Event-related cortical potentials as indicators of neurochemical dysfunction in psychiatric patients

The increasing knowledge concerning anatomical structures and cellular processes underlying event-related potentials (ERP) and methodological advances in ERP data analysis are beginning to bridge the gap between ERP and neurochemical aspects. ERP reflect directly postsynaptic effects of cortical neurotransmitters (e. g. GABA, glutamate) and indirectly modulating effects of neuromodulators (e.g. serotonin, acetylcholine) on cortical neuronal functioning and are therefore promising as noninvasive indicators of the functioning of neurochemical systems. Several recent reports are summarised suggesting that quite specific relationships may exist between certain ERP parameters and central cholinergic, noradrenergic and especially serotonergic function. Converging arguments from preclinical and clinical studies are presented supporting the hypothesis that the dependence of the response of primary auditory cortices on stimulus intensity (loudness) is regulated by the level of central serotonergic neurotransmission. This intensity dependence is shown to be of clinical value because, within different diagnostic categories, subgroups of patients with a serotonergic dysfunction can be identified and can be treated more specifically with serotonergic drugs.