The relationship between regional and inter‐regional functional connectivity deficits in schizophrenia

Abstract

While schizophrenia is frequently characterized as a disorder of disturbed functional connectivity, the causes and pathophysiological origins of such disturbances remain unclear. The aim of this study was to better elucidate the mechanistic causes of abnormal functional connectivity in schizophrenia, measured as the extent of temporal correlation between endogenous fluctuations recorded at anatomically discrete brain regions during resting-state functional MRI. An approach was developed to perform whole-brain connectivity mapping at the resolution of individual pairs of voxels, without the need for arbitrary parcellation of the cerebrum. Between-group connectivity reductions in 12 people diagnosed with schizophrenia and 15 age-, IQ-, and gender-matched healthy volunteers were localized to a distributed network including frontoparietal and occipitoparietal connections. The gray-matter regions comprising this disturbed network showed evidence of local reductions in both intra-regional homogeneity (29%-33% reduction) and signal power (40%-60% reduction). The extent to which inter-regional correlation was reduced between a pair of gray matter regions was found to be strongly correlated with the extent of local decoherence evident within the gray matter regions per se. This suggests measurement of aberrant functional connectivity in schizophrenia is both a measurement of altered coupling between regions as well as a measurement of local decoherence within regions.

Precentral gyrus abnormal connectivity in male and female patients with schizophrenia

“…In conjunction with previous studies [10][11][12][13] , our results indicate the PreCG has abnormal connectivity with brain regions like Thalamus and Hippocampus, but these impairments are not similar in two hemispheres. We also analyzed the functional connectivity differences between male and female patients with schizophrenia and showed the regions like Thalamus are more affected in the female patients with schizophrenia.…”

Hyperconnectivity is a fundamental response to neurological disruption.

“…Investigators have observed a direct relationship between spiking output during neural firing and phase locking across nodes, thus resulting in higher measured connectivity/coherence (Chawla et al, 1999(Chawla et al, , 2000. These latest findings offer evidence that the increased connectivity observed in the literature summarized here There is also evidence that measured changes in functional connectivity between ROIs in clinical samples may be a consequence not only of altered coupling between regions but also of increased heterogeneity in the signals within each ROI (Bassett et al, 2011;Zalesky et al, 2012). In schizophrenia, decreased pairwise regional functional connectivity has been found to strongly correlate with loss of intraregional homogeneity, increased variance, and decreased signal power (Bassett et al, 2011;Zalesky et al, 2012).…”

Optimizing brain connectivity networks for disease classification using EPIC

“…Tzourio-Mazoyer et al defined a neurobiologically-informed cortical parcellation based on regions of interest that are known to house specific functional areas in the brain [11]. By contrast, Zalesky et al [12] proposed a more exhaustive approach that treats each voxel as its own ROI, resulting in tens of thousands of ROIs on the cortex. An intermediate approach proposed by Wig [13] treats the elements of random parcellations of the cortex as nodes, but this approach may still fail to capture the borders of regions that make sense for capturing pathways.…”