Brain Advance Access originally published online on May 28, 2007
Brain 2007 130(8):2085-2096; doi:10.1093/brain/awm121
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Whole brain functional connectivity in the early blind
1National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing 100080 and 2Department of Radiology, Xuanwu Hospital, Capital University of Medical Sciences, Beijing 100053, P.R. China
Correspondence to: Tianzi Jiang, PhD, National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing 100080, P.R. China E-mail: jiangtz{at}nlpr.ia.ac.cn
Early visual deprivation can lead to changes in the brain, which may be explained by either of two hypotheses. The general loss hypothesis has been proposed to explain maladjustments, while the compensatory plasticity hypothesis may explain a superior ability in the use of the remaining senses. Most previous task-based functional MRI (fMRI) studies have supported the compensatory plasticity hypothesis, but it has been difficult to provide evidence to support the general loss hypothesis, since the blind cannot execute visual tasks. The study of resting state fMRI data may provide an opportunity to simultaneously detect the two aspects of changes in the blind. In this study, using a whole brain perspective, we investigated the decreased and increased functional connectivities in the early blind using resting state fMRI data. The altered functional connectivities were identified by comparing the correlation coefficients of each pair of brain regions of 16 early blind subjects (9 males; age range: 15.6–29.3 years, mean age: 22.1 years) with the corresponding coefficients of gender- and age-matched sighted volunteers. Compared with the sighted subjects, the blind demonstrated the decreased functional connectivities within the occipital visual cortices as well as between the occipital visual cortices and the parietal somatosensory, frontal motor and temporal multisensory cortices. Such differences may support the general loss hypothesis. However, we also found that the introduction of Braille earlier in life and for longer daily practice times produced stronger functional connectivities between these brain areas. These findings may support the compensatory plasticity hypothesis. Additionally, we found several increased functional connectivities between the occipital cortices and frontal language cortices in those with early onset of blindness, which indicate the predominance of compensatory plasticity. Our findings indicate that changes in the functional connectivities in the resting state may be an integrated reflection of general loss and compensatory plasticity when a single sensory modality is deprived.
Key Words: blind; resting state fMRI; functional connectivity; general loss; plasticity
Abbreviations: BOLD, blood oxygen level dependent; FDR, false discovery rate; LFF, low frequency fluctuations
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Received September 25, 2006. Revised April 27, 2007. Accepted April 30, 2007.
*The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors.
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