The neural mechanisms of temporal processing

Time, the fourth dimension of the world, is an important parameter in many behaviours and cognitive processes, yet relatively little is understood about how time is represented in the brain. The problem can be framed as two questions: Firstly, what is the brain's metric of time? Secondly, how is temporal informa- I tion used in the brain? This thesis is largely concerned with the second question but through addressing the second question, touches on the first. \Vhilst time is important for many different cognitive systems, it is not necessarily the case that there is a dedicated 'timing system' in the brain. Temporal information could also be represented locally in neural systems concerned with different· functions. In this thesis I use a variety of paradigms in which temporal information is important to look at the neural mechanisms of temporal processing. Is timing represented as a parameter in non-time-dedicated cognitive systems, or is there a timing system? In support of the former possibility: In a perceptual prediction paradigm (Chapter 3), using fMRI, T fo.und that the -cerebellum is engaged when a prediction is required in time as well as space. In temporal-spatial processing, the cerebellum increased its interaction with cortical areas, such as IPS, which contain spatial maps. I suggested a model in which the cerebellum temporally tunes activity in cortical represen- . tations of space. In a behavioural motor learning paradigm (Chapter 6), I again found temporal information was rep):esented as the parameter of a specific representation-in this case a motor program rather than as an entity in itself. In support of the latter possibility: I observed some common factors in the representation of time. I found a similar pattern of activity relating to temporal processing in two fMRI experiments a perceptual judgement task and a motor timing paradigm (Chapter 5). The cerebellum was strongly implicated in temporal processing in both cases.EThOS - Electronic Theses Online ServiceGBUnited Kingdo