FUNCTIONAL PARASAGITTAL COMPARTMENTS IN THE RAT CEREBELLAR CORTEX - AN IN-VIVO OPTICAL IMAGING STUDY USING NEUTRAL RED

1. The spatial patterns of activation in the rat cerebellar cortex evo ked by peripheral stimulation were studied in vivo using optical imagi ng techniques. 2. Crus I and Crus II were stained with the pH sensitiv e dye, neutral red. Electrical stimulation of the vibrissae area of th e ipsilateral face evoked optical responses consisting of parasagittal bands. The bands were 100-300 mu m in width, elongated in the anterio r-posterior direction, commonly extended across at least two folia, an d varied in number from 1 to 7. 3. The optical responses were dependen t on activation of postsynaptic elements since they were decreased sub stantially by the non-N-methyl-D-aspartate antagonist, 6-cyano-7-nitro quinoxaline-2,3-dione. The optical bands were shown to correspond anat omically with the parasagittal compartments revealed by immunostaining with anti-zebrin II. 4. The present study demonstrates that functiona l parasagittal compartments exist in the rat cerebellar cortex and sug gests that zebrin-positive Purkinje cell subgroups are anatomically re lated to this functional organization.