AP Psychology Unit 1.2 - Chemical Messengers and Brain Plasticity/Specialization

Neurons

Cells in the nervous system that transmit information through electrical and chemical signals.

Glial Cells

Cells that support, nourish, and protect neurons. Some form myelin, the insulating covering around nerve fibers.

Reflex Arc

The nerve pathway that produces a quick, automatic response: sensory receptor → sensory neuron → central nervous system → motor neuron → muscle or gland.

Motor Neurons

Neurons that carry instructions from the central nervous system to muscles or glands.

Sensory Neurons

Neurons that carry information from sensory receptors toward the central nervous system.

Interneurons

Neurons within the brain and spinal cord that process information and connect other neurons.

Neural Transmission

The process of sending information within a neuron electrically and between neurons, usually chemically through neurotransmitters.

Threshold

The level of membrane depolarization needed to trigger an action potential.

Action Potential

A brief electrical signal that travels along a neuron’s axon through changes in its membrane voltage.

All-or-nothing Principle

Once threshold is reached, a neuron produces a full action potential; below threshold, it does not. Stronger stimulation can increase firing frequency, rather than the size of each action potential.

Depolarization

A change in membrane voltage that makes the inside of a neuron less negative relative to the outside.

Refractory Period

The brief period after an action potential when a neuron cannot fire again or requires stronger stimulation to do so.

Resting Potential

The electrical voltage across a neuron’s membrane when it is not firing, typically around −70 millivolts, with the inside more negative than the outside.

Reuptake

The removal of released neurotransmitters from the synapse by transport back into the releasing neuron or nearby glial cells.

Multiple Sclerosis (MS)

An immune-mediated disease that damages myelin and nerve fibers in the brain and spinal cord, disrupting nerve signaling.

Myasthenia Gravis

An autoimmune disease that disrupts communication between motor nerves and skeletal muscles, causing weakness that usually worsens with activity.

Neurotransmitters

Chemical messengers released by neurons that bind to receptors on other cells to influence their activity.

Excitatory Neurotransmitters

Neurotransmitters that make a receiving neuron more likely to fire an action potential. Their effects depend on the receptors they activate.

Inhibitory Neurotransmitters

Neurotransmitters that make a receiving neuron less likely to fire an action potential. Their effects depend on the receptors they activate.

Glutamate

The main excitatory neurotransmitter in the brain, increases brain activity. Important for learning and memory.

GABA

Gamma-aminobutyric acid, the main inhibitory neurotransmitter, reduces brain activity (makes you calm).

Dopamine

A neurotransmitter involved in movement, motivation, reward learning, and attention.

Serotonin

A neurotransmitter involved in regulating mood, sleep, appetite, and other functions.

Endorphins

Naturally produced opioid peptides that reduce pain and can contribute to feelings of euphoria and pleasure.

Substance P

A neuropeptide involved in transmitting pain signals and promoting inflammation.

Acetylcholine

A neurotransmitter that triggers skeletal muscle contraction and contributes to attention, learning, memory, and autonomic functions.

Hormones

Chemical messengers released into the bloodstream that affect cells with matching receptors, regulating processes such as growth, metabolism, and reproduction.

Ghrelin

A hormone produced mainly by the stomach that helps stimulate hunger.

Leptin

A hormone released mainly by fat cells that signals stored energy levels to the brain and helps reduce hunger.

Melatonin

A hormone produced by the pineal gland, mainly at night, that helps regulate the body’s sleep–wake timing.

Oxytocin

A hormone made in the hypothalamus and released by the posterior pituitary that stimulates uterine contractions and milk release. It also influences social bonding.

Adrenaline (epinephrine)

A hormone released by the adrenal glands that prepares the body for action by increasing heart rate and energy availability.

Norepinephrine (noradrenaline)

A neurotransmitter and hormone involved in alertness, attention, and the stress response; it also helps raise blood pressure.

Ghrelin

A hormone produced mainly by the stomach that stimulates hunger.

Leptin

A hormone released mainly by fat cells that signals energy stores to the brain and helps reduce hunger.

Melatonin

A hormone produced by the pineal gland, mainly at night, that helps regulate sleep–wake timing.

Oxytocin

A hormone that stimulates uterine contractions and milk release and also influences social bonding.

Plasticity (neuroplasticity)

The nervous system’s ability to change its connections and activity in response to learning, experience, or injury.

Split-brain Research

Research involving people whose corpus callosum has been severed, usually to treat severe epilepsy, that examines how the brain’s hemispheres function when communication between them is limited.

Contralateral Hemisphere

The brain hemisphere on the opposite side from a body part or sensory field. Each hemisphere generally controls movement and processes sensation for the opposite side of the body.

Hemisphere Specialization

The tendency for certain functions to rely more heavily on one cerebral hemisphere than the other, such as language usually relying more on the left hemisphere.

Hemisphere Organization

The arrangement of the cerebrum into left and right hemispheres, each containing lobes and interconnected regions that work together.

Linguistic Processing

The brain’s handling of language, including understanding and producing spoken, written, or signed communication.

Broca’s Area

A region in the frontal lobe, usually on the left, involved in speech production and aspects of language processing.

Broca’s Aphasia

A language disorder characterized by slow, effortful speech and short, grammatically limited sentences. Understanding is often relatively preserved.

Wernicke’s Area

A region traditionally identified in the left temporal lobe that contributes to language comprehension as part of a broader network.

Wernicke’s Aphasia

A language disorder characterized by fluent speech that may lack meaning, along with difficulty understanding language.

Electroencephalogram “EEG”

A recording of the brain’s electrical activity made using electrodes placed on the scalp.

Functional Magnetic Resonance Imaging “fMRI”

A brain imaging method that estimates activity by measuring changes in blood oxygenation associated with neural activity.

Lesioning

Deliberately damaging or destroying a specific area of nervous tissue to study its function or treat a condition. Researchers also study naturally occurring lesions from injury or disease.