Abstract
The anterior insula (AI) is the core hub of salience network that serves to identify the most relevant stimuli among vast sensory inputs and forward them to higher cognitive regions to guide behaviour. As blind subjects were usually reported with changed perceptive abilities for salient non-visual stimuli, we hypothesized that the resting-state functional network of the AI is selectively reorganized after visual deprivation. The resting-state functional connectivity (FC) of the bilateral dorsal and ventral AI was calculated for twenty congenitally blind (CB), 27 early blind (EB), 44 late blind (LB) individuals and 50 sighted controls (SCs). The FCs of the dorsal AI were strengthened with the dorsal visual stream, while weakened with the ventral visual stream in the blind than the SCs; in contrast, the FCs of the ventral AI of the blind was strengthened with the ventral visual stream. Furthermore, these strengthened FCs of both the dorsal and ventral AI were partially negatively associated with the onset age of blindness. Our result indicates two parallel pathways that selectively transfer non-visual salient information between the deprived “visual” cortex and salience network in blind subjects.
Highlights
IntroductionChanges, cross-modal involvement of the visual areas in processing non-visual stimuli were identified by early studies, which included tactile[29,30,31,32,33], auditory[29,34,35,36,37], and olfactory[38] perception, and even higher cognitive processing driven by these non-visual stimuli such as language[39,40], attention[26,27] and working memory[26,28]
Brain regions demonstrating significant interactions were mainly located in the bilateral intraparietal area (IPA), calcarine sulcus (CalS) and lingual gyrus (LG), and right middle occipital gyrus (MOG) (Table 1)
Post hoc analyses revealed that the congenitally blind (CB) had a higher dorsal anterior insula (AI) functional connectivity (FC) with the bilateral IPA and CalS, while a lower FC with the left LG and right MOG than the SC; the early blind (EB) and late blind (LB) had higher dorsal AI FC with IPA, while lower FC with bilateral LG than the SC
Summary
Changes, cross-modal involvement of the visual areas in processing non-visual stimuli were identified by early studies, which included tactile[29,30,31,32,33], auditory[29,34,35,36,37], and olfactory[38] perception, and even higher cognitive processing driven by these non-visual stimuli such as language[39,40], attention[26,27] and working memory[26,28]. Studies have shown that the onset age of blindness has a significant influence on the structure and function of the visual pathways, including cortical thickness[46,47,48], grey matter volume[44], cross-modal activity pattern[15,49], baseline regional activity and metabolism[44,50,51], and FC and functional connectivity density[45,52,53,54], etc These studies indicate that the structural and functional reorganization of the brain after visual deprivation is the complex contribution of development, experience-dependent plasticity and degeneration factors[55]. We hypothesized that developmental factor may contribute to the changes in FC of AI sub-regions in the blindness
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