Preliminary findings of proton magnetic resonance spectroscopy in occipital cortex during sleep deprivation

Proton magnetic resonance spectroscopy (1H MRS) has revealed biochemical alterations in various psychiatric disorders. Changes in brain metabolites may be caused not only by the disease's progression or response to treatment, but also by physiological variability. The aim of this study was to use 1H MRS to assess the effects of specific short-term physiological states on major metabolites. Eight healthy women underwent 1H MRS at the beginning and end of a 40-h period of sleep deprivation. The ratios of N-acetyl-aspartate (NAA), total creatine (tCr), and choline-containing compounds (Cho) to water (H2O) were determined from the occipital cortex during both baseline and photic stimulation conditions. During sleep deprivation, NAA/H2O decreased by 7% and Cho/H2O by 12%. Photic stimulation had no effect on the measured metabolites in the alert state, but in the sleep-deprived state the level of Cho/H2O increased during neuronal activation. The results suggest that NAA/H2O and Cho/H2O may depend on the state of alertness.