Neurobiology of Panic Disorder "There is most evidence for changes in Gamma-aminobutyric acid , with lowered cortical Gamma-aminobutyric acid type levels measured by magnetic resonance spectroscopy, and diminished benzodiazepine -receptor binding in the parietotemporal regions in unmedicated patients with panic disorder (Hasler et al., 2008)." This happens in panic disorder. Gamma-aminobutyric acid is the major inhibitory neurotransmitter in the brain. Benzodiazepine also binds to Gamma-aminobutyric acid type A receptors and increases its firing rate, thus resulting in hyperpolarisation of the cell because of increased chloride influx. So, specific regions in the brain are hyperexcitable in patients with panic disorder. Summary of Hasler et al. Context Studies have implicated the benzodiazepine receptor system in the pathophysiologic mechanism of panic disorder by indirect evidence from pharmacological challenge studies and by direct evidence from single-photon emission