Refer to the figure showing a postsynaptic neuron summing information. The black arrow in the figure indicates
A) the summing of several inhibitory postsynaptic potentials.
B) temporal summation.
C) electrical summation.
D) the summing of postsynaptic potentials created at the same synapse in rapid succession.
E) spatial summation.

Question

Refer to the figure showing a postsynaptic neuron summing information.  The black arrow in the figure indicates
A) the summing of several inhibitory postsynaptic potentials. 
B) temporal summation. 
C) electrical summation. 
D) the summing of postsynaptic potentials created at the same synapse in rapid succession. 
E) spatial summation.

Quizplus · Accepted Answer

The black arrow in the figure indicates spatial summation where multiple excitatory postsynaptic potentials (EPSP) from different synapses are summed up on the postsynaptic neuron. This process can lead to the generation of an action potential if the sum of the EPSPs reaches the threshold potential. In contrast, inhibitory postsynaptic potentials (IPSPs) would reduce the likelihood of an action potential being generated, so A is incorrect. Temporal summation and electrical summation involve the summation of EPSPs or IPSPs at the same synapse either over time or through gap junctions respectively, but neither of these are indicated by the black arrow in the figure, so B and C are incorrect. D is incorrect because it suggests that the postsynaptic potentials are created at the same synapse, whereas spatial summation involves multiple synapses.

Refer to the Figure Showing a Postsynaptic Neuron Summing Information