Phencyclidine (PCP): Effects on auditory evoked potentials in the rhesus monkey

Abstract

Effects of acute and chronic administration of phencyclidine (PCP) on auditory evoked potentials (AEPs) were studied in rhesus monkeys with encephalic electrodes permanently implanted. AEPs were evoked by single clicks (1.0 pps in frequency) generated by an externally triggered audiomonitor. Single PCP injections (dose, 2.0 or 4.0 mg/kg IV) in monkeys produced a striking distortion in the amplitudes of major AEP components. This AEP distortion was manifested in superior temporal cortex (ST) by a complex pattern of amplitude reduction and enhancement, and was manifested in the medial geniculate body (MGB) by amplitude reduction. These effects persisted for 4 to 5 hours. Upon chronic administration (dose, 4.0 mg/kg IV daily), the effects of PCP on AEP components in ST were enhanced while little change was noted in its effect on AEP components in MGB. These results suggest that PCP administration in rhesus monkeys causes a significant disturbance of AEPs within central nervous system structures associated with auditory processing (i.e., ST and MGB), and that chronic PCP administration enhances its effects on AEPs predominantly in the primary auditory cortex while having little additional effects on AEPs from the subcortical auditory pathways.