GABA is the main inhibitory neurotransmitter in the central nervous system. It counteracts the effects of glutamate by allowing chloride ions to pass through postsynaptic neurons, making them less responsive to excitatory signals. This gives GABA a calming effect on the brain. People with phobic disorders may have GABA deficiencies due to stress, diet, caffeine, or drugs like cocaine. Benzodiazepines mimic GABA's effects, allowing more chloride ions into postsynaptic neurons and calming overly active physiological responses caused by phobic stimuli, similar to how alcohol works.