Altered functional connectivity of primary visual cortex in late blindness

Previous studies demonstrated that early blindness is associated with abnormal intrinsic functional connectivity (FC) between the primary visual cortex (V1) and other sensory areas. However, the V1 pattern of spontaneous neural activity occurring in late blindness (LB) remains unknown. The purpose of this study was to investigate the intrinsic FC patterns of V1 in LB.

Thirty LB individuals (18 males and 12 females; mean age: 38.76±14.43 years) and 30 sighted controls (SCs) individuals (18 males and 12 females; mean age: 38.67±13.85 years) closely matched for age, sex, and education, underwent resting-state magnetic resonance imaging scans. Region of interest analysis was performed to extract the correlation coefficient matrix among each pair of Brodmann area (BA) 17 and FC between V1 and vision-related subcortical nuclei.

Compared with SCs, LB individuals showed a decreased FC between the left V1 and the bilateral cuneus (CUN)/lingual gyrus (LGG)/calcarine (CAL) (BA 18/19/30) and left precentral gyrus (PreCG) and the postcentral gyrus (PostCG) (BA 2/3/4). Also, LB individuals showed a decreased FC between the right V1 and the bilateral CUN/LGG/CAL (BA 18/19/30) and the left PreCG and PostCG (BA 2/3/4/6) (voxel-level: P<0.01, cluster-level: P<0.05). Meanwhile, LB individuals showed a decreased FC between the left V1 and the right V1 and increased FC between the left V1 and the right superior colliculus, the right V1, and the left hippocampus (P<0.05). Moreover, a positive correlation was observed between the onset age of blindness and FC values in V1 to CUN/LGG/CAL in LB.

Our results highlighted that LB induces a decreased FC between V1 and higher visual areas, motor cortices, and somatosensory cortices at rest. This might indicate that LB humans could present with impaired top-down modulations, visual imagery, and vision-motor function.