Wayfinding in the blind: larger hippocampal volume and supranormal spatial navigation.
In the absence of visual input, the question arises as to how complex spatial abilities develop and how the brain adapts to the absence of this modality. We explored navigational skills in both early and late blind individuals and structural differences in the hippocampus, a brain region well known to be involved in spatial processing. Thirty-eight participants were divided into three groups: early blind individuals (n = 12; loss of vision before 5 years of age; mean age 33.8 years), late blind individuals (n = 7; loss of vision after 14 years of age; mean age 39.9 years) and 19 sighted, blindfolded matched controls. Subjects undertook route learning and pointing tasks in a maze and a spatial layout task. Anatomical data was collected by MRI. Remarkably, we not only show that blind individuals possess superior navigational skills than controls on the route learning task, but we also show for the first time a significant volume increase of the hippocampus in blind individuals [F(1,36) = 6.314; P < or = 0.01; blind: mean = 4237.00 mm(3), SE = 107.53; sighted: mean = 3905.74 mm(3), SE = 76.27], irrespective of whether their blindness was congenital or acquired. Overall, our results shed new light not only on the construction of spatial concepts and the non-necessity of vision for its proper development, but also on the hippocampal plasticity observed in adult blind individuals who have to navigate in this space.
Centre de Recherche en Neuropsychologie et Cognition, Département de Psychologie, Université de Montréal, Montréal, Québec, Canada.
Madeleine
M
Fortin
Patrice
P
Voss
Catherine
C
Lord
Maryse
M
Lassonde
Jens
J
Pruessner
Dave
D
Saint-Amour
Constant
C
Rainville
Franco
F
Lepore
D000328:Adult; D017668:Age of Onset; D001766:Blindness / Q000151:congenital / Q000473:pathology* / Q000503:physiopathology / Q000523:psychology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D018782:Maze Learning; D008875:Middle Aged; D009473:Neuronal Plasticity; D009483:Neuropsychological Tests; D013028:Space Perception; D055815:Young Adult