Advantages of cluster analysis for multifunctional and intercrossing brain area distribution* Evaluation by functional magnetic resonance imaging

BACKGROUND： Multiple linear regression, general linear test and calculation of correlation values are commonly used in studies of brain function using functional magnetic resonance imaging （fMRI）. However, there are some limitations in their applications. In non-signal data statistics, cluster analysis functions as a very mature method, but it is not reliable in signal data statistics. OBJECTIVE： To investigate the spatial distribution of complex function in brain areas during motor tasks by cluster analysis, and to compare this with multiple linear regression. DESIGN, TIME AND SETTING： Block design, performed at the MR laboratory of Guangzhou University of Chinese Medicine. PARTICIPANTS： Fifteen right-handed, healthy university students （10 males and 5 females, aged 19-21 years）. METHODS： fMRI was performed while the subjects performed a finger movement task with the right hand. The screen showed a gray hand, with red spots presented in a random order on one of the index, middle, ring and little fingers. The subjects were required to remember the sequence of the red spots on the display. After a delay of 14 seconds, the subjects tapped their fingers according to the order of the red spots, as soon as the red spots turned green. After an interval of 14 seconds, another sequence appeared. Every sequence lasted for 28 seconds, including preparation and execution phases. A total of nine sequences per subject were performed. The data were analyzed using deconvolution and cluster methods, and program ＂cluster＂ was used to statistically analyze the coordinate positions of deconvolution and cluster data. MAIN OUTCOME MEASURES： Brain activation maps by deconvolution and brain function maps by clustering of the maximum peak values; blood oxygenation level dependent curves by deconvolution; coordinates of peak values and activation volumes by the two methods. RESULTS： The deconvolution method could not integrate the brain activation maps during different tasks into one activation picture, which ma     

弥散张量纤维素成像三维重建皮质脊髓束定位脑初级运动功能区

Functional MRI (fMRI) is widely used as a non-invasive method for the evaluation of pre-operation motor function.However,patients with cortical function impairment,such as those with hemiparesis,can rarely achieve hand clenching,a typical fMRI task for central sulcus identification,and the method is also of limited use in uncooperative children.Thus,it is important to develop a new method for identifying primary motor areas (PMA) in such individuals.This study used corticospinal tractography to identify the PMA in 20 patients with deep-seated brain tumor.Two regions of interest were set within the brainstem for corticospinal tract (CST) fiber tracking:one at the level of the pons and the other at the level of the cerebral peduncle.The CST fiber tracking results and fMRI activation signals were merged with three-dimensional anatomic MRI findings.The consistency of identifying the PMA by CST and fMRI was analyzed.fMRI activation signals were distributed mainly in the contralateral central sulcus around the omega-shaped hand knob.The CST consistently propagated from the pons and cerebral peduncle to the suspected PMA location.There was a good correlation between CST fiber tracking results and fMRI activation signals in terms of their abilities to identify the PMA.The differences between fMRI and CST fiber tracking findings may result from our functional task,which consisted only of hand movements.Our results indicate that diffusion tensor imaging is a useful brain mapping technique for identifying the PMA in paralyzed patients and uncooperative children.     

Observation of activation status of motor-related cortex of patients with acute ischemic stroke through functional magnetic resonance imaging

BACKGROUND: About more than three fourth of patients with stroke have motor dysfunction at different degrees, especially hand motor dysfunction. Functional magnetic resonance imaging (fMRI) provides very reliable visible evidence for studying central mechanism of motor dysfunction after stroke, and has guiding and applicable value for clinical therapy. OBJECTIVE: To observe the activation of motor-related cortex of patients with acute ischemic stroke with functional magnetic resonance imaging, and analyze the relationship between brain function reconstruction and motor restoration after stroke. DESIGN: A contrast observation. SETTING: Medical Imaging Center, Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA. PARTICIPANTS: Nine patients with acute ischemic stroke who suffered from motor dysfunction and received the treatment in the Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA between August and December 2005 were recruited, serving as experimental group. The involved patients including 5 male and 4 female, aged 16 to 87 years, all met the diagnostic criteria of cerebrovascular disease revised by The Fourth National Conference on Cerebrovascular Disease, mainly presenting paralysis in clinic, and underwent fMRI. Another 9 right handed persons matched in age and gender who simultaneously received healthy body examination were recruited, serving as control group. All the subjects were informed of the detected items. METHODS: ①Muscular strength of patients of the experimental group was evaluated according to Brunnstrom grading muscular strength(Grade Ⅰ-Ⅵ). ② Passive finger to finger motion was used as the mission (alternate style of quiescence, left hand motion and quiescence , right hand motion was repeated 3 times, serving as 1 sequence, 20 s per block and 20 s time interval . The whole process of scanning was 260 s), and subjects of 2 groups were given Bold-fMRI examination with GE1.5T double gradient 16-channel magnetic resonance imaging system. All the data were given off-line management, and fMRI was treated with SPM2 software. The activation of passive finger-to-finger motion-related cortex of subjects in 2 groups was observed. ③ Results of fMRI of subjects in 2 groups were compared. The size of activation region of brain and signal intensity were measured and unilateral index was calculated. The data of activation region of cerebral hemisphere of different sides at finger motion were given statistical analysis of unilateral index. Differences among unilateral indexes at hand motion were compared between intact and affected hands of patients in experimental group. The relationship between unilateral index and muscular strength of affected hands at affected hand motion in patients of the experimental group was performed Spearman correlation analysis. MAIN OUTCOME MEASURES: ① The activation of motion-related cortex passive finger-to-finger motion between handedness and non-handedness was detected with functional magnetic resonance imaging of subjects in 2 groups. ② Relationship between unilateral index and muscular strength of subjects of experimental group at affected hand motion. RESULTS: Nine patients with ischemic stroke and 9 controls all participated in the final result analysis. ① Passive fMRI detection results between handedness and non-handedness of controls: Right-handed finger-to-finger motion of subjects of control group mainly activated contralateral sensorimotor cortex, and left-handed finger-to-finger motion not only activated above-mentioned brain region, but also activated supplementary motor area (SMA) of contralateral brain region; ②In the experimental group, sensorimotor cortex of contralateral hemisphere was activated at affected hand motion, and homolateral posterior parietal cortex (PPC)was also obviously activated. Bilateral sensorimotor cortex was activated at affected hand motion in 2 patients, and homolateral activation area was larger than contralateral one. At intact hand motion, contralateral sensorimotor cortex was activated, but no obvious homolateral activation area was found. ③ Correlation of unilateral index with muscular strength: Passive finger-to-finger fMRI ( between affected and intact hands of subjects of experimental group: Unilateral index at passive single finger motion of affected and intact hand of subjects of experimental group was -0.018±0.01 and 0.319±0.187, respectively, with significant difference (t=4.059, P < 0.01). Unilateral index was significantly positively correlated with the muscular strength of affected hand at affected hand motion(r=0.834, P < 0.05). CONCLUSION: ① fMRI can objectively shows different activation states of motor cortex between patients with ischemic stroke and healthy controls, and brain functional compensation and recombination exist. Both primary sensorimotor cortex and SMA of bilateral hemispheres participant in affected hand motion, at the same time, parietal lobe and cortex of intact side also obviously participant in the affected hand motion. ②Correlation analysis of unilateral index and muscular strength of affected hand performed through fMRI can be used as an effective means to investigate the relationship between motion rehabilitation and brain functional recombination after stroke.     

Longitudial observation of dynamic changes in cortical function and white matter fibrous structure of patients with visual pathway lesions by blood oxygenation level dependent-functional magnetic resonance imaging combined with diffusion tensor imaging

BACKGROUND: Functional magnetic resonance imaging (fMRI) is initially used for visual cortex location. However, the application of fMRI in investigating the development of visual pathway lesions needs to be further observed. OBJECTIVE: This study is to longitudially observe the dynamic changes in cortical function and white matter fibrous structure of patients with visual pathway lesions by blood oxygenation level dependent-functional magnetic resonance imaging (BOLD-fMRI) combined with diffusion tensor imaging (DTI), and to analyze the characteristics of brain function and structural recombination at convalescent period of lesions. DESIGN: Randomized controlled observation. SETTING: Department of Radiology, the General Hospital of Nanjing Military Area Command of Chinese PLA. PARTICIPANTS: Eight patients with unilateral or bilateral visual disorder caused by visual pathway lesions, who admitted to Department of Radiology, the General Hospital of Nanjing Military Area Command of Chinese PLA from January to September 2006 were involved, and served as experimental subjects. The patients, 6 males and 2 females, were aged 16–67 years. They had visual disorder confirmed by clinical examination, i.e. visual pathway lesion, which was further diagnosed by MR or CT. Another 12 subjects generally matching to those patients of experimental group in gender, age and sight, who received health examination in synchronization were involved and served as controls. The subjects had no history of eye diseases. Their binocular visual acuity (or corrected visual acuity) was over 1.0. Both routine examination of ophthalmology and examination of fundus were normal. Informed consents of detected items were obtained from all the subjects. METHODS: Signa Excite HD 1.5T magnetic resonance imaging system with 16 passages (GE Company, USA) and coil with 8 passages were used; brain functional stimulus apparatus (SAV-8800. Meide Company) was used for showing experimental mission. At the early stage and convalescent period of lesions, the patients with visual pathway lesion were examined by BOLD-fMRI combined with DTI, respectively, and brain activation volume, optic radiation anatomical structure and fractional anisotropy (FA) value were compared before and after symptomatic treatment under the stimulation to both eyes. The above-mentioned indexes were observed and compared between experimental and control groups. MAIN OUTCOME MEASURES: BOLD-fMRI and DTI manifestations before and after treatment in the experimental group and control group. RESULTS: All the 8 patients and 12 healthy subjects participated in the final analysis. ①BOLD-fMRI manifestation: Bilateral occipital lobes and calcarine gyri of control subjects were obviously activated. The activation volume of striate cortex under the stimulation to two eyes was obviously reduced in the experimental subjects than in the control subjects (P < 0.05). After treatment, the amount of activated pixel in the stimulated cortex was increased, and the activation area was expanded. ② DTI results: Bilateral optic radiation of healthy controls could be traced in the subcortex. Complete optic radiation of patients with visual pathway lesion could be shown. There was no significant difference in optic radiation between experimental subjects and healthy controls. No significant difference in optic radiation was found before and after observation, either (P > 0.05). In 4 patients with occipital lobe and optical center lesions, optic radial fiber was partially interrupted and tenuous, displacement could be found, and FA value was obviously decreased; After treatment, optic radial fiber bundle recovered to some extent, and FA value was also increased. CONCLUSION: BOLD-fMRI and DTI explain the development of lesion from the aspect of cortical function and fibrous anatomy. It has important significance for investigating the recombination of cortical function area following visual pathway lesion.     

Aging effects of regional activation in a spatial task A functional magnetic resonance imaging study

BACKGROUND： An increasing number of studies have shown the effects of aging in basic cognitive processing and higher cognitive functions using functional magnetic resonance imaging （fMRI）. However, little is known about the aging effects in diverse cognitive abilities, such as spatial learning and reasoning.
OBJECTIVE： To investigate the effect of aging on spatial cognitive performance and regional brain activation based on fMRI.
DESIGN, TIME, AND SETTING： A block design for fMRI observation. This study was performed at the fMRI Laboratory, Brain Science Research Center, Korea Advanced Institute of Science and Technology from March 2006 to May 2009.
PARTICIPANTS： Eight right-handed, male, college students in their 20s （mean age 21.5 years） and six right-handed, male, adults in their 40s （mean age 45.7 years）, who graduated from college, participated in the study. All subjects were healthy and had no prior history of psychiatric or neurological disorders.
METHODS： A spatial task was presented while brain images were acquired using a 3T fMRI system （ISOL Technology, Korea）. The spatial tasks involved selecting a shape that corresponded to a given figure using four examples, as well as selecting a development figure of a diagram.
MAIN OUTCOME MEASURES： The accuracy rate （number of correct answers/total number of items x 100%） of spatial tasks was calculated. Using the subtraction procedure, the activated areas in the brain during spatial tasks were color-coded by T-score. The double subtraction method was used to analyze the effect of aging between the two age groups （20s versus 40s）.
RESULTS： The cerebellum, occipital lobe, parietal lobe, and frontal lobe were similarly activated in the two age groups. Increased brain activations, however, were observed in bilateral parietal and superior frontal lobes of the younger group. More activation was observed in bilateral middle frontal and right inferior frontal lobes in the older group. Compared with the older group, the younger men exhibited greater spatial performance （P = 0.012）.
CONCLUSION： Reduced cognitive function correlated with decreased activation areas in the parietal lobe and altered activation in the frontal lobe.     

Is effect of transcranial direct current stimulation on visuomotor coordination dependent on task difficulty?

Transcranial direct current stimulation(t DCS), an emerging technique for non-invasive brain stimulation, is increasingly used to induce changes in cortical excitability and modulate motor behavior, especially for upper limbs. The purpose of this study was to investigate the effects of t DCS of the primary motor cortex on visuomotor coordination based on three levels of task difficulty in healthy subjects. Thirty-eight healthy participants underwent real t DCS or sham t DCS. Using a single-blind, sham-controlled crossover design, t DCS was applied to the primary motor cortex. For real t DCS conditions, t DCS intensity was 1 m A while stimulation was applied for 15 minutes. For the sham t DCS, electrodes were placed in the same position, but the stimulator was turned off after 5 seconds. Visuomotor tracking task, consisting of three levels(levels 1, 2, 3) of difficulty with higher level indicating greater difficulty, was performed before and after t DCS application. At level 2, real t DCS of the primary motor cortex improved the accurate index compared to the sham t DCS. However, at levels 1 and 3, the accurate index was not significantly increased after real t DCS compared to the sham t DCS. These findings suggest that tasks of moderate difficulty may improve visuomotor coordination in healthy subjects when t DCS is applied compared with easier or more difficult tasks.     

Difference in cortical activation during use of volar and dorsal hand splints:a functional magnetic resonance imaging study

There have been no studies reported on the difference in cortical activation during use of volar and dorsal hand splints. We attempted to investigate the difference in cortical activation in the somatosensory cortical area during use of volar and dorsal hand splints by functional magnetic resonance imaging (fMRI). We recruited eight healthy volunteers. fMRI was performed while subjects who were iftted with volar or dorsal hand splints performed grasp-release movements. Regions of interest were placed on the primary motor cortex (M1), primary somatosensory cortex (S1), posterior parietal cortex (PPC), and secondary somato-sensory cortex (S2). Results of group analysis of fMRI data showed that the total numbers of activated voxels in all ROIs were significantly higher during use of volar hand splint (3,376) compared with that (1,416) during use of dorsal hand splint. In each ROI, use of volar hand splint induced greater activation in all ROIs (M1:1,748, S1:1,455, PPC:23, and S2:150) compared with use of dorsal hand splint (M1:783, S1:625, PPC:0, and S2:8). The peak activated value was also higher during use of volar hand splint (t-value:17.29) compared with that during use of dorsal hand splint (t-value:13.11). Taken together, use of volar hand splint induced greater cortical activation relevant to somatosensory function than use of dorsal hand splint. This result would be important for the physiatrist and therapist to apply appropriate somatosensory input in patients with brain injury.     

Effects of visual information regarding tactile stimulation on the somatosensory cortical activation:a functional MRI study

Many studies have investigated the evidence for tactile and visual interactive responses to activation of various brain regions. However, few studies have reported on the effects of visuo-tactile multisensory inte-gration on the amount of brain activation on the somatosensory cortical regions. The aim of this study was to examine whether coincidental information obtained by tactile stimulation can affect the somatosensory cortical activation using functional MRI. Ten right-handed healthy subjects were recruited for this study. Two tasks (tactile stimulation and visuotactile stimulation) were performed using a block paradigm during fMRI scanning. In the tactile stimulation task, in subjects with eyes closed, tactile stimulation was applied on the dorsum of the right hand, corresponding to the proximal to distal directions, using a rubber brush. In the visuotactile stimulation task, tactile stimulation was applied to observe the attached mirror in the MRI chamber reflecting their hands being touched with the brush. In the result of SPM group analysis, we found brain activation on the somatosensory cortical area. Tactile stimulation task induced brain acti-vations in the left primary sensory-motor cortex (SM1) and secondary somatosensory cortex (S2). In the visuo-tactile stimulation task, brain activations were observed in the both SM1, both S2, and right posterior parietal cortex. In all tasks, the peak activation was detected in the contralateral SM1. We examined the ef-fects of visuo-tactile multisensory integration on the SM1 and found that visual information during tactile stimulation could enhance activations on SM1 compared to the tactile unisensory stimulation.     

Brain activation induced by different strengths of hand grasp: a functional magnetic resonance imaging study

Mirror neuron system can be activated by observation and execution of an action.It has an important function of action understanding.We investigated brain activations in humans by observing the strength of a hand grasp using functional magnetic resonance imaging.Twenty right-handed healthy individuals,consisting of 10 males and 10 females,aged 22.40 ± 2.04 years,were recruited into this study from September to November 2017 via posters.Light hand grasp task video showed a hand lightly grasping and releasing a ball repeatedly.Powerful hand grasp task video showed a hand tightly grasping and releasing a ball repeatedly.Functional magnetic resonance imaging block design paradigm comprised five stimulation blocks alternating with five baseline blocks.Stimulation blocks were presented with two stimulus tasks,consisting of a light grasp and a powerful grasp.Region of interest was defined around the inferior parietal lobule,inferior frontal gyrus,and superior temporal sulcus which have been called mirror neuron system.The inferior parietal lobule,fusiform,postcentral,occipital,temporal,and frontal gyri were activated during light and powerful grasp tasks.The BOLD signal response of a powerful grasp was stronger than that of a light grasp.These results suggest that brain activation of the inferior parietal lobule,which is the core brain region of the mirror neuron system,was stronger in the powerful grasp task than in the light grasp task.We believe that our results might be helpful for instructing rehabilitation of brain injury.This study was approved by the Institutional Review Board of Daegu Oriental Hospital of Daegu Haany University on September 8,2017 (approval No.DHUMC-D-17020-PRO-01).     

Patterns of cortical reorganization in facial synkinesis:a task functional magnetic resonance imaging study

Facial synkinesis,a sequela of peripheral facial nerve palsy,is characterized by simultaneous involuntary facial movement during a voluntary desired one.Maladaptive cortical plasticity might be involved in the dysfunction of facial muscles.This cohort study investigated the cortical functional alterations in patients with unilateral facial synkinesis,using the task functional magnetic resonance imaging.Facial motor tasks,including blinking and smiling,were performed by 16 patients(aged 30.6 ± 4.5 years,14 females/2 males) and 24 age-and sex-matched healthy controls(aged 29.1 ± 4.2 years,19 females/5 males).Results demonstrated that activation in the cortico-facial motor representation area was lower during tasks in patients with facial synkinesis compared with healthy controls.Facial movements on either side performed by patients caused more intensive activation of the supplementary motor area on the contralateral side of the affected face,than those on the unaffected side.Our results revealed that there was cortical reorganization in the primary sensorimotor area and the supplementary motor area.This study was registered in Chinese Clinical Trial Registry(registration number: Chi CTR1800014630).     

Localization of the motor hand area using transcranial magnetic stimulation and functional magnetic resonance imaging.

OBJECTIVE: The anatomical location of the motor area of the hand may be revealed using functional magnetic resonance imaging (fMRI). The motor cortex representation of the intrinsic hand muscles consists of a knob-like structure. This is omega- or epsilon-shaped in the axial plane and hook-shaped in the sagittal plane. As this knob lies on the surface of the brain, it can be stimulated non-invasively by transcranial magnetic stimulation (TMS). It was the aim of our study to identify the hand knob using fMRI and to reveal if the anatomical hand knob corresponds to the hand area of the motor cortex, as identified by TMS, by means of a frameless MRI-based neuronavigation system. METHODS: Suprathreshold transcranial magnetic stimuli were applied over a grid on the left side of the scalp of 4 healthy volunteers. The motor evoked potentials (MEPs) were recorded from the contralateral small hand muscles, and the centers of gravity (CoG) of the MEPs were calculated. The exact anatomical localization of each point on the grid was determined using a frameless MRI-based neuronavigation system. In each subject, the hand area of the motor cortex was visualized using fMRI during sensorimotor activation achieved by clenching the right hand. RESULTS: In all 4 subjects, the activated precentral site in the fMRI and the CoG of the MEP of all investigated muscles lay within the predicted anatomical area, the so-called hand knob. This knob had the form of an omega in two subjects and an epsilon in the other two subjects. CONCLUSIONS: TMS is a reliable method for mapping the motor cortex. The CoG calculated from the motor output maps may be used as an accurate estimation of the location of the represented muscle in the motor cortex.     

The Myelin Content of the Human Precentral Hand Knob Reflects Interindividual Differences in Manual Motor Control at the Physiological and Behavioral Level

The primary motor cortex hand area (M1_HAND) and adjacent dorsal premotor cortex (PMd) form the so-called motor hand knob in the precentral gyrus. M1_HAND and PMd are critical for dexterous hand use and are densely interconnected via corticocortical axons, lacking a sharp demarcating border. In 24 young right-handed volunteers, we performed multimodal mapping to delineate the relationship between structure and function in the right motor hand knob. Quantitative structural magnetic resonance imaging (MRI) at 3 tesla yielded regional R1 maps as a proxy of cortical myelin content. Participants also underwent functional MRI (fMRI). We mapped task-related activation and temporal precision, while they performed a visuomotor synchronization task requiring visually cued abduction movements with the left index or little finger. We also performed sulcus-aligned transcranial magnetic stimulation of the motor hand knob to localize the optimal site (hotspot) for evoking a motor evoked potential (MEP) in two intrinsic hand muscles. Individual motor hotspot locations varied along the rostrocaudal axis. The more rostral the motor hotspot location in the precentral crown, the longer were corticomotor MEP latencies. “Hotspot rostrality” was associated with the regional myelin content in the precentral hand knob. Cortical myelin content also correlated positively with task-related activation of the precentral crown and temporal precision during the visuomotor synchronization task. Together, our results suggest a link among cortical myelination, the spatial cortical representation, and temporal precision of finger movements. We hypothesize that the myelination of cortical axons facilitates neuronal integration in PMd and M1_HAND and, hereby, promotes the precise timing of movements.SIGNIFICANCE STATEMENT Here we used magnetic resonance imaging and transcranial magnetic stimulation of the precentral motor hand knob to test for a link among cortical myelin content, functional corticomotor representations, and manual motor control. A higher myelin content of the precentral motor hand knob was associated with more rostral corticomotor presentations, with stronger task-related activation and a higher precision of movement timing during a visuomotor synchronization task. We propose that a high precentral myelin content enables fast and precise neuronal integration in M1 (primary motor cortex) and dorsal premotor cortex, resulting in higher temporal precision during dexterous hand use. Our results identify the degree of myelination as an important structural feature of the neocortex that is tightly linked to the function and behavior supported by the cortical area.     

Hemispherical asymmetry in human SMA during voluntary simple unilateral movements. An fMRI study

Functional magnetic resonance imaging (fMRI) was used to test the hypothesis of a prevailing role of left supplementary motor area (SMA) during voluntary right and left finger movements, in line with subjects' right hand preference. fMRI responses were quantified using task-related percent increase of the signal from statistically activated voxels in primary somatosensory (S1), primary motor (M1), and SMA cortical regions. Regional analysis comprised both extension and intensity of statistically activated groups of voxels. Results replicated previous fMRI evidence. Right M1 and S1 were much more activated during left rather than right movements, whereas such a difference was less evident in left M1 and S1. A novel finding consisted in an analogous functional hemispherical asymmetry in left and right SMA. Strikingly, left SMA activation did not differ statistically during right (contralateral) vs. left (ipsilateral) movements. It was concluded that, in right-handed subjects, left SMA plays a prevailing role in the control of voluntary movements.     

Functional neural reorganization following ischemic stroke in the precentral knob: an fMRI study]

We evaluated a 63 year-old, right-handed woman by functional MRI (fMRI) in the early and the recovery stages following a cerebral infarction in the right precentral knob. An activated signal in the ipsilateral sensorimotor cortex and contralateral supplementary motor cortex during deteriorated hand grasping (left) was observed in the early stages, whereas being unable to detect in the functionally recovered period. When simultaneous bilateral hand grasping was performed, the activated signal around infarct region was enlarged in recovered period. The functionally neural reorganization processes relating recovered hand movement after localized cortical infarction (precentral knob) was suggested.     

Cortical reorganization demonstrated by diffusion tensor tractography analyzed using functional MRI activation

The diffusion tensor tractography (DTT) allows the corticospinal tract(CST) to be visualized at the subcortical level and functional MRI (fMRI) is capable of precisely identifying activation sites at the cortex. Therefore, it seems that combined DTT/fMRI would allow more accurate evaluation of the state of the CST. We have attempted to demonstrate cortical reorganization in a patient with cortical hemorrhage using DTT analyzed by fMRI activations. Six normal subjects and a 12-year-old female patient with a hemorrhage in the left fronto-parietal cortex were recruited. fMRI was performed at 1.5-T with timed hand grasp-release movements, and DTT was performed using 1.5-T with a Synergy-L Sensitivity Encoding head coil. Three-dimensional reconstructions of the fiber tracts were obtained using the fMRI activation as the seed region of interest and the CST area of the anterior pons as the target region of interest. The tract of the affected hemisphere originated from the lateral area of the injured precentral knob and descended along the known corticospinal tract pathway. It seems that the motor function of the affected hand was reorganized into the lateral area of the injured precentral knob. Therefore, these combined modalities would be helpful in elucidating the state of the CST.     

Activation in primary and secondary motor areas in patients with CNS neoplasms and weakness

OBJECTIVE: To demonstrate whether cortical activation within different cortical motor regions in neurosurgical patients varies with the degree of paresis induced by mass lesions near the central region. METHODS: A total of 110 patients with brain tumors infiltrating the central region and with varying degrees of paresis were investigated employing fMRI during the performance of hand motor tasks. The percent signal change between rest and activation was calculated for four cortical regions: primary motor cortex (M1), supplementary motor area, premotor area, and superior parietal lobule. RESULTS: Significant decreases in activation with increasing degrees of paresis were found in M1, whereas significant increases in activation were noted in secondary motor areas that were not affected by the tumor. CONCLUSIONS: The signal loss in areas adjacent to tumor tissue may relate either to tumor-induced changes in cerebral hemodynamics or to a direct loss of cortical neurons resulting in a lesser degree of hemodynamic changes after motor activation. The increase in activation within secondary motor areas with increasing degrees of paresis supports the growing evidence of a practice- and lesion-dependent reorganization of the cortical motor system and the ability of the brain to modulate its excitatory output according to external demands.     

Functional MRI of human primary somatosensory and motor cortex during median nerve stimulation.

OBJECTIVES: Somatosensory evoked potential (SEP) studies suggested that some early cortical SEP components may be generated in the primary motor cortex (M1) rather than the primary somatosensory cortex (S1). METHODS: We now used functional magnetic resonance imaging (fMRI) to study activation of S1 and M1 by electrical median nerve stimulation in healthy volunteers. RESULTS: The hand areas of both S1 and M1 showed significant activation (correlation coefficients >0.45) in 7 of 9 subjects (activated volume S1 > M1). For comparison, a sequential finger opposition task significantly activated S1 in 7 and M1 in all 9 subjects (activated volume M1 > S1). CONCLUSIONS: These data show that the electrical stimuli used for SEP recording lead to a functional activation of S1 as well as M1.     

正常人手运动功能脑皮质定位的研究

目的 研究正常人手复杂运动时脑皮质的功能定位。方法 采用SIEMENS成像系统的EPI-Bolding程序，采集7例受试运动和静止状态的T1W图像共6个时相，应用相应软件分析得到差异信号图像，在T1W结构图像融合，并进行三维重建。结果 7例受试在执行握拳运动时，对侧皮质中央前回的第一运动区（Broadman 4区）均可见明显激活信号，对侧或双侧的补充运动区均有激活信号，2例运动前区激活，3例可见同侧中央前回运动皮质的激活信号。三维重建显示第一运动区的激活信号主要位于对侧中央沟的中外侧，补充运动区的激活信号位于运动前区（Broadman 6区）近正中的内侧面。结论 正常人手复杂运动时脑皮质运动网络被广泛激活，功能核磁共振的激活信号反映了脑的高级功能活动。