title: Preserved Haptic Shape Processing after Bilateral LOC Lesions.
abstract: The visual and haptic perceptual systems are understood to share a common neural representation of object shape. A region thought to be critical for recognizing visual and haptic shape information is the lateral occipital complex (LOC). We investigated whether LOC is essential for haptic shape recognition in humans by studying behavioral responses and brain activation for haptically explored objects in a patient (M.C.) with bilateral lesions of the occipitotemporal cortex, including LOC. Despite severe deficits in recognizing objects using vision, M.C. was able to accurately recognize objects via touch. M.C.'s psychophysical response profile to haptically explored shapes was also indistinguishable from controls. Using fMRI, M.C. showed no object-selective visual or haptic responses in LOC, but her pattern of haptic activation in other brain regions was remarkably similar to healthy controls. Although LOC is routinely active during visual and haptic shape recognition tasks, it is not essential for haptic recognition of object shape.
  
  
  CONCLUSIONS
  The lateral occipital complex (LOC) is a brain region regarded to be critical for recognizing object shape, both in vision and in touch. However, causal evidence linking LOC with haptic shape processing is lacking. We studied recognition performance, psychophysical sensitivity, and brain response to touched objects, in a patient (M.C.) with extensive lesions involving LOC bilaterally. Despite being severely impaired in visual shape recognition, M.C. was able to identify objects via touch and she showed normal sensitivity to a haptic shape illusion. M.C.'s brain response to touched objects in areas of undamaged cortex was also very similar to that observed in neurologically healthy controls. These results demonstrate that LOC is not necessary for recognizing objects via touch.
authors.affiliation: Department of Psychology, University of Nevada, Reno, Nevada 89557, and jacqueline.c.snow@gmail.com snow@unr.edu.
authors.forename: Jacqueline C
authors.identifier: http://orcid.org/0000-0002-8284-8704
authors.initials: JC
authors.lastname: Snow
authors.affiliation: The Brain and Mind Institute, The Natural Sciences Centre, Department of Psychology, University of Western Ontario, London, Ontario N6A5B7, Canada.
authors.forename: Melvyn A
authors.identifier: http://orcid.org/0000-0001-6748-0561
authors.initials: MA
authors.lastname: Goodale
authors.affiliation: The Brain and Mind Institute, The Natural Sciences Centre, Department of Psychology, University of Western Ontario, London, Ontario N6A5B7, Canada.
authors.forename: Jody C
authors.identifier: http://orcid.org/0000-0003-0754-2999
authors.initials: JC
authors.lastname: Culham
mesh_terms: D000328:Adult; D001930:Brain Injuries / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000098:blood supply / Q000473:pathology*; D010100:Oxygen / Q000097:blood; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011601:Psychophysics; D013997:Time Factors; D014110:Touch; D014796:Visual Perception / Q000502:physiology*
chemical_list: D010100:Oxygen
keywords: haptic; lateral occipital complex; neuropsychological fMRI; shape perception