Abstract
Recently we showed that regional cerebral cortical blood flow (rCBF) responses induced by somatosensory stimulation in anesthetized cats with a transected spinal cord were quite different from those reported in rats: vasodilative responses in cats were restricted to the primary somatosensory cortex contralateral to the stimulated forelimb, while those in rats were bilateral and widespread. The responses in rats were due, in part, to the activation of the basal forebrain-originating cholinergic vasodilator fibers projecting to the cerebral cortex. Therefore, in the present experiments, we aimed to examine whether stimulation of the basal forebrain affects rCBF in the primary somatosensory cortex in cats. We recorded rCBF in anesthetized cats with a transected spinal cord at the first thoracic level to eliminate the influence of changes in blood pressure. The rCBF in the primary somatosensory cortex that was increased by stimulation of the contralateral forepaw was also increased by focal electrical stimulation of the ipsilateral basal forebrain. The response was the largest when the tip of the electrode was located within the area known to contain the cholinergic magnocellular neurons sending axons to the primary somatosensory cortex.These results suggest that neurons originating in the basal forebrain and projecting to the primary somatosensory cortex have the vasodilative function in cats, as previously found in rats. [J Physiol Sci. 2007;57 Suppl:S240]
