Neurons were kept in a physiological solution. During the resting phase, the membrane potential in the axoplasm of neurons was negative compared to the extracellular space and a potential difference of -70 mV was observed in this phase. Neurons were then treated in two different experiments with either gamma-amino butyric acid (GABA; an inhibitory neurotransmitter) or glutamate (an excitatory neurotransmitter) and the membrane potentials were recorded. Choose the correct statement/s:
(A) The resting membrane potential of -70 mV would not change with either GABA or glutamate treatments.
(B) The membrane potential would be even more negative than resting phase with GABA treatment.
(C) The membrane potential would be positive when the neuron was exposed to glutamate.
(D) The membrane potential would be more negative than resting potential after glutamate treatment.
I feel, since, glutamate is excitatory, so resting potential should decrease when exposed to glutamate and increase when exposed to GABA. So (A)&(D) automatically gets eliminated and (B) is correct answer. I am confused at (C)