lobe responsible for language production

Carl Wernicke

Discovered area in left temporal lobe responsible for language comprehension

Roger Sperry

Pioneered split-brain research by cutting the corpus callosum to treat epileptic seizures

Michael Gazzaniga

pioneered split-brain research

Neuron

A nerve cell; the basic building block of the nervous system

Cell body

The part of a neuron that contains the nucleus; the cell's life support center (also called "soma")

Dendrites

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

Axon

Fiber that extends off of the cell body that carries an electrical signal (action potential) to communicate with other neurons or to muscles and glands

Myelin sheath

Fatty tissue layer encasing the axons of some neurons; enables greater transmission speed as the electrical signal travels down the axon

Glial cells (glia)

Cells in the nervous system that support, nourish, and protect neurons; also play a role in learning, thinking, and memory

Action potential

A neural impulse; a brief electrical charge that travels down an axon

Threshold

The level of stimulation required to trigger a neural impulse; can be from the environment or from other neurons

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

All-or-none response

A neuron's reaction of either firing (with a full-strength response) or not firing; increasing level of stimulation does not increase action potential intensity

Synapse

The junction between the axon tip (terminal) of the sending neuron and the dendrite or cell body of the receiving neuron; the tiny gap at this junction is called the synaptic gap or synaptic cleft

Neurotransmitters

Chemical messengers triggered by the action potential that are released from the axon terminals of the sending neuron; they travel across the synaptic gap and bind to receptor sites on the dendrites of the receiving neuron, influencing the receiving neuron to trigger an action potential; faster acting but shorter lasting than hormones

Reuptake

A neurotransmitter's reabsorption by the sending neuron back into the axon terminals

Endorphins

"Morphine within"; natural, opiate-like neurotransmitters linked to pain control and to pleasure

Agonist

A molecule (drug or other chemical) that increases a neurotransmitter's action; may increase the production of a neurotransmitter or block reuptake

Antagonist

A molecule (drug or other chemical) that inhibits or blocks a neurotransmitter's action; may block the receptor site on the dendrite

Nervous system

The body's speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous system

Central nervous system (CNS)

The brain and spinal cord

Peripheral nervous system (PNS)

The sensory and motor neurons that connect the CNS to the rest of the body

Nerves

Bundled axons that form neural cables connecting the central nervous system with muscles, glands, and sense organs

Sensory (afferent) neurons

Neurons that carry incoming information from the body's tissues and sensory receptors to the brain and spinal cord (PNS → CNS)

Motor (efferent) neurons

Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands (CNS → PNS)

Interneurons

Neurons within the brain and spinal cord that process information between the sensory inputs and motor outputs

Somatic nervous system

Division of the PNS that controls the body's skeletal muscles (voluntary movement)

Autonomic nervous system (ANS)

Division of the PNS that controls the glands and muscles of the internal organs (involuntary functions); divided into sympathetic and parasympathetic

Sympathetic nervous system

Division of the ANS that arouses the body, mobilizing its energy ("fight or flight")

Parasympathetic nervous system

Division of the ANS that calms the body, conserving its energy ("rest and digest")

Reflex

A simple, automatic response to a sensory stimulus, such as a knee-jerk response; occurs in the spinal cord (no brain involvement)

Endocrine system

The body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream

Hormones

"Slow" chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissue; slower acting but longer lasting than neurotransmitters

Adrenal glands

A pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine/adrenaline and norepinephrine/noradrenaline) that help arouse the body in times of stress

Pituitary gland

The endocrine system's most influential gland; controlled by the hypothalamus, the pituitary regulates growth and controls other endocrine glands ("master gland")

Lesion

Tissue destruction; a brain lesion is a naturally or experimentally caused destruction of brain tissue

Electroencephalogram (EEG)

Amplified recording of the electrical activity in the outer-layers of the brain; waves are measured by electrodes placed on the scalp; looks at brain FUNCTION

Magnetoencephalogram (MEG)

Brain imaging technique that measures magnetic fields from the brain's natural electrical activity; looks at brain FUNCTION

Computed tomography (CT) scan

Series of X-ray photographs taken from different angles and combined by computer into a composite representation of a slice of the brain; looks at brain STRUCTURE

Positron emission tomography (PET) scan

Visual display of brain activity that detects where a radioactive form of glucose gives while the brain performs a task; looks at brain FUNCTION

Magnetic resonance imaging (MRI)

Technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue; looks at brain STRUCTURE

Functional MRI (fMRI)

Technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans; looks at brain STRUCTURE and FUNCTION

Brainstem

Oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; responsible for automatic survival functions

Medulla

Base of the brainstem; controls heartbeat and breathing

Thalamus

Located at the top of the brainstem, it is the brain's sensory control center ("sensory switchboard"); it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla

Reticular formation

Nerve network that travels through the brainstem into the thalamus and plays an important role in controlling arousal and focus

Cerebellum

The "little brain" at the rear of the brainstem; functions include fine motor control, coordination, posture, and balance

Limbic system

Neural system that includes the amygdala, hippocampus, and hypothalamus and sits around the brainstem and below the cerebral hemispheres; associated with emotions and drives

Amygdala

Two small neural clusters in the limbic system linked to emotion

Hypothalamus

Neural structure lying below the thalamus in the limbic system; it plays a direct role in drives (eating, drinking, body temperature, sex drive), helps govern the endocrine system through the pituitary gland, and is linked to emotion, pleasure, and reward

Hippocampus

Neural structure in the limbic system that helps process for storage explicit (conscious) memories of facts and events

Cerebral cortex

Intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body's ultimate control and information-processing center; also called the cerebrum

Frontal lobes

Portion of the cerebral cortex directly behind the forehead; involved in speaking, muscle movements (motor cortex), and in making plans and judgment, as well as personality

Parietal lobes

Portion of the cerebral cortex lying at the top of the head towards the rear; receives sensory input for touch and body position (somatosensory cortex)

Occipital lobes

Portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields (visual cortex)

Temporal lobes

Portion of the cerebral cortex lying roughly above the ears; includes the auditory areas (auditory cortex), each receiving information primarily from the opposite ear

Motor cortex

An area at the rear of the frontal lobes that controls voluntary movements

Somatosensory cortex

An area at the front of the parietal lobes that registers and processes body touch and movement sensations

Association areas

Areas of the cerebral cortex that are not involved in primary motor or sensory functions; they are involved in higher-order functions such as thinking, remembering, planning, and speaking; takes up majority of cerebral cortex

Plasticity

Brain's ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience

Neurogenesis

The formation of new neurons

Corpus callosum

The large band of neural fibers connecting the two brain hemispheres and carrying messages between them

Split brain

A condition resulting from surgery that isolates the brain's two hemispheres by cutting the fibers connecting them; used to treat epileptic seizures in extreme cases

Consciousness

Our subjective awareness of ourselves and our environment

Cognitive neuroscience

Interdisciplinary study of brain activity linked with cognition (including perception, thinking, memory, and language)

Dual processing

Principle that information is often simultaneously processed on separate conscious and unconscious tracks

Blindsight

A condition in which a person can respond to a visual stimulus without consciously experiencing it

Parallel processing

Processing many aspects of a problem simultaneously; generally used to process well-learned information or to solve easy problems

Blindsight

A condition in which a person can respond to a visual stimulus without consciously experiencing it

Parallel processing

Processing many aspects of a problem simultaneously; generally used to process well-learned information or to solve easy problems

Behavior genetics

Study of the relative power and limits of genetic and environmental influences on behavior

Heredity

The genetic transfer of characteristics from parents to offspring

Environment

Every nongenetic influence, from prenatal nutrition to the people and things around us

Chromosomes

Threadlike structures made of DNA molecules that contain the genes

DNA (deoxyribonucleic acid)

A complex molecule containing the genetic information that makes up the chromosomes

Identical (monozygotic) twins

Develop from a single fertilized egg that splits in two, creating two genetically identical organisms

Fraternal (dizygotic) twins

Develop from separate fertilized eggs; they are genetically no closer than ordinary siblings, but they share prenatal environment

Heritability

Statistical technique measuring the extent to which variation among individuals in a group can be attributed to their differing genes

Interaction

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

Epigenetics

The study of environmental influences on gene expression that occur without a DNA change

Evolutionary psychology

The study of the evolution of behavior and the mind, using principles of natural selection

Natural selection

Principle that inherited traits that better enable an organism to survive and reproduce in a particular environment will most likely be passed onto future generations

Mutation

A random error in gene replication that leads to a change

Sleep

A periodic, natural loss of consciousness

REM sleep

a recurring sleep stage during which vivid dreaming often occurs; also known as "paradoxical sleep" because the muscles are relaxed but other body systems are active and the brain looks awake

Alpha waves

The relatively slow brain waves of a relaxed, awake state

NREM sleep

encompasses all sleep stages except for REM sleep

Hallucinations

False sensory experiences, such as seeing something in the absence of an external visual stimulus

Hypnagogic sensations

Bizarre experiences, such as jerking or a feeling of falling or floating weightlessly, while transitioning to sleep; occur in NREM-1

Delta waves

The large, slow brain waves associated with deep sleep in NREM-3

Suprachiasmatic nucleus (SCN)

Pair of cell clusters in the hypothalamus that controls circadian rhythm; in response to light, the SCN causes the pineal gland to adjust melatonin production, thus modifying feelings of sleepiness

Insomnia

Recurring problems in falling asleep or staying asleep

Narcolepsy

Sleep disorder characterized by uncontrollable sleep attacks; may lapse directly into REM sleep at inopportune times

Sleep apnea

Sleep disorder in which breathing stops temporarily during sleep and there are repeated momentarily awakening

Night terrors

Sleep disorder characterized by high arousal and an appearance of being terrified; unlike nightmares, night terrors occur during NREM-3 and are seldom remembered

Dream

Sequence of images, emotions, and thoughts passing through a sleeping person's mind

Manifest content

According to Freud, the symbolic, remembered storyline of a dream

Latent content

According to Freud, the underlying meaning of a dream