Nervous System, Neural Communication, Neuroplasticity, and Operant Conditioning

Comprehensive vocabulary flashcards covering the human nervous system divisions (CNS, PNS, ENS), neural anatomy and transmission, the spinal reflex, neuroplasticity, neurotransmitters versus neuromodulators, and the three-phase model and principles of operant conditioning.

Cerebral Cortex

The outer layer of the brain, consisting of billions of neurons and interneurons divided into two cerebral hemispheres.

Corpus Callosum

A thick band of nerve fibers that connects the two cerebral hemispheres and enables communication between them.

Spinal Cord

A cable-like column of nerve fibers made of interneurons that extends from the base of the brain to the lower back, serving as a two-way communication link between the brain and body.

Peripheral Nervous System (PNS)

The entire network of nerves located outside the central nervous system, responsible for transmitting sensory information to the CNS and conveying motor commands to muscles, organs, and glands.

Somatic Nervous System

A subdivision of the PNS that carries afferent sensory information to the CNS and efferent motor information from the CNS to control voluntary skeletal muscle movements.

Sensory Neurons (Afferent)

Neurons that receive information from sensory receptor sites in internal and external environments and carry it along afferent pathways to the CNS.

Motor Neurons (Efferent)

Neurons that convey motor instructions from the CNS along efferent pathways to skeletal muscles, internal organs, and glands.

Interneurons

Neurons located exclusively within the CNS that relay information between sensory neurons and motor neurons.

Autonomic Nervous System (ANS)

A subdivision of the PNS that regulates involuntary activity of visceral muscles, internal organs, and glands continuously regardless of level of consciousness.

Sympathetic Nervous System

The branch of the ANS that prepares the body for action, stressful situations, or threat by increasing heart rate, dilating pupils, expanding bronchioles, and slowing digestion.

Parasympathetic Nervous System

The branch of the ANS that maintains everyday homeostatic functioning and restores the body to a calm resting state following stress or danger.

Enteric Nervous System (ENS)

A branch of the autonomic nervous system that specifically controls the activity and functioning of the gastrointestinal tract or gut.

Gut-Brain Axis (GBA)

The bidirectional communication network connecting the gut and the brain, integrating neural, hormonal, and immunological signals.

Vagus Nerve

One of the body's longest nerves within the gut-brain axis, extending directly from the brain stem to the colon.

Dendrites

Thin, branched extensions of a neuron that receive neural information from other neurons via receptor sites and carry it to the soma.

Axon

A single nerve fiber that transmits electrical impulses away from the cell body (soma) toward axon terminals.

Myelin Sheath

A white fatty substance coating and insulating axon fibers that increases the speed of electrical transmission along the neuron.

Synapse

The junction where neural communication takes place, consisting of the pre-synaptic neuron's axon terminals, the synaptic gap, and the post-synaptic neuron's dendrites.

Spinal Reflex

An unconscious, involuntary, and automatically initiated response to a sensory stimulus where an interneuron in the spinal cord relays motor messages directly to effector muscles before the brain perceives the sensation.

Neural Plasticity

The ability of the brain's neural structure or function to be altered by experience throughout the lifespan.

Long-Term Potentiation (LTP)

The long-lasting strengthening of synaptic connections resulting from high-frequency or repeated coactivation, increasing synaptic efficacy and the number of receptor sites.

Long-Term Depression (LTD)

A long-lasting decrease in the strength of synaptic transmission brought about by prolonged low-level stimulation, serving to prune unused synaptic connections according to the 'use it or lose it' rule.

Sprouting

The growth of new branches or extensions on dendrites or axons to form additional synaptic connections.

Rerouting

The process by which an undamaged neuron abandons a damaged pathway to make an alternative synaptic connection with another active neuron.

Synaptic Pruning

The elimination of synaptic connections that are weak, unused, or not adequately activated to improve brain efficiency.

Experience-Expectant Plasticity

Species-wide brain development that relies on environmental experiences ordinarily expected during sensitive periods early in life (e.g., visual input for visual cortex development).

Experience-Dependent Plasticity

Brain modification occurring at any time across the lifespan in response to unique, idiosyncratic learning experiences that do not have critical or sensitive periods.

Neurotransmitter

A fast-acting chemical messenger released from pre-synaptic axon terminals into the synaptic gap that acts directly on one or two adjacent post-synaptic target cells.

Glutamate

The primary excitatory neurotransmitter in the CNS, essential for learning and memory by increasing the likelihood of the post-synaptic neuron firing.

GABA (Gamma-Aminobutyric Acid)

The primary inhibitory neurotransmitter in the CNS that calms neural firing, prevents overexcitation, and reduces anxiety.

Neuromodulator

A chemical messenger that acts slowly and diffusely across large groups of target neurons—often distant from the release site—to modulate overall neural activity via second messengers.

Dopamine

A neuromodulator heavily implicated in motivation, reward-seeking, attention, wakefulness, arousal, and the regulation of movement.

Serotonin

A neuromodulator that stabilizes mood, anxiety, and sleep; over $90\%$ is located in the gastrointestinal tract regulating bowel function and satiety.

Operant Conditioning

A form of learning where the consequences of a voluntary behavior determine the likelihood that the behavior will be repeated in the future.

Operant

Any voluntary response or set of responses that acts ('operates') on the surrounding environment to produce a consequence.

Three-Phase Model (ABC Model)

The operant conditioning framework consisting of an Antecedent (A) that signals the behavior, the voluntary Behaviour (B), and the resulting Consequence (C).

Antecedent (A)

The stimulus (object or environmental event) that precedes a behavior and signals the probable consequence, influencing whether the behavior occurs.

Positive Reinforcement

The delivery of a pleasant or satisfying stimulus after a response has occurred, increasing or strengthening the future likelihood of that response.

Negative Reinforcement

The removal, termination, or avoidance of an unpleasant or aversive stimulus after a response has occurred, strengthening that response.

Positive Punishment

The presentation or addition of an unpleasant stimulus following an operant behavior, which decreases or weakens the likelihood of that behavior recurring.

Negative Punishment

The removal or confiscation of a valued, pleasant stimulus following an operant behavior, which decreases or weakens the likelihood of that behavior recurring.

Stimulus Generalisation (Operant Conditioning)

The occurrence of an established operant response in the presence of a stimulus that is similar to the original antecedent stimulus.

Stimulus Discrimination (Operant Conditioning)

The ability to make an operant response exclusively in the presence of the specific conditioned antecedent, while showing no response to other similar stimuli.

Extinction (Operant Conditioning)

The gradual decrease and eventual disappearance of a learned operant response following consistent non-reinforcement.

Cerebral Cortex

The outer layer of the brain composed of billions of neurons, including many interneurons that process and transmit information within the central nervous system.

Corpus Callosum

A band of nerve fibers that connects the two cerebral hemispheres and enables communication between them.

Spinal Cord

A cable-like column of nerve fibers made of interneurons that extends from the base of the brain to the lower back, serving as a two-way communication link between the brain and the body.

Peripheral Nervous System (PNS)

The entire network of nerves located outside the central nervous system that carries information from sensory and internal organs to the CNS and conveys motor signals from the CNS to muscles, organs, and glands.

Somatic Nervous System

A subdivision of the PNS that carries sensory (afferent) information to the CNS from receptor sites and transmits motor (efferent) information from the CNS to skeletal muscles to control voluntary movements.

Autonomic Nervous System (ANS)

A subdivision of the PNS that regulates the involuntary functioning of internal organs and glands (such as heartbeat, respiration, and digestion) continuously and independently of conscious awareness.

Sympathetic Nervous System

The division of the ANS that prepares the body for vigorous physical activity, stressful situations, or threats by activating internal muscles, organs, and glands in a fight-or-flight response.

Parasympathetic Nervous System

The division of the ANS that counterbalances the sympathetic nervous system by restoring the body to a calm, homeostatic state and maintaining routine functions (rest and digest).

Enteric Nervous System (ENS)

A branch of the autonomic nervous system that specifically controls the activity and functioning of the gastrointestinal tract or gut.

Gut-Brain Axis (GBA)

A bidirectional communication network of neurons connecting the brain and the gastrointestinal tract.

Vagus Nerve

One of the body's longest cranial nerves within the gut-brain axis, extending from the brainstem down to the colon.

Sensory Neurons (Afferent)

Nerve cells that receive information internally and externally from sensory receptor sites and carry it through the PNS to the CNS.

Motor Neurons (Efferent)

Nerve cells that carry outgoing messages from the CNS to muscles, organs, and glands to initiate voluntary or involuntary responses.

Interneurons

Specialized neurons located solely within the central nervous system (CNS) that relay information between sensory neurons and motor neurons.

Dendrites

Thin extensions branching off a neuron that receive chemical messages from other neurons and carry them toward the cell body (soma).

Axon

The long, slender projection of a neuron that transmits neural impulses away from the cell body (soma) toward axon terminals.

Myelin Sheath

A white, fatty protective coating covering the axon that insulates the neural message and increases the speed of electrical transmission.

Synapse

The junction where neural communication occurs, consisting of the axon terminals of the presynaptic neuron, the synaptic gap, and the dendrites of the postsynaptic neuron with receptor sites.

Spinal Reflex

An unconscious, automatic, and involuntary response to a sensory stimulus where spinal cord interneurons trigger an immediate motor withdrawal action before the message reaches the brain for pain interpretation.

Neural Plasticity

The ability of the brain's neural structure or function to adapt and change in response to experience throughout the lifespan.

Long-Term Potentiation (LTP)

The long-lasting strengthening of synaptic connections resulting from repeated coactivation of presynaptic and postsynaptic neurons, leading to enhanced synaptic transmission.

Long-Term Depression (LTD)

A long-lasting decrease in the strength of synaptic transmission caused by prolonged low-level stimulation, which weakens or eliminates unused synaptic pathways.

Sprouting

The process whereby dendrites or axons grow additional branches or extensions to establish new synaptic connections.

Rerouting

The ability of an undamaged neuron connected to a damaged neuron to form an alternative synaptic connection with another undamaged neuron.

Pruning

The selective elimination of disused or non-activated synaptic connections to streamline and optimize neural circuitry.

Experience-Expectant Plasticity

Brain change occurring in response to environmental experiences that are normally expected during species-wide sensitive developmental periods, such as visual inputs required to develop the visual cortex.

Experience-Dependent Plasticity

Brain changes that modify existing neural structures in response to unique individual experiences occurring at any point in the lifespan without a critical period.

Glutamate

The primary excitatory neurotransmitter in the central nervous system, which promotes postsynaptic neuronal firing and is essential for learning and memory.

GABA

The primary inhibitory neurotransmitter in the central nervous system, which calms and slows neural transmission and reduces anxiety.

Neuromodulator

A chemical messenger released by neurons that affects a diverse, widespread population of neurons across distances and via second messengers, producing slow, long-lasting effects.

Dopamine

A neuromodulator heavily involved in reward-seeking, motivation, attention, arousal, and motor control.

Serotonin

A neuromodulator that stabilizes mood, anxiety, and happiness in the brain, with over $90\%$ found in the gastrointestinal tract regulating bowel function and appetite satiety.

Operant Conditioning

A form of learning in which the consequences that follow an operant behavior determine the likelihood and frequency of that behavior recurring in the future.

Operant

Any voluntary response or set of responses that acts on the environment to produce an environmental consequence.

Three-Phase Model of Operant Conditioning

The ABC framework of operant learning comprising the Antecedent stimulus (A), the voluntary Behaviour (B), and the resulting Consequence (C).

Antecedent (A)

The stimulus, object, or environmental event that precedes a voluntary behavior, signals the probable consequence, and prompts the behavior to take place.

Behaviour (B)

The voluntary operant action that an organism performs in the presence of the antecedent stimulus.

Consequence (C)

The environmental event occurring immediately after an operant behavior that alters the strength or frequency of that behavior in the future.

Positive Reinforcer

A pleasant or satisfying stimulus that strengthens or increases the likelihood of a preceding response when added or presented after that response.

Negative Reinforcer

An unpleasant or aversive stimulus that, when removed, avoided, or subtracted following a response, strengthens or increases the likelihood of that response.

Positive Punishment

The presentation or introduction of an unpleasant or aversive consequence following a response, which decreases or weakens the likelihood of that response occurring again.

Negative Punishment

The removal or subtraction of a pleasant or desirable stimulus following a response, which decreases or weakens the likelihood of that response occurring again.

Stimulus Generalisation (Operant)

Occurs when an organism performs a learned operant response to a stimulus that is similar to the original antecedent stimulus.

Stimulus Discrimination (Operant)

Occurs when an organism produces the learned response only to the specific reinforced antecedent stimulus and not to any other similar stimuli.

Extinction (Operant)

The gradual decrease in the strength or rate of a conditioned operant response following consistent non-reinforcement.