The GABA_A receptor is a type of protein found in the brain that plays a crucial role in regulating neurotransmission. It is a receptor for the neurotransmitter gamma-aminobutyric acid (GABA), which is the primary inhibitory neurotransmitter in the central nervous system. When GABA binds to the GABA_A receptor, it typically causes the opening of ion channels, allowing chloride ions to enter the neuron, leading to a decrease in neuronal excitability. These receptors are important for maintaining the balance between excitation and inhibition in the brain, influencing various functions such as mood, anxiety, and sleep. Abnormalities in GABA_A receptor function are associated with several neurological and psychiatric disorders, including epilepsy, anxiety disorders, and schizophrenia.