title="" class="an ">&ensp;</span><span  title="Neuron" class="an Neuron">cell</span><span  title="" class="an ">&ensp;</span>body <span  title="" class="an ">&ensp;</span>and <span  title="" class="an ">&ensp;</span>synaptic <span  title="" class="an ">&ensp;</span>terminal <span  title="" class="an ">&ensp;</span>regions <span  title="" class="an ">&ensp;</span>Although <span  title="" class="an ">&ensp;</span>calcium <span  title="" class="an ">&ensp;</span>a <span  title="" class="an ">&ensp;</span>key 