Which neurotransmitter is the primary excitatory transmitter in the CNS?

Which neurotransmitter is the primary excitatory transmitter in the CNS?

• A. Glutamate
• B. GABA
• C. Dopamine
• D. Serotonin

Answer: (A)

In the central nervous system, the primary fast excitatory signal is glutamatergic transmission. Glutamate is released from presynaptic terminals and binds to ionotropic receptors such as AMPA and NMDA (and kainate), causing cation channels to open. This allows Na+ to flow in (and Ca2+ through NMDA channels), depolarizing the postsynaptic neuron toward the threshold for firing an action potential. This rapid depolarization is the hallmark of excitatory neurotransmission in the CNS and underpins much of cortical signaling and synaptic plasticity. GABA, by contrast, is the main inhibitory neurotransmitter in the brain, promoting hyperpolarization and reducing neuronal firing. Dopamine and serotonin act mainly as modulators, influencing mood, attention, and other functions through various receptor subtypes, rather than serving as the primary fast excitatory transmitters.

In the central nervous system, the primary fast excitatory signal is glutamatergic transmission. Glutamate is released from presynaptic terminals and binds to ionotropic receptors such as AMPA and NMDA (and kainate), causing cation channels to open. This allows Na+ to flow in (and Ca2+ through NMDA channels), depolarizing the postsynaptic neuron toward the threshold for firing an action potential. This rapid depolarization is the hallmark of excitatory neurotransmission in the CNS and underpins much of cortical signaling and synaptic plasticity.

GABA, by contrast, is the main inhibitory neurotransmitter in the brain, promoting hyperpolarization and reducing neuronal firing. Dopamine and serotonin act mainly as modulators, influencing mood, attention, and other functions through various receptor subtypes, rather than serving as the primary fast excitatory transmitters.