Which neurotransmitter is the primary excitatory transmitter in the CNS and is involved in learning and memory?

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

Answer: (B)

Learning and memory hinge on synaptic plasticity driven by excitatory signaling. Glutamate is the primary excitatory neurotransmitter in the CNS, activating receptors such as NMDA and AMPA. When glutamate activates these receptors, especially NMDA receptors, calcium enters the neuron and triggers signaling cascades that strengthen synapses—a process called long-term potentiation, which is central to learning and memory. In contrast, GABA provides inhibition, endorphins are endogenous opioids involved in pain and reward modulation, and dopamine is crucial for reward, motivation, and movement. Because glutamate best fits the description of the main excitatory transmitter involved in learning and memory, it is the best answer.