Response of Regional Cerebral Blood Flow and Oxygen Metabolism to Thalamic Stimulation in Humans as Revealed by Positron Emission Tomography

Abstract

To clarify functional neural pathways originating from the thalamic nucleus ventralis posterolateralis (VPL) in humans, the responses of regional CBF (rCBF) and regional CMRO₂ (rCMRO₂) to VPL stimulation were investigated by positron emission tomography in five patients who had undergone chronic implantation of electrodes into the VPL for therapeutic purposes. Measurement of rCBF and rCMRO₂ under continuous inhalation of C¹⁵O₂ and ¹⁵O₂ by steady-state methods revealed significant increases of rCBF and rCMRO₂ in the frontal, postcentral, and thalamic regions. The increases in rCBF and rCMRO₂ of the postcentral regions were clearly predominant in the stimulated hemisphere insofar as the stimulation produced moderate paresthesia in restricted areas of the body. These results indicate that the VPL relays peripheral somatosensory information, which has previously been demonstrated to be transmitted to the frontal as well as postcentral regions.