Specific cerebral activation following true and sham Waiguan(SJ 5) needling Functional magnetic resonance imaging evidence

Positive activation and negative activation of glucose metabolism can be detected in different brain regions under acupuncture conditions using functional magnetic resonance imaging （fMRI） which reveals acupoint function and location-acupoint specificity. This study observed the regional cerebral activation of the Waiguan （SJ 5） acupoint following true needling at the true Waiguan acupoint, sham needling at the true Waiguan acupoint and true needling at a sham point using fMRI. The fMRI results demonstrated that compared with sham needling, true needling at Waiguan activated the BA8 area and left cerebellum. Compared with needling at the sham point, needling at Waiguan activated the BA2 area, the left cerebellum and the right inferior semilunar lobule. Thus the activated brain areas caused by needling Waiguan may be the basis for treatment of certain diseases.

Differences in functional magnetic resonance imaging following cutaneous and routine acupuncture at different acupoints

Few studies have examined the effects of different stimuli at a single acupoint using functional magnetic resonance imaging.The present study applied acupuncture at the Neiguan（PC 6）,Waiguan（SJ 5）,Zhigou（SJ 6） and Yanglingquan（GB 34） acupoints in healthy volunteers.fMRI was used to examine the activation of brain areas in response to different types of acupuncture（cutaneous or routine acupuncture） at each acupoint.There were no significant differences in the distribution of activation in the regions of interest between cutaneous and routine acupuncture at the Neiguan,Waiguan,and Zhigou acupoints,but some differences were observed between the two methods of acupuncture at the Yanglingquan acupoint.There were no significant differences in the intensity of induced activation between cutaneous and routine acupuncture at the Neiguan,Zhigou and Yanglingquan acupoints,but the activation intensity in the right cerebellum induced by routine acupuncture at the Waiguan acupoint was greater than that induced by cutaneous acupuncture.Results confirmed that cutaneous and routine acupuncture at the Neiguan,Waiguan,Zhigou and Yanglingquan acupoints activated different functional brain areas,and caused activation of different intensities in some areas.

Positron emission tomography study of the specificity of Waiguan (SJ 5) acupoint

Functional brain imaging studies of the specificity of acupoint stimulation have revealed that needling at particular acupoints can induce activation of corresponding brain areas, examined in physiological and pathological states. The present study examined Waiguan （SJ 5） as the acupoint of interest. We tested five conditions： a true needling at true acupoint group, a sham needling at true acupoint group, a true needling at sham acupoint group, a sham needling at sham acupoint group, and a healthy control group. We examined changes in glucose metabolism in different functional cortical regions to determine the specific brain activation elicited by acupuncture at Waiguan. The results revealed that true and sham acupuncture at the same acupoint activated different brain regions. In addition, applying acupuncture at a genuine acupoint and a neighboring sham acupoint activated different brain regions. These findings suggest that acupuncture at Waiguan causes activation in some brain regions.

IN VIVO VALIDATION OF DUAL-MODALITY SYSTEM FOR SIMULTANEOUS POSITRON EMISSION TOMOGRAPHY AND OPTICAL TOMOGRAPHIC IMAGING

We report on tests of combined positron emission tomography(PET)andfluorescence molecular tomography(FMT)imaging system for in vivo investigation on small animals.A nude mouse was inoculated with MD-MB-231 breast cancer cells which expressed redfluorescent protein(RFP).For FMT system,reflective illumination mode was adopted with full-angle data acquisition.[18F]-Fluorodeoxyglucose([18F]-FDG)was used as radioactive tracer for PET.Both data were acquired simultaneously and then reconstructed separately before fusion.Fluorescent tomography results showed exactly where the tumor was located while PET results offered more metabolic information.Results confirmed feasibility for tumor detection and showed superiority to single modality imaging.

Altered regional homogeneity in post-traumatic stress disorder: a resting-state functional magnetic resonance imaging study

Objective Little is known about the brain systems that contribute to vulnerability to post-traumatic stress disorder （PTSD）. Comparison of the resting-state patterns of intrinsic functional synchronization, as measured by functional magnetic resonance imaging （fMRI）, between groups with and without PTSD following a traumatic event can help identify the neural mechanisms of the disorder and targets for intervention. Methods Fifty-four PTSD patients and 72 matched traumatized subjects who experienced the 2008 Sichuan earthquake were imaged with blood oxygen level-dependent （BOLD） fMRI and analyzed using the measure of regional homogeneity （ReHo） during the resting state. Results PTSD patients presented enhanced ReHo in the left inferior parietal lobule and right superior frontal gyrus, and reduced ReHo in the right middle temporal gyrus and lingual gyrus, relative to traumatized individuals without PTSD. Conclusion Our findings showed that abnormal brain activity exists under resting conditions in PTSD patients who had been exposed to a major earthquake. Alterations in the local functional connectivity of cortical regions are likely to contribute to the neural mechanisms underlying PTSD.

Abnormal Metabolic Connectivity in Rats at the Acute Stage of Ischemic Stroke

Stroke at the acute stage is a major cause of disability in adults, and is associated with dysfunction of brain networks. However, the mechanisms underlying changes in brain connectivity in stroke are far from fully elucidated. In the present study, we investigated brain metabolism and metabolic connectivity in a rat ischemic stroke model of middle cerebral artery occlusion （MCAO） at the acute stage using 18F-fluorodeoxyglucose positron emission tomography. Voxel-wise analysis showed decreased metabolism mainly in the ipsilesional hemi- sphere, and increased metabolism mainly in the contrale- sional cerebellum. We used further metabolic connectivity analysis to explore the brain metabolic network in MCAO. Compared to sham controls, rats with MCAO showed most significantly reduced nodal and local efficiency in the ipsilesional striatum. In addition, the MCAO group showed decreased metabolic central connection of the ipsilesional striatum with the ipsilesional cerebellum, ipsilesional hippocampus, and bilateral hypothalamus. Taken together, the present study demonstrated abnormal metabolic con- nectivity in rats at the acute stage of ischemic stroke, which might provide insight into clinical research.

An Automatic Method for Generating an Unbiased Intensity Normalizing Factor in Positron Emission Tomography Image Analysis After Stroke

Positron emission tomography （PET） imaging of functional metabolism has been widely used to investigate functional recovery and to evaluate therapeutic efficacy after stroke. The voxel intensity of a PET image is the most important indicator of cellular activity, but is affected by other factors such as the basal metabolic ratio of each subject. In order to locate dysfunctional regions accurately, intensity normalization by a scale factor is a prerequisite in the data analysis, for which the global mean value is most widely used. However, this is unsuitable for stroke studies. Alternatively, a specified scale factor calculated from a reference region is also used, comprising neither hyper- nor hypo-metabolic voxels. But there is no such recognized reference region for stroke studies. Therefore, we proposed a totally data-driven automatic method for unbiased scale factor generation. This factor was generated iteratively until the residual deviation of two adjacent scale factors was reduced by 〈 5%. Moreover, both simulated and real stroke data were used for evaluation, and these suggested that our proposed unbiased scale factor has better sensi- tivity and accuracy for stroke studies.

Distinct Roles of Dopamine Receptors in the Lateral Thalamus in a Rat Model of Decisional Impulsivity

The thalamus and central dopamine signaling have been shown to play important roles in high-level cognitive processes including impulsivity. However, little is known about the role of dopamine receptors in the thalamus in decisional impulsivity. In the present study,rats were tested using a delay discounting task and divided into three groups： high impulsivity（HI）, medium impulsivity（MI）, and low impulsivity（LI）. Subsequent in vivo voxel-based magnetic resonance imaging revealed that the HI rats displayed a markedly reduced density of gray matter in the lateral thalamus compared with the LI rats. In the MI rats, the dopamine D1 receptor antagonist SCH23390 or the D2 receptor antagonist eticlopride was microinjected into the lateral thalamus. SCH23390 significantly decreased their choice of a large, delayed reward and increased their omission of lever presses. In contrast,eticlopride increased the choice of a large, delayed reward but had no effect on the omissions. Together, our results indicate that the lateral thalamus is involved in decisional impulsivity, and dopamine D1 and D2 receptors in the lateral thalamus have distinct effects on decisional impulsive behaviors in rats. These results provide a new insightinto the dopamine signaling in the lateral thalamus in decisional impulsivity.

Factors affecting the voxel-based analysis of diffusion tensor imaging

Diffusion tensor imaging(DTI)provides a unique method to reveal the integrity of white matter microstructure noninvasively.Voxel-based analysis(VBA),which is a highly reproducible and user-independent technique,has been used to analyze DTI data in a number of studies.Fractional anisotropy(FA),which is derived from DTI,is the most frequently used parameter.The parameter setting during the DTI data preprocessing might affect the FA analysis results.However,there is no reliable evidence on how the parameters affect the results of FA analysis.This study sought to quantitatively investigate the factors that might affect the voxel-based analysis of FA;these include the interpolation during spatial normalization,smoothing kernel and statistical threshold.Because it is difficult to obtain the true information of the lesion in the patients,we simulated lesions on the healthy FA maps.The DTI data were obtained from 20 healthy subjects.The FA maps were calculated using DTIStudio.We randomly divided these FA maps into two groups.One was used as a model patient group,and the other was used as a normal control group.Simulated lesions were added to the model patient group by decreasing the FA intensities in a specified region by 5%–50%.The model patient group and the normal control group were compared by two-sample t test statistic analysis voxelby-voxel to detect the simulated lesions.We evaluated these factors by comparing the difference between the detected lesion through VBA and the simulated lesion.The result showed that the space normalization of FA image should use the trilinear interpolation,and the smoothing kernel should be 2–3 times the voxel size of spatially normalized FA image.For lesions with small intensity change,FWE correction must be cautiously used.This study provided an important reference to the analysis of FA with VBA method.