External spatial coordinates for tactile spatial attention are reflected in prestimulus oscillations in sighted but not in blind individuals
Last modified: 2013-05-05
Abstract
Sighted individuals seem to represent skin locations automatically in anatomical and external reference frames (Shore, Spry, & Spence, 2002; Yamamoto & Kitazawa, 2001), which are reflected in lateralized oscillatory activity in the beta and alpha range, respectively (Buchholz, Jensen, & Medendorp, 2013). Congenitally blind individuals do not seem to automatically activate external reference frames suggesting a crucial contribution of developmental vision for touch localization.
We recorded EEG while sighted and congenitally blind participants directed attention to one hand in order to detect rare tactile targets at this hand only. In each trial, the relevant hand was indicated by an auditory cue (S1) which preceded the tactile stimulus (S2) by 1000 ms. Participants either adapted an uncrossed or a crossed hand posture. Attention- and posture-related power modulations in the alpha band were analyzed.
In the sighted orienting attention to one uncrossed hand (S1-S2 interval) was accompanied by an alpha reduction over contralateral parietal cortex and an alpha increase over ipsilateral cortex. With hands crossed a contralateral alpha decrease (relative to the anatomical hand) was still observed, but the ipsilateral alpha increase was less pronounced.
In the blind orienting attention to one of the hands was accompanied by a contralateral alpha decrease over parietal cortex which extended towards the ipsilateral hemisphere as well. By contrast, an alpha increase was not observed. This pattern of alpha activation in the congenital blind remained unchanged when they adopted a crossed hand posture.
These findings complement ERP evidence about deployment of attention in sighted and blind (Eardley & van Velzen, 2011) and extend previous evidence that alpha activity related mechanisms of attention control depend on developmental vision.
We recorded EEG while sighted and congenitally blind participants directed attention to one hand in order to detect rare tactile targets at this hand only. In each trial, the relevant hand was indicated by an auditory cue (S1) which preceded the tactile stimulus (S2) by 1000 ms. Participants either adapted an uncrossed or a crossed hand posture. Attention- and posture-related power modulations in the alpha band were analyzed.
In the sighted orienting attention to one uncrossed hand (S1-S2 interval) was accompanied by an alpha reduction over contralateral parietal cortex and an alpha increase over ipsilateral cortex. With hands crossed a contralateral alpha decrease (relative to the anatomical hand) was still observed, but the ipsilateral alpha increase was less pronounced.
In the blind orienting attention to one of the hands was accompanied by a contralateral alpha decrease over parietal cortex which extended towards the ipsilateral hemisphere as well. By contrast, an alpha increase was not observed. This pattern of alpha activation in the congenital blind remained unchanged when they adopted a crossed hand posture.
These findings complement ERP evidence about deployment of attention in sighted and blind (Eardley & van Velzen, 2011) and extend previous evidence that alpha activity related mechanisms of attention control depend on developmental vision.
References
Buchholz, V. N., Jensen, O., & Medendorp, W. P. (2013). Parietal oscillations code nonvisual reach targets relative to gaze and body. The Journal of Neuroscience, 33(8), 3492-3499.
Eardley, A. F., & van Velzen, J. (2011). Event-related potential evidence for the use of external coordinates in the preparation of tactile attention by the early blind. The European Journal of Neuroscience, 33(10), 1897-1907.
Shore, D. I., Spry, E., & Spence, C. (2002). Confusing the mind by crossing the hands. Brain Research, Cognitive Brain Research, 14(1), 153-163.
Yamamoto, S., & Kitazawa, S. (2001). Reversal of subjective temporal order due to arm crossing. Nature Neuroscience, 4(7), 759-765.