The aim of the proposal is to test critically the current models of how the cerebellum contributes to motor learning, specifically, the role of cerebellar climbing fibres (CFs). CFs were first proposed to play a key role in mediating plasticity in cerebellar cortex on theoretical grounds, and a wealth on in vitro evidence supports this idea. However, evidence on how neural activity generates these plasticity-inducing signals in vivo is missing. There are few experimental learning paradigms in which this can be tested critically, where a specific region of cerebellum is known to be critical for a form of motor adaptation. Arguably the best of these is the conditioned eyeblink nictitating membrane response: using recent technical innovations we have been able to identify of the critical regions of cerebellum and record the activity of the neurons involved. We found previously unexpected patterns of CF activity: after learning, climbing fibres are highly active in response to the stimulus that triggers learned movements. This activity suggests that these signals are ‘secondary reinforcers’, signals that allow learning of a learned signal. This has very big implications for current models of cerebellar function. The experiments will use behavioural neurophysiology, with spatial mapping of cerebellar structures – methods that were recently developed in my lab. If you are interested, it would be a good idea to visit and talk about the project.
- Mostofi A Holtzman T Grout A Yeo CH Edgley SA (2010) Electrophysiological localisation of eyeblink-related microzones in rabbit cerebellar cortex J Neurosci. 30(26):8920-34.
- Xu W, Jones S, Edgley SA.(2013) Event time representation in cerebellar mossy fibres arising from the lateral reticular nucleus.J Physiol. 2013 591:1045-62. doi: 10.1113/jphysiol.2012.244723.
- Zaaimi B, Edgley SA, Soteropoulos DS, Baker SN. Changes in descending motor pathway connectivity after corticospinal tract lesion in macaque monkey. Brain. 2012 135:2277-89. doi: 10.1093/brain/aws115.