High Force Unimanual Handgrip Contractions Increase Ipsilateral Sensorimotor Activation and Functional Connectivity

Imaging and brain stimulation studies seem to correct the classical understanding of how networks, rather than contralateral focal areas, control generation unimanual voluntary force. However, scaling hemispheric-specificity network activation remain less understood. Using fMRI, we examined effects parametrically increasing right-handgrip force on functional connectivity among sensorimotor bilaterally with 25%, 50%, 75% maximal contractions (MVC). High (75% MVC) handgrip resulted in greater ipsilateral motor hemisphere compared a low 25% MVC condition. The cortex strength correlated relative (% MVC). Increases between hemispheres within network.