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The Journal of Neuroscience, October 21, 2009, 29(42):13147-13157; doi:10.1523/JNEUROSCI.3723-09.2009

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Behavioral/Systems/Cognitive
Spatiotemporal Distortions of Visual Perception at the Time of Saccades

Paola Binda,^1,2 Guido Marco Cicchini,^1,7 David C. Burr,^3,4,5 and M. Concetta Morrone^6,7,8

¹Department of Psychology, Università Vita-Salute San Raffaele, 20132 Milan, Italy, ²Italian Institute of Technology–IIT Network, Research Unit of Molecular Neuroscience, 16163 Genoa, Italy, ³Department of Psychology, Università Degli Studi di Firenze, 50135 Florence, Italy, ⁴Institute of Neuroscience, CNR–Pisa, 56124 Pisa, Italy, ⁵Department of Psychology, University of Western Australia, Nedlands Perth, Western Australia 6907, Australia, ⁶Department of Physiological Sciences, Università di Pisa, 56123 Pisa, Italy, ⁷Scientific Institute Stella Maris, 56018 Calambrone, Pisa, Italy, and ⁸Italian Institute of Technology–RBCS Unit, 16163 Genoa, Italy

Correspondence should be addressed to Prof. M. Concetta Morrone, Department of Physiological Sciences, Università di Pisa, Via San Zeno 31, 56123 Pisa, Italy. Email: concetta{at}in.cnr.it

Both space and time are grossly distorted during saccades. Here we show that the two distortions are strongly linked, and that both could be a consequence of the transient remapping mechanisms that affect visual neurons perisaccadically. We measured perisaccadic spatial and temporal distortions simultaneously by asking subjects to report both the perceived spatial location of a perisaccadic vertical bar (relative to a remembered ruler), and its perceived timing (relative to two sounds straddling the bar). During fixation and well before or after saccades, bars were localized veridically in space and in time. In different epochs of the perisaccadic interval, temporal perception was subject to different biases. At about the time of the saccadic onset, bars were temporally mislocalized 50–100 ms later than their actual presentation and spatially mislocalized toward the saccadic target. Importantly, the magnitude of the temporal distortions co-varied with the spatial localization bias and the two phenomena had similar dynamics. Within a brief period about 50 ms before saccadic onset, stimuli were perceived with shorter latencies than at other delays relative to saccadic onset, suggesting that the perceived passage of time transiently inverted its direction. Based on this result we could predict the inversion of perceived temporal order for two briefly flashed visual stimuli. We developed a model that simulates the perisaccadic transient change of neuronal receptive fields predicting well the reported temporal distortions. The key aspects of the model are the dynamics of the "remapped" activity and the use of decoder operators that are optimal during fixation, but are not updated perisaccadically.

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Received July 31, 2009; revised Sept. 7, 2009; accepted Sept. 11, 2009.

Correspondence should be addressed to Prof. M. Concetta Morrone, Department of Physiological Sciences, Università di Pisa, Via San Zeno 31, 56123 Pisa, Italy. Email: concetta{at}in.cnr.it

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