功能性核磁共振成像在计算机辅助的上肢功能训练治疗脑梗死上肢偏瘫中的应用研究

目的:探讨计算机辅助训练上肢对脑可塑性的可能作用。方法:脑卒中上肢偏瘫患者10例,均进行计算机辅助训练,治疗前后采用偏瘫上肢功能测试-香港版(FTHUE-HK),Fulg-Meyer上肢评定(FMA)及改良Barthel指数量表(MBI)评定上肢运动功能,及患者屈伸腕关节时进行功能核磁共振扫描(fMRI)。结果:治疗6周后,10例患侧的上肢功能评定FTHUE-HK、FMA及MBI评分均较治疗前后患侧上肢功能评定变化明显提高(P0.05)。fMRI扫描示:患者健侧手运动脑功能激活区主要位于对侧初级运动皮质区(SMC)及同侧小脑,患者健手在康复训练后脑激活区增多,包括对侧SMC区及同侧小脑、部分边缘系统;患者治疗前患侧手运动激活区分布广泛,而对侧SMC激活减少,同侧SMC激活增多,另主要还见辅助运动区激活增多;治疗后可见双侧SMC及辅助运动区激活,对侧SMC激活较治疗前增多,另主要还见对侧顶上小叶激活增多。结论:计算机训练可以有效改善脑卒中患者上肢运动功能,诱发大脑皮质功能重塑是其机制的重要组成部分。     

运动想象治疗脑卒中患者手部运动功能的功能磁共振研究

目的：探讨运动想象（MI）治疗对脑卒中后脑功能重塑的影响。方法：将16例脑卒中患者随机分为运动想象组（MI）6例、执行运动（EM）组5例、对照组（CG）5例。3组在常规康复治疗基础上,MI组、EM组分别进行运动想象、实际动作治疗,每次30min,每周5次,为期4周。治疗前、后进行运动功能评价,并使用功能磁共振（fMRI）观察患手对指实际动作、想象时偏瘫对侧感觉运动区的激活情况,定量分析治疗前后cSMC区的激活强度t、LI变化。结果：治疗4周后,MI组及EM组FMA、STEF评分较前均有明显提高（均P＜0.05）,且MI组上述评分均更高于其它2组（均P＜0.05）。治疗后,3组MBI评分均有提高,但组内及组间差异无统计学意义。运动想象与运动执行的激活部位相似：治疗前运动想象激活区主要位于双侧SMC区、双侧SMA区,治疗后,各组双侧SMC区激活强度有增大趋势,MI组对侧SMC区激活显著（P＜0.05）,且对侧偏侧化优势较CG组显著（P＜0.05）。结论：运动想象治疗能够明显改善脑卒中后患者手功能,其机制可能与运动想象促进脑功能重塑有关。     

The effects of task-oriented versus repetitive bilateral arm training on upper limb function and activities of daily living in stroke patients

[Purpose] The purpose of this study was to investigate the effects of task-oriented bilateral arm training and repetitive bilateral arm training on upper limb function and activities of daily living in stroke patients. [Subjects] Forty patients with hemiplegia resulting from stroke were divided into a task orientied bilateral arm training group (n=20) and a repetitive bilateral arm training group (n=20). [Methods] The task-oriented group underwent bilateral arm training with 5 functional tasks, and the repetitive group underwent bilateral arm training with rhythmin auditory cueing for 30 minutes/day, 5 times/week, for 12 weeks. [Results] The upper limb function and the ability to perform activities of daily living improved significantly in both groups. Although there were significant differences between the groups, the task-oriented group showed greater improvement in upper limb function and activities of daily living. [Conclusion] We recommend bilateral arm training as well as adding functional task training as a clinical intervention to improve upper limb function activities of daily living in patients with hemiplegia.Key words: Hemiplegia, Upper limb, Bilateral training     

单侧皮层下缺血性脑卒中患者运动功能磁共振成像的纵向研究

目的分析单侧皮层下缺血性脑卒中患者患侧肢体运动时脑部激活区随时间的动态变化过程,以及与运动功能康复水平的关系。方法对6名健康志愿者与3例单侧皮层下缺血性脑卒中患者进行血氧水平依赖功能磁共振成像（BOLD-fMRI）,分别采取单侧手指和患侧手指顺序对指运动任务。采用统计参数图进行数据分析和脑功能区定位,计算不同感兴趣区内激活体素数目,并计算偏侧化指数（LI）。扫描结束后记录患者上肢Fugl-Meyer运动评分。对患者在发病后8个月内分别行两侧BOLD-fMRI检查,比较两次激活区域及LI的变化。结果脑卒中患者激活区较健康人广泛,3例患者在发病早期激活范围存在差异,但均表现为双侧感觉运动区（SMC）激活;在发病晚期,肢体同侧SMC激活减少,对侧SMC激活增多,相应的半球、SMC、M1区LI增高。结论单侧皮层下脑梗死患者随着病程时间延长,功能区逐渐向对侧SMC局限化。     

功能性近红外光谱技术在利手、非利手主动抓握-释放任务下脑区激活研究中的应用

目的 探讨功能性近红外光谱技术(fNIRS)观察健康人利手、非利手复杂运动模式下双侧感觉运动区(SMC)、运动前区(PMC)激活模式中的应用价值。方法 2019年8月至12月,社区招募右利手健康人15例,采用Block设计,执行抓握-释放握力器任务,于双侧SMC、PMC和前额叶皮质行fNIRS探测,根据氧合血红蛋白和脱氧血红蛋白浓度变化观察两种运动状态下脑区激活通道及强度。结果 根据氧合血红蛋白浓度,右(利)手运动时,双侧激活通道数相同,左侧SMC激活平均β值更高(P < 0.05);左(非利)手运动时,对侧激活通道更多,右侧SMC激活平均β值更高(P < 0.05)。根据脱氧血红蛋白浓度,利手或非利手运动时,对侧激活通道更多;右(利)手运动时,左侧SMC激活平均β值更高(P < 0.05),通道12 (左侧PMC)和通道26 (右侧PMC)激活更强(P < 0.05)。结论 fNIRS可用于利手、非利手复杂运动模式下手运动相关脑区激活的研究,应更关注氧合血红蛋白浓度变化的结果。     

针刺穴位联合康复训练治疗急性脑梗死 上肢运动功能障碍并功能磁共振研究

目的:观察针刺穴位联合康复训练治疗急性脑梗死上肢运动功能障碍的疗效,并借助功能磁共振探讨对神经功能重塑的影响。方法:选取急性脑梗死上肢运动功能障碍患者60例,随机分为对照组及治疗组,各30例。对照组行常规药物治疗和运动康复训练,治疗组在对照组的基础上给予针刺穴位治疗;均治疗3个月。于治疗前、后,对2组患者行美国国立卫生院脑卒中量表(NIHSS)评分、Fugl-Meyer上肢运动量表(FMA-UE)评分、患肢的食指轻叩试验检查、握力测量及运动任务态的功能磁共振扫描。结果:治疗后,2组的NIHSS评分、FMA-UE评分、患肢食指轻叩试验及握力测量均较治疗前改善(均P<0.01),且治疗组改善程度较对照组明显(均P<0.01)。治疗前,2组患者左手握拳运动可稳定激活对侧初级运动区(M1)及辅助运动区(SMA);治疗后,2组患者左手握拳运动时,对侧M1区及双侧SAM区较治疗前激活增强(P<0.01),且治疗组较对照组激活增强明显(P<0.01)。结论:针刺穴位联合康复训练治疗急性脑梗死上肢运动功能障碍疗效肯定,促进对侧M1及双侧SAM脑区的激活、调节神经功能重塑可能是其机制之一。     

卒中早期手指被动运动的脑功能磁共振成像研究

目的应用扩散张量成像及BOLD-fMRI技术观察卒中早期手指被动运动时大脑半球相关区域血氧水平的变化情况.方法采用1.5 T MR成像系统对6名早期卒中患者进行BOLD-fMRI及扩散张量成像,采用手指被动屈伸运动作为fMRI的刺激任务.结果在锥体束中断时,卒中早期健手运动时激活双侧SMC区,患手运动可激活对侧半球后顶叶皮层及同侧SMC区;锥体束较完整时健手运动时激活对侧SMC区,患手运动激活双侧SMC区、双侧后顶叶皮层.结论卒中早期可能发生运动功能通路的重构,但锥体束不同损伤情况下运动功能恢复可能存在不同的机制.DTI与fMRI联合应用将是监测和研究脑卒中后恢复的有用工具.     

Effects of virtual reality-based bilateral upper-extremity training on brain activity in post-stroke patients

[Purpose] This study investigated the therapeutic effects of virtual reality-based bilateral upper-extremity training on brain activity in patients with stroke. [Subjects and Methods] Eighteen chronic stroke patients were divided into two groups: the virtual reality-based bilateral upper-extremity training group (n = 10) and the bilateral upper-limb training group (n = 8). The virtual reality-based bilateral upper-extremity training group performed bilateral upper-extremity exercises in a virtual reality environment, while the bilateral upper-limb training group performed only bilateral upper-extremity exercise. All training was conducted 30 minutes per day, three times per week for six weeks, followed by brain activity evaluation. [Results] Electroencephalography showed significant increases in concentration in the frontopolar 2 and frontal 4 areas, and significant increases in brain activity in the frontopolar 1 and frontal 3 areas in the virtual reality-based bilateral upper-extremity training group. [Conclusion] Virtual reality-based bilateral upper-extremity training can improve the brain activity of stroke patients. Thus, virtual reality-based bilateral upper-extremity training is feasible and beneficial for improving brain activation in stroke patients.Key words: Stroke, Virtual reality, Bilateral arm training     

Brain activation of lower extremity movement in chronically impaired stroke survivors

Lower extremity paresis poses significant disability to chronic stroke survivors. Unlike for the upper extremity, cortical adaptations in networks controlling the paretic leg have not been characterized after stroke. Here, the hypotheses are that brain activation associated with unilateral knee movement in chronic stroke survivors is abnormal, depends on lesion location, and is related to walking ability. Functional magnetic resonance imaging of unilateral knee movement was obtained in 31 patients 26.9 months (mean, IQ range: 11.3-68.1) after stroke and in 10 age-matched healthy controls. Strokes were stratified according to lesion location. Locomotor disability (30 ft walking speed) did not differ between patient groups (9 cortical, 12 subcortical, 10 brainstem lesions). Significant differences in brain activation as measured by voxel counts in 10 regions of interest were found between controls and patients with brainstem (P = 0.006) and cortical strokes (P = 0.002), and between subcortical and cortical patients (P = 0.026). Statistical parametric mapping of data per group revealed similar activation patterns in subcortical patients and controls with recruitment of contralateral primary motor cortex (M1), supplementary motor area (SMA), and bilateral somatosensory area 2 (S2). Cortical recruitment was reduced in brainstem and cortical stroke. Better walking was associated with lesser contralateral sensorimotor cortex activation in brainstem, but stronger recruitment of ipsilateral sensorimotor and bilateral somatosensory cortices in subcortical and cortical patients, respectively. A post hoc comparison of brainstem patients with and without mirror movements (50%) revealed lesser recruitment of ipsilateral cerebellum in the latter. Subcortical patients with mirror movements (58%) showed lesser bilateral sensorimotor cortex activation. No cortical patient had mirror movements. The data reveal adaptations in networks controlling unilateral paretic knee movement in chronic stroke survivors. These adaptations depend on lesion location and seem to have functional relevance for locomotion.     

The functional anatomy of parkinsonian bradykinesia

To investigate the difficulty that patients with Parkinson's disease (PD) have in performing fast movements, we used H(2)(15)O PET to study regional cerebral blood flow (rCBF) associated with performance of a simple predictive visuomanual tracking task at three different velocities. Tracking movements in PD patients (versus tracking with the eyes alone) were associated with a general underactivation of the areas normally activated by the task (sensorimotor cortex contralateral to the moving arm, bilateral dorsal premotor cortices, and ipsilateral cerebellum). Presupplementary motor cortex (pre-SMA) ipsilateral to the moving arm had greater than normal movement-related activations. Increasing movement velocity led to increased rCBF in multiple premotor and parietal cortical areas and basal ganglia in the patients as opposed to the few cerebral locations that are normally velocity-related. The functional correlates of PD bradykinesia are: (1) impaired recruitment of cortical and subcortical systems that normally regulate kinematic parameters of movement such as velocity; and (2) increased recruitment of multiple premotor areas including both regions specialized for visuomotor control (ventral premotor and parietal cortices) and some that are not (pre-SMA). The overactivation of cortical regions observed in patients may be functional correlates of compensatory mechanisms and/or impaired suppression as a facet of the primary pathophysiology of PD.     

运动想象训练促进脑卒中患者上肢运动功能恢复的功能磁共振研究

摘要 目的：利用功能磁共振（fMRI）研究脑卒中患者运动想象训练后上肢功能重组潜在的脑重塑机制,为临床脑卒中患者的康复治疗提供一定的理论基础。 方法：选择9例脑卒中偏瘫患者,进行运动想象训练每周5次,每次约30min,共4周,并进行常规康复训练。应用Fugl-Meyer上肢运动功能量表（FMA-UL）分别在治疗前和治疗后4周评估患者的上肢运动功能。在4周康复干预前后对患者进行患手被动握拳任务下的fMRI检查,采用组块设计,利用SPM8软件进行数据处理,采用感兴趣区（ROI）的个体化分析,统计各ROI区的脑皮质激活情况,比较干预前后对侧感觉运动区（cSMC）的激活变化,分析脑卒中患者的脑重塑模式。 结果：4周运动想象干预后脑卒中患者的FM-UL评分从（22.44±11.59）分提高到（39.78±14.03）分（P=0.011）。比较干预前后两次fMRI检查脑皮质SMC区的激活情况,发现9例脑卒中患者的功能恢复呈现出两种不同的皮质重塑模式：一种模式为募集激活,即大部分患者第二次fMRI检查,患手被动任务下cSMC的激活增加（有6例患者）;另一种模式是集中激活,即小部分患者第二次fMRI检查,患手被动任务下cSMC的激活虽然是减少的,但其偏侧指数（LI-SMC）却是显著增加的（有3例患者）。 结论：运动想象训练可改善脑卒中患者的上肢运动功能,经过4周干预后脑卒中患者存在损伤同侧SMC区的募集激活和集中激活两种脑重塑模式,随着患者上肢功能的恢复,脑重塑机制逐渐倾向于损伤侧SMC的激活。     

Activation likelihood estimation meta-analysis of motor-related neural activity after stroke

Over the past two decades, several functional neuroimaging experiments demonstrated changes in neural activity in stroke patients with motor deficits. Conclusions from single experiments are usually constrained by small sample sizes and high variability across studies. Here, we used coordinate-based activation likelihood estimation meta-analyses to provide a quantitative synthesis of the current literature on motor-related neural activity after stroke. Of over 1000 PubMed search results through January 2011, 36 studies reported standardized whole-brain group coordinates. Meta-analyses were performed on 54 experimental contrasts for movements of the paretic upper limb (472 patients, 452 activation foci) and on 20 experiments comparing activation between patients and healthy controls (177 patients, 113 activation foci). We computed voxelwise correlations between activation likelihood and motor impairment, time post-stroke, and task difficulty across samples. Patients showed higher activation likelihood in contralesional primary motor cortex (M1), bilateral ventral premotor cortex and supplementary motor area (SMA) relative to healthy subjects. Activity in contralesional areas was more likely found for active than for passive tasks. Better motor performance was associated with greater activation likelihood in ipsilesional M1, pre-SMA, contralesional premotor cortex and cerebellum. Over time post-stroke, activation likelihood in bilateral premotor areas and medial M1 hand knob decreased. This meta-analysis shows that increased activation in contralesional M1 and bilateral premotor areas is a highly consistent finding after stroke despite high inter-study variance resulting from different fMRI tasks and motor impairment levels. However, a good functional outcome relies on the recruitment of the original functional network rather than on contralesional activity.     

正常人体针灸效应功能性磁共振成像的研究

目的评价针刺体表穴位对脑部相应区域的功能性磁共振成像(fMRI)表现。方法17例健康志愿者，在1，5TMRI仪上进行针刺足三里(S36)、阳陵泉(G34)的实时动态fMRI检查，观察并分析针刺效果明显者的脑部功能变化情况，判断针刺效果及其意义。结果17例志愿者中13例检查成功，可见躯体感觉运动区(SMC)、运动前区(PMC)、副运动区(SMA)激活明显，额叶前部、扣带回、尾状核头部、豆状核及丘脑、岛叶、岛盖皮质大多有大面积明显激活，小脑和桥脑也可见有激活，在左侧丘脑、SMA、SMC、PMC激活区附近有信号减低的现象，但激活的像素数不多；信号减低区包括两侧额叶内侧面皮质，双侧扣带回前部皮质，两侧海马区，右侧眶回、基底节、尾状核头部等。结论针刺对脑部相关穴位的治疗效应显著，可产生广泛而复杂的脑功能变化，fMRI可清楚显示针刺效应引起的脑部功能变化，是针刺机制及效应良好且直观的评价途径。     

双侧上肢训练影响脑梗死患者脑功能重组的fMRI研究

目的利用BOLD-fMRI技术探讨双侧上肢训练对脑梗死患者脑功能重组的影响。 方法采用随机数字表法将14例患侧上肢功能中度到重度损伤皮质下梗死患者分为双侧训练组及对照组,前者接受双侧上肢训练,后者接受以患侧上肢为主的常规单侧肢体训练。2组患者分别于治疗前、治疗4周后进行上肢功能评定以及BOLD-fMRI扫描,刺激任务为肘关节被动屈伸。 结果治疗后2组患者Fugl-Meyer量表上肢部分（FMA-UE）、改良Barthel指数（MBI）评分均明显提高（P<0.05）,但两组间差异无统计学意义（P>0.05）;治疗后2组患者激活脑区增加,以双侧训练组更明显;治疗后双侧训练组患者出现双侧M1、S1、辅助运动区（SMA）激活;治疗后双侧训练组中度损伤患者呈M1对侧激活趋势,重度损伤患者呈M1同侧激活趋势。 结论双侧上肢训练能提高脑梗死患者上肢运动功能及日常生活能力,其机制可能与促进两侧大脑皮质间抑制正常化及同侧皮质脊髓通路开放有关。     

脑缺血性卒中患者运动功能康复的功能性磁共振成像研究

目的利用功能性磁共振成像（fMRI）技术研究急性期缺血性脑卒中患者（以下简称急性期患者）运动相关皮质的激活情况，并探讨脑卒中后脑功能重组特点及其与肢体运动功能恢复的关系。方法采用GEI．5T双梯度16通道磁共振成像系统，对9例急性期患者和9例健康志愿者行Bold—fMRI检查。fMRI检查以被动对指运动（以下简称运动）为刺激任务，所有数据采用SPM2软件包进行离线后处理。比较健康志愿者与急性期患者fMRI结果的异同点，计算脑激活区体积和单侧化指数（LI），考察急性期患者患手运动LI值与患手运动功能的关系。结果健康志愿者单手运动激活对侧感觉运动皮质（SMC）、双侧辅助运动区（SMA）。急性期患者患手运动时同侧半球脑激话增多，健手运动的fMRI结果与健康志愿者基本一致。LI值也进一步确定，急性期患者患手运动时同侧半球脑激活增多。统计学分析表明，急性期患者患手运动的LI值与患手运动功能呈正相关。结论fMRI检查能客观地反映急性期患者运动相关皮质改变，提示存在脑功能代偿与重组。急性期患者患手运动LI值与患手运动功能呈正相关，提示fMRI是研究缺血性脑卒中后肢体运动功能康复与脑功能重组之间关系的一种有效工具。     

针康法促进脑卒中后下肢运动功能重建的功能性近红外光谱研究北大核心CSCD

目的采用功能性近红外光谱成像技术(fNIRS)研究针康法促进脑卒中患者下肢运动功能重建的脑皮质激活模式的变化。方法2020年12月至2021年7月,黑龙江中医药大学附属第二医院24例脑卒中下肢运动功能障碍患者随机分为康复组(n=12)和针康组(n=12),分别进行4周的常规康复训练和针康法干预。对照组纳入10例年龄等基线信息与脑卒中患者无显著性差异的健康受试者。干预前、后分别用Fugl-Meyer评定量表下肢部分(FMA-LE)评估患者的下肢运动功能,并对受试者进行fNIRS检查。基于氧合血红蛋白(HbO2)计算脑皮质辅助运动区(SMA)、运动前皮质(PMC)及初级感觉运动皮质(SMC)的功能强度变化及偏侧化指数(LI)。结果干预前,康复组和针康组FMA-LE评分无显著性差异(P>0.05);干预4周后,两组FMA-LE评分均显著提高(t>3.770,P<0.001),针康组高于康复组(t=2.252,P<0.05)。干预前,对照组平均功能连接强度高于康复组和针康组(P<0.05),后两组皮质运动相关区域功能连接强度无显著性差异(t=0.458,P>0.05);干预后,康复组和针康组平均功能连接强度均提高(t>2.178,P<0.05),其中针康组患侧PMC功能连接强度增强(P<0.05),针康组SMC区LI提高(P<0.05);针康组FMA-LE评分变化量与患侧PMC功能连接强度的变化量呈正相关(r=0.579,P<0.05)。结论针康法可明显改善脑卒中患者下肢运动功能与SMC的非对称性激活。下肢运动功能恢复可能与患侧PMC的激活增强有关。     

完全性脊髓损伤亚急性期脑运动控制功能变化的功能磁共振研究

目的 探讨完全性脊髓损伤患者脑运动控制功能的变化情况。方法 2017年1月至2019年1月,病程3~6个月完全性脊髓损伤患者11例与健康人12例,在试图/实际运动、意象运动(MI)任务下行功能磁共振成像(fMRI)扫描,观察不同运动任务引发激活效应的空间分布和信号强度。结果 患者试图运动时的脑激活区域显著多于健康人实际运动时的激活区域,包括双侧初级感觉/运动皮质(S1/M1)、辅助运动区(SMA)、外侧苍白球(PA)、小脑、左侧丘脑和壳核等。健康人意象运动的比较,患者激活簇主要存在于右M1、SMA、背侧运动前区(PMd)、左SMA、岛叶和基底核。患者试图运动比意象运动在左M1、双SMA、扣带回运动区和右小脑诱发更多的兴奋。结论 亚急性期完全性脊髓损伤患者执行运动任务时,M1、SMA的兴奋模式基本正常,顶叶和小脑等感觉运动整合区域激活增加,提示发生适应性重组。     

Illusory movements of the paralyzed limb restore motor cortex activity

In humans, limb amputation or brachial plexus avulsion (BPA) often results in phantom pain sensation. Actively observing movements made by a substitute of the injured limb can reduce phantom pain, Proc. R. Soc. London B Biol. Sci. 263, 377-386). The neural basis of phantom limb sensation and its amelioration remains unclear. Here, we studied the effects of visuomotor training on motor cortex (M1) activity in three patients with BPA. Functional magnetic resonance imaging scans were obtained before and after an 8-week training program during which patients learned to match voluntary "movements" of the phantom limb with prerecorded movements of a virtual hand. Before training, phantom limb movements activated the contralateral premotor cortex. After training, two subjects showed increased activity in the contralateral primary motor area. This change was paralleled by a significant reduction in phantom pain. The third subject showed no increase in motor cortex activity and no improvement in phantom pain. We suggest that successful visuomotor training restores a coherent body image in the M1 region and, as a result, directly affects the experience of phantom pain sensation. Artificial visual feedback on the movements of the phantom limb may thus "fool" the brain and reestablish the original hand/arm cortical representation.     

Cortical activation during perception of a rotating wide-field acoustic stimulus.

We describe sound stimuli that produce the perception of complete rotation around the head. Such stimuli are analogous to wide-field motion stimuli used in visual research, though auditory stimuli, unlike visual stimuli, can be perceived at any point around the head; they are the only cues for spatial perception behind the subject. Using PET on six subjects, we have compared regional brain activity during the perception of such motion stimuli, with the perception of a control stimulus producing equivalent amplitude changes without rotation. Rotation produced activation of the premotor cortex bilaterally and the right superior parietal cortex. The premotor activation involved the frontal eye fields and ventral premotor areas. The bifrontal and right parietal activation is consistent with previous demonstrations of activation within a frontoparietal network of areas during perception of a linear motion stimulus. The inferior premotor activation in this experiment may reflect preparation for head turning in response to auditory targets that cannot be tracked visually.     

Activation in the premotor cortex during mental calculation in patients with Alzheimer's disease: relevance of reduction in posterior cingulate metabolism

In vivo brain imaging of people with Alzheimer's disease (AD) has suggested the presence of functional disintegration in the posterior-anterior brain network from the posterior cingulate cortex (PCC) to the prefrontal cortex. To investigate the relationship between the baseline posteromedial metabolism and prefrontal neural activity during cognitomnemonic tasks in AD patients, we measured both glucose metabolism at baseline and cerebral blood flow (CBF) during the execution of mental calculation tasks (serial number subtraction) in 10 early-stage AD patients and six healthy subjects. The present study employed positron emission tomography with (18)F-fluorodeoxyglucose and H(2)(15)O. Group comparison using the region-of-interest (ROI) method and voxel-based statistical parametric mapping (SPM99) showed significant reduction in glucose metabolism in the PCC of the AD group. The PCC metabolism in the AD group was negatively correlated with scores on the Mini-Mental State Examination and with correct responses to the arithmetic task. During the arithmetic task, regional CBF increased significantly in the left parietal and bilateral prefrontal cortices in the normal group, whereas the bilateral premotor cortices were significantly activated in the AD group. Regression analysis showed a significant inverse correlation between the premotor activation and the baseline PCC metabolism in the AD group. These results suggest that the premotor cortex plays a compensatory role in executing mental calculations in AD patients with reduced posteromedial functions, which might reflect the dynamic aspect of the pathophysiology of early AD.