Interhemispheric interplay between the left and right premotor cortex during grasping as assessed by dynamic causal...

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Motor Control

Background:

• Transcallosal connections mediate ipsilateral hemisphere contributions to unilateral movements, but findings are contradictory.
• Understanding interhemispheric dynamics in motor control is crucial for explaining unilateral movement execution and imagery.

Purpose of the Study:

• To investigate effective connectivity within the grasping network during pantomimed and imagined right-hand grasping using fMRI.
• To compare connectivity patterns between homologous parieto-frontal areas across hemispheres.
• To elucidate interhemispheric dynamics during executed and imagined grasping movements.

Main Methods:

• Dynamic Causal Modelling (DCM) and Parametric Empirical Bayes analyses applied to functional Magnetic Resonance Imaging (fMRI) data.
• Examined effective connectivity in the grasping network: anterior intraparietal sulcus, ventral and dorsal premotor cortex (PMd), supplementary motor area, and primary motor cortex (M1).

Main Results:

• A comparable network architecture was observed across hemispheres during executed grasping, but not during imagined grasping.
• During pantomimed grasping, interhemispheric communication was primarily driven by premotor areas.
• Specific findings include inhibitory influence from the right PMd to left premotor/motor areas and excitatory couplings between homologous ventral premotor and supplementary motor regions.

Conclusions:

• Dissociable components of unilateral grasping execution are encoded by a non-lateralized set of brain areas with complex interhemispheric dynamics.
• Motor imagery of grasping movements appears to operate under different neural principles compared to execution.