Novel Form of Spreading Acidification and Depression in the Cerebellar Cortex Demonstrated by Neutral Red Optical Imaging

Abstract

Novel form of spreading acidification and depression in the cerebellar cortex demonstrated by neutral red optical imaging. A novel form of spreading acidification and depression in the rat cerebellar cortex was imaged in vivo using the pH-sensitive dye, Neutral red. Surface stimulation evoked an initial beam of increased fluorescence (i.e., decreased pH) that spread rostrally and caudally across the folium and into neighboring folia. A transient but marked suppression in the excitability of the parallel fiber-Purkinje cell circuitry accompanied the spread. Characteristics differentiating this phenomenon from the spreading depression of Leao include: high speed of propagation on the surface (average of 450 μm/s), stable extracellular DC potential, no change in blood vessel diameter, and repeatability at short intervals. This propagating acidification constitutes a previously unknown class of neuronal processing in the cerebellar cortex.