The cerebellum modulates non-linear behavior of motor planning areas in variable grip-force visuomotor task

The hemodynamic response to neuronal stimuli can be both linear and nonlinear with the applied grip-force of a “squeeze-ball” task, controlled by a visual cue. Dynamic Causal Modelling was applied here to understand the causal effective between-region connectivity shaping the hemodynamic response recorded by functional-MRI. Effective connectivity resulted non-symmetric, with strong excitation from visual to motor areas. Results indicated primary visual cortex linear modulation of the cerebellar response, which exerted nonlinear influence on cortical motor planning, suggesting activation hierarchy in the motor circuit with prominent cerebellar role. This result may have important implications for understanding pathological changes affecting neural mechanisms.