Regional cerebral blood flow during verbal auditory stimulation

Recent evidence suggests that changes in regional cerebral blood flow (rCBF) are reflections of the levels of functional neuronal activity of the cerebral tissue. The Xenon-133 rCBF technique has been used to examine regional variations in cerebral blood flow at rest and during various forms of behavioral activation, including performance on complex psychological tasks. Unfortunately, the latter studies did not address themselves to the possible role of sensorimotor functions involved in input and output as dictated by modality of task administration and response. The purpose of the present study was to examine possible effects of passive auditory stimulation on rCBF using the noninvasive Xenon-133 inhalation technique. Results suggested that the effects of passive sensory stimulation on rCBF cannot be reliably assessed in isolation, but can only be inferred when examined in the context of a task with cognitive specifications. The reliability, precision and reproducibility of the inhalation technique are also discussed, particularly with regard to the "resting state" baseline procedure.