Model simulation of the SSD task for a patient with lesioned thalamus J Schuster1, A Ziesche1, F Ostendorf2, F Hamker1 |
|---|
1Chemnitz University of Technology, Germany |
| Our research studies why we perceive our external environment as stable although the retinal image changes with every eye movement. Particularly, we aim to explain why small displacements of visual targets cannot be detected if the displacement takes place during the eye movement, a phenomenon called saccadic suppression of displacement (SSD) [Deubel et al, 1996, Vision Res, 36(7):985-996]. Many experiments suggested an explanation through predictive remapping [Duhamel et al, 1992, Science, 255(5040):90-92] and corollary discharge signals [Sommer&Wurtz, 2008, Annu Rev Neurosci, 31:317-338]. Recently, Ostendorf [Ostendorf et al, 2010, Proc Natl Acad Sci USA 107(3):1229-1234] presented data of a patient with a right thalamic lesion showing a bias towards perceived backward displacements for rightward saccades in the SSD-task. To better understand the nature of the behavioral impairment following the thalamic lesion we applied a computational model developed by Ziesche and Hamker [Ziesche&Hamker, 2011, J Neurosci, 31:17392-17405] to simulate the patient. As the patient shows normal saccade targeting scatter, our model simulations indicate that an internal eye position signal is not correctly represented, i.e. it shows a bias and is noisier compared to normal subjects. Impairments in corollary discharge and predictive remapping mechanisms are not necessarily required to explain the behavioral data. |
| Up Home |
|---|