Abstract
A recent debate in the literature involves the extent to which supplementary motor area is dedicated to the planning of motor responses. It has been suggested that this region may play a role in a more general manner through the calculation of spatial vector transformations. Evidence for this is provided via a number of non-motor studies, such as mental rotation tasks, where the activation in this region is more closely tied to the calculation of spatial relations than to motor demands (see Leek & Johnston, Nature Reviews Neuroscience, 10, 78, 2009). Here we present a series of functional imaging experiments that attempt to further elucidate the functional properties of supplementary motor area by contrasting the demands placed on this region from a variety of motor and non-motor tasks that make use of spatial vector transformations in a number of ways. The results indicate that the anterior sub-division of SMA, responds more strongly to demands associated with non-motor transformation tasks compared with the more posterior regions of SMA that responds more strongly to motor based tasks. The experiments are discussed in terms of the spatial vector transformation hypothesis.