AP Psychology Unit 3: Brain

Neuron

The fundamental building block of the nervous system responsible for receiving, processing, and transmitting information.

Dendrites

Branching extensions of a neuron that receive electrical or chemical signals from other cells and conduct them toward the cell body.

Cell body (Soma)

The part of a neuron that contains the nucleus and maintains the life support of the cell.

Axon

The lengthy extension of a neuron that carries electrical impulses away from the cell body toward terminal branches.

Myelin sheath

A fatty layer surrounding the axons of many neurons that enables significantly faster transmission speed of neural impulses.

Nodes of Ranvier

Periodic gaps in the myelin sheath along the axon where action potentials are regenerated during saltatory conduction.

Axon terminals

Button-like structures at the end of an axon that release neurotransmitters into the synaptic cleft.

Resting potential

The negative charge inside an inactive neuron relative to the outside, typically around $-70\,\text{mV}$.

Action potential

A brief electrical charge that travels down an axon when a neuron fires, triggered when the membrane threshold of approximately $-55\,\text{mV}$ is reached.

Refractory period

A brief resting pause after a neuron has fired, during which subsequent action potentials cannot occur until the resting state is restored.

Threshold

The minimum level of stimulation required to trigger a neural impulse.

All-or-none response

The biological principle stating that a neuron either fires completely or does not fire at all, with no partial firing.

Synapse

The microscopic junction between the axon terminal of the sending neuron and the dendrite or cell body of the receiving neuron.

Neurotransmitters

Chemical messengers that cross the synaptic gap between neurons to transmit signals to target cells.

Reuptake

The process by which neurotransmitters remaining in the synaptic gap are reabsorbed by the sending neuron.

Acetylcholine (ACh)

A neurotransmitter crucial for muscle action, learning, and memory; deterioration of ACh-producing neurons is associated with Alzheimer's disease.

Dopamine

A neurotransmitter influencing movement, learning, attention, and emotion; oversupply is linked to schizophrenia, while undersupply is linked to Parkinson's disease.

Serotonin

A neurotransmitter that regulates mood, hunger, sleep, and arousal; undersupply is strongly linked to clinical depression.

Norepinephrine

A neurotransmitter and hormone that helps control alertness and arousal during stressful situations.

GABA (Gamma-aminobutyric acid)

The primary inhibitory neurotransmitter in the brain that reduces neuronal excitability; undersupply is linked to seizures, tremors, and insomnia.

Glutamate

The major excitatory neurotransmitter involved in memory; oversupply can overstimulate the brain, producing migraines or seizures.

Endorphins

Opiate-like neurotransmitters naturally produced in the brain that function as pain relievers and mood elevators.

Agonist

A chemical molecule that binds to a receptor site and stimulates a biological response, mimicking the effect of a neurotransmitter.

Antagonist

A chemical molecule that binds to a receptor site and blocks or inhibits a neurotransmitter's action.

Central nervous system (CNS)

The division of the nervous system consisting of the brain and spinal cord.

Peripheral nervous system (PNS)

The sensory and motor neurons connecting the central nervous system to the rest of the body.

Somatic nervous system

The division of the peripheral nervous system that controls voluntary movements of skeletal muscles.

Autonomic nervous system

The part of the peripheral nervous system that controls involuntary visceral functions such as gland activity and internal organ operation.

Sympathetic nervous system

The division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations to trigger the fight-or-flight response.

Parasympathetic nervous system

The division of the autonomic nervous system that calms the body, conserving its energy and returning it to a rest-and-digest state.

Sensory (afferent) neurons

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

Motor (efferent) neurons

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

Interneurons

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

Reflex arc

A simple, involuntary neural pathway in the spinal cord that enables immediate automatic responses to sensory stimuli before conscious brain processing occurs.

Endocrine system

The body's slow chemical communication system, consisting of glands that secrete hormones into the bloodstream.

Hormones

Chemical messengers manufactured by endocrine glands that travel through the bloodstream and affect other tissues.

Pituitary gland

The endocrine system's most influential gland, controlled by the hypothalamus, which regulates growth and controls other endocrine glands.

Adrenal glands

A pair of endocrine glands sitting above the kidneys that secrete epinephrine and norepinephrine to arouse the body during stress.

Thyroid gland

An endocrine gland in the neck that regulates metabolic rate, growth, and energy balance by producing thyroxine.

Electroencephalogram (EEG)

A non-invasive technique that records waves of electrical activity across the brain's surface using electrodes attached to the scalp.

Positron emission tomography (PET) scan

A visual brain imaging technique that tracks the movement of radioactive glucose to show areas of metabolic activity during specific tasks.

Magnetic resonance imaging (MRI)

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

Functional MRI (fMRI)

A neuroimaging technique that measures brain activity by detecting changes in blood flow to specific brain structures.

Computed tomography (CT) scan

A series of X-ray photographs taken from different angles and combined by computer to create cross-sectional images of internal brain structures.

Lesion

Naturally or experimentally caused destruction of brain tissue used by researchers to study functional deficits.

Brainstem

The 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

The base of the brainstem that controls critical involuntary bodily functions such as heartbeat and breathing.

Pons

A brainstem structure located above the medulla that plays a key role in coordinating movement, sleep, and facial expressions.

Reticular formation

A nerve network extending through the brainstem that plays a central role in controlling arousal and alertness.

Cerebellum

The structure located at the rear of the brainstem that coordinates voluntary movement, balance, and nonverbal learning.

Thalamus

The brain's sensory control center located atop the brainstem, directing incoming sensory signals (except smell) to the cerebral cortex.

Limbic system

A neural system located below the cerebral hemispheres associated with emotions, drives, and memory formation.

Amygdala

Two neural clusters in the limbic system primarily responsible for processing emotions, particularly fear and aggression.

Hippocampus

A neural center located in the limbic system that plays a key role in processing explicit memories for long-term storage.

Hypothalamus

A limbic system structure located below the thalamus that regulates eating, drinking, body temperature, and governs the endocrine system via the pituitary gland.

Cerebral cortex

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

Glial cells

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

Frontal lobes

The region of the cerebral cortex lying behind the forehead, involved in speaking, muscle movements, decision-making, and logical reasoning.

Parietal lobes

The portion of the cerebral cortex located at the top and rear of the head, receiving sensory input for touch and body position.

Occipital lobes

The portion of the cerebral cortex located at the back of the head, primarily responsible for processing visual information.

Temporal lobes

The portion of the cerebral cortex lying above the ears, housing auditory areas that process sound from the opposite ear.

Motor cortex

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

Somatosensory cortex

An area located at the front of the parietal lobes that registers and processes bodily tactile sensations.

Association areas

Regions of the cerebral cortex not involved in primary motor or sensory functions, dedicated to higher mental processes like learning, remembering, thinking, and speaking.

Prefrontal cortex

The forwardmost region of the frontal lobe responsible for executive functions, impulse control, abstract reasoning, and personality expression.

Broca's area

A region located in the left frontal lobe that controls motor functions involved in speech production.

Wernicke's area

A region located in the left temporal lobe involved in language comprehension and understanding.

Corpus callosum

The wide band of axon fibers connecting the left and right cerebral hemispheres, enabling communication between them.

Split brain

A condition resulting from surgery that isolates the brain's two hemispheres by cutting the corpus callosum fibers.

Neuroplasticity

The brain's capacity to adapt and modify its structure and neural pathways in response to experience, learning, or injury.

Neurogenesis

The formation and development of new neurons in the brain.

Heritability

The proportion of variation among individuals in a group that can be attributed to genetic differences.

Epigenetics

The study of environmental influences on gene expression that occur without changes to the underlying DNA sequence.