Author's personal copy Research report Specific impairments in visual processing following lesion side in hemianopic patients Ce ´line Cave ´zian a,b , Isabelle Gaudry a,b,c , Ce ´line Perez a,b,c , Olivier Coubard a,b , Gae ¨lle Doucet d , Carole Peyrin a , Christian Marendaz a , Mickae ¨l Obadia b,c , Olivier Gout b,c and Sylvie Chokron a,b,c, * a Laboratoire de Psychologie et NeuroCognition, CNRS, UMR 5105, UPMF, Grenoble, France b ERT TREAT VISION, Fondation Ophtalmologique Rothschild, Paris, France c Service de Neurologie, Fondation Ophtalmologique Rothschild, Paris, France d CI-NAPS, Centre for Imaging-Neurosciences and Applications to Pathologies, CNRS, CEA, Caen University, Paris Descartes University, UMR 6232, Caen, France article info Article history: Received 3 November 2008 Reviewed 25 February 2009 Revised 6 May 2009 Accepted 12 August 2009 Action editor Jane Riddoch Published online 8 September 2009 Keywords: Hemianopia Spatial frequencies Natural scenes Detection Categorization abstract Introduction: Following unilateral damage of the primary visual cortex one of the most common visual field defects observed is Homonymous Hemianopia (HH), a loss of vision of the contralesional hemifield in each eye. The ipsilesional (‘‘intact’’) part of the central visual field is often used to compensate for difficulties encountered in the peripheral hemianopic visual field. However, the quality of vision within the central visual field is not well-known. Methods: To better describe and understand visual processing in hemianopia, two tasks were conducted with 25 healthy controls, six left hemianopes, and five right hemianopes. Filtered (in high, above 6 cycles/degree, or low, below 4 cycles/degree, spatial frequencies – HSF and LSF, respectively) and unfiltered natural scene images (5  of visual angle) were briefly presented (100 msec) centrally on a computer screen. Participants were required either to respond when a natural scene was presented (yes/no detection task) or to indicate if the stimulus was a city or a highway (categorization task). Results: The three groups showed similar accuracy levels but significant differences were observed in response times. More precisely, left hemianopes were impaired both in the detection and in the categorization tasks whereas right hemianopes were only impaired in the categorization task. However, the three groups had similar responses to spatial frequencies: HSF were processed more slowly than LSF. Conclusions: Overall these results suggest that central vision is not intact in hemianopia. Lesion side selectively affects reaction times (RTs) in the detection and the categorization tasks, but does not seem to determine a specific deficit in spatial frequency processing. ª 2009 Elsevier Srl. All rights reserved. * Corresponding author. ERT TREAT Vision, CNRS UMR 5105, Fondation Ophtalmologique Rothschild, 25, rue Manin, 75019 Paris, France. E-mail address: sylvie.chokron@gmail.com (S. Chokron). available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/cortex 0010-9452/$ – see front matter ª 2009 Elsevier Srl. All rights reserved. doi:10.1016/j.cortex.2009.08.013 cortex 46 (2010) 1123–1131