躯体形式疼痛障碍基于ReHo的脑静息态功能磁共振成像研究

目的 采用基于局部一致性(ReHo)的功能磁共振成像(fMRI)分析法探讨躯体形式疼痛障碍(SPD)患者静息状态下的脑功能活动特点.方法 15例SPD患者为病例组,15名健康志愿者为正常对照组(HC组),通过疼痛数字评价量表(N RS)评分后行静息态fMRI(rs-fMRI)数据采集.对所有图像预处理,计算两组受试者全脑ReHo值,经统计学处理后获得SPD患者ReHo值有意义的脑区;将SPD患者ReHo异常脑区的ReHo值与NRS得分做相关性分析.结果 与正常对照组相比,SPD患者在静息状态下ReHo值升高的脑区为右侧小脑后叶,ReHo值减低的脑区为左侧颞上回、左侧中央前回、右侧小脑前叶、右侧小脑山顶及小脑山坡;相关性分析显示上述脑区域ReHo值的改变与NRS得分均无显著相关性(P＞0.05).结论 SPD患者右侧小脑后叶的ReHo值升高,左侧颞上回、左侧中央前回、右侧小脑前叶、右侧小脑山顶及小脑山坡的ReHo值减低,提示这些脑区可能与SPD的潜在病理生理机制有关,SPD患者异常激活脑区ReHo值的改变与疼痛程度均无显著相关性.     

特发性全身性癫痫分数低频振幅及局部一致性的静息态f MR I研究

目的：观察特发性全身性癫痫(IGE)患者静息状态下全脑功能改变情况。方法采用3.0T MR扫描仪对23例 IGE患者(IGE组)及23例健康志愿者(对照组)行全脑3D 结构相及静息态功能磁共振成像(RS-fMRI)扫描,进行全脑分数低频振幅(fALFF)及局部一致性(ReHo)功能分析,并对比 IGE组相比对照组 fALFF及 ReHo 改变的脑区,分析 IGE 组差异脑区与患者病程的相关性。结果与正常对照组相比,IGE组 fALFF升高的脑区位于双侧中央前回、左侧辅助运动区、左侧扣带回、左侧中央旁小叶、左侧距状裂周围皮层、左侧枕上回、左侧枕中回及右侧楔前叶;fALFF降低的脑区位于双侧颞下回、右侧海马旁回、右侧岛叶、右侧楔前叶及左侧顶下小叶(P<0.005)。ReHo 升高的脑区位于左侧距状裂周围皮层、左顶上小叶、左中央后回及右中央前回;ReHo降低的脑区位于右侧梭状回、左侧豆状核、右侧额下回、右内侧额上回、左侧枕中回、右侧岛叶及双侧顶下小叶(P<0.005)。IGE组 fALFF及 ReHo的差异脑区与患者病程均无相关性。结论 IGE患者脑内广泛的脑区功能异常改变可能是 IGE复杂临床表现的神经病理基础。联合应用 RS-fMRI的2种分析方法能较全面地评价静息状态下脑功能状态的改变情况,为 IGE 神经病理生理机制的研究提供可靠的功能神经解剖学依据。     

神经根型颈椎病颈肩痛脑静息态局部一致性研究

【摘要】目的：运用静息态功能磁共振成像(rs-fMRI)局部一致性(ReHo)方法研究神经根型颈椎病慢性颈肩痛状态下静息态脑功能改变。方法：采用Philips公司Achieva 3.0T TX多射频源超导磁共振扫描仪对25例神经根型颈椎病慢性颈肩痛患者及20例健康志愿者进行常规磁共振、高分辨率3D-T1结构像及静息态功能磁共振扫描,扫描结束对每位患者进行视觉模拟评分(VAS)。组间对比分析ReHo的改变,并对ReHo均值与VAS得分进行Pearson相关性分析。结果：与正常对照组相比,神经根型颈椎病慢性颈肩痛组ReHo值减低的脑区位于左侧岛叶(IC)、海马(Hip)、辅助运动区(SMA)、额上回(SFG),右侧中央后回(PoCG)、顶上小叶(SPL);ReHo值增高的脑区位于双侧额中回(MFG)(P＜0.01,AlphaSim矫正,Cluster Size≥18)。神经根型颈椎病慢性颈肩痛组左侧IC的ReHo均值与VAS得分存在显著负相关性(r=-0.552,P=0.004)。结论：神经根型颈椎病慢性颈肩痛导致以额、顶叶为主的部分脑区出现ReHo的异常改变。左侧IC能够感知疼痛强度。神经根型颈椎病慢性颈肩痛脑自发性活动异常主要与认知执行和情感、疼痛感知及记忆等脑功能受到影响相关。     

肝性脊髓病患者自发脑活动局部一致性的变化

目的 探讨肝性脊髓病(HM)患者静息态下局部一致性(ReHo)的差异.方法 对22例HM患者及25例人口学特征匹配的健康对照组(HC)进行静息态功能磁共振成像(rs-fMRI)扫描,用处理软件获得ReHo数据,比较HM患者与正常人在静息状态下大脑ReHo的差异.结果 与HC相比,HM患者ReHo值降低的脑区有左侧颞中回、右侧梭状回、右侧楔前叶和左侧海马旁回,ReHo值升高的脑区有双侧扣带回、双侧中央旁小叶、双侧额中回、右侧中央前回、双侧岛叶、右侧额上回和左侧额下回.结论HM患者的若干脑区存在ReHo升高或降低,提示HM的病理生理机制并非只存在单一脑区的功能异常,而涉及多个大脑功能网络,是一种大脑功能失连接的表现.     

2型糖尿病骨质疏松患者静息态脑功能局部一致性研究

目的 探讨2型糖尿病(T2DM)糖尿病性骨质疏松(DOP)患者静息态脑功能自发性活动改变，揭示骨质疏松对认知损害的影响机制。方法 根据骨质疏松的诊断标准将29例T2DM患者分为DOP组和非DOP组(对照组)。采用认知量表评价被试者的认知状态。通过静息态功能磁共振成像(rs-fMRI)扫描，计算全脑的局部一致性(ReHo)改变差异，并与临床指标、认知评分进行皮尔逊相关分析。结果 DOP组患者左颞中回、右侧枕上回、右侧顶上小叶、右侧角回及左侧楔前叶ReHo值升高。左颞中回ReHo值与平均骨密度(BMD AVG)和平均T值(T AVG)呈正相关；右侧枕上回和右侧顶上小叶的ReHo值与蒙特利尔认知评估(MoCA)评分呈负相关；右侧顶上小叶的ReHo值与骨钙素(OC)呈负相关。结论 DOP组患者在静息态下存在多个脑区的异常活动，提示骨质疏松对T2DM患者的脑认知功能产生联合损伤效应。默认模式网络(DMN)是骨质疏松引起脑功能损害的主要靶网络，OC可能是导致骨质疏松患者认知功能障碍的关键因素。     

重度吸烟依赖者脑局部一致性静息态功能MRI研究

目的 基于脑静息态功能MRI(fMRI)研究重度吸烟依赖者(HS)脑局部一致性(ReHo),探讨HS自我觉醒机制.方法 选取30例HS(HS组)和年龄、性别匹配的31名无酒精烟草滥用健康志愿者(对照组)行3.0T静息态fMRI采集,采用统计参数图(SPM)5软件进行数据预处理,Rest软件计算ReHo值,HS组和对照组间ReHo值比较采用两样本t检验,最终获得ReHo值有统计差异的功能图.结果(1)与对照组比较,静息态下HS组ReHo值减低脑区包括两侧楔前叶、额上回、前额叶内侧及右角回、额下回、枕下回、小脑和左额中回等.(2)与对照组比较,静息态下HS组ReHo值增高脑区包括两侧岛叶、海马旁回、顶叶白质、桥脑及左侧顶下小叶、舌回、丘脑、额下眶回、额颞叶白质、小脑等,且呈左侧化趋势.结论 HS静息态脑默认模式网络活动减低;活动增强脑区组成吸烟成瘾静息态网络,并呈左侧化趋势,反映HS自我觉醒机制.     

失语症患者静息态fMRI成像研究

目的探讨应用局部区域一致性(ReHo)研究失语患者静息态下脑功能区活动改变情况。方法运用SIEMENS verio 3.0T磁共振对23名志愿者及21名失语患者行静息态BOLD-fMRI扫描,应用DPARSF软件进行时间层校正、头动校正、空间标准化、去线性、滤波(0.01Hzf0.08Hz),去除生理噪声(如呼吸、心跳),重采样等预处理后。采用局部区域一致性(ReHo)的分析方法计算两组静息态下脑ReHo情况。所得的结果各组行单样本t检验,两组间行双样本t检验统计比较。结果正常志愿者组静息下存在着广泛的高ReHo脑区,包含了默认网络结构组成脑区以及其负相关网络组成脑区。这些脑区包括双侧扣带回后部PCC/楔前叶,双侧前额内侧回MPFC,双侧顶下小叶IPC,双侧颞下回ITG;也包括双侧辅助运动区SMA,双侧岛叶、双侧颞中回MTC。患者组和正常组对照研究两样本t检验的结果显示,失语症患者组与正常人相比ReHo值升高的区域有:右侧脑岛(BA13/45),左侧扣带回(BA31/24),右额叶内侧回(BA32),右侧额中回(BA32/8),右侧扣带中回(BA31),右侧海马旁回(BA37/19);降低的区域有:左侧颞下回(BA20),左侧颞极(BA38/47),左侧内侧额叶(BA10),左侧额下回(BA46),右侧前扣带回(BA24/32),左侧楔前叶(BA7/19)。结论失语患者静息态下的两个脑网络系统可以发生变化,但以默认网络变化明显。默认网络左侧半球表现为多相关脑区ReHo值的降低和对侧多相关脑区ReHo值升高,可能是提示功能代偿作用,具体机制有待于进一步研究。     

静息态fMRI在帕金森病基线脑活动变化中的初步研究

目的 探讨静息态功能磁共振成像(fMRI)低频振幅(ALFF)方法评价帕金森病(Parkiuson's disease,PD)基线脑活动变化.资料与方法 利用1.5 T MRI系统对PD患者和年龄匹配正常对照组各16例分别进行静息态fMRI.静息态fMRI原始数据采用统计参数图软件(SPM5)预处理和静息态磁共振数据分析工具包(REST)进行ALFF分析,采用SPM5进行t检验统计分析,并用XjView软件确定有统计学意义的脑区解剖位置及MRIcroN软件结果呈现.结果 在静息状态下,相对正常对照组,PD患者以下脑区ALFF增高有统计学意义,这些脑区包括左侧中央后回(BA 5)、左侧顶上小叶(BA 7)、左侧顶下小叶、左侧楔前叶和左侧额上回;右侧枕叶舌回(BA 18);双侧小脑后叶.结论 PD患者静息态下左侧脑默认网络及感觉运动皮质等区域ALFF较对照组明显增高,可能代表了与病情程度及治疗有关的特定病理改变.     

原发性闭角型青光眼手术前后静息态功能MRI的局部一致性研究

目的 应用静息态功能磁共振分析原发性闭角型青光眼(PACG)患者小梁网联合周边虹膜切除手术前后自发性脑活动的变化.方法 40例术前PACG患者及40例年龄、性别匹配的正常健康对照组(HC)均接受静息态fMRI检查,10例PACG患者于术后3个月复查静息态fMRI.计算所有受试者全脑ReHo值,采用两样本t检验比较40例术前PACG患者与HC组ReHo值差异;同时,采用配对样本t检验比较10例PACG患者术前与术后ReHo值差异.结果 与HC组对比,术前PACG组ReHo减低的脑区包括右侧梭状回,双侧枕中回,左侧枕下回,左侧颞中回,双侧中央前回,左侧顶上小叶,右侧中央后回,左侧中央旁小叶;ReHo升高的脑区包括双侧小脑后叶,双侧额上回(AlphaSim校正,P＜0.01,33个体素).10例PACG患者术后与术前对比,右侧颞中回、左侧楔叶神经活动一致性增加,右侧额上回、右侧额下回神经活动一致性减低(AlphaSim校正,P＜ 0.01,33个体素).结论 PACG患者术前存在视觉以及情感认知调节相关脑区局部一致性异常;此外,通过青光眼手术,PACG患者视觉区域出现脑功能活动重塑,为进一步研究PACG的神经病理机制以及监测PACG的治疗提供了一定帮助.     

帕金森病静息态脑功能成像研究

目的研究静息态脑功能成像在帕金森病(parkinson's disease,PD)中的应用。方法帕金森病患者29例和健康对照组33例行磁共振检查,扫描序列包括常规MRI平扫及静息态fMRI成像,通过比较两组之间局部一致性和低频振幅的差异,寻找PD患者发生功能异常的脑区,探讨PD尤其是非运动症状的发生机制。结果 PD组ReHo减低的区域主要位于双侧额叶(包括前额叶、额上回、额中回)、胼胝体和扣带回、左中央前回、右侧角回、右侧颞极、丘脑和左侧脑干;PD组ReHo增高的区域主要位于双侧顶叶(包括中央前回和中央后回)左顶下小叶和右楔叶。PD组ALFF减低的区域主要位于左侧额叶、右侧颞叶、右侧中脑及大脑脚、右侧脑桥、右侧小脑、右侧丘脑、胼胝体、双侧顶上小叶;PD组ALFF增高的区域主要位于左侧中央前回和中央后回、左侧岛叶、左侧壳核和左侧丘脑。结论静息态fMRI的局部一致性(ReHo)和低频振幅(ALFF)的方法能够显示PD功能异常的脑区,有助于研究PD的发生机制。     

Gray matter abnormalities in Internet addiction: A voxel-based morphometry study

Background

This study aims to investigate brain gray matter density (GMD) changes in adolescents with Internet addiction (IA) using voxel-based morphometry (VBM) analysis on high-resolution T1-weighted structural magnetic resonance images.

Methods

Eighteen IA adolescents and 15 age- and gender-matched healthy controls took part in this study. High-resolution T1-weighted magnetic resonance imaging scans were performed on the two groups. VBM analysis was used to compare the GMD between the two groups.

Results

Compared with healthy controls, IA adolescents had lower GMD in the left anterior cingulate cortex, left posterior cingulate cortex, left insula, and left lingual gyrus.

Conclusions

Our findings suggested that brain structural changes were present in IA adolescents, and this finding may provide a new insight into the pathogenesis of IA.     

Test-retest stability analysis of resting brain activity revealed by blood oxygen level-dependent functional MRI

Purpose:

To assess test–retest stability of four functional magnetic resonance imaging (fMRI)‐derived resting brain activity metrics: the seed‐region‐based functional connectivity (SRFC), independent component analysis (ICA)‐derived network‐based FC (NTFC), regional homogeneity (ReHo), and the amplitude of low frequency fluctuation (ALFF).

Methods:

Simulations were used to assess the sensitivity of SRFC, ReHo, and ALFF to noise interference. Repeat resting blood oxygen level‐dependent (BOLD) fMRI were acquired from 32 healthy subjects. The intraclass correlation coefficient (ICC) was used to assess the stability of the four metrics.

Results:

Random noise yielded small random SRFC, small but consistent ReHo and ALFF. A neighborhood size greater than 20 voxels should be used for calculating ReHo in order to reduce the noise interference. Both the anterior cingulate cortex (ACC) and posterior cingulate cortex (PCC)‐based SRFC were reproducible in more spatially extended regions than ICA NTFC. The two regional spontaneous brain activity (SBA) measures, ReHo and ALFF, showed test–retest reproducibility in almost the whole gray matter.

Conclusion:

SRFC, ReHo, and ALFF are robust to random noise interference. The neighborhood size for calculating ReHo should be larger than 20 voxels. ICC > 0.5 and cluster size > 11 should be used to assess the ICC maps for ACC/PCC SRFC, ReHo, and ALFF. BOLD fMRI‐based SBA can be reliably measured using ACC/PCC SRFC, ReHo, and ALFF after 2 months. J. Magn. Reson. Imaging 2012;36:344–354. ©2012 Wiley Periodicals, Inc.     

fMRI成像技术在OSAHS患者中的临床价值研究

目的 采用fMRI图像处理技术对阻塞性睡眠呼吸暂停低通气综合征（obstructive sleep apnea-hypopnea syndrome, OSAHS）患者神经影像学进行研究,运用ReHo法探索患者脑功能及结构变化。方法 选取2021年1月-2022年12月厦门市海沧医院就诊的20例OSAHS患者作为研究对象,另选同期来院体检的健康志愿者20例作为健康对照组,分析比较两组受试者的一般情况并对两组患者进行睡眠监测,同时进行fMRI检查,并运用ReHo法对各组及两组间受试者睡眠前后脑区功能改变情况进行比较。结果 两组受试者一般情况资料差异无统计学意义（P>0.05）,健康对照组AHI(2.35±1.27)低于OSAHS组（32.93±14.90）,最低SpO2值（88.25±3.01）高于OSAHS组（67.25±8.06）,差异均有统计学意义（P<0.05）。健康人群睡眠后ReHo增强脑区有左右侧颞下回、左右侧前扣带回、右侧杏仁核、右侧海马,减弱脑区有左右侧前额叶、左右顶叶。OSAHS患者睡眠后ReHo增强脑区有左右侧颞下回、右侧脑干,减弱脑区有右侧额中回、两侧额上...     

经皮耳迷走神经刺激对功能性消化不良患者大脑局部一致性的影响

目的:观察经皮耳迷走神经刺激(taVNS)对功能性消化不良(FD)患者的临床疗效及对大脑局部一致性(ReHo)的影响.方法:将54例FD患者随机分为迷走刺激组(26例)及非迷走刺激组(28例),对2组进行治疗前后总体症状、尼平消化不良指数(NDI)、Hamilton焦虑(HAMA)及Hamilton抑郁(HAMD)量表...     

帕金森静止性震颤脑局部一致性的功能磁共振研究

目的探讨静息状态下,帕金森静止性震颤患者的脑局部一致性。资料与方法在静息状态下,对9例左侧静止性震颤的帕金森病患者进行功能磁共振成像(functional magnetic resonance imaging,fMRI),分析其脑部局部一致性,并与健康对照组比较。结果与健康对照组相比,单侧静止性震颤的帕金森病患者表现为对侧的楔前叶、额下回、额中回、顶上小叶及同侧前扣带回等区域的局部一致性增强;小脑蚓部的局部一致性减弱。结论静息状态下,帕金森病静止性震颤患者的脑部局部一致性异常,为该病的研究提供了新依据。     

Functional reorganization associated with outcome in hand function after stroke revealed by regional homogeneity

Introduction

Previous studies of task-based functional neuroimaging have shown that various patterns of functional reorganization underlie motor recovery following stroke. However, the mechanisms underlying functional reorganization that contribute to outcome differences in hand function after stroke have not been completely characterized. We, for the first time, investigate subgroups of stroke patients with different outcomes in hand function using a resting-state fMRI approach.

Methods

We selected 24 patients with subcortical stroke and divided them into two subgroups: completely paralyzed hands (CPH, 12 patients) and partially paralyzed hands (PPH, 12 patients). Twenty-four healthy controls (HCs) matched for age and handedness were also recruited. We used regional homogeneity (ReHo) method to map regional spontaneous activity across the whole brain and performed a two-sample t test between each pair of the three diagnostic groups.

Results

Compared to HCs, we found increased ReHo in the ipsilesional hemisphere in PPH and, conversely, increased ReHo in the contralesional hemisphere in CPH. Moreover, we detected decreased ReHo in the ipsilesional primary sensorimotor cortex and superior temporal gyrus, in addition to increased ReHo in the contralesional premotor cortex and ipsilesional medial frontal gyrus in CPH compared to PPH. Additionally, the ReHo index of these regions significantly correlated with the Fugl-Meyer assessment scores (hand + wrist) across all stroke patients.

Conclusions

Our study offers a new insight into relationships between functional reorganization and outcomes in hand function after subcortical stroke, and the ReHo method can provide an effective tool for evaluating the efficiency of rehabilitative therapies following stroke.     

头颅降温对高温环境下人脑局部一致性的影响

目的 探讨高温环境下头颅降温对人脑神经活动的影响及其保护机制.方法 16名被试者分别在常温(25℃)、高温(50℃)、头颅降温(舱温:50℃、降温帽:5℃)3组条件下暴露1 h,并采集静息态功能磁共振成像(rs-fMRI)数据.采用REST2.0软件对3组被试者全脑局部一致性(ReHo)值进行单因素方差分析,进一步提取差异显著脑区的ReHo值利用SPSS18.0进行单因素方差分析,并进行事后检验,明确任意2组各脑区神经活性的差异.结果 3组条件下的差异脑区位于右侧眶回、左侧额中回、双侧杏仁核、左侧颞中回、左侧海马、双侧顶下缘角回、左侧中央前回.与常温组相比,头颅降温组ReHo值增大的脑区有右侧眶回,降低的脑区有左侧中央前回、左侧额中回、左侧角回,未见变化的脑区有双侧杏仁核、左侧颞中回、左侧海马、右侧角回.与高温组比较,头颅降温组ReHo值增大的脑区有左侧颞中回、左侧海马、右侧角回,降低的脑区有双侧杏仁核、左侧角回,未见变化的脑区有右侧眶回、左侧中央前回、左侧额中回.结论 头颅降温组ReHo的特异性变化,表明头颅降温可以部分消除高温对大脑ReHo的影响,且与情绪功能存在密切联系.     

Brain regional homogeneity changes following transjugular intrahepatic portosystemic shunt in cirrhotic patients support cerebral adaptability theory—A resting-state functional MRI study

Purpose

The exact neuro-pathophysiological effect of transjugular intrahepatic portosystemic shunt (TIPS) on brain function remains unclear. The purpose of this study was to investigate the longitudinal brain activity changes in cirrhotic patients with TIPS insertion using resting-state functional MRI (fMRI) with regional homogeneity (ReHo) method.

Methods

Fifteen cirrhotic patients without overt hepatic encephalopathy (OHE) planned for TIPS procedure and 15 age- and gender-matched healthy controls were included in this study. Eleven of the 15 patients underwent repeated fMRI examinations at median 7-day following TIPS, 8 patients in median 3-month, and 7 patients in median 1-year follow-up duration, respectively. Regional homogeneity was calculated by the Kendall's coefficient of concordance (KCC) and compared between patients before TIPS and healthy controls with two-sample t test as well as pre-and post-TIPS patients with paired t test. Correlations between the pre- and post-TIPS changes of ReHo and the changes of venous blood ammonia level and number connection test type A (NCT-A)/digit symbol test (DST) scores were calculated by crossing subjects.

Results

Compared with healthy controls, 15 cirrhotic patients before TIPS procedure showed decreased ReHo in the bilateral frontal, parietal, temporal and occipital lobes and increased ReHo in the bilateral caudate. Compared with the pre-TIPS patients, 11 post-TIPS patients in the median 7-day follow-up examinations demonstrated decreased ReHo in the medial frontal gyrus (MFG), superior parietal gyrus (SPG), middle/superior temporal gyrus (M/STG), anterior cingulate cortex (ACC), caudate, and increased ReHo in the insula. Eight post-TIPS patients in the median 3-month follow-up examinations showed widespread decreased ReHo in the bilateral frontal and parietal lobes, ACC, caudate, and increased ReHo in the insula and precuneus/cuneus. In the median 1-year follow-up studies, seven post-TIPS patients displayed decreased ReHo in the bilateral frontal and parietal lobes, ACC, supplementary motor area (SMA), posterior cingulate cortex (PCC), and increased ReHo in the caudate and insula (P < 0.05, Alphasim corrected). The changes of ReHo values in bilateral IPL, MFG, caudate and SMA were correlated with changes of DST scores during the median 3-month follow-up (all P < 0.05).

Conclusion

The TIPS implantation had a persistent effect on brain function in cirrhotic patients including both predominant impairment and compensation mechanisms, with the most significant alterations in the median 3-month period after TIPS. The ReHo analysis may be potentially valuable for uncovering the mechanism of TIPS’ effects on brain function.     

平原正常成人脑的高海拔适应性改变：静息态f MR I研究

目的：应用基于体素形态学(VBM)、低频振幅(ALFF)和局部一致性(ReHo)方法探讨平原正常成人脑结构及脑功能对高海拔低氧的适应性变化。方法对19例年龄、受教育程度、原居住地海拔高度相匹配的初入高海拔1周内的平原成人行静息态功能磁共振(fMRI)全脑扫描,移居1年后同批受检者再行此检查,应用 VBM技术、ALFF 和 ReHo 方法对脑功能数据进行分析。结果平原正常成人移居高海拔地区1年前后自身脑结构比较,未发现显著性差异;在静息状态下,脑功能方面存在显著性差异,移居高海拔1年后受检者左侧额中回 ALFF增加,右侧舌回的 ALFF减低(P<0.01);左侧眶内额上回的 ReHo增加,右侧楔叶、右侧顶叶 ReHo减低(P<0.05)。结论正常成人移居高海拔1年后存在脑功能的改变,这可能与长期处于低氧环境有关。