Functional specialization in the supplementary motor complex

Domain General Sequence Operations Contribute to Pre-SMA Involvement in Visuo-spatial Processing

“…Wexler et al ( 1998 ) suggested that one component of this association is visuomotor anticipation—that is, functional processes involved in computing the visual consequences of movement also support visuo-spatial transformation operations. This is consistent with functional imaging evidence linking MR and pre-SMA—a region traditionally associated with the planning and online control of visually guided movement (Passingham, 1996 ; Picard and Strick, 1996 ; Tanji, 1996 ; Nachev et al, 2008 , 2009 ). However, the SMA is neither an anatomically nor functionally homogenous area (e.g., Ashe and Ugurbil, 1994 ; Johansen-Berg et al, 2004 ; Lehéricy et al, 2004 ; Nachev et al, 2007 , 2008 , 2009 ; Leek and Johnston, 2009 ).…”

“…This is consistent with functional imaging evidence linking MR and pre-SMA—a region traditionally associated with the planning and online control of visually guided movement (Passingham, 1996 ; Picard and Strick, 1996 ; Tanji, 1996 ; Nachev et al, 2008 , 2009 ). However, the SMA is neither an anatomically nor functionally homogenous area (e.g., Ashe and Ugurbil, 1994 ; Johansen-Berg et al, 2004 ; Lehéricy et al, 2004 ; Nachev et al, 2007 , 2008 , 2009 ; Leek and Johnston, 2009 ). The pre-SMA can be distinguished from the more caudal SMA-proper by distinct projections to the anterior and posterior striatum (e.g., Lehéricy et al, 2004 ).…”

Functional specialization within the supplementary motor area: A fNIRS study of bimanual coordination

“…In our view, the anterior SMA likely performs real time spatiotemporal transformations based on incoming sensory information and goal signals from prefrontal cortices, and implements motor signal perturbations as necessary (e.g., to maintain movements in an anti-phase pattern) through its bidirectional interactions with the SMA proper (Ashe et al, 2006; Hoshi & Tanji, 2004; Kennerley et al, 2004; Makoshi et al, 2011). Understanding the anterior SMA as a center for performing real time spatiotemporal transformations is consistent with the region’s involvement in mental rotation and other cognitive tasks, and such functionality has been championed by other investigators (Leek & Johnston, 2009). …”

“…However, several studies in humans have shown that lesions in the SMA complex can produce striking higher-level deficits such as alien-limb syndrome, where the affected limb moves or grasps objects outside the subject’s voluntary control, and/or utilization behaviors, where objects appear to drive behavior in a stimulus driven fashion (e.g., just seeing eyeglasses causes the subject to put them on; Boccardi et al, 2002; Feinberg et al, 1992). Given such results, there remains little agreement and no working model or theory of SMA function that explains the full gamut of behaviors linked to the region (Leek & Johnston, 2009; Nachev et al, 2008). …”

“…There is clear evidence that the pre-SMA preferentially receives complex sensory input (somatosensory, proprioceptive, and visual), and that it may perform multifaceted transformations which potentially serve future movement planning and guidance of ongoing movements through interaction with the SMA proper (Ashe et al, 2006; Hoshi and Tanji, 2004; Nachev et al, 2008). Performing these real time spatiotemporal transformations, based on incoming sensory information and goal signals from prefrontal regions, would position the anterior SMA as a crucial brain center for maintaining anti-phase pattern movements, and there is at least strong circumstantial evidence supporting such functionality (Aramaki et al 2006; Hoshi and Tanji, 2004; Kennerley et al, 2004; Leek and Johnston, 2009; Makoshi et al, 2011). …”