Disturbed resting functional inter-hemispherical connectivity of the ventral attentional network in alpha band is associated with unilateral spatial neglect.

Tsutomu Sasaki,Hajime Kamada,Masayuki Abe,Kensuke Sekihara,Toyoji Okada,Wataru Ide,Kimito Kondo,Eiichi Okumura,Yu-Feng Zang

doi:10.1371/journal.pone.0073416

Abstract

Unilateral spatial neglect (USN) is one of the most common symptoms of right hemisphere damage; its classical symptom is that patients fail to respond to information on their left side. It has been postulated that disturbance of 2 separate attentional networks relates to the occurrence of USN. However, little is known about the underlying mechanism and neuronal substrates. In this study, we measured spontaneous neural activity by means of magnetoencephalography in 13 patients with brain damage and 5 control subjects. To study the relationship between functional connectivity at rest and severity of USN symptoms, we determined the imaginary coherence values relating to the inter-hemispherical ventral and dorsal attentional networks, as well as the clinical severity of USN using neuropsychological tests and behavioral rating scales. The present results showed that inter-hemispherical connectivity in the ventral attentional network, especially between the left and right angular gyri, detected in the alpha band is associated with the severity of USN symptoms. This may suggest that connectivity of inter-hemispherical homologous regions of the ventral attentional network in the alpha band could be one of the biomarkers of attentional network imbalance occurring in patients with USN.

Highlights

There has been an increasing interest in understanding how the human brain works when it is at rest
ANOVA revealed, that no statistical difference was found among groups for the comparison between the left dorsal attentional network (DAN) and the left ventral attentional network (VAN) (F2,15 = 2.828, p > 0.1 for delta band: F2,15 = 2.914, p > 0.1 for theta band), and between left hemisphere and right hemisphere (F2,15 = 1.407, p > 0.1 for delta band: F2,15 = 1.099, p > 0.1 for theta band)
I.e., the beta band, the low-gamma band, and the high-gamma band, no significant relation was found excepting the relation between the IC of the left/right STG and unilateral spatial neglect (USN) index in the high-gamma band (F(1,11) = 5.290, p = 0.04, r2 = 0.325). This is the first report demonstrating a relationship between MEG measures of resting-state functional connectivity in specific oscillatory bands and clinical symptoms in patients with USN

Summary

Introduction

There has been an increasing interest in understanding how the human brain works when it is at rest. Unilateral damage to subcortical regions such as the thalamus [18,19,20], striatum, internal capsule [20], putamen, caudate nucleus, pulvinar [21], and cerebellar region [22] have been reported to cause USN symptoms. These findings imply that structural damage of specific focal brain regions cannot fully explain the neural mechanisms underlying USN, leading to the idea that USN may be better explained by the dysfunction of distributed cortical networks that control attention [23,24,25]

Objectives

Methods

Results

Conclusion