Investigating behavior inhibition in obsessive-compulsive disorder: Evidence from eye movements

We investigated the role of inhibition failure in Obsessive Compulsive Disorder (OCD) through an eye tracking experiment. Twenty-five subjects with OCD were recruited, as well as 25 with Generalized Anxiety Disorder (GAD) and 25 healthy controls. A 3 (group: OCD group, GAD group and control group) × 2 (target eccentricity: far and near) × 2 (saccade task: prosaccade and antisaccade) mixed design was used, with all participants completing two sets of tasks involving both prosaccade (eye movement towards a target) and antisaccade (eye movement away from a target). The main outcome was the eye movement index, including the saccade latency (the time interval from the onset of the target screen to the first saccade) and the error rate of saccade direction. The antisaccade latency and antisaccade error rates for OCDs were much higher than those for GADs and healthy controls. OCDs had longer latency and error rates for antisaccades than for prosaccades, and for far-eccentricity rather than near-eccentricity stimuli. These results suggest that OCDs experience difficulty with behavior inhibition, and that they have higher visual sensitivity to peripheral stimuli. In particular, they show greatest difficulty in inhibiting behavior directed towards peripheral stimuli.     

任务指导语及实验范式对朝向和反向眼跳的影响

采用2（眼跳方向）×3（实验范式）×4（任务指导语）的完全被试内实验设计研究任务指导语和实验范式对朝向和反向眼跳的影响效应。结果：（1）朝向眼跳潜伏期显著快于反向眼跳,且不受实验范式的影响;（2）在朝向眼跳任务中,空白范式下的延迟型指导语导致眼跳潜伏期延长;（3）在反向眼跳任务中,空白和重叠范式下延迟型指导语潜伏期最长;零范式下速度型指导语的潜伏期较短;（4）空白范式下的反向眼跳错误率显著低于重叠范式和零范式,反向眼跳潜伏期显著短于后两种范式。实验结果支持眼跳竞争模型。     

Pro- and Antisaccades: Dissociating Stimulus and Response Influences the Online Control of Saccade Trajectories

The authors examined whether the diminished online control of antisaccades is related to a trade-off between movement planning and control or the remapping of target properties to a mirror-symmetrical location (i.e., vector inversion). Pro- and antisaccades were examined in a standard no-delay schedule wherein target onset served as the movement imperative and a delay cuing schedule wherein responses were initiated 2,000 ms following target onset. Importantly, the delay cuing schedule was employed to equate pro- and antisaccade reaction times. Online control was evaluated by indexing the strength of trajectory amendments at normalized increments of movement time. Antisaccades exhibited fewer online corrections than prosaccades, and this result was consistent across cuing schedules. Thus, the diminished online control of antisaccades cannot be tied to a trade-off between movement planning and control. Rather, the authors propose that the intentional nature of dissociating stimulus and response (i.e., vector inversion) engenders a slow mode of cognitive control that is not optimized for fast oculomotor corrections.