Altered functional connectivity of primary visual cortex in early blindness

Abstract

In early blindness, the primary visual area (PVA) loses the ability to process visual information, and shifts to working on the processing of somatosensory input, auditory input, and some higherlevel cognitive functions. It has not yet been investigated whether such functional changes can lead to alterations of the functional connectivity between the PVA and other brain areas in resting state. The purpose of this study is to investigate the differences in the functional connectivity of the PVA between early blind and sighted subjects using resting functional MRI data. The altered functional connectivity was identified by comparing the correlation coefficients of the PVA with other brain areas between 16 early blind subjects (blindness onset within 1 year of age) and 32 gender-and age-matched healthy sighted volunteers. Compared with the sighted, the early blind subjects showed decreased functional connectivity between the left PVA and the bilateral supplementary motor area (SMA), pre-and postcentral gyri, superior parietal lobule, and the left superior and middle temporal gyri. Early blind subjects also showed decreased functional connectivity between the right PVA and the bilateral SMA, preand postcentral gyri. Our findings suggest that early deprivation of a single sensory modality induces alterations of functional connectivity between the deprived functional area and other associated brain

Corticocortical Connections Mediate Primary Visual Cortex Responses to Auditory Stimulation in the Blind

“…A finding that initially seems at odds with our data is that Liu et al (2007) and Yu et al (2008) reported decreased functional connectivity [i.e., correlations of the BOLD signal between brain regions (Friston et al, 1993)] in blind volunteers compared with controls between visual and auditory cortical areas during resting-state fMRI. However, if one considers that the visual cortex can also be activated by auditory stimuli in sighted if the task requires high levels of attention (Cate et al, 2009), the results seem more alike: possibly, the visual cortex of blind people is predominantly recruited during demanding tasks or when relevant information is supplied (Röder et al, 1996).…”

“…However, if one considers that the visual cortex can also be activated by auditory stimuli in sighted if the task requires high levels of attention (Cate et al, 2009), the results seem more alike: possibly, the visual cortex of blind people is predominantly recruited during demanding tasks or when relevant information is supplied (Röder et al, 1996). This would explain why resting-state studies (no attentional demands) failed to find coupling (Liu et al, 2007;Yu et al, 2008), whereas activation-based effective-connectivity studies did find enhanced coupling in the blind (Fujii et al, 2009;present study). This hypothesis is also backed by studies that found attentional modulations of visual cortex activity in the blind (Liotti et al, 1998;Stevens et al, 2007).…”

The Fine-Scale Functional Correlation of Striate Cortex in Sighted and Blind People

“…The thresholded map shows that a region within the pars opercularis and pars triangularis (classic Broca's area) has differential functional correlation to the left striate cortex in the blind and sighted, in general agreement with prior findings (Bedny et al, 2011;Watkins et al, 2012), although these prior studies used the lateral occipital cortex as a seed region. Also, in agreement with prior findings, a small area within the somatosensory cortex demonstrated decreased functional correlation to the left striate cortex in the blind population (Liu et al, 2007;Yu et al, 2008;Bedny et al, 2011).…”

“…We distinguish the modeling of fine-scale correlation within a cortical region from studies of the relationship between entire cortical regions (Liu et al, 2007;Yu et al, 2008;Watkins et al, 2012). By measuring the point-to-point structure of correlations within a cortical region, we may examine whether resting-state signals are related in a systematic way to the local functional organization of cortex.…”

Multimodal Magnetic Resonance Imaging for Brain Disorders: Advances and Perspectives

“…ROI based connectivity analysis and whole brain connectivity are the two most common methods. Using these two methods, researchers can investigate alterations in patients with a brain disorder (He et al 2007b;Johnston et al 2008;Liu et al 2007Liu et al , 2008bSupekar et al 2008;Tian et al 2008;Wang et al 2006aWang et al , b, 2007Yu et al 2008;Zang et al 2007;Zhou et al 2008). In recent years, a functional network, the so-called "default mode network (DMN)" of the brain, a set of regions characterized by decreased neural activity during goal-oriented tasks (Raichle et al 2001), has attracted significant interest as well as controversy (Buckner and Vincent 2007;Morcom and Fletcher 2007a, b;Raichle and Snyder 2007).…”