Week 2 – Neurons (Behavioural & Cognitive Neuroscience, PSY224)

Vocabulary flashcards covering neuron anatomy, ion channels, synaptic physiology, neurotransmitters, and related neuropharmacology from Week 2 notes.

Neuron

A nerve cell specialized for transmitting electrical and chemical signals.

Sensory Neuron

Neuron that carries information from sensory receptors toward the central nervous system (CNS).

Motor Neuron

Neuron that carries commands from the CNS to muscles or glands.

Interneuron

Neuron that connects other neurons within the CNS, mediating internal communication.

Myelin

Fatty insulation around axons that speeds nerve impulse conduction.

Nodes of Ranvier

Gaps between myelin segments where action potentials jump during saltatory conduction.

Oligodendrocyte

CNS glial cell that forms myelin sheaths around multiple axons.

Schwann Cell

PNS glial cell that myelinates a single axon segment.

Multiple Sclerosis

Autoimmune disease where oligodendrocyte myelin is attacked, disrupting CNS signaling.

Glial Cell

Non-neuronal support cell of the nervous system (e.g., astrocytes, microglia, oligodendrocytes, Schwann cells).

Astrocyte

Star-shaped glial cell that regulates blood–brain barrier, blood flow, and extracellular environment.

Microglia

Small CNS glia serving immune functions; respond to injury and disease.

Blood–Brain Barrier

Selective barrier formed by endothelial cells (influenced by astrocytes) that limits substance entry to the CNS.

Resting Membrane Potential

Baseline electrical charge (≈ –70 mV) across a neuron’s membrane due to unequal ion distribution.

Lipid Bilayer

Hydrophobic double-layer membrane that restricts ion movement in neurons.

Voltage Gradient

Electrical force driving ions toward areas of opposite charge across a membrane.

Concentration Gradient

Diffusion force driving ions from high to low concentration regions.

Ligand-Gated Ion Channel

Membrane channel that opens when a specific neurotransmitter binds.

Voltage-Gated Ion Channel

Channel that opens or closes in response to membrane voltage changes.

Excitatory Postsynaptic Potential (EPSP)

Depolarizing graded potential that brings the membrane closer to action-potential threshold.

Inhibitory Postsynaptic Potential (IPSP)

Hyperpolarizing graded potential that drives the membrane away from threshold.

Summation

Combined effect of multiple EPSPs and IPSPs at the axon hillock determining action-potential initiation.

Action Potential Threshold

Membrane voltage (≈ –55 mV) that must be reached to trigger an action potential.

Depolarization

Phase of an action potential when voltage-gated Na⁺ channels open, making the membrane potential more positive.

Repolarization

Return toward resting potential via Na⁺ channel closure and K⁺ channel opening.

Hyperpolarization

Overshoot below resting potential due to continued K⁺ efflux after an action potential.

Absolute Refractory Period

1–2 ms post-spike interval when a second action potential cannot be generated.

Relative Refractory Period

Period after the absolute phase when a stronger-than-normal stimulus can fire another spike.

Sodium–Potassium Pump

Active transporter exchanging 3 Na⁺ out / 2 K⁺ in to maintain ion gradients.

Exocytosis

Vesicle-mediated release of neurotransmitter into the synaptic cleft.

Voltage-Gated Calcium Channel

Presynaptic channel whose opening (by depolarization) triggers Ca²⁺-dependent neurotransmitter release.

Neurotransmitter

Chemical messenger released by neurons to communicate across synapses.

Glutamate

Primary excitatory neurotransmitter in the CNS.

GABA (γ-Aminobutyric Acid)

Primary inhibitory neurotransmitter in the CNS.

Dopamine

Monoamine involved in reward, motivation, and motor control.

Norepinephrine

Monoamine that heightens arousal, attention, and heart rate.

Serotonin

Monoamine mediating mood, reward, learning, and memory.

Acetylcholine

Neurotransmitter at neuromuscular junction; also modulates attention, arousal, and motivation.

Second Messenger (G Protein)

Intracellular signaling molecule activated by metabotropic receptors to modulate cellular processes.

Non-Directed Synapse

Synaptic configuration where neurotransmitter diffuses broadly to surrounding targets.

Axo-Axonic Synapse

Synapse where an axon terminal contacts another axon, modulating its transmitter release.

Acetylcholinesterase

Enzyme that breaks down acetylcholine in the synaptic cleft.

Galantamine

Acetylcholinesterase inhibitor prescribed for Alzheimer’s disease to boost cholinergic signaling.

Cholinergic Basal Forebrain

Region providing widespread acetylcholine projections throughout the brain.