Effects of Mild Traumatic Brain Injury (Sports-related Concussion) on Eye-head-hand Coordination

An example of the waypoint control task for two subjects. Vertical position is plotted as a function of horizontal position. The task requires the subject to align the joystick-controlled laser at the start (X) position and then direct this laser spot to the end (O) going through the waypoint (in this case a 5deg circle centered at (15, 22.5)). In A, an 18 year old subject performs the task by driving the joystick directly to the waypoint, and then continuing to the end point. However, in B, the subject was aged 72 years and this subject begins moving the joystick to the end target location before making an online adjustment to the waypoint. In panels C and D the line of sight (gaze) is superimposed for comparison. Note that the older subject makes a large gaze shift to a location intermediate to the waypoint and the target, then looks to the end target before looking back to the waypoint. In contrast, the younger subject first looks toward the waypoint, and then toward the end-target location. Although not shown, eye movement relative to the head as well as head movements are also recorded. The displacement of start and end targets, the location of the waypoint and the size of the waypoint circle are parameters of interest that are varied during data collection.

Despite the prevalence of mild traumatic brain injuries (sports-related concussions are estimated to occur over 3.5 million times annually in the U.S.), prevention, identification, treatment, rehabilitation, and determination of recovery time-points are largely inadequate due to the paucity of parametric factors that can be easily and reliably measured both in the field and in the clinic. We have designed a battery of visual-spatial tasks that require coordination of the eyes, head and hand and address sensorimotor plasticity, spatial working memory, and orientation in order to identify parameters that reliably track behavioral markers of mTBI. Current work in the lab is focused on effects of mTBI and of normal aging on eye-head and hand coordination in human subjects. Using techniques developed during our earlier work (see below) to characterize changes in coordinated visual orienting behaviors.

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