Historic notes on anatomic, physiologic, and clinical research on the cerebellum.

This chapter is concerned with ideas on the function, structure, and pathology that shaped our present knowledge of the cerebellum. One of the main themes in its early history is its localization subtentorially, leading to misattributions due to clinical observations in trauma and lesion experiments that caused collateral damage to the brainstem. Improvement of techniques led to the insight that it plays a role in movement control (Rolando) or coordination (Flourens). Purkinje initiated the histology of the cerebellar cortex in 1837. Luciani's experiments in 1891 led him to conclude that the cerebellum has a tonic facilitating effect on central structures. Cajal identified the elements of the cortex and their circuitry (1888-1891). The inhibitory nature of the interneurons and the Purkinje cells, and the excitatory connections of the mossy and climbing afferents and the granule cells were established much later by Eccles and Ito. A functional localization for the coordinating action of the cerebellum of the motor system, based on local expansion of the folial chains, was devised by Bolk in 1906. Babinski and Holmes contributed to anatomoclinical insights. Magnus and coworkers showed the cerebellum does not play an essential role in body posture. The heterogeneity of the Purkinje cells with respect to their connections and histochemistry found its expression in the zonal organization of the cerebellar cortex. The roots of modern developments, like cerebellar learning and its involvement in cognition and emotion, can be traced to the theories of Marr and Albus and the pioneering work of the Leiners and Dow.