Neuroscience MCAT Practice Question
During synaptic transmission, an action potential triggers voltage-gated calcium channels to open in the presynaptic terminal, allowing calcium influx. This calcium influx promotes the fusion of synaptic vesicles with the presynaptic membrane via SNARE proteins. A neurotoxin blocks the SNARE protein complex, preventing vesicle fusion. What is the direct consequence of this blockade on neurotransmitter release?
Answer choices
- AIncreased frequency of spontaneous vesicle release events
- BEnhanced postsynaptic receptor sensitivity
- CAbolished or severely reduced evoked neurotransmitter releaseCorrect answer
- DIncreased duration of neurotransmitter dwell time in the synaptic cleft
- EEnhanced retrograde signaling via endocannabinoid systems
- FUnopposed accumulation of calcium in the presynaptic terminal leading to excitotoxicity
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