Modality-specific involvement of occipital cortex in Early Blind?

What happens in occipital cortex when neuronal activity is no longer evoked by regular visual stimulation? Studying brain activity induced by tactile and auditory stimuli in the blind may provide an answer. Several studies indicate that occipital cortex in the blind is recruited in simple tasks, like auditory localization, and complex tasks, involving verbal memory. The goal of the current study was to establish whether or not this occipital recruitment is modality-specific when highly comparable tactile and auditory tasks are carried out. Early-blind subjects performed auditory and tactile duration discrimination tasks while their EEG was being measured. Source localization on secondary activity, after about 250 ms, revealed an occipito-parietal and occipito-temporal locus in case of auditory and tactile stimuli, respectively. This modality-specific result was underlined by a correlation between right occipital activity and performance on auditory targets. These findings suggest that specific parts of occipital cortex are more suitable for the takeover of modality-specific functions, which may possibly be related to the distinction between dorsal and ventral visual pathways