Atransient shortage of oxygen (global ischemia) releases excess glutamate into the extracellular fluid of the brain. this causes neuronal death by hyperexcitation to a greater extent in the hippocampus than in the cortex. which reason best explains why the hippocampus is selectively vulnerable during global ischemia? (a) the mag of ap is greater in hippocampal than cortical neurons(b) the expression of nmda receptors is more abundant in hippocampal than cortical neuorns(c) hippocampal neurons generate a more negative postsynaptic potential than cortical neurons(d) hippocampal synapses have faster neurotransmitter diffusion rates compared to cortical synapses