Mesial Motor Areas in Self-Initiated Versus Externally Triggered Movements Examined With fMRI: Effect of Movement Type and Rate

Abstract

The human frontomesial cortex reportedly contains at least four cortical areas that are involved in motor control: the anterior supplementary motor area (pre-SMA), the posterior SMA (SMA proper, or SMA), and, in the anterior cingulate cortex, the rostral cingulate zone (RCZ) and the caudal cingulate zone (CCZ). We used functional magnetic resonance imaging (fMRI) to examine the role of each of these mesial motor areas in self-initiated and visually triggered movements. Healthy subjects performed self-initiated movements of the right fingers (self-initiated task, SI). Each movement elicited a visual signal that was recorded. The recorded sequence of visual signals was played back, and the subjects moved the right fingers in response to each signal (visually triggered task, VT). There were two types of movements: repetitive (FIXED) or sequential (SEQUENCE), performed at two different rates: SLOW or FAST. The four regions of interest (pre-SMA, SMA, RCZ, CCZ) were traced on a high-resolution MRI of each subject's brain. Descriptive analysis, consisting of individual assessment of significant activation, revealed a bilateral activation in the four mesial structures for all movement conditions, but SI movements were more efficient than VT movements. The more complex and more rapid the movements, the smaller the difference in activation efficiency between the SI and the VT tasks, which indicated an additional processing role of the mesial motor areas involving both the type and rate of movements. Quantitative analysis was performed on the spatial extent of the area activated and the percentage of change in signal amplitude. In the pre-SMA, activation was more extensive for SI than for VT movements, and for fast than for slow movements; the extent of activation was larger in the ipsilateral pre-SMA. In the SMA, the difference was not significant in the extent and magnitude of activation between SI and VT movements, but activation was more extensive for sequential than for fixed movements. In the RCZ and CCZ, both the extent and magnitude of activation were larger for SI than for VT movements. In the CCZ, both indices of activation were also larger for sequential than for fixed movements, and for fast than for slow movements. These data suggest functional specificities of the frontomesial motor areas with respect not only to the mode of movement initiation (self-initiated or externally triggered) but also to the movement type and rate.

Three-dimensional locations and boundaries of motor and premotor cortices as defined by functional brain imaging: A meta-analysis

“…For instance, the ventral limit of pre-SMA was at z = 33, the ventral limit where SMA intersects the VCA line was at z = 40, and the ventral limit of SMA proper was at z = 44. Therefore, our data suggest that the ventral limit is more ventral rostrally than it is caudally, and this finding is consistent with previous depictions (in figures) (Crosson et al, 1999;Deiber et al, 1999;Johansen-Berg et al, 2004). It is interesting to note that these values were ventral to the location of the cingulate sulcus in the Talairach and Tournoux atlas (1988).…”

“…These two regions have been previously differentiated in the monkey (Dum and Strick, 1991;Matelli et al, 1991;Matsuzaka et al, 1992). Since then, this demarcation has been supported in humans across studies using cytoarchitectonic data (Vorobiev et al, 1998;Geyer et al, 2000a), PET (Fink et al, 1997), functional MRI (Deiber et al, 1999), diffusion tensor imaging , and diffusion weighted imaging (Johansen-Berg et al, 2004). The boundary between pre-SMA and SMA proper estimated by the ALE method remained consistent at y = 0mm throughout the coronal plane (Fig.…”

“…1). This boundary was also quantified at 30mm rostral to the VCA line (17.1% of 175mm in rostro-caudal length) during a study investigating finger movements (Deiber et al, 1999). Based on 95% of the significant ALE values, we determined that the rostral boundary of MPMC was y = 12 at z = 70, and y = 26 at z = 40 (Fig.…”

“…Caudally, MPMC is bound by SMC in the rostral portion of the paracentral lobule and it has been suggested that this boundary corresponds with the VCP line (y ≅ 23mm) (Deiber et al, 1999;Chainay et al, 2004). However, it has also been posited that the boundary between MPMC and SMC is unknown due to a lack of macroanatomical and cytoarchitectonic boundaries (Roland and Zilles, 1996;Geyer et al, 2000a), and because the cytoarchitectonic border between areas 4 and 6 is the most variable in the paracentral lobule (Brodmann, 1909;White et al, 1997).…”

A new approach to corpus callosum anomalies in idiopathic scoliosis using diffusion tensor magnetic resonance imaging

“…This study reported different pattern of response in the supplementary motor area (SMA) of patients as compared to controls, and higher asymmetry index. This area is responsible for preparation and execution of movements and participates in the control of posture [29,30]. The authors, therefore, hypothesized that a defective sensorimotor integration at cortical level plays a role in IS pathogenesis.…”