Functional brain imaging studies on specificity of meridian and acupoints

At present, the specificity of meridians and acupoints has been studied using functional brain imaging techniques from many standpoints, including meridians, acupoints, and sham acupoints, as well as different meridians and acupoints, coordination of acupoints, and factors influencing meridian and acupoint specificity Preliminary experimental data have demonstrated that acupuncture at meridians and acupoints is specific with regard to brain neural information. However, research findings are contradictory, which may be related to brain functional complexity, resolution of functional brain imaging techniques, and experimental design. Future studies should further improve study method, and should strictly control experimental conditions to better analyze experimental data and acquire more beneficial data. Because of its many advantages, the functional brain imaging technique is a promising method for studying meridian and acupoint specificity.

Functional magnetic resonance imaging evidence for activated functional brain areas following acupoint needling in the extremities

Totally three articles focusing on functional magnetic resonance imaging features of brain function in the activated brain regions of stroke patients undergoing acupuncture on the healthy limbs and healthy controls undergoing acupuncture on the lower extremities are published in three issues. We hope that our readers find these papers useful to their research.

DISCRIMINATION OF MENTAL WORKLOAD LEVELS IN HUMAN SUBJECTS WITH FUNCTIONAL NEAR-INFRARED SPECTROSCOPY

We have applied functional near-infrared spectroscopy(fNIRS)to the human forehead to distinguish different levels of mental workload on the basis of hemodynamic changes occurring in the prefrontal cortex.We report data on 3 subjects from a protocol involving 3 mental workload levels based on to working memory tasks.To quantify the potential of fNIRS for mental workload discrimination,we have applied a 3-nearest neighbor classification algorithm based on the amplitude of oxyhemoglobin(HbO2)and deoxyhemoglobin(HbR)concentration changes associated with the working memory tasks.We have found classification success rates in the range of 44%-72%,which are significantly higher than the corresponding chance level(for random data)of 19.1%.This work shows the potential of fNIRS for mental workload classification,especially when more parameters(rather than just the amplitude of concentration changes used here)and more sophisticated classification algorithms(rather than the simple 3-nearest neighbor algorithm used here)are considered and optimized for this application.

Modulatory effects of acupuncture on brain networks in mild cognitive impairment patients

Functional magnetic resonance imaging has been widely used to investigate the effects of acupuncture on neural activity. However, most functional magnetic resonance imaging studies have focused on acute changes in brain activation induced by acupuncture. Thus, the time course of the therapeutic effects of acupuncture remains unclear. In this study, 32 patients with amnestic mild cognitive impairment were randomly divided into two groups, where they received either Tiaoshen Yizhi acupuncture or sham acupoint acupuncture. The needles were either twirled at Tiaoshen Yizhi acupoints, including Sishencong（EX-HN1）, Yintang（EX-HN3）, Neiguan（PC6）, Taixi（KI3）, Fenglong（ST40）, and Taichong（LR3）, or at related sham acupoints at a depth of approximately 15 mm, an angle of ± 60°, and a rate of approximately 120 times per minute. Acupuncture was conducted for 4 consecutive weeks, five times per week, on weekdays. Resting-state functional magnetic resonance imaging indicated that connections between cognition-related regions such as the insula, dorsolateral prefrontal cortex, hippocampus, thalamus, inferior parietal lobule, and anterior cingulate cortex increased after acupuncture at Tiaoshen Yizhi acupoints. The insula, dorsolateral prefrontal cortex, and hippocampus acted as central brain hubs. Patients in the Tiaoshen Yizhi group exhibited improved cognitive performance after acupuncture. In the sham acupoint acupuncture group, connections between brain regions were dispersed, and we found no differences in cognitive function following the treatment. These results indicate that acupuncture at Tiaoshen Yizhi acupoints can regulate brain networks by increasing connectivity between cognition-related regions, thereby improving cognitive function in patients with mild cognitive impairment.

Decoding brain responses to pixelized images in the primary visual cortex: implications for visual cortical prostheses

Visual cortical prostheses have the potential to restore partial vision. Still limited by the low-resolution visual percepts provided by visual cortical prostheses, implant wearers can currently only ＂see＂ pixelized images, and how to obtain the specific brain responses to different pixelized images in the primary visual cortex（the implant area） is still unknown. We conducted a functional magnetic resonance imaging experiment on normal human participants to investigate the brain activation patterns in response to 18 different pixelized images. There were 100 voxels in the brain activation pattern that were selected from the primary visual cortex, and voxel size was 4 mm × 4 mm × 4 mm. Multi-voxel pattern analysis was used to test if these 18 different brain activation patterns were specific. We chose a Linear Support Vector Machine（LSVM） as the classifier in this study. The results showed that the classification accuracies of different brain activation patterns were significantly above chance level, which suggests that the classifier can successfully distinguish the brain activation patterns. Our results suggest that the specific brain activation patterns to different pixelized images can be obtained in the primary visual cortex using a 4 mm × 4 mm × 4 mm voxel size and a 100-voxel pattern.

Functional organization of complex brain networks modulated by acupuncture at different acupoints belonging to the same anatomic segment

Background Noninvasive functional magnetic resonance imaging （fMRI） techniques have opened a ＂window＂ into the brain, allowing us to investigate the anatomical and physiological function involving acupuncture needling. Imaging its sustained effect rather than acute effect on the brain networks may further help elucidate the mechanisms by which acupuncture achieves its therapeutic effects. In this study, we aimed to investigate the functional brain networks during the post-resting state following acupuncture at KI3 in comparison with acupuncture at GB40. Methods Needling at acupoints GB40 and KI3 was performed in twelve subjects. Six minutes of scanning at rest were adopted before and after acupuncture at different acupoints. Then we divided the whole brain into 39 regions and constructed functional brain networks during the post-acupuncture resting states （PARS）. Results For direct comparisons, increased correlations during post-resting state following acupuncture at KI3 compared to resting state （RS） were primarily located between the dorsolateral prefrontal cortex （DLPFC） and post temporal cortex, ventromedial prefrontal cortex （vmPFC） and post temporal cortex. These brain regions were all cognitive-related functions. In contrast, the increased connections between the anterior insula and temporal cortex mainly emerged following acupuncture at GB40 compared with the RS. Conclusions The present study demonstrates that acupuncture at different acupoints belonging to the same anatomic segment can exert different modulatory effects on the reorganizations of post-acupuncture RS networks. The heterogeneous modulation patterns between twoconditions may relate to the functional specific modulatory effects of acupuncture.

Continuous representation of human portraits and natural scenery in human ventral temporal cortex: evidence from functional magnetic resonance imaging

Background Functional magnetic resonance imaging (fMRI) has become a powerful tool for tracking human brain activity in vivo. This technique is mainly based on blood oxygenation level dependence (BOLD) contrast. In the present study, we employed this newly developed technique to characterize the neural representations of human portraits and natural sceneries in the human brain.Methods Nine subjects were scanned with a 1.5 T magnetic resonance imaging (MRI) scanner using gradient-recalled echo and echo-planar imaging (GRE-EPI) pulse sequence while they were visually presented with 3 types of white-black photographs: natural scenery, human portraits, and scrambled nonsense pictures. Multiple linear regression was used to identify brain regions responding preferentially to each type of stimulus and common regions for both human portraits and natural scenery. The relative contributions of each type of stimulus to activation in these regions were examined using linear combinations of a general linear test.Results Multiple linear regression analysis revealed two distinct but adjacent regions in both sides of the ventral temporal cortex. The medial region preferentially responded to natural scenery, whereas the lateral one preferentially responded to the human portraits. The general linear test further revealed a distribution gradient such that a change from portraits to scenes shifted areas of activation from lateral to medial.Conclusions The boundary between portrait-associated and scenery-associated areas is not as clear as previously demonstrated. The representations of portraits and scenes in ventral temporal cortex appear to be continuous and overlap.

Effects of methylphenidate on resting-state brain activity in normal adults: an fMRI study

Methylphenidate （MPH） is one of the most commonly used stimulants for the treatment of attention deficit hyperactivity disorder （ADHD）. Although several studies have evaluated the effects of MPH on human brain activation during specific cognitive tasks using functional magnetic resonance imaging （fMRI）, few studies have focused on spontaneous brain activity. In the current study, we investigated the effect of MPH on the intra-regional synchronization of spontaneous brain activity during the resting state in 18 normal adult males. A handedness questionnaire and the Wechsler Adult Intelligence Scale were applied before medication, and a resting-state fMRI scan was obtained 1 h after medication （20 mg MPH or placebo, order counterbalanced between participants）. We demonstrated that： （1） there were no significant differences in the performance of behavioral tasks between the MPH and placebo groups; （2） the left middle and superior temporal gyri had stronger MPH-related regional homogeneity （ReHo）; and （3） the left lingual gyrus had weaker MPH-related ReHo. Our findings showed that the ReHo in some brain areas changes with MPH compared to placebo in normal adults, even though there are no behavioral differences. This method can be applied to patients with mental illness who may be treated with MPH, and be used to compare the difference between patients taking MPH and normal participants, to help reveal the mechanism of how MPH works.