Maya Glasman^1,3, Jose Reynoso^1,2,3, Brian Keane^1,2,3, Duje Tadin^1,2,3, Diana Freed^1,2,3; ¹University of Rochester, ²University of Rochester Medical Center, ³Center for Visual Science

Proprioceptively-guided reaching relies on internal sensory feedback, which is often impaired in schizophrenia. While prior research illustrates sensorimotor integration abnormalities in schizophrenia, less is known about how it affects reaching trajectories in virtual reality. Here, we assess the trajectories of reaches guided mainly by vision or proprioception. We hypothesized that individuals with schizophrenia will show less direct and less smooth reaching movements compared to our healthy control group. We used a virtual reality test to study reaching accuracy guided by proprioception or vision and recorded subjects' reaching trajectories throughout. Additionally, directness and smoothness of reaching trajectories in 19 participants with schizophrenia and 18 age-matched controls was assessed. Participants reached to tap a virtual target using their index finger with either a visible (visually-guided reach) or invisible hand (proprioceptively-guided reach). Directness was measured as the ratio of total path length to straight-line distance between movement start and end points, with values closer to 1 indicating a more direct path. Smoothness was quantified as the R^2 of a 3D cubic fit to the movement trajectory (made to begin and end at the true endpoints), with values closer to 1 indicating smoother, less complex movements. We found that when the hand was visible during the reach movement, reach trajectories were more direct (p=1e-05) and smoother (p=1e-07) relative to proprioceptively-guided reaches. This was the case for both healthy controls (all p<0.035) and patients (all p<0.0001). We found no differences between patients and controls in reach smoothness (all p>0.22). However, we found a trend for less direct reach movements (all trials p=0.08; hand visible p=0.12; hand invisible p=0.063) in patients. Our findings suggest that visual feedback improves reaching abilities in both groups. However, those with schizophrenia show reduced movement efficiency, illustrated through less direct trajectories, even when smoothness is preserved.