Question

What type of postsynaptic potential is always less negative?

1) Excitatory postsynaptic potential (EPSP)
2) Inhibitory postsynaptic potential (IPSP)
3) Both EPSP and IPSP
4) None of the above

Answer 1

The type of postsynaptic potential that is always less negative is the Excitatory postsynaptic potential (EPSP), as it causes depolarization of the postsynaptic neuron's membrane potential.

Step-by-step explanation:

A postsynaptic potential (PSP) is a graded potential that occurs in the dendrites of a neuron receiving synapses from other cells. There are two types of PSPs: excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs). An EPSP is a depolarization event that brings the membrane potential closer to the threshold for firing an action potential, making it more positive, or 'less negative'. On the other hand, an IPSP is a hyperpolarization event that moves the membrane potential further from the threshold, making the neuron less likely to fire an action potential, and thereby more negative.

Thus, in response to the question, the type of postsynaptic potential that is always less negative is the Excitatory postsynaptic potential (EPSP).