Constraints during bimanual coordination: the role of direction in relation to amplitude and force requirements

The present study addressed the status of spatial encoding during a bimanua l task paradigm. This was based on the premise that patterns of contralater al interference during bimanual coordination provide a window into those mo vement parameters that are primarily encoded within the central nervous sys tem. Results showed that both direction and amplitude were subject to (bila teral) interference when different specifications were to be generated simu ltaneously for each limb. Directional interference was found to be partiall y independent of the amount and pattern of underlying muscle activation, su ggesting that direction is encoded at a rather abstract level in the centra l nervous system. The findings are consistent with single-cell recording st udies that have pointed to the role of directional tuning in various brain areas. Moreover, the findings suggest that spatial parameters of movement c onstrain the coordination of limb movements in addition to temporal paramet ers. (C) 2001 Elsevier Science B.V. All rights reserved.