Functional Neuroscience – Olympiad Review

60 Q&A flashcards covering action potentials, pain pathways, memory systems, synaptic plasticity, sleep, reflexes, emotion, neurotransmitters, and stress—designed for high-level Neuroscience Olympiad preparation.

What maintains the neuron's resting membrane potential at about –70 mV?

The Na⁺/K⁺-ATPase pump (3 Na⁺ out, 2 K⁺ in) together with K⁺ leak channels that allow more K⁺ efflux than Na⁺ influx.

Approximately what voltage is the threshold potential that triggers an action potential?

About –55 mV.

Which voltage-gated ion channels open rapidly during the depolarization phase of an action potential?

Voltage-gated Na⁺ channels.

What causes the repolarization (falling) phase of an action potential?

Inactivation of Na⁺ channels and opening of voltage-gated K⁺ channels leading to K⁺ efflux.

Why does hyperpolarization (undershoot) occur after an action potential?

K⁺ channels close slowly, allowing excess K⁺ efflux so the membrane becomes more negative than resting.

During which refractory period is it impossible to fire another action potential regardless of stimulus strength?

Absolute refractory period.

What feature of saltatory conduction speeds up action potentials in myelinated axons?

The AP "jumps" from Node of Ranvier to Node of Ranvier because myelin insulates internodal segments.

Name a disease in which myelin damage severely impairs action-potential propagation.

Multiple Sclerosis.

Which myelinated fibers conduct fast, sharp pain?

A-delta fibers.

Which unmyelinated fibers conduct slow, dull, throbbing pain?

C fibers.

What is the key difference between nociception and pain?

Nociception is neural encoding of noxious stimuli; pain is the conscious, unpleasant sensory and emotional experience.

List the three main clinical categories of pain.

Acute pain, chronic pain, and neuropathic pain.

Where are the cell bodies of primary afferent nociceptors located?

In the Dorsal Root Ganglion (DRG).

In the pain pathway, where do primary afferents first synapse with second-order neurons?

The dorsal horn of the spinal cord.

At what point do second-order pain neurons cross to the opposite side of the spinal cord?

Immediately after synapsing in the dorsal horn (decussation).

Which thalamic nucleus receives spinothalamic pain signals?

The Ventral Posterior Nucleus (VPN) of the thalamus.

Which cortical area localizes and assesses the intensity of pain?

Primary Somatosensory Cortex (S1).

Which brainstem region initiates descending opioid-mediated pain inhibition?

The periaqueductal gray (PAG) (with raphe nuclei involvement).

What neurotransmitters are released by descending pain-modulation pathways to inhibit pain?

Endogenous opioids (endorphins, enkephalins) and monoamines such as serotonin and norepinephrine.

How do learning and memory differ?

Learning is acquiring new knowledge or skills; memory is storing and retaining that information over time.

According to Miller’s law, what is the typical capacity of short-term/working memory?

About 7 ± 2 items.

Which brain structure is essential for consolidating short-term memories into long-term memory?

The hippocampus (and medial temporal lobe structures).

Differentiate episodic and semantic memory.

Episodic memory is personal experiences/events; semantic memory is general facts and knowledge.

Which brain regions are critical for procedural (skill) memory?

Basal ganglia and cerebellum.

What synaptic process is considered the cellular basis of learning and memory?

Long-Term Potentiation (LTP).

Through which receptor does Ca²⁺ influx trigger LTP?

The NMDA receptor once the Mg²⁺ block is removed.

During LTP, what postsynaptic change strengthens the synapse?

Insertion of additional AMPA receptors and increased AMPA receptor conductance.

What is Long-Term Depression (LTD)?

A long-lasting weakening of synapses, often via removal or dephosphorylation of AMPA receptors after low-frequency stimulation.

Which EEG waves dominate deep N3/slow-wave sleep?

Delta waves.

During which sleep stage do vivid dreams and muscle atonia occur?

Rapid Eye Movement (REM) sleep.

Which hypothalamic nucleus acts as the body’s master circadian clock?

The Suprachiasmatic Nucleus (SCN).

What hormone released by the pineal gland promotes sleep?

Melatonin.

Which hypothalamic neuropeptide system promotes wakefulness?

Orexin/hypocretin neurons in the hypothalamus.

Which hypothalamic area uses GABA to promote sleep onset?

The ventrolateral preoptic area (VLPO).

Give two key restorative functions of sleep.

Physical restoration/immune support and memory consolidation (others include energy conservation and emotional regulation).

Name the five components of a basic reflex arc.

Sensory receptor, afferent neuron, integration center, efferent neuron, and effector.

Which monosynaptic reflex causes contraction of a stretched muscle?

The stretch (myotatic) reflex (e.g., knee-jerk).

What is reciprocal inhibition during the stretch reflex?

An interneuron inhibits the antagonist muscle while the agonist muscle contracts.

Which reflex withdraws a limb from a painful stimulus?

The withdrawal (flexor) reflex.

Which accompanying reflex stabilizes the opposite limb during withdrawal?

The crossed-extensor reflex.

Which brainstem reflex constricts both pupils when light enters one eye?

The pupillary light reflex (direct and consensual).

Which limbic structure is critical for fear and rapid emotional responses?

The amygdala.

Which cortical region integrates emotion with cognition and pain processing?

The anterior cingulate cortex.

Which neurotransmitter drives reward and motivation in the mesolimbic pathway?

Dopamine.

From which midbrain area do mesolimbic dopamine neurons originate?

The Ventral Tegmental Area (VTA).

Name the three components of the HPA axis activated during chronic stress.

Hypothalamus (CRH), pituitary gland (ACTH), and adrenal cortex (cortisol).

List two negative effects of prolonged cortisol exposure.

Impaired hippocampal memory formation and suppressed immune function (among others).

Which theory of emotion states that emotion requires both physiological arousal and cognitive interpretation?

Schachter-Singer two-factor theory.

Which primary inhibitory neurotransmitter is often low in anxiety disorders?

GABA.

Which sleep stage is especially important for procedural memory consolidation and emotional regulation?

REM sleep.

What does the synaptic homeostasis hypothesis propose occurs during slow-wave sleep?

Global down-scaling of synaptic strengths to maintain neural balance and allow future plasticity.

Does the withdrawal reflex involve interneurons?

Yes, it is polysynaptic and relies on multiple interneurons.

What property makes an action potential an "all-or-none" event?

Once threshold is reached, its amplitude is constant; partial firing is impossible.

What ensures one-way propagation of the action potential along an axon?

The absolute refractory period caused by Na⁺ channel inactivation behind the advancing AP.

Why is saltatory conduction more energy-efficient than continuous conduction?

Fewer Na⁺ enter the axon overall, so less ATP is needed by Na⁺/K⁺ pumps to restore gradients.

Which type of pain is typically burning or shooting and results from nervous system damage?

Neuropathic pain.

Which brainstem region and neurotransmitter system generate REM sleep?

The pontine reticular formation’s cholinergic neurons.

How do absolute and relative refractory periods differ?

Absolute: no AP possible; Relative: AP possible but only with a stronger-than-normal stimulus.

Which type of memory stores unconscious skills like riding a bike?

Procedural (implicit) memory.

Which neurotransmitters in the reticular activating system promote wakefulness?

Acetylcholine, norepinephrine, serotonin, and dopamine.