Ultrasound-responsive microfibers promoted infected wound healing with neuro-vascularization by segmented sonodynamic therapy and electrical stimulation.

Bacteria-infected wounds pose challenges to healing due to persistent infection and associated damage to nerves and vessels. Although sonodynamic therapy can help kill bacteria, it is limited by the residual oxidative stress, resulting in prolonged inflammation. To tackle these barriers, novel 4 octyl itaconate-coated Li-doped ZnO/PLLA piezoelectric composite microfibers are developed, offering a whole-course "targeted" treatment under ultrasound therapy. The inclusion of Li atoms causes the ZnO lattice distortion and increases the band gap, enhancing the piezoelectric and sonocatalytic properties of the composite microfibers, collaborated by an aligned PLLA conformation design. During the infection and inflammation stages, the piezoelectric microfibers exhibit spatiotemporal-dependent therapeutic effects, swiftly eliminating over 94.2 % of S. aureus within 15 min under sonodynamic therapy. Following this phase, the microfibers capture reactive oxygen species and aid macrophage reprogramming, restoring mitochondrial function, achieving homeostasis, and shortening inflammation cycles. As the wound progresses through the healing stages, bioactive Zn2+ and Li + ions are continuously released, improving cell recruitment, and the piezoelectrical stimulation enhances wound recovery with neuro-vascularization. Compared to commercially available dressings, our microfibers accelerate the closure of rat wounds (Φ = 15 mm) without scarring in 12 days. Overall, this "one stone, four birds" wound management strategy presents a promising avenue for infected wound therapy.

Pain-Discriminating Information Decoded From Spatiotemporal Patterns of Hemodynamic Responses Measured by fMRI in the Human Brain.

Functional magnetic resonance imaging (fMRI) has been widely used in studying the neural mechanisms of pain in the human brain, primarily focusing on where in the brain pain-elicited neural activities occur (i.e., the spatial distribution of pain-related brain activities). However, the temporal dynamics of pain-elicited hemodynamic responses (HDRs) measured by fMRI may also contain information specific to pain processing but have been largely neglected. Using high temporal resolution fMRI (TR = 0.8 s) data acquired from 62 healthy participants, in the present study we aimed to test whether pain-distinguishing information could be decoded from the spatial pattern of the temporal dynamics (i.e., the spatiotemporal pattern) of HDRs elicited by painful stimuli. Specifically, the peak latency and the response duration were used to characterize the temporal dynamics of HDRs to painful laser stimuli and non-painful electric stimuli, and then were compared between the two conditions (i.e., pain and no-pain) using a voxel-wise univariate analysis and a multivariate pattern analysis. Furthermore, we also tested whether the two temporal characteristics of pain-elicited HDRs and their spatial patterns were associated with pain-related behaviors. We found that the spatial patterns of HDR peak latency and response duration could successfully discriminate pain from no-pain. Interestingly, we also observed that the Pain Vigilance and Awareness Questionnaire (PVAQ) scores were correlated with the average response duration in bilateral insula and secondary somatosensory cortex (S2) and could also be predicted from the across-voxel spatial patterns of response durations in the middle cingulate cortex and middle frontal gyrus only during painful condition but not during non-painful condition. These findings indicate that the spatiotemporal pattern of pain-elicited HDRs may contain pain-specific information and highlight the importance of studying the neural mechanisms of pain by taking advantage of the high sensitivity of fMRI to both spatial and temporal information of brain responses.

Technical report on intra-operative trigeminal root mapping in percutaneous lesioning for trigeminal neuralgias.

PURPOSE: Percutaneous lesioning-techniques for treating refractory Trigeminal Neuralgias not amenable to Micro-Vascular Decompression remain useful in neurosurgical practice. Success, avoidance of complications and reduction of side-effects depend on the accurate location of the lesion-maker especially for Radio-Frequency-Thermo-Rhizotomy (RF-Th-Rh). Added to X-ray-guidance, Intra-Operative Neurophysiology can be of significant help to achieve optimal accuracy of the surgery. Based on previous research, this article aims to describe the simplest way to use direct electrical stimulation of the trigeminal root to evoke clinically observable muscle responses allowing to precisely position the tip of the needle for accurate lesioning. TECHNIQUE TO EVOKE SPECIFIC LOCALIZING MUSCLE RESPONSES: Masticatory twitches can be easily produced by stimulating the motor root, through orthodromic conduction to the masticatory muscles. Evoked Muscle Responses (EMRs) can be elicited in the facial nerve territory by stimulating the sensory rootlets, through Trigemino-Facial Reflexes' pathways (TFRs). Responses in the Orbicularis Oculi is the well-known and readily used "Blink reflex". On the contrary, TFRs in the lower territory of the facial nerve escaped clinical investigations not having been explored under direct stimulation of the trigeminal root. For both, stimulation at 5 c/s produces better observable twitches (because saccadic) than at 50 c/s which elicits tetanic contractions. CONCLUSION: The localizing-value of these facial EMRs (associated to evocation of paresthesias) and of the masticatory responses, justifies mapping the trigeminal root before lesioning. Their use could be extended to the other lesioning-techniques: not only Glycerol Neurolysis but also to Balloon Compression (to ascertain location of the trocar at the contact of the TGN inside the Meckel cave) and Open partial Rhizotomies (before deciding to cut the rootlets corresponding to the trigger-zone). This is of importance since lesioning-techniques are needed because not all trigeminal neuralgias are responsive to or even indications of Micro-Vascular Decompression.

Tinnitus Suppression with Electrical Stimulation at the Most Basal Contact of the Cochlear Implant Electrode as a Model for Round Window Stimulation.

The objective of this research was to test whether efficient tinnitus suppression could be achieved by electrical stimulation of the single most basal electrode contact of a cochlear implant. This approach simulates the effects of electrical stimulation using a round-window electrode. The study was performed in 10 adult cochlear implant patients showing complete or almost complete tinnitus suppression during electrical stimulation with their standard fitting-MAP. In all patients, tinnitus appeared again when the implant was switched off. Five Nucleus implant (1 CI532, 4 CI24RE CA) users and 5 Mi12xx series with FLEX28 electrodes with at least 6 months of CI experience were included. Two types of stimulation were presented at the most basal CI contact: a constant pulse train and a modulated pulse train. The variation in pulse rates was low rate (100-300 pps) and high (≥900 pps), and the current level ranged from the C-level to less than the T-level for both stimulation types. The effect of acute electrical stimulation at the most basal electrode contact was compared to the effect obtained with multichannel stimulation with the patient's current fitting MAP. Electrical stimulation was paused between tests with different stimulation types until tinnitus returned to baseline intensity. Patients reported Visual Analog Scale (VAS) scores for tinnitus loudness and intrusiveness during normal CI use and for each single contact stimulation type. Eight participants perceived complete suppression with one or more stimulation patterns. In 2 patients, suppression was less efficient than full-band CI stimulation. Louder stimuli are generally perceived as annoying and less effective in reducing tinnitus. In FLEX28 patients, it was also possible to obtain full tinnitus suppression with current amplitudes under the thresholds for auditory perception (this was not tested in patients with the Nucleus device). In 8 of the 10 included patients, we were able to obtain complete or almost complete tinnitus suppression with electrical stimulation at only 1 most basal electrode contact. Therefore, round-window stimulation with a single electrode may be a potential treatment for tinnitus in patients with significant residual hearing. The long-term effects of this therapy should be confirmed in future studies.

Impact of background input on memory consolidation.

Memory consolidation involves repeated replay of new information by the hippocampus, which transfers memories to the neocortex for long-term storage. This occurs mainly during slow wave sleep, a phase characterized in the cortex by low cholinergic tone and low afferent input. High cholinergic tone has been shown to hamper memory consolidation, probably mediated by reduced network excitability (the ease of activity propagation in a network). We used cortical neuronal networks on multi electrode arrays to investigate whether low background input contributes to memory consolidation. Networks received focal electrical stimuli to memorize, with or without background afferent input (global optogenetic stimulation). Background stimulation hampered memory formation and consolidation, confirming the importance of low background input. Moreover, it lowered network excitability, similar to high cholinergic tone. These findings suggest that high network excitability is a critical feature of slow wave sleep that facilitates memory consolidation.

Low-intensity transcranial ultrasound stimulation modulates neurovascular coupling in mouse models of Alzheimer's disease.

Neurovascular coupling plays an important role in the progression of Alzheimer's disease. However, it is unclear how ultrasound stimulation modulates neurovascular coupling in Alzheimer's disease. Here, we found that (i) transcranial ultrasound stimulation modulates the time domain and frequency domain characteristics of cerebral blood oxygen metabolism in Alzheimer's disease mice; (ii) transcranial ultrasound stimulation can significantly modulate the relative power of theta and gamma frequency of local field potential in Alzheimer's disease mice; and (iii) transcranial ultrasound stimulation can significantly modulate the neurovascular coupling in time domain and frequency domain induced by forepaw electrical stimulation in Alzheimer's disease mice. It provides a research basis for the clinical application of transcranial ultrasound stimulation in Alzheimer's disease patients.

Electrical stimulation of biofidelic engineered muscle enhances myotube size, force, fatigue resistance, and induces a fast-to-slow-phenotype shift.

Therapeutic development for skeletal muscle diseases is challenged by a lack of ex vivo models that recapitulate human muscle physiology. Here, we engineered 3D human skeletal muscle tissue in the Biowire II platform that could be maintained and electrically stimulated long-term. Increasing differentiation time enhanced myotube formation, modulated myogenic gene expression, and increased twitch and tetanic forces. When we mimicked exercise training by applying chronic electrical stimulation, the "exercised" skeletal muscle tissues showed increased myotube size and a contractility profile, fatigue resistance, and gene expression changes comparable to in vivo models of exercise training. Additionally, tissues also responded with expected physiological changes to known pharmacological treatment. To our knowledge, this is the first evidence of a human engineered 3D skeletal muscle tissue that recapitulates in vivo models of exercise. By recapitulating key features of human skeletal muscle, we demonstrated that the Biowire II platform may be used by the pharmaceutical industry as a model for identifying and optimizing therapeutic drug candidates that modulate skeletal muscle function.

Long-range cross-correlations between center of pressure velocity and colored noises provided during quiet standing.

Unperceivable electrical noise stimulation has been applied to improve postural control through the enhancement of somatosensory feedback. It has been observed that stimulation with a pink noise (1/f) structure is more effective than stimulation with other noise structures. In addition, the 1/f structure embedded in the postural control system may have a superior effect on postural control stabilization. However, the direct relationship between the long-range correlations of the pink-noise signal applied to somatosensory receptors and those of the postural control system has not been elucidated. Thus, we aimed to explore a common long-range correlation factor shared in the time series of the provided noise and foot center of pressure (CoP) during quiet standing. Sixteen young adults stood quietly on the force platform for 65 s. Four noise conditions (no stimulation and stimulation of knee joints with white-, pink-, and red-noise-like signals) were employed during the standing trials. The detrending moving-average cross-correlation analysis revealed that in each of the anteroposterior and mediolateral directions, the CoP velocity time series displayed significant long-range cross-correlations with the white and pink noise signals provided at that time, whereas such an effect was not observed in the red noise signal. This result indicates that pink and white noise signals would alter the temporal behavior of the CoP during quiet standing, although the mechanism remains to be elucidated.

Adapting spatiotemporal gait symmetry to functional electrical stimulation during treadmill walking.

Individuals with neurological impairments often exhibit asymmetrical gait patterns. This study explored the potential of using functional electrical stimulation (FES) as a perturbation method during treadmill walking to promote gait symmetry adaptation by investigating whether the FES perturbation could induce gait adaptation concerning spatial and temporal gait symmetry in healthy subjects. In the FES perturbation, both legs received electrical pulses at the same period as the subjects' initial stride duration, and the temporal gap between the two pulses for each leg was manipulated over a 7-min period. Following this, subjects continued to walk for another 5 minutes without FES. Subjects participated in two trials: implicit and explicit. In the implicit trial, they walked comfortably during FES perturbation without consciously adjusting their gait. In the explicit trial, they voluntarily synchronized their toe-off phase to the stimulation timing. To examine the effects of the FES perturbation, we measured step length and stance time and then analyzed changes in step length and stance time symmetries alongside their subsequent aftereffects. During the explicit trial, subjects adapted their gait patterns to the electrical pulses, resulting in a directional change in stance time (temporal) symmetry, with the left stance becoming shorter than the right. The stance time asymmetry induced by FES perturbation showed a slight residual effect. In the implicit trial, the directional change trend was slightly observed but not statistically significant. No consistent trend in step length (spatial) symmetry changes was observed in either condition, indicating that subjects may adapt their spatial gait patterns independently of their temporal patterns. Our findings suggest that the applied FES perturbation strategy under explicit condition can induce adaptations in subjects' temporal gait asymmetry, particularly in stance. The implicit condition showed a similar slight trend but was not statistically significant. Further experiments would provide deeper understanding into the mechanism behind subjects' response to FES perturbations, as well as the long-term effects of these perturbations on the spatial and temporal aspects of gait symmetry.

Stimulated C2C12 Myotube Headspace Volatile Organic Compound Analysis.

Understanding exercise metabolism and the relationship with volatile organic compounds (VOCs) holds potential in both health care and sports performance. Exercise metabolism can be investigated using whole body exercise testing (in vivo) or through the culture and subsequent electrical pulse stimulation (EPS) of myotubes (in vitro). This research investigates the novel headspace (HS) analysis of EPS skeletal muscle myotubes. An in vitro system was built to investigate the effect of EPS on the volatile constituents in the HS above EPS skeletal muscle. The C2C12 immortalised cell line was chosen. EPS was applied to the system to induce myotube contraction. The in vitro system was applied to the analysis of VOCs using thermal desorption (TD) sampling. Samples were collected under four conditions: environmental samples (enviro), acellular media HS samples (blank), skeletal muscle myotubes without stimulation HS samples (baseline) and EPS of skeletal muscle myotube HS samples (stim). TD sampling combined with gas-chromatography mass spectrometry (GC-MS) detected two compounds that, after multivariate and univariate statistical analysis, were identified as changing due to EPS (p < 0.05). These compounds were tentatively assigned as 1,4-Dioxane-2,5-dione, 3,6-dimethyl- and 1-pentene. The former is a known lactide and the latter has been reported as a marker of oxidative stress. Further research should focus on improvements to the EPS system, including the use of more relevant cell lines, quantification of myotube contractions, and the application of targeted analysis, metabolic assays and media analysis.

High-resolution transcranial optical imaging of in vivo neural activity.

Rapid sub-nanometer neuronal deformations have been shown to occur as a consequence of action potentials in vitro, allowing for optical registration of discrete axonal and synaptic depolarizations. Such optically-measured deformations are a novel signature for recording neural activity. We demonstrate this signature can be extended to in vivo measurements through recording of rapid neuronal deformations on the population level with holographic, optical phase-based recordings. Our system demonstrates, for the first time, non-invasive recordings of in vivo tissue deformation associated with population level neuronal activity, including through-skull. We confirmed this technique across a range of neural activation models, including direct epidural focal electrical stimulation, anesthetic-induced cortical deactivation, activation of primary somatosensory cortex via whisker barrel stimulation, and pharmacologically-induced seizures. Collectively, we show holographic imaging provides a pathway for high-resolution, label-free, non-invasive recording of transcranial in vivo neural activity at depth, making it highly advantageous for studying neural function and signaling.

THE EFFECTS OF HYDROCORTISONE ON SYNAPTIC PROCESSES IN PARKINSON'S DISEASE UNDERLYING THE POTENTIAL THERAPEUTIC STRATEGIES.

The study was carried out electrophysiological effects of hydrocortisone for protection on the prelimbic cortex (PrL) neurons in rats, particularly in response to high-frequency stimulation (HFS) of the Caudate-Putamen nuclear complex (CPu) on the models of Parkinson's disease (PD). The study involved 19 rats of the Albino line, each weighing 250 gr. The rats were divided into three experimental groups: intact, rotenone model of Parkinson's disease (PD), and rats with PD but treated with hydrocortisone for protection. Extracellular recording was conducted to measure the impulse activity of single neurons in the prelimbic cortex (PrL) particularly in response to high-frequency stimulation (HFS) of the Caudate-Putamen nuclear complex (CPu) on the models of PD and PD treated with hydrocortisone for protection. In rats with the PD model, there was a decrease in post-stimulus synaptic depressor tetanic effects compared to the norm. This means that the ability of synapses to depress their activity after stimulation was reduced in PD. Conversely, excitatory effects increased in PD rats compared to the norm. This indicates an increase in the excitatory response of neurons in the PD model. When hydrocortisone was applied in PD rats, the frequency of impulse activity dropped sharply, even falling below the levels observed in the normal condition. This indicates that hydrocortisone treatment mitigated the heightened neural activity induced by PD, possibly returning it to a more normal state. Overall, these findings suggest that PD alters synaptic responses and neural activity in the PrL, and hydrocortisone treatment seems to reverse some of these effects.

Centrally mediated responses to NMES are influenced by muscle group and stimulation parameters.

Wide-pulse high-frequency neuromuscular electrical stimulation (WPHF NMES) can generate a progressive increase in tetanic force through reflexive recruitment of motor units, called extra force. This phenomenon has previously been observed on different muscle groups, but little is known on potential inter-muscle differences. We compared extra force and sustained electromyographic (EMG) activity induced by NMES between plantar flexors, knee extensors, elbow flexors and within muscle groups using pulse durations of 0.2, 1 and 2 ms and stimulation frequencies of 20, 50, 100 and 147 Hz. Extra force production and sustained EMG activity were higher for plantar flexors compared to elbow flexors at all tested parameters (except 0.2 ms for extra force). When compared to elbow flexors, extra force of the knee extensors was only higher at 100 Hz and with 1 ms while sustained EMG activity was higher at all frequencies with pulse durations of 0.2 and 2 ms. Peripheral nerve architecture as well as muscle typology and function could influence the occurrence and magnitude of centrally-mediated responses to NMES. The present findings suggest that the use of wide-pulse high-frequency NMES to promote reflexive recruitment seems to be more pertinent for lower limb muscles, plantar flexors in particular.

Investigating the Effect of Polypyrrole-Gelatin/Silk Fibroin Hydrogel Mediated Pulsed Electrical Stimulation for Skin Regeneration.

In clinical practice to treat complex injuries, the application of electrical stimulation (ES) directly to the skin complicates the wound. In this work, the effect of a conductive hydrogel mediated electric field on skin regeneration is investigated. Polypyrrole incorporated matrices of gelatin and silk fibroin were prepared by two-step interfacial polymerization. The maximum electrical conductivity of 10-4 S cm-1 was achieved when 200 mM polypyrrole was loaded. Mechanically stable and cytocompatible hydrogels were evidenced to have antioxidant and blood compatible characteristics. Human dermal fibroblast cells responded to pulsed stimulation of 100 or 300 mV mm-1 as observed from the increased expressions of TGFß1, αSMA, and COLIAI genes. Further, the increase in the αSMA protein expression with the magnitude of electrical stimulation also suggested transdifferentiation of the fibroblast to myofibroblast. Moreover, Raman spectroscopy identified two fingerprint regions (collagen and lipid) to differentiate ES treated and nontreated samples. Therefore, the combination of hydrogels and electrical stimulation has potential therapeutic effects for accelerating the rate of skin regeneration.

The Biomimetic Electrical Stimulation System Inducing Osteogenic Differentiations of BMSCs.

Electrical stimulation has been used clinically as an adjunct therapy to accelerate the healing of bone defects, and its mechanism requires further investigations. The complexity of the physiological microenvironment makes it challenging to study the effect of electrical signal on cells alone. Therefore, an artificial system mimicking cell microenvironment in vitro was developed to address this issue. In this work, a novel electrical stimulation system was constructed based on polypyrrole nanowires (ppyNWs) with a high aspect ratio. Synthesized ppyNWs formed a conductive network in the composited hydrogel which contained modified gelatin with methacrylate, providing a conductive cell culture matrix for bone marrow mesenchymal stem cells. The dual-network conductive hydrogel had improved mechanical, electrical, and hydrophilic properties. It was able to imitate the three-dimensional structure of the cell microenvironment and allowed adjustable electrical stimulations in the following system. This hydrogel was integrated with cell culture plates, platinum electrodes, copper wires, and external power sources to construct the artificial electrical stimulation system. The optimum voltage of the electrical stimulation system was determined to be 2 V, which exhibited remarkable biocompatibility. Moreover, this system had significant promotion in cell spreading, osteogenic makers, and bone-related gene expression of stem cells. RNA-seq analysis revealed that osteogenesis was correlated to Notch, BMP/Smad, and calcium signal pathways. It was proven that this biomimetic system could regulate the osteogenesis procedure, and it provided further information about how the electrical signal regulates osteogenic differentiations.

Effects of unconscious tactile stimuli on autonomic nervous activity and afferent signal processing.

Autonomic nervous system (ANS) is a mechanism that regulates our internal environment. In recent years, the interest in how tactile stimuli presented directly to the body affect ANS function and cortical processing in humans has been renewed. However, it is not yet clear how subtle tactile stimuli below the level of consciousness affect human heart rate and cortical processing. To examine this, subthreshold electrical stimuli were presented to the left forearm of 43 participants during an image-viewing task, and electrocardiogram (ECG) and electroencephalogram (EEG) data were collected. The changes in the R-wave interval of the ECG immediately after the subthreshold electrical presentation and heartbeat-evoked potential (HEP), the afferent signal processing of cardiac activity, were measured. The results showed that heart rate decelerated immediately after the presentation of subthreshold electrical stimuli. The HEP during stimulus presentation was amplified for participants with greater heart rate acceleration immediately after this deceleration. The magnitude of these effects depended on the type of the subthreshold tactile stimuli. The results suggest that even with subthreshold stimulation, the changes in autonomic activity associated with orienting response and related afferent signal processing differ depending on the clarity of the tactile stimuli.

Special at-rich sequence-binding protein 2 and its role in healing of the experimental mandible bone tissue defect filling with a synthetic bone graft material and electrical stimulation impact.

OBJECTIVE: Aim: The purpose of the study was to identify the role of SATB2 in healing of the experimental mandible bone tissue defect filling with a synthetic bone graft material and electrical stimulation impact. PATIENTS AND METHODS: Materials and Methods: An experiment was carried out on 48 mature male rats of the WAG population, which were divided into 4 groups. Each group included 12 experimental animals. Group 1 included rats that were modeled with a perforated defect of the lower jaw body. Group 2 included animals that were modeled with a perforated defect similar to group 1. In animals, a microdevice for electrical action was implanted subcutaneously in the neck area on the side of the simulated bone defect. The negative electrode connected to the negative pole of the battery was in contact with the bone defect. The battery and electrode were insulated with plastic heat shrink material. Group 3 included rats that were modeled with a perforated defect similar to previous groups, the cavity of which was filled with synthetic bone graft "Biomin GT" (RAPID, Ukraine). Group 4 included animals that were modeled with a perforated defect similar to groups 1-3, the cavity of which was filled with synthetic bone graft "Biomin GT" (RAPID, Ukraine). The simulation of electrical stimulation was the same as in group 2. The material for the morphological study was a fragment of the body of the lower jaw from the zone of the perforated defect. Immunohistochemical study was performed using rabbit anti-human SATB2 monoclonal antibody. RESULTS: Results: In the regenerate filling the defect in the bone tissue of the lower jaw of rats, there was an increase in SATB2 expression under conditions of electrical stimulation; filling the defect with a synthetic bone graft material; simultaneous filling the defect with a synthetic bone graft material and electrical stimulation. The most pronounced expression of SATB2 was observed under conditions of simultaneous filling the defect with a synthetic bone graft material and electrical stimulation; minimally expressed - in conditions of filling the defect with a synthetic bone graft material; moderately expressed - under conditions of electrical stimulation. In the regenerate, in cases of all treatment methods, SATB2 was expressed by immune cells, fibroblastic differon cells, osteoblasts, and in case of electrical stimulation, also by adipocytes, vascular pericytes and endothelial cells, epidermis. CONCLUSION: Conclusions: The activation of SATB2 expression identified by the authors is one of the mechanisms for stimulating reparative osteogenesis under the conditions of electrical stimulation; filling the defect with a synthetic bone graft material; simultaneous filling the defect with a synthetic bone graft material and electrical stimulation.

Clinical Applications and Future Translation of Somatosensory Neuroprostheses.

Somatosensory neuroprostheses restore, replace, or enhance tactile and proprioceptive feedback for people with sensory impairments due to neurological disorders or injury. Somatosensory neuroprostheses typically couple sensor inputs from a wearable device, prosthesis, robotic device, or virtual reality system with electrical stimulation applied to the somatosensory nervous system via noninvasive or implanted interfaces. While prior research has mainly focused on technology development and proof-of-concept studies, recent acceleration of clinical studies in this area demonstrates the translational potential of somatosensory neuroprosthetic systems. In this review, we provide an overview of neurostimulation approaches currently undergoing human testing and summarize recent clinical findings on the perceptual, functional, and psychological impact of somatosensory neuroprostheses. We also cover current work toward the development of advanced stimulation paradigms to produce more natural and informative sensory feedback. Finally, we provide our perspective on the remaining challenges that need to be addressed prior to translation of somatosensory neuroprostheses.

Improving working memory by electrical stimulation and cross-frequency coupling.

Working memory (WM) is essential for the temporary storage and processing of information required for complex cognitive tasks and relies on neuronal theta and gamma oscillations. Given the limited capacity of WM, researchers have investigated various methods to improve it, including transcranial alternating current stimulation (tACS), which modulates brain activity at specific frequencies. One particularly promising approach is theta-gamma peak-coupled-tACS (TGCp-tACS), which simulates the natural interaction between theta and gamma oscillations that occurs during cognitive control in the brain. The aim of this study was to improve WM in healthy young adults with TGCp-tACS, focusing on both behavioral and neurophysiological outcomes. Thirty-one participants completed five WM tasks under both sham and verum stimulation conditions. Electroencephalography (EEG) recordings before and after stimulation showed that TGCp-tACS increased power spectral density (PSD) in the high-gamma region at the stimulation site, while PSD decreased in the theta and delta regions throughout the cortex. From a behavioral perspective, although no significant changes were observed in most tasks, there was a significant improvement in accuracy in the 14-item Sternberg task, indicating an improvement in phonological WM. In conclusion, TGCp-tACS has the potential to promote and improve the phonological component of WM. To fully realize the cognitive benefits, further research is needed to refine the stimulation parameters and account for individual differences, such as baseline cognitive status and hormonal factors.

A bioabsorbable mechanoelectric fiber as electrical stimulation suture.

In surgical medicine, suturing is the standard treatment for large incisions, yet traditional sutures are limited in functionality. Electrical stimulation is a non-pharmacological therapy that promotes wound healing. In this context, we designed a passive and biodegradable mechanoelectric suture. The suture consists of multi-layer coaxial structure composed of (poly(lactic-co-glycolic acid), polycaprolactone) and magnesium to allow safe degradation. In addition to the excellent mechanical properties, the mechanoelectrical nature of the suture grants the generation of electric fields in response to movement and stretching. This is shown to speed up wound healing by 50% and reduce the risk of infection. This work presents an evolution of the conventional wound closure procedures, using a safe and degradable device ready to be translated into clinical practice.