Comprehensive Neurobiology and Psychopathology: Brain Structures, Neurotransmitters, and Disorders

Neuron

A cell in the nervous system responsible for information processing by accumulating and transmitting electrical activity.

Motor Neuron

Neuron with soma in the spinal cord that conducts impulses along its axon to a muscle or gland to produce movement.

Sensory Neuron

Neuron specialized to respond to a particular stimulus (e.g., light, sound, touch).

Dendrites

Branching structures that receive synaptic input from other neurons; greater surface area increases input.

Synapse

The junction where the axon terminal of one neuron meets the dendrite or soma of another neuron to transmit signals.

Cell body

Soma containing nucleus, mitochondria, and ribosomes; metabolic machinery of the neuron.

Axons

Long process that carries nerve impulses away from the cell body to other neurons, muscles, or glands.

Afferent

Carrying information toward a structure (incoming signals).

Intrinsic

Completely contained within a single structure.

Efferent

Carrying information away from a structure (outgoing signals).

Myelin Sheath

Insulating layer around axons that speeds conduction of electrical impulses.

Nodes of Ranvier

Interruptions in the myelin sheath where action potentials are regenerated to speed transmission.

Presynaptic terminal

End of an axon that releases neurotransmitters into the synaptic cleft.

Glia

Non-neuronal CNS cells that support neurons and modulate signaling; 50% of total volume of CNS.

Astrocyte

Glial cell that modulates synapses and dilates blood vessels to supply nutrients.

Microglia

Glial cells that remove waste, pathogens, and dead neurons.

Oligodendrocytes

Glial cells in CNS that create and maintain the myelin sheath around axons.

Schwann Cells

Peripheral glial cells that form myelin around axons in the PNS.

Radial Glia

Glial cells guiding neuron migration and growth of axons/dendrites during development.

Action Potential

Rapid change in membrane potential that propagates along the axon to transmit a signal.

Hyperpolarization

Increase in polarization; inside becomes more negative, reducing likelihood of firing.

Depolarization

Reduction of polarization toward zero; increases likelihood of firing.

Threshold of Excitation

Minimum stimulus level required to trigger an action potential.

Resting Potential

Baseline electrical potential across the neuron's membrane when at rest.

Neurotransmitters

Chemicals released at the synapse to alter the activity of the postsynaptic neuron.

Glutamate

Major excitatory neurotransmitter in the brain.

GABA

Major inhibitory neurotransmitter; opens chloride channels to hyperpolarize neurons.

Acetylcholine

Neurotransmitter involved in motor control and many brain functions; modified amino acid.

Serotonin

Monoamine neurotransmitter involved in mood, arousal, and other functions.

Dopamine

Monoamine neurotransmitter linked to reward, movement, and attention.

Norepinephrine

Monoamine neurotransmitter involved in arousal and alertness.

Epinephrine

Monoamine neurotransmitter also known as adrenaline; involved in stress responses.

Endorphins

Neuropeptides that act as natural analgesics and pain modulators.

Adenosine

Purine neurotransmitter/neuromodulator with inhibitory effects; promotes sleep.

ATP

Purine neurotransmitter.

Nitric Oxide

Gaseous neurotransmitter involved in signaling and regulation of blood flow.

MAO

Monoamine oxidase enzyme that breaks down monoamines/excess neurotransmitters to regulate transmitter levels.

Acetylcholinesterase

Enzyme that breaks down acetylcholine in the synapse for reuptake.

MAO inhibitors

Drugs that inhibit MAO, increasing availability of monoamines.

Synaptic transmission sequence

The process by which neurons communicate through the release and reception of neurotransmitters.

Action potentials

Electrical impulses that travel down the axon of a neuron.

Synaptic cleft

The space between presynaptic and postsynaptic neurons.

Ionotropic receptor

A receptor that forms an ion channel and produces fast, brief postsynaptic effects.

Excitatory synapse

A synapse where neurotransmitter increases postsynaptic likelihood of firing, often involving glutamate.

Inhibitory synapse

A synapse where neurotransmitter decreases postsynaptic likelihood of firing, often involving GABA.

Inhibition

An active brake that suppresses excitation in the nervous system.

Cannabinoids

Endogenous or external compounds that modulate neurotransmission via cannabinoid receptors.

Amphetamine

A stimulant that increases dopamine/norepinephrine release and blocks reuptake.

Cocaine

A drug that blocks reuptake of dopamine and other monoamines, elevating their levels.

Methylphenidate

Also known as Ritalin; it blocks reuptake of dopamine and other transmitters.

MDMA

Also known as Ecstasy; it releases serotonin and enhances serotonin signaling.

Nicotine

A stimulant that binds nicotinic acetylcholine receptors, increasing arousal and dopamine release.

Opiates

Opioid drugs such as heroin and morphine that activate endorphin receptors and produce analgesia.

Hallucinogens

Psychedelics that primarily affect serotonin receptors, such as LSD.

5-HT2A

A serotonin receptor subtype linked to hallucinogenic effects.

Proliferation

The production of new cells (neurons and glia) during development.

Migration

The movement of primitive cells to their destined locations in the brain.

Differentiation

The developmental process by which cells become specific neuron or glial types.

Synaptogenesis

The formation of synapses between neurons, beginning before birth and continuing throughout life.

Myelination

The development of myelin sheath around axons to speed conduction.

Apoptosis (pruning)

Programmed cell death used to prune unnecessary neurons during development.

Nerve Growth Factor

A protein that promotes survival and growth of axons.

Neurotrophin

A chemical that supports neuron survival, growth, and synaptic formation.

Necrosis

Cell death caused by injury or toxic substance.

Forebrain

The front part of the brain including thalamus, hypothalamus, cerebral cortex, hippocampus, and basal ganglia.

Thalamus

The sensory information relay station to the cerebral cortex.

Hypothalamus

The part of the brain that regulates eating, drinking, temperature, and reproductive behaviors.

Cerebral Cortex

Outer layer of the brain governing higher cognitive functions.

Limbic System

Group of structures including olfactory bulb, hypothalamus, hippocampus, amygdala, cingulate gyrus.

Hippocampus

Critical for certain memories especially for individual events and for monitoring where you are and where you are going.

Amygdala

Circuit central for evaluating emotional information especially in regard to fear.

Basal Ganglia

Group of subcortical structures including caudate nucleus, putamen, and globus pallidus. Damage here impairs movement (i.e. parkinsons, huntingtons). Integrate motivational and emotional behavior to increase vigor of actions. Critical for learned skills and habits.

Midbrain

Includes tectum, tegmentum, superior colliculus, inferior colliculus, substantia nigra.

Tectum

Roof of midbrain.

Superior colliculus

Important for vision processing.

Inferior colliculus

Important for hearing processing.

Tegmentum

Under the tectum.

Substantia Nigra

Gives rise to dopamine containing pathways that facilitate readiness for movement.

Brainstem

Includes medulla, pons, midbrain, and some structures of the forebrain.

Hindbrain

Includes medulla, pons, cerebellum.

Medulla

Cranial nerves originating here control vital reflexes like breathing, heart rate, vomiting, salivation, coughing, sneezing.

Pons

Axons from each half of the brain cross to the opposite side of the spinal cord so that the left hemisphere controls muscles of the right side of the body and the right hemisphere controls the left side.

Cerebellum

Contributes to the control of movement, importance for balance and coordination.

Occipital Lobe

Processes visual information; primary visual cortex.

Parietal Lobe

Contains primary somatosensory cortex; responsible for body sensations.

Temporal Lobe

Responsible for hearing, advanced visual processing, understanding spoken language (left).

Frontal Lobe

Involved in planning of movements, recent memory, and some emotions.

Prefrontal cortex

Involved in decision making, movement, working memory, cognitive control, emotional reactions.

Primary motor cortex

Located in the precentral gyrus.

Primary somatosensory cortex

Located in the postcentral gyrus.

Corpus Callosum

Bundles of axons that help with communication of neurons in corresponding parts of the other hemisphere.

CSF

Cushions the brain against mechanical shock when the head moves. Supports weight of the brain, provides a reservoir of hormones and nutrition for brain and spinal cord.

Left hemisphere/language in the brain

Controls speech.

Aphasia

Language impairment.

Broca's Aphasia

Nonfluent, left frontal cortex; area is important for language production but damage limited to that area produces only minor or brief language impairment.

Wernicke's Aphasia

Fluent aphasia; left temporal cortex; patients could speak and write, but poor language comprehension.

Bottom-up process

Depends on the stimulus; something grabs your attention.

Top-down process

Intentional; looking for something; can overrule bottom up.

Factual decision making

Part of the prefrontal cortex called the frontal orienting fields respond; frontal cortex provides all or none outcome.

Ventromedial prefrontal cortex

Modifies responses of basal ganglia; orbitofrontal cortex gets info from ventromedial and responds based on how an expected reward compares to other possible choices.