Increased internal noise cannot account for motion coherence processing deficits in migraine

Aim: This study aimed to revisit previous findings of superior processing of motion direction in migraineurs with a more stringent direction discrimination task and to investigate whether increased internal noise can account for motion processing deficits in migraineurs. Methods: Groups of 13 migraineurs (4 with aura, 9 without aura) and 15 headache-free controls completed three psychophysical tasks: one detecting coherence in a motion stimulus, one discriminating the spiral angle in a glass pattern and another discriminating the spiral angle in a global-motion task. Internal noise estimates were obtained for all tasks using an N-pass method. Results: Consistent with previous research, migraineurs had higher motion coherence thresholds than controls. However, there were no significant performance differences on the spiral global-motion and global-form tasks. There was no significant group difference in internal noise estimates associated with any of the tasks. Conclusions: The results from this study suggest that variation in internal noise levels is not the mechanism driving motion coherence threshold differences in migraine. Rather, we argue that motion processing deficits may result from cortical changes leading to less efficient extraction of global-motion signals from noise.