Neural correlates of olfactory processing in congenital blindness

• Published in: Neuropsychologia Vol. 49; no. 7; pp. 2037 - 2044
• Main Authors: Kupers, R., Beaulieu-Lefebvre, M., Schneider, F.C., Kassuba, T., Paulson, O.B., Siebner, H.R., Ptito, M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.06.2011; Elsevier
• Subjects: Adult; Amygdala - physiology; Behavior; Biological and medical sciences; Blindness; Blindness - congenital; Blindness - physiopathology; Blindness - psychology; Cross-modal plasticity; Female; fMRI; Frontal Lobe - physiology; Fundamental and applied biological sciences. Psychology; Handicap; Heart - physiology; Hippocampus - physiology; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Medical sciences; Mediodorsal Thalamic Nucleus - physiology; Neuronal Plasticity - physiology; Occipital Lobe - physiology; Odorants; Olfaction; Ophthalmology; Oximetry; Oxygen - blood; Psychology and medicine; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychomotor Performance - physiology; Respiratory Mechanics - physiology; Smell - physiology; Somatosensory Cortex - physiology; Stimulation, Chemical; Vision disorders; Visual Cortex - physiology; fMRI; Cross-modal plasticity; Behavior; Blindness; Olfaction; Human; Congenital; Vision disorder; Central nervous system; Cognition; Nuclear magnetic resonance imaging; Encephalon; Eye disease; Plasticity; Functional magnetic resonance imaging; Intermodal perception; Functional imaging
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2011.03.033

► The olfactory system is highly plastic. ► Congenitally blind (CB) subjects are prone to crossmodal plasticity. ► We used fMRI to test crossmodal plasticity of olfactory processing. ► Compared to sighted controls, CB showed increased responses in olfactory and visual cortices. ► Our data add new evidence for the supramodal function of the occiptal cortex in CB. Adaptive neuroplastic changes have been well documented in congenitally blind individuals for the processing of tactile and auditory information. By contrast, very few studies have investigated olfactory processing in the absence of vision. There is ample evidence that the olfactory system is highly plastic and that blind individuals rely more on their sense of smell than the sighted do. The olfactory system in the blind is therefore likely to be susceptible to cross-modal changes similar to those observed for the tactile and auditory modalities. To test this hypothesis, we used functional magnetic resonance imaging to measure changes in the blood-oxygenation level-dependent signal in congenitally blind and blindfolded sighted control subjects during a simple odor detection task. We found several group differences in task-related activations. Compared to sighted controls, congenitally blind subjects more strongly activated primary (right amygdala) and secondary (right orbitofrontal cortex and bilateral hippocampus) olfactory areas. In addition, widespread task-related activations were found throughout the whole extent of the occipital cortex in blind but not in sighted participants. The stronger recruitment of the occipital cortex during odor detection demonstrates a preferential access of olfactory stimuli to this area when vision is lacking from birth. This finding expands current knowledge about the supramodal function of the visually deprived occipital cortex in congenital blindness, linking it also to olfactory processing in addition to tactile and auditory processing.