Selective Functional Disconnection of the Dorsal Subregion of the Temporal Pole in Schizophrenia.

Lixue Xu,Yongjie Xu,Xingyun Liu,Jiajia Zhu,Wen Qin,Chuanjun Zhuo,Huaigui Liu,Chunshui Yu

doi:10.1038/srep11258

Abstract

Although extensive resting-state functional connectivity (rsFC) changes have been reported in schizophrenia, rsFC changes in the temporal pole (TP) remain unknown. The TP contains several subregions with different connection patterns; however, it is not known whether TP subregions are differentially affected in schizophrenia. Sixty-six schizophrenia patients and 76 healthy comparison subjects underwent resting-state fMRI using a sensitivity-encoded spiral-in (SENSE-SPIRAL) imaging sequence to reduce susceptibility-induced signal loss and distortion. The TP was subdivided into the dorsal (TPd) and ventral (TPv) subregions. Mean fMRI time series were extracted for each TP subregion and entered into a seed-based rsFC analysis. Direct between-group comparisons revealed reduced rsFC between the right TPd and brain regions involved in language processing and multisensory integration in schizophrenia, including the left superior temporal gyrus, left mid-cingulate cortex, and right insular cortex. The rsFC changes of the right TPd in schizophrenia were independent of the grey matter reduction of this subregion. Moreover, these rsFC changes were unrelated to illness severity, duration of illness and antipsychotic medication dosage. No significant group differences were observed in the rsFC of the left TPd and bilateral TPv subregions. These findings suggest a selective (the right TPd) functional disconnection of TP subregions in schizophrenia.

Highlights

Extensive resting-state functional connectivity changes have been reported in schizophrenia, rsFC changes in the temporal pole (TP) remain unknown
For all TP subregions, the mean relative signal intensity (rSI) derived from the SENSE-SPIRAL functional MRI (fMRI) were greater than 0.5; the mean rSI of the left TPm derived from the echo-planar imaging (EPI) fMRI was less than 0.5
Using the structural images as a gold standard, the normalized functional images derived from the SENSE-SPIRAL fMRI exhibited less distortion in the TP and orbitofrontal cortex than those derived from the EPI fMRI (Figure S6 in Supplement 1)

Summary

Introduction

Extensive resting-state functional connectivity (rsFC) changes have been reported in schizophrenia, rsFC changes in the temporal pole (TP) remain unknown. No significant group differences were observed in the rsFC of the left TPd and bilateral TPv subregions These findings suggest a selective (the right TPd) functional disconnection of TP subregions in schizophrenia. Based on rsFC patterns, the left TP is divided into the dorsal, ventromedial, medial, and anterolateral subregions[26] These findings suggest that each TP subregion has a specific connection pattern and that these subregions may be involved in different functional networks. Most fMRI studies examine blood oxygenation level-dependent (BOLD) signals using the EPI technique, which inevitably causes susceptibility-induced signal loss and distortion in the TP region This flaw reduces our confidence in reliability of TP functional changes in schizophrenia derived from previous fMRI studies based on the EPI technique. This technique can improve the fMRI quality of the TP and makes rsFC analysis of the TP more reliable than the conventional EPI sequence

Objectives

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Conclusion