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Neurology. 2014 Aug 5;83(6):542-51. doi: 10.1212/WNL.0000000000000672. Epub 2014 Jul 2.

Brain functional connectivity network breakdown and restoration in blindness.

Author information

1
From the Institute of Medical Psychology (M.B., C.G., A.F., B.A.S.), Department of Computer Science (C.M.), and Department of Neurology (H.H.), Otto-von-Guericke University of Magdeburg; Department of Behavioral Neurology (H.H.), Leibniz Institute for Neurobiology, Magdeburg; and German Center for Neurodegenerative Diseases (DZNE) (H.H.), Magdeburg, Germany.
2
From the Institute of Medical Psychology (M.B., C.G., A.F., B.A.S.), Department of Computer Science (C.M.), and Department of Neurology (H.H.), Otto-von-Guericke University of Magdeburg; Department of Behavioral Neurology (H.H.), Leibniz Institute for Neurobiology, Magdeburg; and German Center for Neurodegenerative Diseases (DZNE) (H.H.), Magdeburg, Germany. bernhard.sabel@med.ovgu.de.

Abstract

OBJECTIVE:

To characterize brain functional connectivity in subjects with prechiasmatic visual system damage and relate functional connectivity features to extent of vision loss.

METHODS:

In this case-control study, resting-state, eyes-closed EEG activity was recorded in patients with partial optic nerve damage (n = 15) and uninjured controls (n = 13). We analyzed power density and functional connectivity (coherence, Granger causality), the latter as (1) between-areal coupling strength and (2) individually thresholded binary graphs. Functional connectivity was then modulated by noninvasive repetitive transorbital alternating current stimulation (rtACS; 10 days, 40 minutes daily; n = 7; sham, n = 8) to study how this would affect connectivity networks and perception.

RESULTS:

Patients exhibited lower spectral power (p = 0.005), decreased short- (p = 0.015) and long-range (p = 0.033) coherence, and less densely clustered coherence networks (p = 0.025) in the high-alpha frequency band (11-13 Hz). rtACS strengthened short- (p = 0.003) and long-range (p = 0.032) alpha coherence and this was correlated with improved detection abilities (r = 0.57, p = 0.035) and processing speed (r = 0.56, p = 0.049), respectively.

CONCLUSION:

Vision loss in the blind is caused not only by primary tissue damage but also by a breakdown of synchronization in brain networks. Because visual field improvements are associated with resynchronization of alpha band coherence, brain connectivity is a key component in partial blindness and in restoration of vision.

PMID:
24991030
DOI:
10.1212/WNL.0000000000000672
[Indexed for MEDLINE]

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