Sensory Perception Thresholds Research Articles

Vitamin B5 is a context-dependent dietary regulator of nociception.

Chronic pain has an enormous impact on the quality of life of billions of patients, families, and caregivers worldwide. Current therapies do not adequately address pain for most patients. A basic understanding of the conserved genetic framework controlling pain may help us develop better, non-addictive pain therapies. Here we identify new conserved and druggable analgesic targets using tissue-specific functional genomic screening of candidate "pain" genes in the fly. From these efforts we describe 23 new pain genes for further consideration. This included Acsl, a fatty acid-metabolizing enzyme and mammalian orthologs are involved in arachidonic acid metabolism. Acsl knockdown and mutant larvae showed delayed nocifensive responses to localized and global noxious heat. Mechanistically, knockdown of Acsl reduced dendritic branching of nociceptive neurons. Surprisingly, the pain phenotype in these animals could be rescued through dietary intervention with vitamin B5, highlighting the interplay between genetics, metabolism and nutrient environment to establish sensory perception thresholds. Together, our functional genomic screening within the sensory nociceptor has identified new nociception genes that provide a better understanding of pain biology and can help guide the development of new painkillers.

Electrical Stimulation of Regenerative Peripheral Nerve Interfaces (RPNIs) Induces Referred Sensations in People With Upper Limb Loss.

Individuals with upper limb loss lack sensation of the missing hand, which can negatively impact their daily function. Several groups have attempted to restore this sensation through electrical stimulation of residual nerves. The purpose of this study was to explore the utility of regenerative peripheral nerve interfaces (RPNIs) in eliciting referred sensation. In four participants with upper limb loss, we characterized the quality and location of sensation elicited through electrical stimulation of RPNIs over time. We also measured functional stimulation ranges (sensory perception and discomfort thresholds), sensitivity to changes in stimulation amplitude, and ability to differentiate objects of different stiffness and sizes. Over a period of up to 54 months, stimulation of RPNIs elicited sensations that were consistent in quality (e.g. tingling, kinesthesia) and were perceived in the missing hand and forearm. The location of elicited sensation was partially-stable to stable in 13 of 14 RPNIs. For 5 of 7 RPNIs tested, participants demonstrated a sensitivity to changes in stimulation amplitude, with an average just noticeable difference of 45 nC. In a case study, one participant was provided RPNI stimulation proportional to prosthetic grip force. She identified four objects of different sizes and stiffness with 56% accuracy with stimulation alone and 100% accuracy when stimulation was combined with visual feedback of hand position. Collectively, these experiments suggest that RPNIs have the potential to be used in future bi-directional prosthetic systems.

Behavioral paradigm for the evaluation of stimulation-evoked somatosensory perception thresholds in rats.

Intracortical microstimulation (ICMS) of the somatosensory cortex via penetrating microelectrode arrays (MEAs) can evoke cutaneous and proprioceptive sensations for restoration of perception in individuals with spinal cord injuries. However, ICMS current amplitudes needed to evoke these sensory percepts tend to change over time following implantation. Animal models have been used to investigate the mechanisms by which these changes occur and aid in the development of new engineering strategies to mitigate such changes. Non-human primates are commonly the animal of choice for investigating ICMS, but ethical concerns exist regarding their use. Rodents are a preferred animal model due to their availability, affordability, and ease of handling, but there are limited choices of behavioral tasks for investigating ICMS. In this study, we investigated the application of an innovative behavioral go/no-go paradigm capable of estimating ICMS-evoked sensory perception thresholds in freely moving rats. We divided animals into two groups, one receiving ICMS and a control group receiving auditory tones. Then, we trained the animals to nose-poke - a well-established behavioral task for rats - following either a suprathreshold ICMS current-controlled pulse train or frequency-controlled auditory tone. Animals received a sugar pellet reward when nose-poking correctly. When nose-poking incorrectly, animals received a mild air puff. After animals became proficient in this task, as defined by accuracy, precision, and other performance metrics, they continued to the next phase for perception threshold detection, where we varied the ICMS amplitude using a modified staircase method. Finally, we used non-linear regression to estimate perception thresholds. Results indicated that our behavioral protocol could estimate ICMS perception thresholds based on ~95% accuracy of rat nose-poke responses to the conditioned stimulus. This behavioral paradigm provides a robust methodology for evaluating stimulation-evoked somatosensory percepts in rats comparable to the evaluation of auditory percepts. In future studies, this validated methodology can be used to study the performance of novel MEA device technologies on ICMS-evoked perception threshold stability using freely moving rats or to investigate information processing principles in neural circuits related to sensory perception discrimination.

Removal of 4-Ethylphenol and 4-Ethylguaiacol, from Wine-like Model Solutions, by Commercial Modified Activated Carbons Produced from Coconut Shell

When present in high concentrations in red wine, 4-ethylphenol (4-EP) and 4-ethylguaiacol (4-EG) are responsible for the introduction of unpleasant aromas, which causes wine depreciation. The work presented concerns the performance of textural and chemical-modified activated carbons (ACs), produced from coconuts shells, in the treatment of spoiled wines. ACs were submitted to basic and acid treatment, by impregnation into solutions containing NaOH and HNO3, respectively. Modified ACs showed only a small, but noticeable, increase in apparent surface area and micropore volume when compared to the original AC. However, the surface chemistry underwent significant changes. The ability of modified ACs to remove 4-EP and 4-EG, which cause the off-flavor known as “Brett character”, from wine-like solutions has been successfully achieved. On the systems studied, 4-EG was retained in greater extension, but 4-EP was retained more strongly on the surface of the ACs. Ethanol was found to compete with 4-EP and 4-EG for the adsorptive centres. However, when 4-EP and 4-EG were present in the same solution, the addition of ethanol promoted a cooperative effect and favoured the adsorption of both compounds. It should be noted that the modified ACs were able to eliminate 4-EP and 4-EG to levels below their sensory perception thresholds referred for red wine.

Change of Fibroblast Growth Factor 21 Level Correlates with the Severity of Diabetic Sensory Polyneuropathy after Six-Week Physical Activity.

Diabetic neuropathy (DN) is a very frequent microvascular complication of type 2 diabetes mellitus (T2DM). Obesity and physical inactivity are well-known risk factors for T2DM. Fibroblast growth factor 21 (FGF21) is a liver-secreted hormone with several beneficial effects on obesity-related metabolic disorders. We aimed to investigate the effect of short-term physical activity on the levels of FGF21, and its correlation with the severity of peripheral sensory polyneuropathy in T2DM patients. Thirty patients with DN were enrolled in the study, compared to age- and gender-matched controls. We conducted a six-week aerobic training program, which meant treadmill and cycle ergometers three times a week. Anthropometric and laboratory parameters were measured for each patient before and after intervention. Serum levels of FGF21, TNF-alpha, irisin, leptin and adiponectin were measured by ELISA. The sensory perception threshold (CPT) was quantitatively measured using Neurometer®. We found significant decreases in BMI, waist circumference, HbA1c and TNF-alpha levels. From baseline to six-week follow-up, FGF21 levels were significantly increased in DN patients. Significant negative correlations were shown between the changes in FGF21 levels and BMI, between changes in FGF21 and the improvement of CPT values, and between the changes in FGF21 and TNF-alpha levels. There was no difference in irisin, adiponectin and leptin levels in DN patients after aerobic training program. The physical activity may increase the level of FGF21 in T2DM patients with neuropathy. Our results highlight the importance of regular physical activity in the treatment of diabetic neuropathy.

Sensory Thresholds and Peripheral Nerve Responses in Chronic Tension-Type Headache and Neuropsychological Correlation.

Chronic tension-type headache (CTTH) is a common disease with no fully defined pathophysiological processes. We designed a study to value electrophysiological responses in these patients and their correlation with possible psychopathological manifestations in order to deepen understanding of central and peripheral mechanisms of CTTH. In 40 patients with CTTH and 40 healthy controls, we used electrical stimulation to determine sensory threshold (SPT) and pain perception threshold (PPT) and the characteristics of the electrophysiological sensory nerve action potential (SNAP): initial sensory response (ISR) and supramaximal response (SMR). We then calculated the intensity differences between thresholds (IDT), namely SPT-PPT, ISR-SMR and SMR-PPT, and correlated these IDTs with psychological characteristics: trait and state anxiety, depression, and emotional regulation. The SPT, together with the ISR and SMR thresholds, were higher (p < 0.01) in CTTH patients. The SMR-PPT IDT was smaller and correlated with significantly higher indicators of depression, state and trait anxiety, and poorer cognitive reappraisal. CTTH patients have less capacity to recognize non-nociceptive sensory stimuli, greater tendency toward pain facilitation, and a poor central pain control requiring higher stimulation intensity thresholds to reach the start and the peak amplitude of the SNAP. This is consistent with relative hypoexcitability of the Aβ nerve fibers in distant regions from the site of pain, and therefore, it could be considered a generalized dysfunction with a focal expression. Pain facilitation is directly associated with psychological comorbidity.

Will repeated Intense Pulsed Light (IPL) treatment sessions affect facial skin sensitivity? Results of a twelve-Month, prospective, randomized split-face study.

Despite the widespread use of intense pulsed light (IPL) technology in cosmetic dermatology, the effects of its repeated use on facial skin sensitivity in healthy individuals remains unknown. Seventeen healthy female volunteers were included in the study. We measured objective biophysical parameters of the skin, including transepidermal water loss (TEWL), skin glossiness, thickness and density of the epidermis and dermis, sensory nerve current perception threshold (CPT), and regional blood flow before and after treatment at different time points. Sixteen volunteers completed a follow-up of 12months. The treated side of the face showed a decreased TEWL on D1 and D3, which reverted to normal on D7. Epidermal thickness increased and skin glossiness decreased on the treated side on D1, but returned to normal on D3. We found no statistically significant differences in CPT values or in regional blood flow volume and velocity, with the exception of D1, which exhibited a higher regional blood flow volume on the treated side. Repeated IPL treatments had no effects on facial skin barrier function, skin nerve sensitivity, or local microcirculation among healthy individuals. IPL is a safe skin care procedure that does not affect skin sensitivity.

Sustainable Effects of Human Dental Pulp Stem Cell Transplantation on Diabetic Polyneuropathy in Streptozotocine-Induced Type 1 Diabetes Model Mice.

Dental pulp stem cells (DPSCs) are suitable for use in regenerative medicine. Cryopreserved human DPSCs (hDPSCs) ameliorate diabetic polyneuropathy, and the effects of hDPSC transplantation are related to VEGF and NGF secretion. This study evaluated the long-term effects of a single transplantation of hDPSCs on diabetic polyneuropathy. hDPSCs were obtained from human third molars extracted for orthodontic treatment, which were then transplanted into the unilateral hindlimb skeletal muscles 8 weeks after streptozotocin injection in nude mice. The effects of hDPSC transplantation were analyzed at 16 weeks post-transplantation. DPSC transplantation significantly improved delayed nerve conduction velocity, decreased blood flow, and increased sensory perception thresholds. Furthermore, the hDPSC-conditioned medium promoted the neurite outgrowth of dorsal root ganglion neurons. In conclusion, the therapeutic effects of hDPSC transplantation with a single injection last for prolonged periods and may be beneficial in treating long-term diabetic polyneuropathy.

C-tactile touch perception in patients with chronic pain disorders.

Slow brushing over the skin activates C-tactile nerve fibers that transmit pleasant tactile experiences in healthy subjects, leading to an inverted U-shaped velocity dependence of ratings: C-tactile optimal stroking stimulations are rated as more pleasant than slower or faster stimulations. Chronic pain diseases such as postherpetic neuralgia (PHN) and complex regional pain syndrome show altered C-fiber innervation density, sensory loss, and pain sensitization. We aimed to investigate whether C-tactile function is affected in painful conditions. We assessed psychophysically C-tactile function and sensory perception thresholds in 16 patients with PHN, 19 patients with complex regional pain syndrome, and 22 healthy controls. Assessment of C-tactile function showed a significantly altered perceived pleasantness of CT stimulation between healthy controls and patients with chronic pain. In specific, tactile stimulation was perceived less pleasant on the affected and contralateral side when compared with controls. In patients with PHN, velocity-dependent pleasantness ratings could not be obtained, suggesting highly impaired C-tactile function with functional loss of pleasant touch perception. In conclusion, this is the first report of impaired C-tactile function in patients with PHN. Reduced pleasantness resulting from gentle touch can reflect defective C-fiber function or result from central nervous system effects in a chronic pain state.

Transplantation of human dental pulp stem cells ameliorates diabetic polyneuropathy in streptozotocin-induced diabetic nude mice: the role of angiogenic and neurotrophic factors

BackgroundDental pulp stem cells (DPSCs) have high proliferation and multi-differentiation capabilities that maintain their functionality after cryopreservation. In our previous study, we demonstrated that cryopreserved rat DPSCs improved diabetic polyneuropathy and that the efficacy of cryopreserved rat DPSCs was equivalent to that of freshly isolated rat DPSCs. The present study was conducted to evaluate whether transplantation of cryopreserved human DPSCs (hDPSCs) is also effective for the treatment of diabetic polyneuropathy.MethodshDPSCs were isolated from human impacted third molars being extracted for orthodontic reasons. Eight weeks after the induction of diabetes in nude mice, hDPSCs (1 × 105/limb) were unilaterally transplanted into the hindlimb skeletal muscle, and vehicle (saline) was injected into the opposite side as a control. The effects of hDPSCs were analyzed at 4 weeks after transplantation.ResultshDPSC transplantation significantly ameliorated reduced sensory perception thresholds, delayed nerve conduction velocity, and decreased the blood flow to the sciatic nerve in diabetic mice 4 weeks post-transplantation. Cultured hDPSCs secreted the vascular endothelial growth factor (VEGF) and nerve growth factor (NGF) proteins. A subset of the transplanted hDPSCs was localized around the muscle bundles and expressed the human VEGF and NGF genes at the transplanted site. The capillary/muscle bundle ratio was significantly increased on the hDPSC-transplanted side of the gastrocnemius muscles in diabetic mice. Neutralizing antibodies against VEGF and NGF negated the effects of hDPSC transplantation on the nerve conduction velocity in diabetic mice, suggesting that VEGF and NGF may play roles in the effects of hDPSC transplantation on diabetic polyneuropathy.ConclusionsThese results suggest that stem cell transplantation with hDPSCs may be efficacious in treating diabetic polyneuropathy via the angiogenic and neurotrophic mechanisms of hDPSC-secreted factors.

Abstract 100: Restoration Of Proprioceptive And Cutaneous Sensation Using Regenerative Peripheral Nerve Interfaces (RPNIs) In Humans With Upper-limb Amputations

Purpose: Without meaningful and intuitive sensory feedback, even the most advanced prosthetic devices remain insensate, burdensome, and are associated with enormous cognitive demand. To provide a bidirectional motor and sensory neural interface, we have developed the Regenerative Peripheral Nerve Interface (RPNI). An RPNI consists of a free muscle graft that is reinnervated by a transected peripheral nerve. In previous human studies, RPNI’s have demonstrated stable high amplitude motor EMG signals with high signal to noise ratio for prosthetic control, and have been used to treat and prevent neuroma pain. In this study, we investigate if applying electrical stimulation through the RPNIs can produce meaningful proprioceptive and/or tactile sensations in participants with upper-limb amputations. Materials and Methods: Two distal transradial participants underwent surgical implantation of RPNIs for treatment of neuroma pain. One RPNI was created on each of the median and ulnar nerve for participant 1, while participant 2 had two RPNIs created on the ulnar nerve and one on the median nerve. The RPNIs were stimulated with a monopolar, charge balanced, biphasic square wave using intramuscular bipolar electrodes. To determine the sensory perception threshold, a stepwise increment of 0.1 mA was used at a constant 20 Hz frequency and 200 µS pulse-width. Stimulation lasted for 1 to 2 seconds for each increment. After each increment, participants were asked to report the sensations they felt. Once a sensation was felt, the amplitude was decremented until the sensation stopped, and then increased until a sensation was felt again. Amplitudes were then marked as the perception threshold. After a threshold was determined, amplitudes were increased until participants could clearly perceive the sensation. Participants then reported the location of the sensation on their phantom limb using their contralateral intact hand, and a description of the invoked sensation. Results: Stimulation of the RPNIs resulted in both participants reporting proprioceptive sensations in their phantom limb. In particular, stimulation of the median nerve RPNI activated a flexing sensation in the thumb or index finger of participant 1, while stimulation of the ulnar nerve RPNI invoked a flexing sensation of the ring or small finger. Likewise, during stimulation of ulnar nerve RPNI 1, participant 2 felt a flexed sensation at the ring finger distal interphalangeal (DIP) joint, specifically describing that only the DIP joint was being flexed on the phantom ring finger. Stimulation of the ulnar nerve RPNI 2 and the median nerve RPNI resulted in cutaneous sensations that corresponded to the dermatome of their respective nerve. Sensory stimulation thresholds remained stable across 7 and 11 months with an average amplitude of 1.27 ± 0.52 mA for participant 2, and 0.98 ± 0.04 mA for participant 1, respectively. Conclusions: These results suggest that RPNIs have the potential to restore proprioceptive and skin-referred sensory feedback that could improve prosthesis motor performance, producing a stable bidirectional interface for advanced prosthesis control.

Sensory perception testing by monofilaments in the digits of controls and workers with HAVS

ObjectiveTo determine if heavy manual work affects sensory perception in the digits and whether Semmes–Weinstein monofilaments (SWM) can be used as a screening tool to detect sensory neuropathy in the digits of workers exposed to hand-transmitted vibration (HTV).MethodsA cross-sectional study of office workers, heavy manual workers not exposed to HTV and workers with hand-arm vibration syndrome (HAVS). Sensory perception was measured in the digits by SWM using a forced-choice method to determine variability by sex, age, hand and digit. Frequency distributions were used to determine limit values and linear weighted kappa for intra-digit variability. Poisson regression was used to explore the relationship between sensory perception by SWM and abnormalities of thermal and vibration perception in the hands of workers with HAVS.ResultsThe sensory perception threshold of office workers did not vary by hand or digit. It was significantly lower in women < 30 than women aged ≥ 30 years. The 95th percentile for heavy manual workers was 1.00 (95% CI 0.60–1.00) and significantly higher than for office workers at 0.16 (95% CI 0.16–0.16). Heavy manual workers > 50 years had the highest threshold at 1.40 (95% CI 1.00–2.00). Weighted kappa for reliability was 0.63 (95% CI 0.53–0.70). A mean SWM threshold of ≥ 1.0 gram-force had a 79% sensitivity and 64% specificity for detecting abnormalities of thermal and vibration perception in the ipsilateral index and little fingers of workers with HAVS.ConclusionsSWM are a useful screening tool for detecting sensory loss in the digits of workers exposed to HTV.

Volatile metabolites, quality and sensory parameters of “Ferrovia” sweet cherry cold stored in air or packed in high CO2 modified atmospheres

Volatile organic compounds, quality and sensory attributes of sweet cherry cv “Ferrovia”, cold packaged in Air or in different modified atmospheres (Low-O2 = 1% O2/0.03% CO2; High-CO2 = 16% O2/20% CO2; Mix = 1% O2/20% CO2), were monitored until 21 days of conservation. Results showed that sweet cherry cv “Ferrovia” is sensitive to CO2 accumulation (over 20%) in low oxygen (about 1%) modified atmosphere, as showed by the increase in respiration rate, biosynthesis of fermentative volatile metabolites, and sensory perception of off-odours. However, High-CO2 treatment seemed to preserve quality and sensory traits, presumably due to the high initial concentration of O2 (16%) that could limit the synthesis of ethyl esters and γ-butyrolactone, keeping the accumulation of off-flavours below their sensory perception threshold. Finally, PLSR analysis allowed to select 1-pentanol as putative marker of sensory alteration and hexanal and 2-hexenal as possible predictors of freshness for “Ferrovia” sweet cherries.

(437) Comparison of quantitative sensory testing and current perception threshold testing results in patients with chronic pain following lower extremity fracture and healthy controls

(437) Comparison of quantitative sensory testing and current perception threshold testing results in patients with chronic pain following lower extremity fracture and healthy controls

Quantitative Sensory Testing in adults with Autism Spectrum Disorders.

Altered sensory perception has been found in patients with autism spectrum disorders (ASD) and might be related to aberrant sensory perception thresholds. We used the well-established, standardized Quantitative sensory testing (QST) protocol of the German Research Network on Neuropathic Pain to investigate 13 somatosensory parameters including thermal and tactile detection and pain thresholds in 13 ASD adults and 13 matched healthy controls with normal IQ values. There were no group differences between somatosensory detection and pain thresholds. Two ASD patients showed paradoxical heat sensations and another two ASD subjects presented dynamic mechanical allodynia; somatosensory features that were absent in controls. These findings suggest that central mechanisms during complex stimulus integration rather than peripheral dysfunctions probably determine somatosensory alterations in ASD.

Pelvic floor dysfunction and sensory impairment: Current evidence.

To explore the role of sensory nerve impairment in women with pelvic organ prolapse, painful bladder syndrome, urinary and fecal incontinence, and sexual dysfunction. Medline and Embase were searched for articles in which sensory testing, either quantitative sensory testing or current perception thresholds, had been used to evaluate women with pelvic organ prolapse, stress and urge urinary incontinence, fecal incontinence and female sexual dysfunction. All search terms were expanded within each database prior to searching. Research to date has included small numbers of participants, used poorly matched controls, lacked a systemic sensory examination and applied non-standardized sensory testing techniques. However, the evidence suggests women with pelvic organ prolapse demonstrate sensory dysfunction. The role of sensory impairment in stress urinary incontinence is inconclusive. In women with urge urinary incontinence there is some evidence to suggest it may be urethrally mediated. Women with painful bladder syndrome may have more sensitive nerve endings which are unable to ignore repeated stimuli. Sensory impairment is common in women with sexual dysfunction, typically involving larger nerve fibres. There were no studies evaluating sensory function in women with fecal incontinence. Current evidence suggests women with pelvic floor dysfunction demonstrate sensory impairment though the causes remain unclear. Further studies are needed to investigate the different conditions of pelvic floor dysfunction using standardized sensory testing techniques, as well as evaluate the timing and mechanism by which any sensory impairment develops. Neurourol. Urodynam. 36:550-556, 2017. © 2016 Wiley Periodicals, Inc.

Arsenic groundwater contamination and its health effects in Patna district (capital of Bihar) in the middle Ganga plain, India

We investigated the extent and severity of groundwater arsenic (As) contamination in five blocks in Patna district, Bihar, India along with As in biological samples and its health effects such as dermatological, neurological and obstetric outcome in some villages. We collected 1365 hand tube-well water samples and analyzed for As by the flow injection hydride generation atomic absorption spectrometer (FI-HG-AAS). We found 61% and 44% of the tube-wells had As above 10 and 50 μg/l, respectively, with maximum concentration of 1466 μg/l. Our medical team examined 712 villagers and registered 69 (9.7%) with arsenical skin lesions. Arsenical skin lesions were also observed in 9 children of 312 screened. We analyzed 176 biological samples (hair, nail and urine). Out of these, 69 people had arsenical skin lesions and rest without skin lesions. We found 100% of the biological samples had As above the normal levels (concentrations of As in hair, nail and urine of unexposed individuals usually ranges from 20 to 200 μg/kg, 20–500 μg/kg and <100 μg/l, respectively), indicating many people are sub-clinically affected. Arsenical neuropathy was observed in 40.5% of 37 arsenicosis patients with 73.3% prevalence for predominant sensory neuropathy and 26.7% for sensor-motor. Among patients, different clinical and electrophysiological neurological features and abnormal quantitative sensory perception thresholds were also noted. The study also found that As exposed women with severe skin lesions had adversely affected their pregnancies. People including children in the affected areas are in danger. To combat As situation in affected areas, villagers urgently need (a) provision of As-safe water for drinking and cooking, (b) awareness about the danger of As toxicity, and (c) nutritious food.

Short Term Sensory and Cutaneous Vascular Responses to Cold Water Immersion in Patients with Distal Radius Fracture (DRF)

Study Design: Repeated Measures. Objectives: To determine the short term impact of cold water immersion on sensory and vascular functions in patients with Distal Radius Fracture (DRF) and compare responses in the injured and uninjured hands. Background: Cold exposure is used to assess neurovascular function. Cold is also used as therapeutic agent to reduce pain and swelling. There is a scarcity of trials that have looked at the impact of cold exposure in patients with DRF. Methods: Twenty patients with DRF, aged 18 to 65 yrs. were recruited after cast removal. All patients underwent Immersion in Cold water Evaluation (ICE) which consisted of 5 min of hand immersion in water at 12°C. Skin Blood Flow (SBF) in hands, Skin Temperature (S Temp.) in index and little fingers and sensory Perception Thresholds (sPT) at 2000Hz (for Aβ fiber) and 5 Hz (for C fiber) were obtained from ring finger, before ICE, immediately after (0 min, 1 min) and 10 min later. Differences were analyzed using repeated measures.

Changes in Sensory Function After Transcranial Direct Current Stimulation on Primary Motor Cortex Area

Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers low-intensity direct current to cortical areas, thereby facilitating or inhibiting spontaneous neuronal activity. This study was designed to investigate changes in various sensory functions after tDCS. We conducted a single-center, single-blinded, randomized trial to determine the effect of a single session of tDCS with the current perception threshold (CPT) in 50 healthy volunteers. Nerve conduction studies were performed in relation to the median sensory and motor nerves on the dominant hand to discriminate peripheral nerve lesions. The subjects received anodal tDCS with 1 mA for 15 minutes under two different conditions, with 25 subjects in each groups: the conditions were as follows tDCS on the primary motor cortex (M1) and sham tDCS on M1. We recorded the parameters of the CPT a with Neurometer(R) at frequencies of 2000, 250, and 5 Hz in the dominant index finger to assess the tactile sense, fast pain and slow pain, respectively. In the test to measure CPT values of the M1 in the tDCS group, the values of the distal part of the distal interphalangeal joint of the second finger statistically increased in all of 2000 Hz (p=.000), 250 Hz (p=.002), and 5 Hz (p=.008). However, the values of the sham tDCS group decreased in all of 2000 Hz (p=.285), 250 Hz (p=.552), and 5 Hz (p=.062), and were not statistically significant. These results show that M1 anodal tDCS can modulate sensory perception and pain thresholds in healthy adult volunteers. The study suggests that tDCS may be a useful strategy for treating central neurogenic pain in rehabilitation medicine.

Proteome analysis of stratum corneum from atopic dermatitis patients by hybrid quadrupole-orbitrap mass spectrometer

Proteome analysis of stratum corneum from atopic dermatitis patients by hybrid quadrupole-orbitrap mass spectrometer