Patricia Dredge - Experimental Neuropsychology Research Unit

Motor overflow is a developmental motor phenomenon involving "unnecessary" involuntary muscle activity that coincides with voluntary movement. Motor overflow is observable in neurologically healthy populations including children and older adults (in healthy young adults overflow may be apparent to a very small degree that can only be detected with sensitive measurement). Using a finger force exertion task where participants maintained a percentage of their maximal force output with one hand while overflow was recorded as force in the passive hand, it has been demonstrated that children and older adults not only exhibit greater overflow than young adults, but that overflow for the former groups is also differentially effected by motor and attentional demands of the task. The developmental pattern of overt-covert-overt overflow production has been attributed to changes in functioning of brain structures such as the corpus callosum and the motor programming and execution areas such as the supplementary motor area. However, to date the precise pathways and structures mediating motor overflow remain debatable. One way of examining the structures that may be involved in overflow production is to study the pattern of overflow production presented in stroke patients with various lesion sites. This is the aim of my final study.