What role does GABA play in the nervous system?

GABA, or gamma-aminobutyric acid, is the primary inhibitory neurotransmitter in the central nervous system. Its primary role is to reduce neuronal excitability throughout the nervous system. By binding to its receptors, GABA facilitates the opening of ion channels, allowing negatively charged ions to enter the neuron. This action hyperpolarizes the neuron, making it less likely to fire and thereby inhibiting the transmission of signals.

In contrast, the other options pertain to different functions or effects that do not directly relate to GABA's role. Communication between neurons is generally enhanced by excitatory neurotransmitters rather than inhibited, and regulating blood pressure and affecting heart rate typically involve other neurotransmitters and systems, such as the sympathetic and parasympathetic nervous systems, rather than the action of GABA. This highlights how GABA's primary function is centered on inhibition within the nervous system, leading to calming effects, which can help regulate anxiety and prevent overstimulation.