The impact of traumatic brain injury on inhibitory control processes assessed using a delayed antisaccade task.

It has been well established that traumatic brain injury (TBI) can affect cognitive function such as attention, working memory and executive functions. In the present study, we further investigated TBI-related changes in cognitive functions by investigating the ability to reorient visuospatial attention using a modified antisaccade task. Performing an antisaccade requires disengaging attention, inhibiting a reflexive saccade, and then engaging attention to execute a voluntary saccade in a direction opposite to a peripheral target. Particularly we quantified the time (latency), and accuracy (directional and disinhibition errors) of 26 TBI and 33 normal participants in making an antisaccade after a variable period of delay (0, 0.0625, 0.125, 0.250, 0.500 or 1.0 s). Changing the delay period allowed to systematically quantify the temporal and spatial characteristics of preparing and initiating an antisaccade and whether this process is affected by TBI. TBI participants took longer (approximately 33-66 ms for variable delays) to generate correct delayed antisaccades and showed increased directional errors (2-11 % for variable delays) and increased disinhibition prosaccade errors (2-6 % for variable delays) compared to controls. However, both groups made similar disinhibition antisaccade errors. These findings indicate that TBI participants required a longer time to process information, and a possible poorer response inhibition and poor spatial information processing due to head injury.