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Talk by Dr. Fahad Sultan

Kognitive Neurologie, Hertie-Institut für klinische Hirnforschung, Tübingen

17.Jul.2012 14:00
17.Jul.2012 15:00
INM-6, Bldg. 15.22, Seminar Room 3009, 1. OG

Unravelling cerebellar pathways with high temporal precision targeting motor and extensive sensory and parietal networks

The function of the cerebellum remains enigmatic. Yet, increasing evidence has implicated the cerebellum in providing forward models of motor plants predicting the sensory consequences of actions (Shadmehr et al., 2010). Sensory prediction facilitates the fine-tuning of motor acts and may also help to deal with the perceptual consequences of actions. In other words, the forward model hypothesis may provide a unifying computational basis that could account for the well-established role of the cerebellum in motor control as well as for its role in perception. Assuming that cerebellar input to the cerebral cortex contributes to the cerebro-cortical processing by adding forward model signals, we would expect to find projections emphasising motor and sensory cortical areas. However, this expectation is only partially met by studies of cerebello-cerebral connections based on conventional anatomical techniques. To readdress the structure of cerebello-cerebral connections using an independent technique enabling us to delineate a more complete pattern of cerebello-cerebral projections in an individual, we resorted to electrical stimulation induced fMRI. When stimulating the gateway of the cerebellar output, the deep cerebellar nuclei, we observed stimulation-induced BOLD activity not only in the classical cerebellar projection target, the primary motor cortex, but also in a number of additional areas in insular, parietal and occipital cortex, including all major sensory cortical representations. Independent of the specific cerebral area activated, responses were strongest for very high stimulation frequencies (=> 400Hz). This points to a projection system that has been optimised to mediate fast and temporarily precise information. In conclusion, both the topography of the stimulation effects and its emphasis on temporal precision is in full accordance with the concept of cerebellar forward model information modulating cerebro-cortical processing.