Motor Areas Serve Attention: Functional Magnetic Resonance Imaging on Memory-Driven versus Stimulus-Driven Sequencing

Serial prediction of perceptual events engages the premotor cortex (PM) in the absence of motor requirements, supporting attentional functions in this area. The present fMRI study used a modified serial prediction task (SPT) to investigate whether mesial and lateral portions of PM may support different sub-functions of this task. According to the canonical view on motor functions, mesial PM (pre-supplementary motor area, preSMA) serves internally driven processes rather than externally driven ones, whereas the opposite is true for the lateral PM. Capitalizing on this dichotomy, the present study introduced a parametric fMRI design that aimed to force internally driven aspects, and hence preSMA engagement, in serial prediction. 16 young healthy volunteers participated in the study. Imaging was performed at 3 T on a Bruker Medspec 30/100 system. Slices were positioned parallel ACPC, with 22 slices (4/1mm) covering the whole brain. Results revealed that both lateral PM and SMA were activated by the SPT paradigm, as expected. Moreover, we found the internally driven processes to draw on anterior portions of both mesial and lateral premotor areas extending into prefrontal cortex. However, activation in SMA exposed the best fit to the manipulation forcing internally driven sequencing. The present results confirm a functional dichotomy between SMA and PM even in the attentional (non-motor) domain.