BACKGROUND:Neuropathic Pain (NP) is a chronic pain caused by damage to the nervous system, often manifested as spontaneous pain, pain allergy and abnormal pain. Cold abnormal pain is one of the common manifestations of neuropathic pain, which seriously affects the quality of life of patients. Lumbar sympathetic nerve resection has been widely used to treat lower limb pain, but its specific mechanism in cold abnormal pain is not yet clear. MATERIALS:A chronic constriction injury (CCI) of the sciatic nerve model and a lumbar sympathectomy (LS) model were established to investigate the effect of LS on abnormal cold pain in CCI rats and its molecular mechanism. The effect of LS on cold allodynia in CCI rats was observed through behavioral tests, including the measurement of mechanical pain threshold, the acetone cold stimulation test, and the cold plate test. The changes in the levels of differentially expressed genes in CCI rats after LS were further observed by transcriptome sequencing (bulk RNA-seq). RESULT:Through behavioural experiments and transcriptome sequencing (bulk RNA-Seq) analysis, we found that lumbar sympathectomy (LS) significantly alleviated cold allodynia, cold-evoked allodynia and cold pain sensitivity in CCI rats, and changed the spinal cord transcriptome, including pathways related to inflammatory signal transduction and tissue remodelling. The functional enrichment analysis of differential expression genes (DEGs) revealed a number of signalling pathways associated with pain regulation. This study provides a new molecular biological basis for the application of LS in alleviating cold abnormal pain.
OBJECTIVE:To evaluate physical activity and balance in children with OBPP (Obstetric Brachial Plexus Palsy) and investigate the relationship between these variables. PARTICIPANTS AND SETTING:The study included 58 children with OBPP and 58 healthy controls aged 7-12 years. METHODS:Physical activity was measured using the Physical Activity Questionnaire for Children (PAQ-C). Dynamic balance was evaluated with the Y Balance Test (YBT), and static balance was assessed using the One-Leg Standing (OLS) test. Outcome measures included scores from these assessments and group comparisons. RESULTS:Children with OBPP showed significant deficits in dynamic balance, particularly in the posterolateral direction (p < 0.05), while static balance and physical activity levels did not differ significantly between groups (p > 0.05). Logistic regression identified the left posterolateral balance score as a significant positive predictor for group classification (p < 0.001). CONCLUSION:Children with OBPP experience significant impairments in dynamic balance, emphasizing the need for targeted interventions to address postural control and lateral stability. Comprehensive assessments incorporating physical activity and balance measures are crucial for developing effective rehabilitation strategies.
Aim of the study: To characterize differences in somatosensory gating associated with maturation, we compared the amplitude ratio of responses to the second stimulus (S2) over the first stimulus (S1) between adolescents and young adults using a paired-pulse stimulation paradigm while recording somatosensory-evoked potentials (SEPs). Methods: Thirteen right-handed adolescent males (14.1 ± 0.3 yrs) and twenty-four adult males (21.2 ± 1.2 yrs) participated. We focused on SEP components at Fz and C3', and sensory gating for each component was quantified as the S2/S1 amplitude. Components showing significant gating were identified within each group. Subsequently, S2/S1 amplitude ratios between groups and bivariate correlations among gated components were examined. Results: Adolescents showed significant gating for N30 at Fz and P22 and P45 at C3', and adults showed significant gating for N30 at Fz and P22 and N60 at C3'. The S2/S1 amplitude ratios for N30 at Fz and P45 at C3' were significantly smaller in adolescents than adults, whereas other components did not differ. Correlations among S2/S1 amplitude ratios were not significant in either group, suggesting component-specific mechanisms. Conclusions: Adolescents showed stronger frontal N30 gating and a different centroparietal pattern relative to adults, suggesting immature and region-specific inhibitory processes. The absence of correlations among S2/S1 ratios supports the presence of partially independent generator and neurochemical mechanisms across SEP components. These findings provide a developmental profile of somatosensory gating.
OBJECTIVE:Light touch sensitivity of the foot sole is typically measured when individuals are seated or lying down; yet, a critical function of the foot sole is to support cutaneous feedback during standing and walking activities. The objective of this study was to evaluate how individuals perceive light touch stimulation across the foot sole while in different postures including standing. METHODS:We measured light touch perceptual threshold (LTPT) in standing, seated, and supine postures in 19 volunteers (10 females, 9 males), using Semmes-Weinstein Monofilaments. Perceptual thresholds were calculated at three foot sole locations (1st metatarsal, lateral arch, and heel) in each posture. RESULTS:Perceptual thresholds were significantly higher in the standing condition compared to the seated and supine conditions across all foot locations; perceptual thresholds were significantly higher while seated compared to supine only at the heel and not at the lateral arch or 1st metatarsal. Our results demonstrate that postural changes significantly influence sensitivity across the foot sole. CONCLUSION:Performing perceptual threshold assessments of the foot sole while standing may offer more relevant insights into the capacity of foot sole cutaneous afferents to convey light touch information in conditions where such feedback plays a vital role in maintaining balance.
AIM:Hemispheric asymmetry is well established in tactile processing, with higher cortical responses observed on the contralateral side of the stimulation area. However, the effect of the interstimulus interval on lateralization is poorly understood. In this context, we aimed to reveal the effects of repeated non-painful tactile stimuli on brain responses and hemispheric lateralization via static ISIs. METHODS:Twenty-six healthy participants (13 females; mean age 22.2 ± 3.30 years) participated in the study. Tactile stimuli were delivered to the index fingertip of the right hand via a pneumatic stimulator with static ISIs (2s, 4s, and 8s applied as separate sessions). Electroencephalography was performed throughout the procedure. We determined the ROI and primarily analysed nine electrodes (Fz, Cz, Pz, F3, C3, P3, F4, C4, and P4). We measured the peak-to-peak maximum amplitudes (PPmaxN2P3) between N200 and P300, labelling N200 as N2 and P300 as P3. RESULTS:The results revealed no significant differences in the amplitudes of PPmaxN2P3 between the ipsilateral and contralateral hemispheres. Constant ISI manipulation altered the laterality of non-painful tactile stimuli. Furthermore, the amplitude of the brain responses would be higher in both the ipsilateral and contralateral hemispheres when the ISI increased. The evaluation of the duration of PPmaxN2P3 was prolonged in the frontal, central, and parietal areas. CONCLUSION:The results indicate that manipulation of the interstimulus interval (ISI) can potentially negate the traditional contralateral advantage observed in tactile processing.
The maintenance of proprioception in upright standing posture and joint position sense accuracy (JPSA), is contingent on the coordination of sensory inputs made available to individuals during the task. Adding texture to augment cutaneous feedback on neuromuscular control of the ankle joint has yet to be studied in JPSA, thus motivating the purpose of this research to investigate the changes in ankle joint proprioception when wearing textured (FOTs) and non-textured orthoses (FOs) during a passive ankle joint position reproduction task in healthy young and middle-aged individuals (n = 48; 31 under 30 years, 17 over 30 years). Error accuracy, tibialis anterior and medial gastrocnemius muscle activity, and centre of pressure displacement were recorded from 48 participants while completing four ankle JPSA replication tasks (5°, 10° plantarflexion, 5°, 10° dorsiflexion) in stance. When the middle-aged participants (over 30 years) completed the dorsiflexion 5° JPSA task, a 31% error reduction was observed standing in FOTs compared to FOs. These results provide evidence supporting the effectiveness of adding cutaneous feedback to improve proprioception in middle-aged individuals.
Often, somatosensory and motor symptoms frequently co-occur in individuals with neurological conditions. These two systems exert reciprocal influences on one another; thus, an effective neurological rehabilitation protocol in clinical practice should concurrently address both motor and sensory assessment and training procedures. Although neurological rehabilitation guidelines emphasize the motor and sensory systems, it is valuable to examine contemporary approaches to their assessment and rehabilitation separately and in detail. In this review, we synthesize current neurological rehabilitation strategies for Stroke, Multiple Sclerosis, and Parkinson's Disease. In addition to outlining the clinical presentation of these pathologies, we provide a comprehensive overview of motor and sensory assessment methods as well as current rehabilitation approaches.
PURPOSE:To investigate the effects of Marmara propolis on the duration of sensory, deep sensory, and motor block recovery when used alone or in combination with bupivacaine in a rat sciatic nerve block model. MATERIALS AND METHODS:Thirty-two Wistar-Albino rats were randomly divided into four groups (n = 8): Group Bupivacaine (Group B) received 0.2 mL of 0.5% bupivacaine perineurally; Group Propolis (Group P) received 30 mg/kg of Marmara propolis (0.2 ml) perineurally; Group Bupivacaine + Propolis (Group BP) received a combination of 0.2 mL bupivacaine and 30 mg/kg propolis perineurally; Group Bupivacaine + Propolis intraperitoneally (Group BPip) received 0.2 mL bupivacaine perineurally and 30 mg/kg propolis intraperitoneally. Sensory, deep sensory, and motor function recoveries were assessed every 5 min until full recovery. RESULTS:Group BP showed significantly longer recovery times for all three modalities compared to all other groups (p < 0.001). Group BPip also demonstrated prolonged deep sensory and motor recovery times compared to Groups B and P (p < 0.001). Group P exhibited the shortest recovery times across all measurements. CONCLUSIONS:Marmara propolis, particularly when used in combination with bupivacaine, prolongs sensory, deep sensory, and motor block durations. These findings suggest that propolis may have both local and systemic adjuvant effects in regional anaesthesia applications.HIGHLIGHTS OF THE STUDYMarmara propolis significantly prolonged sensory, deep sensory, and motor block durations when administered perineurally in a rat sciatic nerve block model.Intraperitoneal administration of propolis also resulted in prolonged deep sensory and motor block recovery, indicating systemic analgesic activity.The combination of bupivacaine and propolis produced the longest block durations, suggesting a synergistic or adjuvant effect.This is the first study to investigate both local and systemic applications of propolis as an adjunct to regional anaesthesia.Findings support the potential use of propolis as a natural, plant-based adjuvant in peripheral nerve blocks.
OBJECTIVE:To investigate the relationship between newly identified senataxin (SETX) gene mutations and the clinical manifestation of Amyotrophic Lateral Sclerosis (ALS), enhancing understanding of the genetic underpinnings associated with this disorder. METHODS:A cohort study was conducted at Nanfang Hospital, involving comprehensive genetic sequencing of ALS patients to identify novel SETX mutations. Homology modelling and structural analysis were employed to predict the functional impacts of these mutations on the senataxin protein. Clinical assessments, including symptom evaluation, age of onset, and progression rate, were integrated with electrophysiological studies to establish correlations between genetic variants and clinical outcomes. RESULTS:Ten novel SETX mutations were identified, expanding the genetic landscape of ALS. These mutations exhibited diverse impacts on clinical presentations, with patients showing variability in onset age, symptom severity, and progression rates. Computational modelling suggested that certain mutations cause significant structural changes in senataxin, potentially affecting its RNA/DNA helicase function. Electrophysiological findings consistently revealed nerve conduction abnormalities, indicating that these mutations may influence neuronal excitability and contribute to ALS pathogenesis. CONCLUSION:The discovery of novel SETX mutations provides valuable insights into the genetic and clinical complexity of ALS. This study underscores the importance of genetic screening for SETX mutations and suggests potential personalised therapeutic approaches targeting senataxin dysfunction. By elucidating genotype-phenotype correlations, these findings contribute to the broader understanding of ALS and offer pathways for developing targeted interventions to address the challenges posed by this disabling disease.
PURPOSE:The objective assessment of the upper limbs of stroke survivors is challenging. Serious game-based assessments may allow for an objective assessment of this population. The present work aims to investigate the validity of the metrics provided by the Upper Extremity Smart Exercises-Innovative Treatment (USE-IT) assessment method for upper limb rehabilitation. MATERIALS AND METHODS:Thirty-three stroke survivors were included in this study. We assessed the stroke survivors using The Fugl-Meyer Upper Extremity Scale (FM-UE), The Wolf Motor Function Test (WMFT), The Action Research Arm Test (ARAT), ABILHAND, ACTIVLIM, and the USE-IT. Validity was assessed by examining the correlation of the USE-IT metrics with the clinical scales. RESULTS:All clinical scales and the Global Reaching Map total score, one of the two outputs of the USE-IT assessment method, were found to be moderately correlated (|r| = 0.52-0.69) (p < .05). The other outputs of the USE-IT assessment method, the Local Reaching Map total score, showed a correlation with the Fugl-Meyer Assessment Upper Arm (FM-UA), The Action Research Arm Test (ARAT) Grip, and the Wolf Motor Function Test (WMFT) parameters (|r| = 0.34-0.38) (p < .05). CONCLUSIONS:This study showed that the USE-IT assessment is well correlated with commonly used clinical scales for the upper limb motor function in stroke survivors. Therefore, the USE-IT is a valid game-based system for assessing upper limb impairment in stroke survivors.
Perineuronal nets (PNNs) are specialised extracellular matrix structures of the central nervous system that predominantly surround inhibitory interneurons. The development of PNNs is activity dependent and relies on sensory input to mature to an adult expression pattern, coinciding with the crysallization of synaptic circuitry following the closure of the developmental critical period. Our results of a neocortical characterisation demonstrate that the density of PNNs in the neocortex of the Long Evans rat was consistent across animals but varied as a function of the cortical region. Utilising a non-biased random effect model, it was shown that the retrosplenial granular cortex had the highest PNN density and the intermediate endopiriform cortex had the lowest. Given the importance of mystacial vibrissae to the behaviour of rodents, we further analysed the laminar distribution of PNNs within the primary somatosensory cortex (S1). Our results revealed that the layer IV, the 'barrel' region, contained the highest density of PNNs. Within S1, PNN density was consistent across all subregions. S1 had a significantly higher density of PNNs compared with the primary motor (M1) cortex, and PNN levels did not show lateralisation in either M1 or S1. Independent of cortical location, we observed a novel class of relatively large, brightly stained neurons ensheathed by PNNs, which were present exclusively along the layer VI-white matter border. A better understanding of PNNs and their distribution can assist in our understanding of how PNN manipulation can affect neurological conditions such as schizophrenia, epilepsy, stroke, central nervous system injuries, and degenerative processes.
PURPOSE:The H reflex recruitment curve represents the gold standard for quantifying changes in spinal circuitries. However, there is no agreement on how many stimulations should be applied for each parameter. Thus, we explored the impact of varying the number of stimulations (3, 6, 9, 12 and 15 stimuli per intensity) on between-day reliability of soleus H reflex. MATERIALS AND METHODS:Twenty healthy participants (11 males, 9 females; age: 22.4 ± 2.3 years) visited the laboratory on two days for H-recruitment curves construction, using a 3 s inter-stimuli interval. To explore whether H reflex parameters differed between days, without varying the number of stimulations, paired-sample t tests were performed. Relative and absolute reliability were calculated using the intraclass correlation coefficients (ICCs) and the coefficients of variation (CVs), respectively. RESULTS:Mmax, Hmax/Mmax, H slope, Hthresh, current at 50% of Hmax and current at Hmax were not significantly different between days (all p > 0.05). ICCs of Mmax, Hmax/Mmax and Hthresh were all good (0.79-0.89). H slope ICCs were moderate (0.56-0.73) between 3 and 12, but good (0.75) with 15 stimulations. Current at Hmax ICCs were moderate (0.55-0.0.73) with all stimulations, except with 9 (good: 0.76). CVs of the current at Hmax were all moderate (between 5-to-10%). Hthresh CV was poor (>10%) with three, but moderate for other stimulations. Mmax, Hmax/Mmax and H slope CVs were generally poor. CONCLUSIONS:9 stimulations are required to ensure higher between-day reliability of H reflex parameters, except for H slope that requires 15 stimulations.
IntroductionConditioned pain modulation (CPM) allows to investigate endogenous pain modulation and its clinical outcomes. Although co-activation of emotions has been shown to affect CPM, the impact of 'threat,' which may accompany CPM stimulation itself, has been mostly neglected. A critical factor for the threat level of the conditioning stimulus (CS) may be its predictability.Methods38 healthy participants (18 female) took part in a CPM study with pressure stimulation on the leg (blood-pressure cuff) serving as CS and heat stimulation on the forearm (contact thermode; CHEPS) serving as test stimulus (TS). While CS varied in intensity and -as operationalisation of threat- in temporary predictability, TS was kept constant. CPM effects were studied by EEG parameters (N2P2) and pain ratings.ResultsWe found a significant CPM effect when considering N2P2, with low CS predictability augmenting CPM inhibition; in contrast, a surprisingly facilitatory CPM effect occurred in pain ratings (in the high CS predictability condition). The threat manipulation was only partially successful because CS intensity increased the threat ratings but not -as intended- CS predictability. Correlations between subjective and psychophysiological CPM responses were low.DiscussionThe differing CPM effects in subjective and psychophysiological responses, with both inhibitory and facilitatory effects, is puzzling but has already been observed earlier. The consideration of the CPM stimulation as major threat that is emotionally active is theoretically clearly justifiable but the operationalisation by means of different levels of CS predictability as in the present study might not have been ideal. Thus, further attempts of experimental verification are warranted.
AimThis study aimed to determine the effects of Kinesio tape applied to the plantar soles on static and dynamic balance in children with Down syndrome (DS).Materials and MethodsThe study was carried out in children with DS. The participants were grouped as Kinesio Taping (KT) (n = 12, DS) and Sham Taping (ST) (n = 12, DS). The Functional Reach Test (FRT) was used to evaluate functional balance and the Fast-Timed Up and Go (FAST-TUG) test to evaluate functional balance and capacity. The Modified Clinical test of Sensory Interaction on Balance (MCTSIB) was used to evaluate static balance. For both groups, all the assessments were made three times: at baseline (T0), right after the taping application (T1), and 40-45 minutes later (T2).ResultsBaseline FAST-TUG, FRT, and Eyes Open (EO) and Closed (EC) Sway velocity scores of the KT (medians- FAST-TUG:7.75 s, FRT:23.90 cm, EO: 0.70 deg/s, EC: 0.60 deg/s) and ST (medians-FAST-TUG:7.98 s, FRT:24 cm, EO: 0.85 deg/s, EC: 0.95 deg/s) groups were similar (p >0.05). Intragroup comparisons showed that FAST-TUG and FRT scores improved after the taping compared with T0 values in both KT (KT (FAST-TUG:7.75s-FRT:23.90cm)/KT1(FAST-TUG:7.55 s-FRT:28.25cm), KT(FAST-TUG:7.75s-FRT:23.90cm)/KT2(FAST-TUG:6.85s-FRT:27.50cm)) and ST groups (ST(FAST-TUG:7.98s-FRT:24cm)/ST1(FAST-TUG:7,95s-FRT:26.40cm), ST(FAST-TUG:7.98s-FRT:24cm)/ST2(FAST-TUG:7.26s-FRT:26.15cm)) (p < 0.05), while the sway velocity values were similar before and after the taping (p > 0.05).ConclusionsTaping on the plantar soles of children with DS may be affecting the immediate dynamic balance scores while it actually did not affect the static balance scores independent of the technique used. The interpretation of the results of this study should be made with caution. Further studies with long-term evaluations are needed.
BACKGROUND The benefits of Blood Flow Restriction Therapy (BFRT) have gained attention in recent times. OBJECTIVE This review aimed to evaluate the immediate (up to 24 hours), intermediate (up to 6 weeks), and long term (6-10 weeks) effects of BFRT plus exercises (EX) compared to EX only on athletic performance (sprint and jump performance), muscle strength, and hypertrophy in athletes and physically active population. METHODS A literature search was conducted to select randomized controlled trials across four electronic databases from inception till April 2021. The search yielded twenty-seven studies in total. RESULTS Based on eligibility criteria, twenty-one studies were analyzed. No differences were found between both groups for immediate (standardized mean difference [SMD] -0.02, 95% confidence interval [CI] -0.31, 0.27) and long-term effects (SMD -0.30, 95%CI -0.90, 0.30) on sprint performance. For jump performance, no significant effect was observed immediately (SMD -0.02 (95% CI -1.06, 1.02) and long term (SMD -0.40 (95% CI -1.46, 0.67). Similarly, muscle torque at intermediate (SMD 0.90 (95% CI -1.01, 2.81) and long term (SMD -0.54 (95% CI -1.19, 0.12), muscle strength at intermediate (SMD 1.12 (95% CI 0.20, 2.04) , and long term (SMD -0.07 (95% CI -0.56, 0.42) also showed non-significant effects. Muscle hypertrophy at intermediate (SMD 0.16 (95% CI -0.31, 0.63) and long term (SMD -0.20 (95% CI -0.90, 0.50) were not statistically significant. CONCLUSIONS There was no significant difference observed in BFRT plus EX group compared to the EX-group on athletic performance, muscle strength, and muscle hypertrophy.
PURPOSEThe aim of this study is to determine whether the 360° turn test is a reliable and valid evaluator that can be used to assess dynamic balance in patients with early (radiographic grades I and II) and advanced (radiographic grades III and IV) knee osteoarthritis.MATERIALS AND METHODSThis study is a methodological research. For the test time and step count of 360° turn test; test-retest reliability were determined by calculating the intraclass correlation coefficient and concurrent validity in patients with knee osteoarthritis was investigated by correlation with the timed up and go test time.RESULTSThe final analysis was made on 117 participants. The intraclass correlation coefficient values for the test time and step count of 360° turn test in patients with early knee osteoarthritis are 0.931 and 0.902, respectively, while they are 0.923 and 0.943 in patients with advanced knee osteoarthritis. The Pearson correlation coefficients between the time and step count of 360° turn test and the test time of the timed up and go test in patients with early knee osteoarthritis, respectively; while they are 0.547 and 0.388, the correlation in patients with advanced knee osteoarthritis are 0.697 and 0.700, respectively (p < 0.01).CONCLUSIONSThe 360° turn test is a evaluator that has excellent test-retest reliability and moderate to strong concurrent validity in patients with both early and advanced knee osteoarthritis and can be used in the assessment of dynamic balance in this population.
INTRODUCTION Multiple Sclerosis Intimacy and Sexuality Questionnaire-19 (MSISQ-19) explores optimally impact of MS on sexual activity/satisfaction/intimacy. AIM The present study aims to provide the only validation of the Greek Version of MSISQ-19, and compare results to validation studies in other languages. METHODS The original/English version of the MSISQ-19 was translated into Greek according to standardized guidelines, while validity/reliability, correlations with other scales and sexual dysfunction prevalence were tested. Subjects were requested to complete all questionnaires and MSISQ-19, being re-tested three weeks later. Construct-validity of the Greek version of the MSISQ-19 was confirmed with principal-component-analysis. Bartlett's test assessed correlation-adequacy between items. Pearson's correlation explored internal-construct-validity between subscales and overall score, and external-construct-validity with disease-status variables, cognitive testing and patient-reported outcomes regarding fatigue, depression/anxiety, MS impact, and quality of life. RESULTS 201 PwMS (130 female). Mean age was 39.3 ± 11.8 years with median disease-duration 11.7 ± 7.9 years. 79.1% RRMS, PPMS (10.4%) and SPMS (10.4%). Cronbach's alpha coefficient was 0.949. MSISQ-19 correlations between items were large. Significant associations of sexual dysfunction were identified with age (rho = 0.392, p < 0.01), years of education (rho=-0.199, p = 0.006), the Expanded Disability Status Scale (rho = 0.518, p < 0.01) and MS duration (rho = 0.354, p < 0.01). Correlations were disclosed with the Brief International Cognitive Assessment for MS (rho=-0.247, p < 0.05), Modified Fatigue Impact Scale (rho = 0.374, p < 0.05), Depression Anxiety Stress Scale (rho = 0.375, p < 0.05), Multiple Sclerosis Impact Scale (rho = 0.442, p < 0.05), and EuroQoL-five-dimensional instrument (rho = 0.375, p < 0.05). Internal consistency of the Greek version of the MSISQ-19 was confirmed with Cronbach's alpha. Test-retest reliability (31 PwMS) was excellent with intraclass-correlation-coefficients > 0.90. CONCLUSION Besides Greek MSISQ-19 satisfactory validity/reliability/reproducibility and being first to include cognitive-testing, authors estimated sexual-dysfunction prevalence affecting half PwMS.HIGHLIGHTSThis study provides the only validation of the Greek Version of the MSISQ-19.The latter was found with satisfactory validity, reliability and reproducibility.50% of the Greek PwMS sample was found to be afflicted with sexual dysfunction.This is also the first validation study to examine associations with cognitive testing.Sexual function is still an underestimated functionality parameter upon examination.
AIM OF THE STUDY:The application of a noxious stimulus reduces the perception and responsiveness to other pain stimuli. This inhibition can be experimentally assessed with a method called 'counterirritation'. The question arises if counterirritation acts also on the perception and responsiveness to aversive but non-nociceptive stimuli (e.g., loud tones). Since aversive stimulation is often associated with state anxiety or state fear, we investigated in addition the modulatory effects of these emotions on counterirritation. MATERIAL AND METHODS:51 subjects participated in our study. We presented tones with aversive loudness (105 dB), first alone then during counterirritation (immersion of the hand in a hot water bath of 46 °C) to assess inhibition of loudness perception and responsiveness. Influences of state anxiety and state fear on counterirritation were investigated by using the Neutral-Predictable(fear)- Unpredictable(anxiety) Paradigm (NPU), which is based on classical conditioning. Loudness ratings (perception of the aversive tones) and startle reflex (defensive reaction to aversive tones) were assessed. RESULTS:Counterirritation reduced startle reflex amplitudes, but not the loudness ratings. Although state anxiety and state fear were successfully induced, counterirritation remained unaffected. CONCLUSIONS:Our study showed that pain inhibits the responsiveness to aversive stimuli (loud tones). Thus, the postulate that 'pain inhibits pain' might be better changed to 'pain inhibits aversiveness'. Consequently, our findings may also question the assumption of a clear pain specificity in inhibitory action as assumed by theoretical approaches like 'conditioned pain modulation' (CPM). Furthermore, counterirritation appeared one more time resistant to the influence of negative emotions.
This study assesses human identification of vibrotactile patterns by using real-time discrete event-driven feedback. Previously acquired force and bend sensor data from a robotic hand were used to predict movement-type (stationary, flexion, contact, extension, release) and object-type (no object, hard object, soft object) states by using decision tree (DT) algorithms implemented in a field-programmable gate array (FPGA). Six able-bodied humans performed a 2- and 3-step sequential pattern recognition task in which state transitions were signaled as vibrotactile feedback. The stimuli were generated according to predicted classes represented by two frequencies (F1: 80 Hz, F2: 180 Hz) and two magnitudes (M1: low, M2: high) calibrated psychophysically for each participant; and they were applied by two actuators (Haptuators) placed on upper arms. A soft/hard object was mapped to F1/F2; and manipulating it with low/high force was assigned to M1/M2 in the left actuator. On the other hand, flexion/extension movement was mapped to F1/F2 in the right actuator, with movement in air as M1 and during object manipulation as M2. DT algorithm performed better for the object-type (97%) than the movement-type (88%) classification in real time. Participants could recognize feedback associated with 14 discrete-event sequences with low-to-medium accuracy. The performance was higher (76 ± 9% recall, 76 ± 17% precision, 78 ± 4% accuracy) for recognizing any one event in the sequences. The results show that FPGA implementation of classification for discrete event-driven vibrotactile feedback can be feasible in haptic devices with additional cues in the physical context.
AIM OF THE STUDY:Brain-computer interfaces (BCIs) may help patients with severe neurological deficits communicate with the external world. Based on microelectrocorticography (µECoG) data recorded from the primary somatosensory cortex (S1) of unrestrained behaving rats, this study attempts to decode lever presses in a psychophysical detection task by using machine learning algorithms. MATERIALS AND METHODS:16-channel Pt-Ir microelectrode arrays were implanted on the S1 of two rats, and µECoG was recorded during a vibrotactile yes/no detection task. For this task, the rats were trained to press the right lever when they detected the vibrotactile stimulus and the left lever when they did not. The multichannel µECoG data was analysed offline by time-frequency methods and its features were used for binary classification of the lever press at each trial. Several machine learning algorithms were tested as such. RESULTS:The psychophysical sensitivities (A') were similar and low for both rats (0.58). Rat 2 (B'': -0.11) had higher bias for the right lever than Rat 1 (B'': - 0.01). The lever presses could be predicted with accuracies over 66% with all the tested algorithms, and the highest average accuracy (78%) was with the support vector machine. CONCLUSION:According to the recent studies, sensory feedback increases the benefit of the BCIs. The current proof-of-concept study shows that lever presses can be decoded from the S1; therefore, this area may be utilised for a bidirectional BCI in the future.
