title: Differential occipital responses in early- and late-blind individuals during a sound-source discrimination task.
abstract: Blind individuals do not necessarily receive more auditory stimulation than sighted individuals. However, to interact effectively with their environment, they have to rely on non-visual cues (in particular auditory) to a greater extent. Often benefiting from cerebral reorganization, they not only learn to rely more on such cues but also may process them better and, as a result, demonstrate exceptional abilities in auditory spatial tasks. Here we examine the effects of blindness on brain activity, using positron emission tomography (PET), during a sound-source discrimination task (SSDT) in both early- and late-onset blind individuals. This should not only provide an answer to the question of whether the blind manifest changes in brain activity but also allow a direct comparison of the two subgroups performing an auditory spatial task. The task was presented under two listening conditions: one binaural and one monaural. The binaural task did not show any significant behavioural differences between groups, but it demonstrated striate and extrastriate activation in the early-blind groups. A subgroup of early-blind individuals, on the other hand, performed significantly better than all the other groups during the monaural task, and these enhanced skills were correlated with elevated activity within the left dorsal extrastriate cortex. Surprisingly, activation of the right ventral visual pathway, which was significantly activated in the late-blind individuals during the monaural task, was negatively correlated with performance. This suggests the possibility that not all cross-modal plasticity is beneficial. Overall, our results not only support previous findings showing that occipital cortex of early-blind individuals is functionally engaged in spatial auditory processing but also shed light on the impact the age of onset of blindness can have on the ensuing cross-modal plasticity.
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Case Postale 6128, Succursale Centre-ville, Montréal, Québec, Canada H3C 3J7.
authors.forename: Patrice
authors.initials: P
authors.lastname: Voss
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Case Postale 6128, Succursale Centre-ville, Montréal, Québec, Canada H3C 3J7.
authors.forename: Frederic
authors.initials: F
authors.lastname: Gougoux
authors.affiliation: Neuropsychology/Cognitive Neuroscience Unit, Montreal Neurological Institute, McGill University, Montréal, Québec, Canada.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Zatorre
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Case Postale 6128, Succursale Centre-ville, Montréal, Québec, Canada H3C 3J7.
authors.forename: Maryse
authors.initials: M
authors.lastname: Lassonde
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Case Postale 6128, Succursale Centre-ville, Montréal, Québec, Canada H3C 3J7. Electronic address: franco.lepore@umontreal.ca.
authors.forename: Franco
authors.initials: F
authors.lastname: Lepore
mesh_terms: D000328:Adult; D017668:Age of Onset; D001307:Auditory Perception / Q000502:physiology*; D001766:Blindness / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009778:Occipital Lobe / Q000503:physiopathology*; D049268:Positron-Emission Tomography