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Neuroscience Flashcards

7 cards from real NBME practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. A patient loses fine touch, vibration, and proprioception below the level of a thoracic spinal cord lesion, bilaterally. Which tract is most likely damaged?

    Answer: Dorsal columns (posterior funiculus)

    The dorsal columns (fasciculus gracilis and cuneatus) carry ipsilateral fine touch, vibration, and proprioception; bilateral loss indicates bilateral dorsal column damage.

  2. A patient sustains a left hemisection of the thoracic spinal cord (Brown-Séquard). Which finding is expected below the lesion?

    Answer: Left-sided loss of proprioception; right-sided loss of pain/temperature

    Brown-Séquard: ipsilateral (left) UMN weakness and dorsal column loss because those tracts are uncrossed at that level; contralateral (right) spinothalamic (pain/temp) loss because the STT crosses within 1-2 spinal levels.

  3. Which dopaminergic pathway is most associated with the positive symptoms of schizophrenia?

    Answer: Mesolimbic pathway

    Hyperactivity of the mesolimbic dopaminergic pathway (VTA to nucleus accumbens/limbic areas) underlies the positive symptoms (hallucinations, delusions) of schizophrenia.

  4. An ascending demyelinating polyneuropathy with albuminocytologic dissociation on CSF analysis and autonomic instability is most consistent with which diagnosis?

    Answer: Guillain-Barré syndrome

    Guillain-Barré syndrome is an autoimmune demyelinating polyradiculoneuropathy with ascending weakness, areflexia, albuminocytologic dissociation (high protein, normal cells), and potential autonomic dysfunction.

  5. A patient presents with fasciculations, muscle atrophy, hyperreflexia, and a Babinski sign in the same extremities. Which diagnosis best explains both upper and lower motor neuron signs?

    Answer: Amyotrophic lateral sclerosis (ALS)

    ALS selectively destroys both UMNs (cortex, corticospinal tract) and LMNs (anterior horn cells, cranial motor nuclei), producing simultaneous hyperreflexia/spasticity and fasciculations/atrophy.

  6. During synaptic transmission at the neuromuscular junction, which event directly triggers vesicle fusion and acetylcholine release?

    Answer: Calcium influx through voltage-gated P/Q-type channels

    Action potential depolarization opens presynaptic voltage-gated Ca²⁺ (P/Q-type) channels; the resulting Ca²⁺ influx triggers SNARE-mediated vesicle fusion and ACh exocytosis.

  7. Which neurotransmitter is the primary inhibitory neurotransmitter in the brain, and benzodiazepines enhance its effect at which receptor type?

    Answer: GABA; GABA-A receptor (Cl⁻ channel)

    GABA is the principal inhibitory CNS neurotransmitter; benzodiazepines bind the GABA-A receptor (a ligand-gated Cl⁻ channel) and increase frequency of Cl⁻ channel opening.