What key role does glutamate play in the brain?

Glutamate is the primary excitatory neurotransmitter in the brain, meaning it plays a crucial role in promoting the activation of neurons and the communication between them. This excitation is essential for various brain functions, including learning, memory, and overall cognitive functioning. When glutamate binds to its receptors on target neurons, it usually leads to an influx of calcium ions, which stimulates the neuron and can lead to increased neural circuit activity.

The other choices represent functions that are not primarily associated with glutamate. For instance, inhibiting neural activity is typically the role of neurotransmitters like gamma-aminobutyric acid (GABA), while controlling motor functions is largely dependent on other neurotransmitters and neuronal pathways. Regulation of hormonal responses also involves a complex interplay of hormones and other signaling molecules, rather than being direct actions of glutamate itself. Thus, understanding glutamate's excitatory role is essential when studying neural communication and its impact on behavior and cognition.