EFFECT OF PHOTIC-STIMULATION ON ENERGY-METABOLISM IN THE HUMAN BRAIN MEASURED BY P-31-MR SPECTROSCOPY

Effect of photic stimulation (PS) on energy metabolism in the human oc cipital cortex was examined by using phosphorus-31 magnetic resonance spectroscopy in 9 normal subjects. Phosphocreatine (PCr)/total phospho rus signal peak area ratio significantly decreased from 12.3% to 10.9% during the 12 minutes of PS (P <0.05). PCr once returned to a normal level after PS (11.9%) but significantly decreased again 12-18 minutes after PS (10.8%; P <0.05). Intracellular pH increased from 7.08 to 7. 16 during PS, although this increase was not significant. These result s suggest that functional alteration of energy metabolism in the brain is different from that in muscles.