TMS over V5 disrupts motion prediction.
Bottom Line: As in previous studies, we found that predictable in-time targets were better detected than unpredictable out-of-time targets.Our results are causal evidence that V5 is necessary for a prediction effect, which has been shown to modulate V1 activity (Alink et al. 2010).Thus, our findings suggest that information processing between V5 and V1 is crucial for visual motion prediction, providing experimental support for the predictive coding framework.
Affiliation: Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QB, UK Current address: Department of Neuroscience, Laboratory for Behavioral Neurology and Imaging of Cognition, Medical School and Swiss Center for Affective Sciences, University of Geneva, Geneva 1205, Switzerland.Show MeSH
Mentions: Two apparent motion stimuli (white squares, 2.5° each, 14.8° vertical distance) were flashed in rapid succession (67 ms, interstimulus interval [ISI]: 67 ms, 3.75 Hz) at 8.5° to the right of the central fixation cross (0.06°, see Fig. 1A). The target (white square, 2°) was flashed for one frame of 13.3 ms at either an upper or lower position on the apparent motion trace (2.3° distance from the midline). The target was presented either spatio-temporally congruent with a linearly moving illusory token (in-time targets) or incongruent (out-of-time targets), that is, at the same time but at the wrong position (see Fig. 1B and Supplementary Video clips). Each cycle of apparent motion lasted 20 frames (267 ms): 5 frames of upper apparent motion stimulus, 5 frames ISI, 5 frames of lower apparent motion stimulus, and 5 frames ISI. The targets were displayed in either the second or the fourth frame of the ISI. Each trial consisted of 10 cycles of apparent motion, with the target flashed in cycles 4–6 (randomized). The target appeared equally often in either upward or downward apparent motion. Target timing and position were counter-balanced across trials. There was no intertrial interval and apparent motion stimulation continued for blocks of 16 trials without interruption. Thus, start and end of the individual trials were not perceptible for subjects. Only in TMS trials, the TMS pulse indicated the presence of a trial. After blocks of 16 trials (42.7 s), apparent motion was interrupted for 25 s with a natural scene display to prevent apparent motion breakdown due to adaptation and to give subjects a rest from TMS. The optimal target contrast was assessed for each individual by varying the gray level of the background in a brief behavioral pretest. Stimuli were presented on a 16-inch Dell Trinitron CRT monitor (75 Hz, resolution 1024 × 768).Figure 1.
Affiliation: Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QB, UK Current address: Department of Neuroscience, Laboratory for Behavioral Neurology and Imaging of Cognition, Medical School and Swiss Center for Affective Sciences, University of Geneva, Geneva 1205, Switzerland.