Question

Which of the following statements is INCORRECT regarding action potentials?

A. The axon terminal of a neuron can send only one type of NT to the dendrites of its postsynaptic neighbor.

B. AP signals can be summed spatially, but cannot be summed temporally because they are all-or-nothing events.

C. Post-synaptic neurons can receive information from many different neurons via their NT receptors.

D. If an NT causes the postsynaptic cell’s membrane to become hyperpolarized, this reduces the likelihood that it will transmit a signal onward.

E. If a postsynaptic neuron receives both ESPS and ISPS from different neurons, it is possible that its membrane potential will remain at its resting potential.

Answer 1

The correct answer is Option B - AP signals can be summed spatially, but cannot be summed temporally because they are all-or-nothing events.

Explanation: According to All-or-nothing law, the size of the action potential does not depend on the size of the stimulus because the size of the action potential does not vary, it is constant. So, the action potential either occurs or does not.

A single excitatory postsynaptic potential cannot produce sufficient depolarization to propagate an action potential in the postsynaptic neuron. So, the depolarizing effect of several excitatory postsynaptic potentials is additive.

AP signals are summed spatially when two or more signals arising simultaneously at different regions on the same neuron and AP signals are summed temporally when the repeated release of neurotransmitter from several synaptic vesicles by the same synaptic knob occurs, as a result of an intense stimulus.

So, AP signals can be summed spatially as well as temporally.