Unit 1 - Biological Bases of Behavior

Heredity/Nature

The genetic transfer of characteristics from parents to offspring.

Environment/Nurture

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

Evolutionary Perspective

An approach to psychological inquiry that views human cognition and behavior in a Darwinian context of adaptation to physical and social environments and new intellectual challenges.

Eugenics

a philosophy that seeks to eradicate genetic defects and improve the genetic makeup of populations through selective human breeding.

Central Nervous System

The brain and spinal cord.

Peripheral Nervous System

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

Autonomic Nervous System

The part of the peripheral nervous system that controls the glands and muscles of the internal organs.

Somatic Nervous System

The division of the PNS that controls the body's skeletal muscles. Also called the skeletal nervous system.

Parasympathetic Nervous System

The division of the ANS that calms the body, conserving its energy.

Sympathetic Nervous System

The division of the autonomic nervous system that arouses the body, mobilizing its energy.

Neuron

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

Glial Cells

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

Reflex Arc

the nerve pathway involved in a reflex action - at its simplest, a sensory nerve and a motor nerve with a synapse between.

Sensory Neurons

Also known as afferent neurons. Neurons that carry incoming information from the body's tissues and sensory receptors to the brain and spinal cord.

Motor Neurons

Also known as efferent neurons. Neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.

Interneurons

Neurons witin the brain and spinal cord; they communicate internally and process information between the sensory inputs and motor outputs.

All-or-Nothing Principle

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

Depolarization

a reduction in the electric potential across the plasma membrane of a neuron, such that the inner surface of the membrane becomes less negative in relation to the outer surface.

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.

Reuptake

A neurotransmitter's reabsorption by the sending neuron.

Multiple Sclerosis

a chronic, progressive disease involving damage to the sheaths of nerve cells in the brain and spinal cord. Symptoms may include numbness, impairment of speech and of muscular coordination, blurred vision, and severe fatigue.

Threshold

The level of stimulation required to trigger a neural impulse.

Myasthenia Gravis

an autoimmune disorder in which the body produces antibodies against acetylcholine receptors, causing faulty transmission of nerve impulses at neuromuscular junctions.

neurotransmitter

Chemical messengers that cross the synaptic gaps between neurons. When released, they bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.

excitatory neurotransmitter

Chemicals that depolarize postsynaptic neurons, resulting in a greater likelihood of an action potential.

inhibitory neurotransmitter

chemicals that hyperpolarize the postsynaptic neurons, resulting in a lessened likelihood of an action potential.

Dopamine

a neurotransmitter that has an important role in motor behavior and is implicated in numerous mental conditions and emotional states, as well as within the brain's reward center. Abnormalities regarding this neurotransmitter are associated with Parkinson's Disease, ADHD, and Schizophrenia.

Serotonin

A common neurotransmitter with roles in emotional processing, mood, appetite, and sleep. It is implicated in many psychological conditions, including depressive disorders, anxiety disorders, sleep disorders, aggression, and psychosis.

Norepinephrine

A chemical classified as both a hormone and neurotransmitter that assists in the regulation of arousal, attention, cognitive function, and stress reactions.

Glutamate

The predominant excitatory neurotransmitter in the brain. Plays a critical role in cognitive, motor, and sensory functions.

GABA

a major inhibitory neurotransmitter in the nervous system.

Endorphin

Neurotransmitters produced in the brain that block the perception of pain and increase feelings of wellbeing.

Substance P

A neurotransmitter that is involved in the transmission of pain messages to the brain.

Acetylcholine

a major neurotransmitter that plays an important role in memory formation and learning. Is implicated in both Alzheimer's disease and myasthenia gravis.

Hormone

A chemical messenger that is manufactured by endocrine glands, travel through the bloodstream, and affect other tissues.

Adrenaline

A neurotransmitter and hormone that is secreted in large amounts when an individual is stimulated by fear, anxiety, or a similar stress-related situation. Increases the heart rate and force of heart contractions, relaxes bronchial and intestinal smooth muscle, and produces varying effects on blood pressure.

Leptin

A hormone produced by fat cells acting mainly in the regulation of appetite and fat storage.

Ghrelin

A hunger-arousing hormone secreted by an empty stomach.

Melatonin

A hormone manufactured by the pineal gland that produces sleepiness.

Oxytocin

a hormone released by the pituitary gland that causes increased contraction of the uterus during labor and stimulates the ejection of milk into the ducts of the breasts. Important for the formation of attachment between mother and child.

Psychoactive Drug

Any substance that has significant effects on psychological processes, such as thinking, perception, and emotion.

Agonist

A molecule that increases a neurotransmitter's action.

Antagonist

A molecule that inhibits or blocks a neurotransmitter's action.

Stimulants

Drugs that excite neural activity and speed up body functions.

Depressants

Drugs that reduce neural activity and slow body functions.

Hallucinogens

Psychedelic, "mind manifesting" drugs that distort perceptions and evoke sensory images in the absence of sensory input.

Opioids

Opium and its derivatives; drugs that depress neural activity, temporarily lessening pain and anxiety.

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.

Addiction

The everyday term for compulsive substance use.

Brain Stem

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

Medulla

The hindbrain structure that is the brainstem's base; controls heart rate and breathing.

Reticular Activating System

The nerve network that travels through the brain stem and into the thalamus; it filters information and plays an important role in controlling arousal.

Cerebellum

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

Cerebral Cortex

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

Limbic System

Neural system located mostly in the forebrain - below the cerebral hemispheres - that includes the amygdala, hypothalamus, hippocampus, thalamus, and pituitary gland; associated with emotions and drives.

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.

Hypothalamus

A limbic system neural structure lying below the thalamus. It directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system, and is linked to emotion and reward.

Amygdala

Two lima bean sized neural clusters in the limbic system, linked with emotion.

Pituitary Gland

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

Hippocampus

A neural center located in the limbic system; helps process explicit memories - of facts and events - for storage.

Corpus Callosum

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

Occipital Lobe

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

Parietal Lobe

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

Frontal Lobe

portion of the cerebral cortex lying just behind the forehead. Enables linguistic processing, muscle movements, higher-order thinking, and executive functioning (such as making plans and decisions)

Temporal Lobe

The portion of the cerebral cortex lying roughly above the ears. It includes the auditory areas, which receive information primarily from the opposite ear. The left hemisphere also enables language processing.

Motor Cortex

A cerebral cortex area at the rear of the frontal lobe athat controls voluntary movement.

Broca's Area

A frontal lobe brain area, usually in the left hemisphere, that helps control language expression by directing the muscle movements involved in speech.

Wernicke's Area

A brain area, usually in the left temporal lobe, involved in language comprehension and expression.

Split Brain Research

Surgical cutting of the corpus callosum to study the effects of disconnecting the right and left brain hemispheres - specifically, the independent functioning of the two hemispheres.

Brain Plasticity

The brain's ability to change, especially during childhood, by reorganizing after damage or by building new pathways.

Brain Lateralization

The organization of the brain into right and left hemispheres, with each hemisphere performing unique and specialized functions.

EEG (Electroencephalogram)

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

fMRI

A technique for revealing blood flow, and therefore, brain activity by comparing successive MRI scans. Show function as well as structure.

Lesions

Tissue destruction. May occur naturally, during surgery, or experimentally.

MRI (magnetic resonance imaging)

a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. Show brain anatomy.

Circadian Rhythm

the biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle

NREM Sleep

Quiet, typically dreamless sleep in which rapid eye movements are absent; divided into four stages; also called quiet sleep.

REM Sleep

A recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active.

Activation Synthesis Theory

Theory that dreams reflect inputs from brain activation originating in the pons, which the forebrain then attempts to weave into a story

Consolidation Theory

The theory that circuits wired together during the waking period are consolidated, or strengthened, during sleep

Insomnia

Tecurring problems in falling or staying asleep

Narcolepsy

A sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse directly into REM sleep, often at inopportune times.

REM Sleep Behavior Disorder

A neurological disorder in which the person does not become paralyzed during REM sleep and thus acts out dreams.

Sleep Apnea

a sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings

Somnambulism

The condition of walking or performing some other activity without awakening; also known as sleepwalking

Sensation

The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment

Absolute Threshold

The minimum intensity of stimulation that must occur before you experience a sensation.

Just-Noticeable Difference

the threshold at which one can distinguish two stimuli that are of different intensities.

Sensory Adaptation

A decrease in sensitivity to a constant level of stimulation

Weber's Law

the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount).

Synesthesia

A condition in which stimulation of one sense generates a simultaneous sensation in another.

Retina

The light-sensitive inner surface of the eye, containing the receptor rods and cones plus layers of neurons that begin the processing of visual information.

Blind Spot

The point at which the optic nerve leaves the eye, creating a "blind" spot because there are no receptor cells located there.

Accommodation

In sensation, the process by which the eye's lens changes shape to focus images of near or far objects on the retina.

Trichromatic Theory

The theory that the retina contains three different types of color receptors - one most sensitive to red, one to green, and one to blue - which, when stimulated in combination, can produce the perception of any color.

Opponent-Process Theory

The theory that opposing retinal processes (red-green, blue-yellow, black-white) enable color vision. For example, some cells are stimulated by green and inhibited by red, but others may be stimulated by red and inhibited by green.

Fovea

The central focal point in the retina, around which the eye's cones cluster.

Cones

Retinal receptors that are concentrated near the center of the retina and that function in daylight or well-lit conditions. Cones detect detail and give rise to color sensations.

Afterimage

A visual image that persists after a stimulus is removed.

Rods

Retinal receptors that detect black, white, and gray, and are sensitive to movement; necessary for peripheral and twilight vision, when cones don't respond.