This study examined the usefulness of 123I-iomazenil SPECT (IMZ-SPECT), a type of brain scintigram that focuses on the central benzodiazepine receptor in order to determine its distribution and the function of inhibitory neurons. IMZ-SPECT has been used for the detection of epileptogenic foci, especially when surgical intervention is considered. Interictal study by IMZ-SPECT is widely available at numerous institutions and its usefulness has been confirmed in patients with not only focal cortical dysplasia and hippocampal sclerosis, but also tuberous sclerosis and neuronal migration disorders, even when magnetic resonance image fails to demonstrate any abnormal findings. When interpreting scintigrams, the developmental dynamic change of the central benzodiazepine receptor in childhood and the duration of the benzodiazepine exposure period should be taken into consideration. It is expected that IMZ-SPECT will be used in various neurological disorders other than epilepsy in the future allow medical services to be provided based on findings in the inhibitory synaptic system obtained with IMZ-SPECT.