Unit #2 - Biological Basis of Behavior

nature-nurture issue

the longstanding controversy over the relative contributions that genes and experience make to the development of psychological traits and behaviors. Today's science sees traits and behaviors arising from the interaction of nature and nurture

Mutation

a random error in gene replication that leads to a change

natural selection

the principle that, among the range of inherited trait variations, those contributing to reproduction and survival will most likely be passed on to succeeding generations

adaptation

a change or the process of change by which an organism or species becomes better suited to its environment.

Evolution

the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.

genes

the biochemical units of heredity that make up the chromosomes; a segment of DNA capable of synthesizing a protein

DNA

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

Chromosomes

threadlike structures made of DNA molecules that contain the genes

heritability

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

behavior genetics

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

endocrine system

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

gland

specialized cell, group of cells, or organ that selectively removes materials from the blood, concentrates or alters them, and secretes them for further use in the body or elimination from the body

hormones

chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues

pituitary gland

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

adrenal glands

a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.

nervous system

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

Nerves

neural "cables" containing many axons. These bundled axons, which are part of the peripheral nervous system, connect the central nervous system with muscles, glands, and sense organs

sensory neurons

neurons that carry incoming information from the sensory receptors to the brain and spinal cord

motor neurons

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

interneurons

neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs

Central Nervous System (CNS)

brain and spinal cord

Peripheral Nervous System (PNS)

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

somatic nervous system

the division of the peripheral nervous system that controls the body's skeletal muscles

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.

sympathetic nervous system

the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations

parasympathetic nervous system

the division of the autonomic nervous system that calms the body, conserving its energy

dendrite

the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body

Soma

cell body of a neuron

Axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

myelin sheath

A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.

Nodes of Ranvier

Gaps in the myelin sheath to which voltage-gated sodium channels are confined.

axon terminals (terminal buttons)

endings of axon; contains neurotransmitters which are released after depolarization and neural impulse

resting potential

the state of the neuron when not firing a neural impulse

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

Depolarization

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.

Synapse

the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron

Neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

excitatory neurotransmitters

chemicals released from the terminal buttons of a neuron that excite the next neuron into firing

inhibitory neurotransmitters

chemicals released from the terminal buttons of a neuron that inhibit the next neuron from firing

Acetylcholine (ACh)

A neurotransmitter that enables learning and memory and also triggers muscle contraction

Dopamine

a neurotransmitter that regulates motor behavior, motivation, pleasure, and emotional arousal

Serotonin

A neurotransmitter that affects hunger,sleep, arousal, and mood.

Norepinephrine

A neurotransmitter involved in arousal, as well as in learning and mood regulation

Endorphins

"morphine within"--natural, opiatelike neurotransmitters linked to pain control and to pleasure.

GABA (gamma-aminobutyric acid)

A major inhibitory neurotransmitter. Undersupply linked to seizures, tremors, and insomnia.

Glutamate

A major excitatory neurotransmitter; involved in memory

Reuptake

a neurotransmitter's reabsorption by the sending neuron

SSRIs (selective serotonin reuptake inhibitors)

selectively inhibits serotonin reuptake from synaptic gap and results in potentiation of serotonergic neurotransmissions. Examples: Luvox, Paxilo, Prozac, Zoloft

Agonists

chemical substances that mimic or enhance the effects of a neurotransmitter on the receptor sites of the next cell, increasing or decreasing the activity of that cell

Antagonists (drugs)

invades receptors, because it is close in shape to neurotransmitters, but plugs receptors and gates

old brain

the part of the human brain that evolved first; encompasses the brainstem and limbic system; focuses on survival functions, emotion, and memory

Brainstem

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

Medulla

the base of the brainstem; controls heartbeat and breathing

reticular formation

a nerve network in the brainstem that plays an important role in controlling arousal

limbic system

neural system located below the cerebral hemispheres; associated with emotions and drives

Hippocampus

A neural center located in the limbic system that helps process explicit memories for storage.

Amygdala

two lima bean-sized neural clusters in the limbic system; linked to emotion.

Hypothalamus

A 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.

Thalamus

the brain'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

Cerebellum

the "little brain" at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance

cerebral cortex

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

frontal lobes

the portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgments

parietal lobes

portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position

occipital lobes

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

temporal lobes

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

association areas

areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking

motor cortex

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

somatosensory cortex

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

Wernicke's area

controls language reception - a brain area involved in language comprehension and expression; usually in the left temporal lobe

Broca's area

Controls language expression - an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech.

left brain

language and logic

right brain

creative and spatial

Forebrain

controls body temperature, reproductive functions, eating, sleeping, and the display of emotions; includes cerebral hemispheres, thalamus and hypothalamus

Midbrain

A small part of the brain above the pons that integrates sensory information and relays it upward.

Hindbrain

An area of the brain that coordinates information coming into and out of the spinal cord

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 (mainly those of the corpus callosum) connecting them

Electroencephalogram (EEG)

An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.

fMRI (functional MRI)

A technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function.

Lesioning

small areas of damage in the brain; surgical lesioning can be used as a treatment

neurogenesis

creation of new neurons in the adult brain

Neuroplasticity

the ability within the brain to constantly change both the structure and function of many cells in response to experience or trauma

consciousness

our awareness of ourselves and our environment

altered consciousness

various mental states in which the mind can be aware but is not in its usual wakeful condition, such as during substance use

psychoactive drugs

a chemical substance that alters perceptions and moods

Depressants

drugs (such as alcohol, barbiturates, and opiates) that reduce neural activity and slow body functions

Stimulants

drugs that excite neural activity and speed up body functions

Hallucinogens

psychedelic ("mind-manifesting") drugs, such as LSD, that distort perceptions and evoke sensory images in the absence of sensory input

dependence

a physiological need for a drug, marked by unpleasant withdrawal symptoms when the drug is discontinued; a psychological need to use a drug, such as to relieve negative emotions

addiction

compulsive drug craving and use, despite adverse consequences

tolerance

the diminishing effect with regular use of the same dose of a drug, requiring the user to take larger and larger doses before experiencing the drug's effect

withdrawal

the discomfort and distress that follow discontinuing the use of an addictive drug

circadian rhythm

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

sleep

periodic, natural loss of consciousness--as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation

NREM-1

the transition into sleep, marked by slowed breathing and irregular brain waves; hypnagogic sensations/hallucinations, and myoclonic jerks may occur (alpha waves)

alpha waves

the relatively slow brain waves of a relaxed, awake state

NREM-2

Sleep stage characterized by its periodic sleep spindles, or bursts of rapid, rhythmic brain-wave activity. About half the night is spent in this phase.

sleep spindles

short bursts of brain waves detected in stage 2 sleep

NREM-3

sleep stage that lasts about 30 minutes and your brain emits large, slow delta waves, and you are hard to awaken.