Clinical Research Progress of the Post-Stroke Upper Limb Motor Function Improvement via Transcutaneous Auricular Vagus Nerve Stimulation.

Stroke is a disease with high morbidity and disability, and motor impairment is a common sequela of stroke. Transcutaneous auricular vagus nerve stimulation (taVNS) is a type of non-invasive stimulation, which can effectively improve post-stroke motor dysfunction. This review discusses stimulation parameters, intervention timing, and the development of innovative devices for taVNS. We further summarize the application of taVNS in improving post-stroke upper limb motor function to further promote the clinical research and application of taVNS in the rehabilitation of post-stroke upper limb motor dysfunction.

The assessment of interhemispheric imbalance using functional near-infrared spectroscopic and transcranial magnetic stimulation for predicting motor outcome after stroke.

Objective: To investigate changes in interhemispheric imbalance of cortical excitability during motor recovery after stroke and to clarify the relationship between motor function recovery and alterations in interhemispheric imbalance, with the aim to establish more effective neuromodulation strategies. Methods: Thirty-one patients underwent assessments of resting motor threshold (RMT) using transcranial magnetic stimulation (TMS); the cortical activity of the primary motor cortex (M1), premotor cortex (PMC), and supplementary motor area (SMA) using functional near-infrared spectroscopy (fNIRS); as well as motor function using upper extremity Fugl-Meyer (FMA-UE). The laterality index (LI) of RMT and fNIRS were also calculated. All indicators were measured at baseline(T1) and 1 month later(T2). Correlations between motor function outcome and TMS and fNIRS metrics at baseline were analyzed using bivariate correlation. Results: All the motor function (FMA-UE1, FMA-UE2, FMA-d2) and LI-RMT (LI-RMT1 and LI-RMT2) had a moderate negative correlation. The higher the corticospinal excitability of the affected hemisphere, the better the motor outcome of the upper extremity, especially in the distal upper extremity (r = -0.366, p = 0.043; r = -0.393, p = 0.029). The greater the activation of the SMA of the unaffected hemisphere, the better the motor outcome, especially in the distal upper extremity (r = -0.356, p = 0.049; r = -0.367, p = 0.042). There was a significant moderate positive correlation observed between LI-RMT2 and LI-SMA1 (r = 0.422, p = 0.018). The improvement in motor function was most significant when both LI-RMT1 and LI-SMA1 were lower. Besides, in patients dominated by unaffected hemisphere corticospinal excitability during motor recovery, LI-(M1 + SMA + PMC)2 exhibited a significant moderate positive association with the proximal upper extremity function 1 month later (r = 0.642, p = 0.007). Conclusion: The combination of both TMS and fNIRS can infer the prognosis of motor function to some extent. Which can infer the role of both hemispheres in recovery and may contribute to the development of effective individualized neuromodulation strategies.

Case report: High-frequency repetitive transcranial magnetic stimulation for treatment of hereditary spastic paraplegia type 11.

Hereditary spastic paraplegia (HSP) is a heterogeneous group of inherited neurodegenerative disorders that currently have no cure. HSP type 11 (SPG11-HSP) is a complex form carrying mutations in the SPG11 gene. Neuropathological studies demonstrate that motor deficits in these patients are mainly attributed to axonal degeneration of the corticospinal tract (CST). Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique that can induce central nervous system plasticity and promote neurological recovery by modulating the excitability of cortical neuronal cells. Although rTMS is expected to be a therapeutic tool for neurodegenerative diseases, no previous studies have applied rTMS to treat motor symptoms in SPG11-HSP. Here, we report a case of SPG11-HSP with lower extremity spasticity and gait instability, which were improved by applying high-frequency rTMS (HF-rTMS) at the primary motor cortex (M1). Clinical and physiological features were measured throughout the treatment, including the Modified Ashworth Scale (MAS), Berg Balance Scale (BBS), the timed up and go (TUG) test and the 10-meter walk test time (10 MWT). The structure and excitability of the CST were assessed by diffusion tensor imaging (DTI) and transcranial magnetic stimulation (TMS), respectively. After treatment, the patient gained 17 points of BBS, along with a gradual decrease in MAS scores of the bilateral lower extremity. In addition, the TUG test and 10 MWT improved to varying degrees. TMS assessment showed increased motor evoked potential (MEP) amplitude, decreased resting motor threshold (RMT), decreased central motor conduction time (CMCT), and decreased difference in the cortical silent period (CSP) between bilateral hemispheres. Using the DTI technique, we observed increased fractional anisotropy (FA) values and decreased mean diffusivity (MD) and radial diffusivity (RD) values in the CST. It suggests that applying HF-rTMS over the bilateral leg area of M1 (M1-LEG) is beneficial for SPG11-HSP. In this study, we demonstrate the potential of rTMS to promote neurological recovery from both functional and structural perspectives. It may provide a clinical rationale for using rTMS in the rehabilitation of HSP patients.

Effects of integrated action and sensory observation therapy based on mirror neuron and embodied cognition theory on upper limb sensorimotor function in chronic stroke: a study protocol for a randomised controlled trial.

INTRODUCTION: This study protocol aims to explore the effectiveness and neural mechanism of the integration of action observation therapy (AOT) and sensory observation therapy (SOT) for post-stroke patients on upper limb sensorimotor function. METHODS AND ANALYSIS: This is a single-centre, single-blind, randomised controlled trial. A total of 69 patients with upper extremity hemiparesis after stroke will be recruited and randomly divided into an AOT group, a combined action observation and somatosensory stimulation therapy (AOT+SST) group, and a combined AOT and SOT (AOT+SOT) group in a 1:1:1 ratio. Each group will receive 30 min of daily treatment, five times weekly for 4 weeks. The primary clinical outcome will be the Fugl-Meyer Assessment for Upper Extremity. Secondary clinical outcomes will include the Box and Blocks Test, modified Barthel Index and sensory assessment. All clinical assessments and resting-state functional MRI and diffusion tensor imaging data will be obtained at pre-intervention (T1), post-intervention (T2) and 8 weeks of follow-up (T3). ETHICS AND DISSEMINATION: The trial was approved by the Ethics Committee of Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Chinese Traditional Medicine (Grant No. 2020-178). The results will be submitted to a peer-review journal or at a conference. TRIAL REGISTRATION NUMBER: ChiCTR2000040568.

Neural signatures for the n-back task with different loads: An event-related potential study.

The n-back task is widely used in working memory (WM) research. However, it remains unclear how the electrophysiological correlates of WM processes, the P2, N2, P300, and negative slow wave (NSW), are affected by differences in load. Specifically, while previous work has examined the P300, less attention has been paid to the other components assessing the load of the n-back paradigm. The present study aims to investigate whether other sub-processes in WM (such as inhibitory control) are as sensitive to n-back load changes as the update process by observing changes in the above event-related potential (ERP) components. The results showed poorer behavioral performance with increasing WM load. Greater NSW and smaller P300 amplitudes were elicited by n-back task with a higher load compared to that with lower load. In contrast, there was no significant effect of the n-back load on the amplitudes of P2 and N2. These findings suggest that the updating process and the maintenance process are sensitive to the n-back load change. Therefore, changes in the updating and maintenance processes should be considered when using the n-back task to manipulate the WM load in experiments. The present study may contribute to the understanding of the complexity of WM loads. Additionally, a theoretical basis for follow-up research to explore ways of improving WM performance with high load is provided.

Gamma oscillations and application of 40-Hz audiovisual stimulation to improve brain function.

BACKGROUND: Audiovisual stimulation, such as auditory stimulation, light stimulation, and audiovisual combined stimulation, as a non-invasive stimulation, which can induce gamma oscillation, has received increased attention in recent years, and it has been preliminarily applied in the clinical rehabilitation of brain dysfunctions, such as cognitive, language, motor, mood, and sleep dysfunctions. However, the exact mechanism underlying the therapeutic effect of 40-Hz audiovisual stimulation remains unclear; the clinical applications of 40-Hz audiovisual stimulation in brain dysfunctions rehabilitation still need further research. OBJECTIVE: In order to provide new insights into brain dysfunction rehabilitation, this review begins with a discussion of the mechanism underlying 40-Hz audiovisual stimulation, followed by a brief evaluation of its clinical application in the rehabilitation of brain dysfunctions. RESULTS: Currently, 40-Hz audiovisual stimulation was demonstrated to affect synaptic plasticity and modify the connection status of related brain networks in animal experiments and clinical trials. Although its promising efficacy has been shown in the treatment of cognitive, mood, and sleep impairment, research studies into its application in language and motor dysfunctions are still ongoing. CONCLUSIONS: Although 40-Hz audiovisual stimulation seems to be effective in treating cognitive, mood, and sleep disorders, its role in language and motor dysfunctions has yet to be determined.

Comparison of Sensory Observation and Somatosensory Stimulation in Mirror Neurons and the Sensorimotor Network: A Task-Based fMRI Study.

Objective: This study aimed to investigate brain plasticity by somatosensory stimulation (SS) and sensory observation (SO) based on mirror neuron and embodied cognition theory. Action observation therapy has been widely adopted for motor function improvement in post-stroke patients. However, it is uncertain whether the SO approach can also contribute to the recovery of sensorimotor function after stroke. In this study, we explored the therapeutic potential of SO for sensorimotor dysfunction and provided new evidence for neurorehabilitation. Methods: Twenty-six healthy right-handed adults (12 men and 14 women), aged 18-27 (mean, 22.12; SD, 2.12) years were included. All subjects were evaluated with task-based functional magnetic resonance imaging (fMRI) to discover the characteristics and differences in brain activation between SO and SS. We adopted a block design with two conditions during fMRI scanning: observing a sensory video of brushing (task condition A, defined as SO) and brushing subjects' right forearms while they watched a nonsense string (task condition B, defined as SS). One-sample t-tests were performed to identify brain regions and voxels activated for each task condition. A paired-sample t-test and conjunction analysis were performed to explore the differences and similarities between SO and SS. Results: The task-based fMRI showed that the bilateral postcentral gyrus, left precentral gyrus, bilateral middle temporal gyrus, right supramarginal gyrus, and left supplementary motor area were significantly activated during SO or SS. In addition to these brain regions, SO could also activate areas containing mirror neurons, like the left inferior parietal gyrus. Conclusion: SO could activate mirror neurons and sensorimotor network-related brain regions in healthy subjects like SS. Therefore, SO may be a promising novel therapeutic approach for sensorimotor dysfunction recovery in post-stroke patients.

The Modulation of Working-Memory Performance Using Gamma-Electroacupuncture and Theta-Electroacupuncture in Healthy Adults.

Working memory (WM), a central component of general cognition, plays an essential role in human beings' daily lives. WM impairments often occur in psychiatric, neurodegenerative, and neurodevelopmental disorders, mainly presenting as loss of high-load WM. In previous research, electroacupuncture (EA) has been shown to be an effective treatment for cognitive impairments. Frequency parameters are an important factor in therapeutic results, but the optimal frequency parameters of EA have not yet been identified. In this study, we chose theta-EA (θ-EA; 6 Hz) and gamma-EA (γ-EA; 40 Hz), corresponding to the transcranial alternating-current stimulation (tACS) frequency parameters at the Baihui (DU20) and Shenting (DU24) acupoints, in order to compare the effects of different EA frequencies on WM. We evaluated WM performance using visual 1-back, 2-back, and 3-back WM tasks involving digits. Each participant (N = 30) attended three different sessions in accordance with a within-subject crossover design. We performed θ-EA, γ-EA, and sham-EA in a counterbalanced order, conducting the WM task both before and after intervention. The results showed that d-prime (d') under all three stimulation conditions had no significance in the 1-back and 2-back tasks. However, in the 3-back task, there was a significant improvement in d' after intervention compared to d' before intervention under θ-EA (F [1, 29] = 22.64; P < 0.001), while we saw no significant difference in the γ-EA and sham-EA groups. Reaction times for hits (RT-hit) under all three stimulation conditions showed decreasing trends in 1-, 2-, and 3-back tasks but without statistically significant differences. These findings suggest that the application of θ-EA might facilitate high-load WM performance.

[Novel resources utilization technique for rural domestic refuse].

In order to speed up rural domestic refuse resources utilization, intermittent aeration and continuous aeration were applied to treat rural domestic refuse after anaerobic fermentation. Three kinds of refuse were selected on base of fermentative age, i.e. three months, five months and seven months. Results showed that aeration could remove water and organic materials of the refuse effectively. Points of view on aeration, continuous aeration was better than intermittent aeration, and on the other side, water removal rate increased with ventilation and decreased with fermentative age in the condition of intermittent aeration. On organic materials removal point, it was affected by fermentative age significantly, i. e. increase of fermentative age could resulted in decrease in the removal efficiency. In conclusion, intermittent aeration of 0.06 m3/(min x m3) was considered to be feasible for treatment. The water removal efficiency of three months, five months and seven months fermentative age refuse could be up to 49.1%, 45.3% and 44.0%, and organic compound removal efficiency was 41.9%, 24.8% and 13.1%, respectively, after intermittent aeration for 21 d. Moreover, concentrated effect was presented on major nutrient ingredients, such as total nitrogen, phosphorus, and potassium during the aeration, which realized for resources utilization.