Neural substrates of movement and music: An fMRI approach

In this dissertation, we examined the neural correlates of motor coordination and music perception using a set of four fMRI experiments. The neural correlates of goal-directed action were examined in a group of healthy adults in experiment I using execution and imagery of a unimanual and a bimanual finger-sequencing task. Similar neural networks were engaged for execution and imagination of movement sequences. Interestingly, we also found that the sensorimotor cortical and cerebellar areas are functionally decoupled from the task network when people imagine but do not actually execute sequential actions. In experiment 2, we used the same finger-sequencing paradigm to study recovery of function during recovery from stroke. It was observed that the wide spread neural activity during the initial session became more localized during the last session. In addition, using imagery tasks, we showed that hemiplegic patients retained the ability to activate neural pathways that are normally involved in executing goal-directed action sequences, despite the loss of ability to actually execute movements. In experiment 3, we examined brain activity when musicians and non-musicians listened to expressive and mechanical versions of a musical piece. The expressive performance activated the limbic areas more than the mechanical version in both groups of subjects suggesting perception of affect. The pattern of neural activity was also dictated by their experience and familiarity with the piece of music. In addition, we found activation of language related areas when musicians listened to the expressive version suggesting shared neural resources for language and music. The neural basis of sensorimotor coordination and timing in Parkinson's disease was investigated in the last experiment, using a synchronization-syncopation task and the continuation paradigm. Different neural areas subserved timing during the two different modes of coordination. However, these differences persisted during their respective continuation phases. In order to compensate for the functional deficiency in Parkinson's disease, patients recruited functionally segregated circuits that connect the striatum and association areas of the parietal, premotor and prefrontal cortices.