How do excitatory neurotransmitters primarily affect neuron activity?

Excitatory neurotransmitters play a crucial role in modifying the activity of neurons by increasing the likelihood of an action potential firing. When an excitatory neurotransmitter is released into the synaptic cleft, it binds to specific receptors on the postsynaptic neuron. This binding usually leads to the opening of ion channels that allow positively charged ions, such as sodium (Na+), to enter the neuron. The influx of positive ions causes depolarization of the neuron's membrane potential, moving it closer to the threshold required to trigger an action potential. As a result, the probability that the neuron will fire increases significantly.

This mechanism is fundamental to neural communication, as it enables the transmission of signals throughout the nervous system, facilitating processes such as reflexes, sensory processing, and cognitive functions. Understanding the role of excitatory neurotransmitters is key to grasping how neurons communicate and how various neurological processes occur.