The Inferior Olive: coupling, oscillations and bursting activity

The inferior olive is part of the olivo-cerebellar system and it plays a key role because it provides one of the major sensory inputs to the cerebellar cortex. For this reason, we wanted to answer those questions about the physiology of olivary neurons that still were unanswered. We dedicated our efforts in the first place to explore the inhibitory input to the IO, namely the nucleo-olivary projection, and the role GABA plays in re-setting the phase of the subthreshold oscillations (chapter 2). After investigating the inputs of the IO, we focused on the electrotonical coupling and we explored the pathways that regulate the coupling between olivary neurons. We determined that the phosphorylation of Cx36 is one of these mechanisms and we identified that CaMKII and PKA play a role in this pathway, the first sustaining and the latter reducing the coupling between olivary neurons (chapter 3). We then focused on the output of the olivary neurons, investigating the variables that were influencing the bursting activity of olivary neurons. We performed these experiments in vivo, because we wanted to investigate the relationship between spikelets and oscillations in an intact network, which was also able to convey somatosensory information (chapter 4). We could conclude that in our experimental condition the phase relationship between the phase of the SSTOs and the spikelet count was not present, whereas the amplitude of the SSTOs was determining the number of the spikelets. We then generated a computer model bridging our in vivo results with the ones obtained in vitro by Mathy et al. (2009) (chapter 5).

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