Changes of local cerebral blood flow accompanied by increased neuronal activity in the thalamic relay nucleus and somatosensory cortex induced by sensory stimulation (author's transl)

Abstract

Activities of neurons of the thalamic relay nucleus and cortical somatosensory area which are capable of producing excitatory potentials in response to stimulation of the sciatic nerve were recorded, and local cerebral blood flow was measured simultaneously using a double microelectrode under local anesthesia in both non-pretreated cats and cats having undergone chemical denervation of the vasoadrenergic nerves by intraventricular injection of 6-OHDA, to unmask the neural control on the cerebral vessels during increases of local metabolic rate. The results obtained may be summarized as follows: (1) A positive correlation was found between an increase in firing rate of a single neuron in the thalamic relay nucleus and somatosensory area, and an increase in local cereb al blood flow following stimulation of the sciatic nerve. A distinct spatial and quantitative correlation was thus observed between neural activity and cerebral blood flow. (2) In 6-OHDA-pretreated cats, an increase in neuronal firing rate was observed following stimulation of the sciatic nerve, as it was in non-pretreated cats, but the concurrent response of local cerebral blood flow was seriously impaired. All these findings indicate that the increase in local cerebral blood flow occurring in association with increased neural activity does not result solely from increased local metabolism and a consequent increase in CO2 production, but requires that certain basic conditions be satisfied and maintained by the vasoadrenergic innervation.