Ventral and dorsal visual pathways support auditory motion processing in the blind: evidence from electrical neuroimaging

• Published in: The European journal of neuroscience 2013-10, Vol.38 (8), p.3201-3209
• Main Authors: Lewald, Jörg, Getzmann, Stephan
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; blindness; Blindness - physiopathology; Brain Mapping; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Evoked Potentials, Auditory; Eye and associated structures. Visual pathways and centers. Vision; Female; Fundamental and applied biological sciences. Psychology; Hearing; human; Humans; Male; Motion Perception; multisensory plasticity; Occipital Lobe - physiopathology; sound localization; spatial hearing; Temporal Lobe - physiopathology; Vertebrates: nervous system and sense organs; Visual Pathways - physiopathology
• ISSN: 0953-816X; 1460-9568
• DOI: 10.1111/ejn.12306

Blindness induces processes of neural plasticity, resulting in recruitment of the deafferentated visual areas for non‐visual sensory functions. These processes are related to superior abilities of blind compared with sighted individuals for specific auditory and tactile tasks. Recently, an exceptional performance of the blind has been demonstrated for auditory motion perception, with a minimum audible movement angle that was half that of sighted controls (J. Lewald (2013) Neuropsychologia, 51, 181–186). The present study revealed an electrophysiological correlate of this finding by analysing the so‐called motion‐onset response, a prominent auditory‐evoked potential to the onset of motion. The cN1 component of this response, appearing about 170 ms after motion onset, was two times higher in amplitude for blind compared with matched sighted control subjects. At the time of the cN1, electrical neuroimaging using sLORETA revealed stronger activation in blind than sighted subjects primarily in ventral visual areas (V1v, V2v, VP, V4v) of the right occipital lobe. Activation was also obtained in middle temporal area V5. These findings suggest that blindness results in stronger involvement of both non‐motion areas of the ventral visual stream and motion areas of the dorsal visual stream in processing of auditory motion at the same point in time after motion onset. This argues against the view that visual motion areas, such as area V5, are preferentially recruited for auditory motion analysis in the blind. Rather, cross‐modal reorganization of cortical areas induced by blindness seems to be largely independent of the specific visual functions of the same areas in sighted persons. Correlates of auditory motion processing are substantially enhanced in blind compared to sighted human subjects about 170 ms after motion onset. Stronger activations in blind than sighted subjects were found primarily in ventral visual areas of the occipital cortex, while specific visual motion areas were involved to a lesser degree. This suggests a recruitment of visual areas for motion processing in the blind that is largely independent of the specific function in sighted persons.