Unit 1

Absolute Threshold

Minimum amount of stimulation required to trigger a reaction or produce a sensation.

Accommodation

Process by which the focus of the eye is changed to allow near or distant objects to form sharp images on the retina.

Action Potential

Change in electric potential that propagates along the axon of a neuron during the transmission of a nerve impulse or the contraction of a muscle.

Agonist

Drug or other chemical agent that binds to a particular receptor and produces a physiological effect, typically one similar to that of the body's own neurotransmitter at that receptor.

All-or-None Response

Principle that a neuron either fires completely or does not fire at all.

Amygdala

The almond-shaped structure in the temporal lobe is a limbic system component and is considered part of the basal ganglia. It's a major processing center for emotions. It also links your emotions to many other brain abilities, especially memories, learning, and senses.

Antagonist

Drug or other chemical agent that inhibits the action of another substance.

Association Areas

Areas of the cerebral cortex that are not involved in primary motor or sensory functions but are involved in higher mental functions such as learning, remembering, thinking, and speaking.

Autonomic Nervous System

Portion of the nervous system innervating smooth muscle and glands, including the circulatory, digestive, respiratory, and reproductive organs.

Axon

Long, thin, hollow, cylindrical extension of a neuron that normally carries a nerve impulse away from the cell body.

Blindsight

Capacity of some individuals with damage to the striate cortex to detect and even localize visual stimuli presented to the blind portion of the visual field. The person is unable to visually see images, but somehow some part of the unconscious brain can still perceive them and their locations in space.

Bottom-Up Processing

Information processing in which incoming stimulus data initiate and determine the higher level processes involved in their recognition, interpretation, and categorization.

Brainstem

Part of the brain that connects the cerebrum with the spinal cord.

Central Nervous System

Entire complex of neurons, axons, and supporting tissue that constitute the brain and spinal cord.

Cerebellum

Portion of the hindbrain dorsal to the rest of the brainstem, to which it is connected by the cerebellar peduncles.

Cerebral Cortex

Layer of gray matter that covers the outside of the cerebral hemispheres in the brain and is associated with higher cognitive functions, such as language, learning, perception, and planning.

Circadian Rhythm

Periodic variation in physiological or behavioral activity that repeats at approximately 24-hour intervals, such as the sleep-wake cycle.

Conduction Hearing Loss

Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.

Cones

Photoreceptor cells in the retina that are responsible for color vision and fine detail.

Corpus Callosum

Large tract of nerve fibers running across the longitudinal fissure of the brain and connecting the cerebral hemispheres: It is the principal connection between the two sides of the brain.

fMRI

Technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans.

Fovea

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

Frequency Theory

The theory is that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch. Simply meaning the pitch of a sound is perceived based on the rate at which nerve impulses are fired in the ear,

Frontal Lobes

The portion of the cerebral cortex lying just behind the forehead, involved in planning and judgment.

Gate-Control Theory

The theory that the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain.

Genes

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

Glial Cells

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

Gustation

Sense of taste.

Heredity

Genetic transmission of characteristics from parents to offspring.

Hippocampus

Neural center located in the limbic system that helps process explicit memories for storage. This small structure helps you remember, both short- and long-term, and gain awareness from your environment.

Hormones

Chemical messengers produced by the endocrine glands and circulated in the bloodstream, regulating the activity of target cells or organs.

Hypothalamus

A neural structure lying below the thalamus, regulating bodily functions such as hunger, thirst, body temperature, and sexual behavior, and controlling the pituitary gland.

Insomnia

Persistent problems falling asleep or staying asleep.

Interneurons

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

Kinesthesis

The sense of the body's position and movement of body parts relative to each other.

Lens

The transparent structure behind the pupil that changes shape to help focus images on the retina.

Lesion

Damage to body tissue, often caused by disease or injury.

Limbic System

A set of structures in the brain, including the amygdala, hypothalamus, and hippocampus, involved in emotion, motivation, and memory.

Medulla

Base of the brainstem, controlling heartbeat and breathing.

Motor (Efferent) Neurons

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

Motor Cortex

Area at the rear of the frontal lobes that controls voluntary movements. Involved in planning, controlling, and execution of voluntary movements.

Narcolepsy

A sleep disorder characterized by uncontrollable sleep attacks, often triggered by strong emotions.

Nature-Nurture Issue

The debate over the relative contributions of genetic inheritance and environmental factors to human development.

Pituitary Gland

Controlled by the hypothalamus. Responsible for the release of hormones throughout the body by controlling all endocrine glands.

Hallucinogens

Drugs that alter perception and cause hallucinations or profound distortions in a person's perceptions of reality.

Electroencephalogram (EEG)

Method of studying brain waves using an instrument that amplifies and records the electrical activity of the brain through electrodes placed at various points on the scalp.

Sensory (Afferent) Neurons

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

Neuroplasticity

The brain's ability to reorganize itself by forming new neural connections throughout life, particularly in response to learning, experience, or injury.

Neurotransmitters

Chemical messengers that transmit signals across the synaptic gap between neurons. They enable the brain to provide a variety of functions, through the process of chemical synaptic transmission

Occipital Lobes

Regions of the cerebral cortex located at the back of the brain, responsible for processing visual information.

Reuptake

Reabsorption of neurotransmitters by the sending neuron after they have been released into the synaptic gap.

Somatic Nervous System

Division of the peripheral nervous system that controls the body's skeletal muscles and transmits sensory information to the central nervous system.

Parasympathetic Nervous System

Division of the autonomic nervous system that calms the body, conserving its energy and promoting rest and digestion.

Parietal Lobe

Regions of the cerebral cortex located at the top of the brain, responsible for processing sensory information such as touch and spatial awareness.

Peripheral Nervous System

Sensory and motor neurons that connect the central nervous system to the rest of the body, transmitting information to and from the brain and spinal cord.

Withdrawal

Discomfort and distress that follow discontinuing the use of an addictive drug or behavior.

Tolerance

Diminishing effect of a drug with regular use, requiring larger doses to achieve the same effect.

Temporal Lobe

Regions of the cerebral cortex located above the ears, responsible for processing auditory information and containing areas involved in memory, language comprehension, and emotion.

Thalamus

The brain's sensory control center, located on top of the brainstem, relaying sensory information (except for smell) to the appropriate areas of the cerebral cortex.

Sympathetic Nervous System

Division of the autonomic nervous system that mobilizes the body's resources during stress and emergencies, preparing the body for "fight or flight" responses.

Psychoactive Drug

Chemical substance that alters perception, mood, consciousness, cognition, or behavior.

Stimulants

Drugs that excite neural activity and speed up body functions, such as caffeine, nicotine, amphetamines, and cocaine.

Somatosensory Cortex

Brain region located in the parietal lobe that processes sensory information from the skin and internal body receptors for touch, temperature, and body position.

Refractory Period

Brief period after a neuron has fired during which it cannot generate another action potential.

Rods

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

Frequency Theory

The theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.

Sensory Adaptation

Diminished sensitivity to an unchanging stimulus over time. Refers to the way our senses adjust to different stimuli

Sensorineural Deafness (Hearing Loss)

Hearing loss caused by damage to the cochlea's hair cells or the auditory nerve.

Sensory Interaction

Principle that one sense may influence another, as when the smell of food influences its taste.

Sleep Apnea

Sleep disorder characterized by pauses in breathing or shallow breaths during sleep, leading to disrupted sleep and daytime fatigue.

REM Sleep

Rapid Eye Movement sleep; a stage of sleep characterized by rapid eye movements, vivid dreams, and muscle paralysis.

REM Rebound

Tendency for REM sleep to increase following REM sleep deprivation.

REM Sleep Behavior Disorder

Sleep disorder characterized by the acting out of violent or dramatic dreams during REM sleep.

Retina

Light-sensitive inner surface of the eye, containing receptor cells (rods and cones) and layers of neurons that begin the processing of visual information.

NREM Sleep

Non-Rapid Eye Movement sleep; the sleep stages characterized by slow brain waves, relaxed muscles, and decreased heart rate and breathing.

Opponent Process Theory

Theory of color vision proposing that the brain processes color information in pairs of complementary colors (e.g., red-green, blue-yellow).

Perception

Process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

Pitch

Tone's experienced highness or lowness; depends on frequency.

Place Theory

Theory that links the pitch we hear with the place where the cochlea's membrane is stimulated.

Weber’s Law

Principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage rather than a constant amount. This means that the larger the original stimulus, the larger the just noticeable difference needs to be for it to be detected.

Vestibular Sense

Sense of body movement and position, including the sense of balance.

Top-Down Processing

Information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations.