The cerebellar corticovestibular projection in the cat as studied with retrograde transport of horseradish peroxidase

The cerebellar corticovestibular projection in the cat was studied by means of retrograde transport of HRP. After injections confined to the vestibular nuclei retrogradely labelled Purkinje cells were found ipsilaterally in vermal lobules I through X, crus I, the ventral paraflocculus and flocculus. The neurons projecting to the vestibular nuclei are located in all parts of the cerebellar folia (bottom, side and top). Most of the vestibular projecting Purkinje cells are located within a sagittal band (corresponding to Voogd's B zone) in the lateral vermis. In some of our cats the width of this band exceeds 1 mm in lobule I, 800 microns in lobule II and 1.5 mm in lobule V. However, the sagittal band is not sharply demarcated, and some retrogradely labelled Purkinje cells were present almost in the midline while others were located more than 4 mm lateral to this. The findings are discussed with special emphasis on the cerebellar sagittal zonal arrangement and related to previous studies on the cerebellar corticovestibular projection.