Functions
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The computations occurring in the intermediate zone involve mossy fiber barrages associated with the pontocerebellar fibers carrying information from the hand and arm region of MI about the intended movement. This information is somehow "compared" with information conveyed via the dorsal and cuneocerebellar fibers (what is really happening to the muscles). This comparing will happen in the hand and arm part of the anterior and posterior lobes. The inputs need to be sharpened temporally (feedback inhibition via Golgi cells) and spatially (feedforward inhibiton via basket cells. The Purkinje cell signals being sent to interpositus mix with the direct signals from mossy and climbing fibers, and an ongoing correction signal is sent to the red nucleus (quick adjustments via the rubrospinal tract) and back to MI (slower adjustments). Lesions of the intermediate zone and nucleus interpositus are thought to result in similar deficits as those in the lateral zone and the dentate. Such lesions interrupt the ability of the cerebellum to correct movements once they are started. In contrast to cells in the dentate nucleus, cell in the interpositus fire after the movement has begun. Such cells are involved in updating ongoing movements versus planning such movements (dentate). |