Neuroanatomy, Sensory Physiology, and Autonomic Control

Comprehensive vocabulary flashcards covering central nervous system organization, subcortical and cortical processing, sleep, sensory physiology, phototransduction, hearing, and the autonomic nervous system.

Central Nervous System (CNS)

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

Peripheral Nervous System (PNS)

The division of the nervous system consisting of nerves and ganglia outside the CNS that carry information to and from it.

Gray Matter

Nervous tissue containing many neuronal cell bodies and synapses.

White Matter

Nervous tissue consisting primarily of myelinated axons.

Myelin

A substance that insulates axons and increases conduction speed through saltatory conduction.

Choroid Plexus

A structure located in the ventricles of the brain responsible for producing cerebrospinal fluid (CSF).

Blood-Brain Barrier (BBB)

A selectively permeable barrier formed by capillary endothelial tight junctions, astrocytes, and pericytes that controls the movement of substances from the blood into CNS tissue.

Functional Magnetic Resonance Imaging (fMRI)

A neuroimaging technique that detects changes in blood oxygenation associated with local neuronal activity.

Positron Emission Tomography (PET)

A neuroimaging technique that utilizes radioactive tracers, such as labeled glucose, to measure glucose utilization and identify areas of increased metabolic activity.

Thalamus

A major subcortical relay station that directs sensory information traveling to the cortex, with the exception of initial olfactory signaling.

Hypothalamus

A subcortical brain structure that regulates homeostasis by coordinating temperature, hunger, thirst, water balance, and related endocrine and autonomic responses.

Basal Nuclei

Subcortical structures that help regulate and coordinate movement.

Corpus Callosum

A large white-matter tract that connects the left and right cerebral hemispheres.

Limbic System

A group of brain structures including the hippocampus, amygdala, and cingulate gyrus that participates in learning, memory, and emotional processing.

Hippocampus

A limbic system structure critical for learning and the formation of new memories.

Amygdala

A limbic structure involved in emotional processing, particularly fear and disgust.

Diffuse Modulatory Systems

Brain systems in which relatively small populations of neurons project axons across widespread regions to release neuromodulators such as norepinephrine, dopamine, serotonin, and acetylcholine.

Electroencephalogram (EEG)

A recording of electrical potential differences at the scalp that primarily reflects summed postsynaptic activity across populations of cortical neurons.

Synchronization (EEG)

Simultaneous, similarly oriented electrical activity across cortical neurons that sums together to generate high-amplitude EEG signals.

REM Sleep

A sleep stage characterized by rapid eye movements, skeletal muscle atonia, and desynchronized, low-amplitude EEG activity resembling wakefulness.

Crossover

The anatomical decussation of neural pathways so that one cerebral hemisphere processes or controls sensory and motor information associated with the opposite side of the body.

Lateralization

The phenomenon wherein specific neural functions, such as language in the left hemisphere, are more strongly associated with one hemisphere than the other.

Optic Chiasm

The anatomical site where nerve fibers from the nasal halves of the retinas cross to the opposite hemisphere.

Broca's Area

A frontal cortical region responsible for speech production; damage causes effortful, slow, halting, nonfluent speech with preserved comprehension.

Wernicke's Area

A cortical region responsible for language comprehension; damage causes fluent but meaningless speech and impaired language comprehension.

Hebbian Plasticity

A synaptic principle describing the strengthening of connections between neurons that repeatedly activate together.

Long-Term Potentiation (LTP)

A persistent increase in synaptic strength following specific patterns of repetitive, coordinated neuronal activity.

Sensory Receptor

A cell or specialized neuronal ending that detects an environmental stimulus and converts it into an electrical or chemical signal.

Receptive Field

The specific physical area or stimulus range (such as skin territory, visual field, or sound frequency) that activates a particular sensory neuron.

Convergence

A neural configuration where multiple primary sensory neurons synapse onto fewer downstream neurons, enlarging the effective receptive field and reducing spatial localization precision.

Inhibitory Surround

A sensory mechanism in which strongly activated primary pathways inhibit adjacent neighboring pathways via inhibitory interneurons to increase contrast and improve localization.

Labeled-Line Coding

A coding mechanism where specific modalities and receptive fields are transmitted through dedicated anatomical pathways directly to specialized cortical areas.

Tonic Receptors

Slowly adapting sensory receptors that fire continuously throughout the duration of a sustained, maintained stimulus.

Phasic Receptors

Rapidly adapting sensory receptors that respond primarily to stimulus onset, changes, and cessation rather than sustained background stimulation.

Referred Pain

Pain perceived in a somatic region other than its actual visceral source, caused by convergence of somatic and visceral afferents onto shared central ascending pathways.

Gate Control Theory

A model of pain modulation in which non-painful mechanical touch fibers activate inhibitory spinal interneurons to suppress ascending transmission of pain signals.

Gustducin

A specialized G protein involved in the intracellular signaling cascade of G-protein-coupled receptors for sweet, bitter, and umami tastes.

Endolymph

The potassium-rich fluid found within the cochlear duct that enables hair-cell depolarization when stereocilia are bent toward the tallest member.

Basilar Membrane

A mechanical structure in the cochlea whose variable stiffness separates frequencies: high frequencies maximally displace the stiff base near the oval window, and low frequencies displace the flexible apex.

Phototransduction

The retinal process where light triggers rhodopsin, activates transducin, and stimulates phosphodiesterase to degrade cGMP, closing cGMP-gated channels and causing photoreceptor hyperpolarization and reduced glutamate release.

Dark Current

The continuous inward depolarizing ion flow in photoreceptors maintained in darkness by open cGMP-gated cation channels.

Antagonistic Control

An autonomic regulatory mechanism in which sympathetic and parasympathetic divisions exert opposing physiological actions on the same target organ.

Neuroeffector Junction

The synapse between an autonomic postganglionic neuron and its effector tissue, characterized by neurotransmitter release from axon swellings called varicosities.

Chromaffin Cells

Modified postganglionic sympathetic cells in the adrenal medulla that release catecholamines (predominantly epinephrine) directly into the blood following stimulation by preganglionic acetylcholine.

Atropine

A muscarinic acetylcholine receptor antagonist that blocks parasympathetic activity, leading to increased heart rate, dilated pupils, and decreased salivation and digestive secretions.