Is Human Brain Activity During Driving Operations Modulated by the Viscoelastic Characteristics of a Steering Wheel?: An fMRI Study

To date, a neuroscientific investigation of drivers' steering behavior has never been performed because the reaction forces generated by the mechanical characteristics of a steering wheel have been difficult to assess in a magnetic resonance imaging (MRI) environment. In this study, using our previously developed MRI-compatible unit for steering reaction force generation, we investigated changes in human brain activity induced by varying the viscoelastic characteristics associated with manipulating a car steering wheel. Participants performed a simulated driving task with three levels of stiffness and viscosity. An amplitude effect of reaction forces on the measured brain activity due to varying stiffness was found in the primary motor cortex (M1) associated with hand representation. Conversely, the changes in the brain activity induced by varying viscosity were found more dorsally in the premotor cortex and the M1 than in regions associated with hand representation. These results are the first to demonstrate that various viscoelastic characteristics activate different motor regions; more specifically, stiffness and viscosity of the steering wheel mainly affected the motor control of the distal and proximal muscles, respectively.