Fabius, J. H., Nijboer, T. C.W., Fracasso, A. and Van der Stigchel, S. (2020) Intra-saccadic displacement sensitivity after a lesion to the posterior parietal cortex. Cortex, 127, pp. 108-119. (doi: 10.1016/j.cortex.2020.01.027) (PMID:32172025) (PMCID:PMC7254053)
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Abstract
Visual perception is introspectively stable and continuous across eye movements. It has been hypothesized that displacements in retinal input caused by eye movements can be dissociated from displacements in the external world using extra-retinal information, such as a corollary discharge from the oculomotor system. The extra-retinal information can inform the visual system about an upcoming eye movement and accompanying displacements in retinal input. The parietal cortex has been hypothesized to be critically involved in integrating retinal and extra-retinal information. Two tasks have been widely used to assess the quality of this integration: double-step saccades and intra-saccadic displacements. Double-step saccades performed by patients with parietal cortex lesions seemed to show hypometric second saccades. However, recently idea has been refuted by demonstrating that patients with very similar lesions were able to perform the double step saccades, albeit taking multiple saccades to reach the saccade target. So, it seems that extra-retinal information is still available for saccade execution after a lesion to the parietal lobe. Here, we investigated whether extra-retinal signals are also available for perceptual judgements in nine patients with strokes affecting the posterior parietal cortex. We assessed perceptual continuity with the intra-saccadic displacement task. We exploited the increased sensitivity when a small temporal blank is introduced after saccade offset (blank effect). The blank effect is thought to reflect the availability of extra-retinal signals for perceptual judgements. Although patients exhibited a relative difference to control subjects, they still demonstrated the blank effect. The data suggest that a lesion to the posterior parietal cortex (PPC) alters the processing of extra-retinal signals but does not abolish their influence altogether.
| Item Type: | Articles |
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| Additional Information: | This work was supported by a VIDI Grant 452-13-008 and a VENI Grant 451-10-013 from the Netherlands Organisation for Scientific Research awarded to Stefan Van der Stigchel and Tanja Nijboer, respectively. Alessio Fracasso is supported by grant BB/S006605/1 from the Biotechnology and Biological Sciences Research Council (BBSRC). |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Fracasso, Dr Alessio and Fabius, Mr Jasper |
| Creator Roles: | Fabius, J. H.Conceptualization, Methodology, Software, Validation, Data curation, Formal analysis, Visualization, Writing – original draft, Project administration Fracasso, A.Methodology, Writing – review and editing, Supervision |
| Authors: | Fabius, J. H., Nijboer, T. C.W., Fracasso, A., and Van der Stigchel, S. |
| College/School: | College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience |
| Journal Name: | Cortex |
| Publisher: | Elsevier |
| ISSN: | 0010-9452 |
| ISSN (Online): | 1973-8102 |
| Published Online: | 19 February 2020 |
| Copyright Holders: | Copyright © 2020 The Authors |
| First Published: | First published in Cortex 127:108-119 |
| Publisher Policy: | Reproduced under a Creative Commons license |
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