| The ability to generate rhythmic activity and gap junctional coupling are prominent features of inferior olive (IO) neurons and are hypothesized to contribute greatly to IO function. IO cells generate spontaneous oscillations, due to their rhythmogenic capability, and are known to be electrically coupled, presumably due to the presence of gap junctions, and these properties may underlie rhythmic and synchronous activity observed in the cerebellum. But, the extent to which these two features define IO activity patterns is uncertain.; Several specific questions regarding the functional roles of oscillations and gap junctional coupling in the IO persist. First, while it is known that IO neurons possess a set of membrane conductances that allow them to generate spontaneous, oscillatory spike activity, it is unclear whether these oscillatory capabilities regulate IO interactions with other brain areas, or if they shape patterns of evoked olivocerebellar activity in the cerebellum. Second, IO neurons are electrically coupled by gap junctions, and electrical coupling in the IO may underlie synchronous spike activity in the cerebellum. At the time work on this thesis began, however, this idea had not been directly tested. Last, if IO gap junctions do in fact underlie olivocerebellar synchrony, changes in effective IO gap junction coupling patterns should result in changes in cerebellar activity patterns. Although this idea has been tested using intra-IO injections of pharmacological agents, a physiological mechanism of synchrony modulation has not been identified. These three issues were addressed using the multielectrode recording technique to simultaneously record olivocerebellar activity from groups of cerebellar Purkinje cells, in combination with different stimulation techniques and genetic manipulations. The results seek to provide insight into the functionality of IO oscillations and gap juncitional coupling, and into the IO's role in cerebellar function. |
