Interhemispheric functional connectivity in the primary motor cortex distinguishes between training on a physical and a virtual surgical simulator

Functional brain connectivity using functional near-infrared spectroscopy (fNIRS) during a pattern cutting (PC) task was investigated in physical and virtual simulators. 14 right-handed novice medical students were recruited and divided into separate cohorts for physical (N=8) and virtual (N=6) PC training. Functional brain connectivity measured were based on wavelet coherence (WCOH) from task-related oxygenated hemoglobin (HBO2) changes from baseline at left and right prefrontal cortex (LPFC, RPFC), left and right primary motor cortex (LPMC, RPMC), and supplementary motor area (SMA). HBO2 changes within the neurovascular frequency band (0.01-0.07Hz) from long-separation channels were used to compute average inter-regional WCOH metrics during the PC task. The coefficient of variation (CoV) of WCOH metrics and PC performance metrics were compared. WCOH metrics from short-separation fNIRS time-series were separately compared. Partial eta squared effect size (Bonferroni correction) between the physical versus virtual simulator cohorts was found to be highest for LPMC-RPMC connectivity. Also, the percent change in magnitude-squared WCOH metric was statistically (p<0.05) different for LPMC-RPMC connectivity between the physical and the virtual simulator cohorts. Percent change in WCOH metrics from extracerebral sources was not different at the 5% significance level. Also, higher CoV for both LPMC-RPMC magnitude-squared WCOH metric and PC performance metrics were found in physical than a virtual simulator. We conclude that interhemispheric connectivity of the primary motor cortex is the distinguishing functional brain connectivity feature between the physical versus the virtual simulator cohorts. Brain-behavior relationship based on CoV between the LPMC-RPMC magnitude-squared WCOH metric and the FLS PC performance metric provided novel insights into the neuroergonomics of the physical and virtual simulators that is crucial for validating Virtual Reality technology.