Selective pharmacological activation of limbic structures in human volunteers: a positron emission tomography study.

Using a pharmacological probe, procaine hydrochloride, the authors elicited consistent and selective activation of anterior limbic and paralimbic structures in normal human volunteers as documented by H215O positron emission tomography. This activation was associated with a range of emotional, somatic, and visceral experiences, often similar to those experienced during the aura of temporal lobe epilepsy. Several subjects also experienced panic attacks. This study confirms that selective anterior limbic/paralimbic activity in normal human volunteers evokes many emotional phenomena as well as common "ill-defined" symptoms observed in clinical conditions. The present combination of procaine challenge and neuroimaging provides a noninvasive procedure to probe the contribution of different anterior limbic and paralimbic structures to normal human emotions and to neuropsychiatric disorders.