Investigating the neural regions involved in the storage of dynamic and static motion after effect using TMS R Camilleri1, M Maniglia1, A Pavan2, G Campana1 |
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1Department of General Psychology, University of Padova, Italy |
| Prolonged exposure to directional motion biases the perceived direction of subsequently presented stimuli towards the opposite direction. This motion aftereffect (MAE) illusion is due to changes in the response of direction-selective cortical neurons. Different neural populations seem to be involved in its generation, depending on the spatiotemporal characteristics of the stimuli. The specific locus along the motion processing hierarchy where the different types of MAE take place is still debated. In particular, although MAE with stationary test stimuli (sMAE) appears to occur at early levels of motion processing, neuroimaging and neurointerference techniques have showed the involvement of various cortical sites. Conversely, while the tuning characteristics of MAE with dynamic (flickering) test stimuli (dMAE) indicate higher levels of processing, fMRI studies found a direction-selective decrease of neural activity already in V1. By using repetitive TMS (rTMS), we investigated the locus of processing of sMAE and dMAE. Results showed that rTMS over either V2/V3 and V5/MT decreased the perceived sMAE duration, indicating that sMAE is due to activity of units located at multiple sites of the motion processing stream. Conversely, no significant disruption of MAE duration was found when using a dynamic test stimulus, suggesting the involvement of higher-level processing. |
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