The acts of opening and closing the eyes are of importance for congenital blindness: Evidence from resting-state fMRI.

Closing the eyes alters resting-state brain activity in both sighted and congenitally blind individuals, suggesting that the effect is inherent to human nature rather than learned from vision. The study compared 21 congenitally blind participants with 21 sighted controls using functional MRI. In both groups, eye closure increased low-frequency fluctuations in sensorimotor and occipital regions and decreased them in the medial prefrontal cortex. No differences appeared between blind participants with and without light perception. Between-group differences in the posterior insula and fusiform were attributed to experience (nurture). The authors contend that volitional eye closure focuses attention inward and is a natural human action, not dependent on visual experience.

Study at a glance

Abstract

Volitional eye closure is observed only in conscious and awake humans, and is rare in animals. It is believed that eye closure can focus one's attention inward and facilitate activities such as meditation and mental imagery. Congenital blind individuals are also required to close their eyes for these activities. Resting-state functional magnetic resonance imaging (RS-fMRI) studies have found robust differences between the eyes-closed (EC) and eyes-open (EO) conditions in some brain regions in the sighted. This study analyzed data from 21 congenital blind individuals and 21 sighted controls by using amplitude of low-frequency fluctuation (ALFF) of RS-fMRI. The blind group and the sighted group shared similar pattern of differences between the EC and EO condition: ALFF was higher in the EC condition than the EO condition in the bilateral primary sensorimotor cortex, bilateral supplementary motor area, and inferior occipital cortex, while ALFF was lower in the EC condition than the EO condition in the medial prefrontal cortex, highlighting the "nature" effect on the difference between the EC and EO conditions. The results of other matrices such as fractional ALFF (fALFF) and regional homogeneity (ReHo) showed similar patterns to that of ALFF. Moreover, no significant difference was observed between the EC-EO pattern of the two subgroups of congenital blind (i.e., with and without light perception), suggesting that the EC-EO difference is irrespective of residual light perception which reinforced the "nature" effect. We also found between-group differences, i.e., more probably "nurture effect", in the posterior insula and fusiform. Our results suggest that the acts of closing and opening the eyes are of importance for the congenital blind, and that these actions and their differences might be inherent in the nature of humans.