Final answer:
Prolonged opening of calcium channels in the presynaptic membrane leads to an increase in neurotransmitter release and enhances synaptic transmission, playing a key role in synaptic strength and plasticity.
Step-by-step explanation:
The process of synaptic transmission involves the release of neurotransmitters from the presynaptic neuron, which are then received by the postsynaptic neuron. When an action potential reaches the axon terminal, it causes voltage-gated calcium channels to open. The influx of Ca²⁺ ions into the presynaptic neuron initiates a signaling cascade that allows synaptic vesicles containing neurotransmitter molecules to fuse with the presynaptic membrane and release their contents into the synaptic cleft. Prolonged opening of these calcium channels results in an increased influx of calcium ions, which in turn leads to more neurotransmitters being released into the synaptic cleft.
This enhances synaptic transmission by increasing the chance of neurotransmitter-receptor interactions on the postsynaptic membrane, potentially leading to stronger or more prolonged postsynaptic responses such as long-term potentiation (LTP). Therefore, the duration that calcium channels remain open is critical to the regulation of synaptic strength and plasticity, which are fundamental to learning and memory.