2009-03-18 at 11:30
Conference Room 501, UMR7102, UPMC, Bat B 5th floor, 9, quai st Bernard, 75005 Paris
In vivo whole cell recordings applied to analyze the processing of sensory input to the cerebellar granule layer
In the cerebellar system devoted to voluntary arm-hand control, we have performed a series of investigations concerning the general connectivity organization as well as the basic firing dynamics and intracellular analysis of synaptic inputs in all cerebellar neuron types in the non-anesthetized in vivo preparation. Thereby, we can provide a description of the general computational properties of the constituent neuron types when they are provided with natural patterns of synaptic input. As for the processing of somatosensory inputs, which will be the focus of the presentation, it primarily occurs in the precerebellar nuclei, like the cuneate nucleus and the lateral reticular nucleus, and in the cerebellar granule layer, before they are combined with the non-sensory inputs in the molecular layer interneurons and Purkinje cells. Whole cell recordings can be used to analyze the contribution of the individual synapses to the processing of the different neuron types. By using a controlled stimulation, we can then compare the effects in different specific synapses and how that input is integrated by the postsynaptic neuron. In the case of the cuneate nucleus, for example, the contribution of individual primary afferents is analyzed. In the case of the granule cells, the contribution of individual mossy fiber synapses, and what types of processed input they represent, is analyzed. Combined with investigations of a wide range of sensory inputs, we can form a relatively complete picture of the processing of sensory input in the precerebellar-granule layer axes.