title: Crossmodal Processing of Haptic Inputs in Sighted and Blind Individuals.
abstract: In a previous behavioral study, it was shown that early blind individuals were superior to sighted ones in discriminating two-dimensional (2D) tactile angle stimuli. The present study was designed to assess the neural substrate associated with a haptic 2D angle discrimination task in both sighted and blind individuals. Subjects performed tactile angle size discriminations in order to investigate whether the pattern of crossmodal occipital recruitment was lateralized as a function of the stimulated hand. Task-elicited activations were also compared across different difficulty levels to ascertain the potential modulatory role of task difficulty on crossmodal processing within occipital areas. We show that blind subjects had more widespread activation within the right lateral and superior occipital gyri when performing the haptic discrimination task. In contrast, the sighted activated the left cuneus and lingual gyrus more so than the blind when performing the task. Furthermore, activity within visual areas was shown to be predictive of tactile discrimination thresholds in the blind, but not in the sighted. Activity within parietal and occipital areas was modulated by task difficulty, where the easier angle comparison elicited more focal occipital activity along with bilateral posterior parietal activity, whereas the more difficult comparison produced more widespread occipital activity combined with reduced parietal activation. Finally, we show that crossmodal reorganization within the occipital cortex of blind individuals was primarily right lateralized, regardless of the stimulated hand, supporting previous evidence for a right-sided hemispheric specialization of the occipital cortex of blind individuals for the processing of tactile and haptic inputs.
authors.affiliation: Department of Neurology and Neurosurgery, Cognitive Neuroscience Unit, Montreal Neurological Institute, McGill University, Montreal QC, Canada.
authors.forename: Patrice
authors.initials: P
authors.lastname: Voss
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal QC, Canada.
authors.forename: Flamine
authors.initials: F
authors.lastname: Alary
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal QC, Canada.
authors.forename: Latifa
authors.initials: L
authors.lastname: Lazzouni
authors.affiliation: Groupe de Recherche sur le Système Nerveux Central, Département de Physiologie and École de Réadaptation, Faculté de Médecine, Université de Montréal, Montréal QC, Canada.
authors.forename: C E
authors.initials: CE
authors.lastname: Chapman
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal QC, Canada.
authors.forename: Rachel
authors.initials: R
authors.lastname: Goldstein
authors.affiliation: Département de Radiologie, Faculté de Médicine, Université de Montréal, Montréal QC, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Bourgoin
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal QC, Canada.
authors.forename: Franco
authors.initials: F
authors.lastname: Lepore
keywords: blind; crossmodal plasticity; discrimination task; fMRI BOLD; tactile perception