Reflex Latency Research Articles

Sympathetic nerve outflow to skin in a case with dentatorubral-pallidoluysian atrophy

Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder characterized by slowly progressive cerebellar ataxia. Previously, autonomic symptoms or dysfunction have not been reported. To evaluate subclinical autonomic dysfunction regarding thermoregulatory function in SCA, we recorded sympathetic outflow to skin in a DRPLA patient confirmed by genetic analysis. We recorded skin sympathetic nerve activity (SSNA), which was elicited and recorded by using the microneurographical technique. In results, the resting frequency of SSNA bursts was very low (8.2 ± 0.4 bursts/min [institutional normal range: 20.8 ± 2.4 bursts/min]). However, acceleration of SSNA bursts induced by mental arithmetic stress was confirmed. The amplitude of reflex bursts induced by electrical stimuli was slightly low (9.6 ± 1.6 μV [institutional normal range: 10.9 ± 2.2 μV]), and the reflex latency was mildly prolonged (872 ± 23.7 msec [institutional normal range: 761.9 ± 51.7 msec]). These results suggest potentially central autonomic dysfunction in this patient with DRPLA. To our knowledge, this is the first report to record SSNA and confirm subclinical autonomic dysfunction in a case with DRPLA.

CLP290 promotes the sedative effects of midazolam in neonatal rats in a KCC2-dependent manner: A laboratory study in rats.

Immature neurons dominantly express the Na+-K+-2Cl- cotransporter isoform 1 (NKCC1) rather than the K+-Cl- cotransporter isoform 2 (KCC2). The intracellular chloride ion concentration ([Cl-]i) is higher in immature neurons than in mature neurons; therefore, γ-aminobutyric acid type A (GABAA) receptor activation in immature neurons does not cause chloride ion influx and subsequent hyperpolarization. In our previous work, we found that midazolam, benzodiazepine receptor agonist, causes less sedation in neonatal rats compared to adult rats and that NKCC1 blockade by bumetanide enhances the midazolam-induced sedation in neonatal, but not in adult, rats. These results suggest that GABA receptor activation requires the predominance of KCC2 over NKCC1 to exert sedative effects. In this study, we focused on CLP290, a novel KCC2-selective activator, and found that midazolam administration at 20 mg/kg after oral CLP290 intake significantly prolonged the righting reflex latency even in neonatal rats at postnatal day 7. By contrast, CLP290 alone did not exert sedative effects. Immunohistochemistry showed that midazolam combined with CLP290 decreased the number of phosphorylated cAMP response element-binding protein-positive cells in the cerebral cortex, suggesting that CLP290 reverted the inhibitory effect of midazolam. Moreover, the sedative effect of combined CLP290 and midazolam treatment was inhibited by the administration of the KCC2-selective inhibitor VU0463271, suggesting indirectly that the sedation-promoting effect of CLP290 was mediated by KCC2 activation. To our knowledge, this study is the first report showing the sedation-promoting effect of CLP290 in neonates and providing behavioral and histological evidence that CLP290 reverted the sedative effect of GABAergic drugs through the activation of KCC2. Our data suggest that the clinical application of CLP290 may provide a breakthrough in terms of midazolam-resistant sedation.

Changes of Blink Reflex in Type 2 Diabetes Mellitus.

Blink reflex provides an objective assessment of the cranial and central nervous systems. However, the relationships between body mass index, dizziness, and BR have not been explored in patients with type 2 diabetes mellitus (T2DM). Moreover, R2 duration, one of the parameters of the blink reflex, has not been studied to date. In the present study, we aimed to investigate the characteristics and influencing factors of blink reflex in patients with T2DM. We included 45 healthy subjects and 105 hospitalized patients with T2DM. The relationships between these parameters and sex, age, body mass index, duration of T2DM, hemoglobin A1c, distal symmetrical polyneuropathy (DSPN), and dizziness symptoms were analyzed. The results showed that blink reflex latencies (including R1, ipsilateral R2, and contralateral R2 latency) were negatively associated with body mass index but were positively correlated with the duration of T2DM. There were no correlations between blink reflex parameters and sex, age, and hemoglobin A1c. Patients with DSPN had longer blink reflex latencies and shorter R2 durations than those without DSPN. Patients with dizziness had longer latencies (including R1, ipsilateral R2, and contralateral R2 latencies) and shorter R2 durations (including ipsilateral R2 and contralateral R2 durations) than those without dizziness. R2 duration was also a predictive factor for blink reflex abnormality. R2 latency was the most sensitive factor and the optimal predictor of dizziness. These results demonstrate that patients with T2DM with low body mass index, longer duration of T2DM, DSPN, and dizziness-related symptoms had more abnormal blink reflex parameters, indicating more serious injuries to the cranial nerves or the central nervous system.

The Effect of Cold on the Trigeminal Reflexes

Objective: Effects of muscle cooling on the spinal stretch and monosynaptic reflexes have been studied to describe the properties of Group I and II afferents of muscle spindles. Masseter muscle differs from extremity muscles in structural and numerical features of the muscle spindles. The aim of this study was to examine the muscle spindle afferent features of masseter muscle by applying cold to understand the role of Group I and II afferents in reflexes of masseter. Patients and Methods: We included 12 healthy subjects (7 females and 5 males) in the study. Masseter inhibitory reflex (MIR), jaw tendon reflex (JTR), trigeminal motor evoked potential (MEP), and trigeminal somatosensory evoked potential (SEP) were studied before and after cold application. Left masseter muscle was cooled down to 18°C. We compared the data obtained before and after cold application. Results: After cold application, the mean total duration of MIR was shortened and it was absent in four subjects. The mean amplitude of JTR was higher after cold application (P = 0.018) without any significant change in latency. The mean latency of MEP was delayed without any change in amplitude (P = 0.003). There was no significant difference in SEPs. Conclusions: Changes observed in MIR, JTR, and MEP could not be ascribed to any specific type of muscle spindle afferents. Delayed mean reflex latencies were attributed to the effect of cold on nerve conduction. Summation of peripheral cold and pain receptor features, spindle afferents, and cortical mechanisms might have caused cold-associated changes.

Automated Pupillometry Identifies Absence of Intracranial Pressure Elevation in Intracerebral Hemorrhage Patients

IntroductionAlthough automated pupillometry is increasingly used in critical care settings, predictive value of automatically assessed pupillary parameters during different intracranial pressure (ICP) levels and possible clinical implications are unestablished.MethodsThis retrospective cohort study at the neurocritical care unit of the University of Erlangen-Nuremberg (2016–2018) included 23 nontraumatic supratentorial (intracerebral hemorrhage) ICH patients without signs of abnormal pupillary function by manual assessment, i.e., absent light reflex. We assessed ICP levels by an external ventricular drain simultaneously with parameters of pupillary reactivity [i.e., maximum and minimum apertures, light reflex latency (Lat), constriction and redilation velocities (CV, DV), and percentage change of apertures (per-change)] using a portable pupillometer (NeurOptics®). Computed tomography (CT) scans were analyzed to determine lesion location, size, intraventricular hemorrhage, hydrocephalus, midline shift, and compression or absence of the basal cisterns. We performed receiver operating characteristics analysis to investigate associations of ICP levels with pupillary parameters and to determine best cutoff values for prediction of ICP elevation. After dichotomization of assessments according to ICP values (normal: < 20 mmHg, elevated: ≥ 20 mmHg), prognostic performance of the determined cutoff parameters of pupillary function versus of CT-imaging findings was analyzed by calculating sensitivity, specificity, positive and negative predictive values (logistic regression, corresponding ORs with 95% CIs).ResultsIn 23 patients (11 women, median age 59.0 (51.0–69.0) years), 1,934 assessments were available for analysis. A total of 74 ICP elevations ≥ 20 mmHg occurred in seven patients. Best discriminative thresholds for ICP elevation were: CV < 0.8 mm/s (AUC 0.740), per-change < 10% (AUC 0.743), DV < 0.2 mm/s (AUC 0.703), and Lat > 0.3 s (AUC 0.616). Positive predictive value of all four parameters to indicate ICP elevation ranged between 7.2 and 8.3% only and was similarly low for CT abnormalities (9.1%). We found high negative predictive values of pupillary parameters [CV: 99.2% (95% CI 98.3–99.6), per-change: 98.7% (95% CI 97.8–99.2), DV: 98.0% (95% CI 97.0–98.7), Lat: 97.0% (95% CI 96.0–97.7)], and CT abnormalities [99.7% (95% CI 99.2–99.9)], providing evidence that both techniques adequately identified ICH patients without ICP elevation.ConclusionsOur data suggest an association between noninvasively detected changes in pupillary reactivity and ICP levels in sedated ICH patients. Although automated pupillometry and neuroimaging seem not sufficient to noninvasively indicate ICP elevation, both techniques, however, adequately identified ICH patients without ICP elevation. This finding may facilitate routine management by saving invasive ICP monitoring or repeated CT controls in patients with specific automated pupillometry readings.

Pharmacological investigation of Thespesea populnea bark extract for analgesic activity

Background: Pain is an unpleasant and distressing common problem with profound impact on individuals and society. Existing treatment modalities used for pain management are either less effective or exhibits several side effects. The aim of current study is to investigate the analgesic activity of stem bark extract of Thespesea populnea for pain management.Methods: Thirty Swiss albino were divided into five groups including control, standard and three tests groups (different doses of Thespesea populnea bark extract). Groups were investigated for analgesic activity using hot plate induced paw withdrawal, acetic acid induced writhing and formalin induced paw licking models.Results: Findings of hot plate model revealed that, percent increase in reflex latency of paw licking response in mice for test drug (10 mg/kg), attained peak effect of 136% at 180 minutes, whereas for standard pentazocine peak effect of 125% was attained at 180 minutes. In acetic acid model, the maximum percent inhibition in number of writhings for the test drug (30 mg/kg) was 68% and for standard diclofenac, it was 80%. In formalin model, percent inhibition in licking response in early and late phases for test drug (30 mg/kg) were 81% and 91% and for standard diclofenac it was 56% and 94% respectively. It was thus depicted that analgesic activity of test drug was significantly more than the standard in early phase and equivalent to standard in late phase.Conclusions: It was concluded that Thespesea populnea bark extract at a dose of 10 mg/kg showed potential peripheral and central analgesic activity.

Arm cycling increases the short-latency reflex from ankle dorsiflexor afferents to knee extensor muscles.

Low-intensity electrical stimulation of the common peroneal nerve (CPN) evokes a short latency reflex in the heteronymous knee extensor muscles (referred to as the CPN reflex). The CPN reflex is facilitated at a heel strike during walking, contributing to body weight support. However, the origin of the CPN reflex increase during walking remains unclear. We speculate that this increase originates from multiple sources due to a body of evidence suggesting the presence of neural coupling between the arms and legs. Therefore, we investigated the extent to which the CPN reflex is modulated during rhythmic arm cycling. Twenty-eight subjects sat in an armchair and were asked to perform arm cycling at a moderate cadence using a stationary ergometer while performing isometric contraction of the knee extensors, such that the CPN reflex was evoked. The CPN reflex was evoked by stimulating the CPN [0.9-2.0× the motor threshold (MT) in the tibialis anterior muscle] at the level of the neck of the fibula. The CPN-reflex amplitude was measured from the vastus lateralis (VL). The biphasic reflex response in the VL was evoked within 27-45 ms following CPN stimulation. The amplitude of the CPN reflex increased during arm cycling compared with that before cycling. The modulation of the CPN reflex during arm cycling was detected only for CPN stimulation intensity around 1.2× MT. Furthermore, CPN-reflex modulation was not observed during the isometric contraction of the arm or passive arm cycling. Our results suggest the presence of neural coupling between the CPN-reflex pathways and neural systems generating locomotive arm movement.NEW & NOTEWORTHY Whether locomotive arm movements contribute to the control of the reflex pathway from ankle dorsiflexor afferents to knee extensor muscles [common peroneal nerve (CPN)-reflex] is an unresolved issue. The CPN reflex in the stationary leg was facilitated only by arm cycling, and not by passive or isometric motor tasks. Our results suggest that the arm locomotor system modulates the reflex pathway from ankle dorsiflexor afferents to the knee extensor muscles.

Comparison of the temporal properties of medium latency responses induced by cortical and peripheral stimulation

Sudden foot dorsiflexion lengthens soleus muscle and activates stretch-based spinal reflexes. Dorsiflexion can be triggered by activating tibialis anterior (TA) muscle through peroneal nerve stimulation or transcranial magnetic stimulation (TMS) which evokes a response in the soleus muscle referred to as Medium Latency Reflex (MLR) or motor-evoked potential-80 (Soleus MEP80), respectively. This study aimed to examine the relationship between these responses in humans. Therefore, latency characteristics and correlation of responses between soleus MEP80 and MLR were investigated. We have also calculated the latencies from the onset of tibialis activity, i.e., subtracting of TA-MEP from MEP80 and TA direct motor response from MLR. We referred to these calculations as Stretch Loop Latency Central (SLLc) for MEP80 and Stretch Loop Latency Peripheral (SLLp) for MLR. The latency of SLLc was found to be 61.4 ± 5.6 ms which was significantly shorter (P = 0.0259) than SLLp (64.0 ± 4.2 ms) and these latencies were correlated (P = 0.0045, r = 0.689). The latency of both responses was also found to be inversely related to the response amplitude (P = 0.0121, r = 0.451) probably due to the activation of large motor units. When amplitude differences were corrected, i.e. investigating the responses with similar amplitudes, SLLp, and SLLc latencies found to be similar (P = 0.1317). Due to the identical features of the soleus MEP80 and MLR, we propose that they may both have spinal origins.

Pregnancy exposure to carbon black nanoparticles induced neurobehavioral deficits that are associated with altered m6A modification in offspring

Increasing occupational and accidental exposure to carbon black nanoparticles (CBNPs) raise concerns over their possible effects on the nervous system. However, the influences of CBNPs on the neurodevelopment remain unclear. Thus, in this study, pregnant mice were exposed to different doses of CBNPs by intranasal instillation on gestation days 9–18. Our results demonstrated that maternal exposure to CBNPs caused significant changes on maternal behaviors. Pregnancy exposure to CBNPs also delayed the onset of incisor eruption, testes descent and vaginal opening in offspring, and caused the reduced body weight until adulthood. In the neurobehavioral tests, CBNPs-exposed offspring exhibited the elevated latency of negative geotaxis and surface right reflex, reduced grasping time and increased cliff avoidance. Histopathological changes were present in F1 generation but not in F2 generation. Intriguingly, our data revealed that the levels of total m6A modification were significantly decreased by CBNPs. Similar trends were observed on the mRNA expressions of m6A methyltransferases and demethylases. In summary, these findings provide the novel evidence that pregnancy exposure to CBNPs affects the maternal behaviors and partially induces the neurobehavioral, muscular and histopathological changes in offspring. Of note, these adverse effects may be associated with reduced levels of total m6A modification in brain.

Acoustic Reflexes in Individuals Having Hyperacusis of the Auditory Origin.

Functional role of the acoustic reflex in preventing over stimulation of the inner auditory system by decreasing sound intensity along with the previous reports of acoustic reflex abnormalities in individuals having hyperacusis point towards the involvement of acoustic reflex deficit in the origin of hyperacusis especially when any medical condition leading to hyperacusis is not associated. However this issue remains contradictory owing to limited comprehensive investigation. This study was undertaken to ascertain the relationship between hyperacusis and the acoustic reflex. Threshold, amplitude and latency of the acoustic reflex were measured in two different groups of individuals having hyperacusis; Group 1: 14 individuals having hyperacusis with hearing loss (HwHL) and Group 2: 17 individuals having hyperacusis without hearing loss (HwoHL). Control group (Group 3) consisted of 15 normal hearing individuals who never experienced hyperacusis. Result showed a significant group effect on all the measured characteristics of the acoustic reflex. ARTs were found to be significantly higher in HwHL and HwoHL when compared to NHwoH. ARTs were statistically similar for HwoHL and NHwoH. HwoHL's ARAs and ARLs were significantly smaller and prolonged, respectively, when compared to HwHL and NHwoH. HwHL and NHwoH had statistically similar ARAs and ARLs. This study confirms acoustic reflex abnormalities in some individuals having hyperacusis with or without hearing loss. It further highlight the importance of involving acoustic reflex testing in the assessment of hyperacusis especially when hyperacusis is not associated with hearing loss or any other medical condition that may lead to hyperacusis.

The Effect of Pitch Auditory Feedback Perturbations on the Production of Anticipatory Phrasal Prominence and Boundary.

Purpose In this study, we investigated how the direction and timing of a perturbation in voice pitch auditory feedback during phrasal production modulated the magnitude and latency of the pitch-shift reflex as well as the scaling of acoustic production of anticipatory intonation targets for phrasal prominence and boundary. Method Brief pitch auditory feedback perturbations (±200 cents for 200-ms duration) were applied during the production of a target phrase on the first or the second word of the phrase. To replicate previous work, we first measured the magnitude and latency of the pitch-shift reflex as a function of the direction and timing of the perturbation within the phrase. As a novel approach, we also measured the adjustment in the production of the phrase-final prominent word as a function of perturbation direction and timing by extracting the acoustic correlates of pitch, loudness, and duration. Results The pitch-shift reflex was greater in magnitude after perturbations on the first word of the phrase, replicating the results from Mandarin speakers in an American English-speaking population. Additionally, the production of the phrase-final prominent word was acoustically enhanced (lengthened vowel duration and increased intensity and fundamental frequency) after perturbations earlier in the phrase, but more so after perturbations on the first word in the phrase. Conclusion The timing of the pitch perturbation within the phrase modulated both the magnitude of the pitch-shift reflex and the production of the prominent word, supporting our hypothesis that speakers use auditory feedback to correct for immediate production errors and to scale anticipatory intonation targets during phrasal production.

Sacral Reflex Characteristics of Patients with Multiple System Atrophy.

Objectives To observe and analyze the parameters of the sacral reflex and pudendal nerve somatosensory evoked potential (SSEP) in patients with multiple system atrophy (MSA) with respect to factors such as age, disease course, and subtype and provide evidence for the clinical diagnosis of MSA. Materials and Methods A total of 51 MSA patients and 30 healthy controls were selected from the First Affiliated Hospital of Wenzhou Medical University from May 2013 to November 2015. Electrophysiological sacral reflex detection and SSEP detection were performed using the Keypoint EMG/EP system. The extraction rate, latency, and amplitude of the sacral reflex and SSEP in the MSA group and control group were compared. Results The sacral reflex latency and amplitude in patients with MSA were statistically different from those of the healthy controls. The latency of sacral reflex increases with the prolongation of the disease course, and the amplitude and initiation rate decrease with the prolongation of the disease course. There was no significant difference in sacral reflex latency and amplitude between MSA patients of different ages and subtypes. There was no significant difference in the latency or amplitude of SSEP between the MSA group and healthy control group. Conclusions The latency of sacral reflex increases with the prolongation of the disease course, and the amplitude and extraction rate decrease with the prolongation of the disease course. There was no significant difference in the parameters of sacral reflex between young MSA patients and elderly patients. And there was no statistically significant difference between MSA-P subtypes and MSA-C subtypes. This trial is registered with ISRCTNCR2009041.

Composite nanofibers incorporating alpha lipoic acid and atorvastatin provide neuroprotection after peripheral nerve injury in rats

Despite the new treatment strategies within the last 30 years, peripheral nerve injury (PNI) is still a worldwide clinical problem. The incidence rate of PNIs is 1 in 1000 individuals per year. In this study, we designed a composite nanoplatform for dual therapy in peripheral nerve injury and investigated the in-vivo efficacy in rat sciatic nerve crush injury model. Alpha-lipoic acid (ALA) was loaded into poly lactic-co-glycolic acid (PLGA) electrospun nanofibers which would release the drug in a faster manner and atorvastatin (ATR) loaded chitosan (CH) nanoparticles were embedded into PLGA nanofibers to provide sustained release. Sciatic nerve crush was generated via Yasargil aneurism clip with a holding force of 50 g/cm2. Nanofiber formulations were administered to the injured nerve immediately after trauma. Functional recovery of operated rat hind limb was evaluated using the sciatic functional index (SFI), extensor postural thrust (EPT), withdrawal reflex latency (WRL) and Basso, Beattie, and Bresnahan (BBB) test up to one month in the post-operative period at different time intervals. In addition to functional recovery assessments, ultrastructural and biochemical analyses were carried out on regenerated nerve fibers. L-929 mouse fibroblast cell line and B35 neuroblastoma cell line were used to investigate the cytotoxicity of nanofibers before in-vivo experiments. The neuroprotection potential of these novel nanocomposite fiber formulations has been demonstrated after local implantation of composite nanofiber sheets incorporating ALA and ATR, which contributed to the recovery of the motor and sensory function and nerve regeneration in a rat sciatic nerve crush injury model.

Anterior cruciate ligament reconstructed individuals demonstrate slower reactions during a dynamic postural task.

To determine whether individuals with a history of anterior cruciate ligament reconstruction (ACLR) exhibit altered neuromotor function compared to healthy controls. It was hypothesized that the ACLR group would have slower postural responses compared to healthy individuals of similar age. Sixteen adults with a unilateral ACLR and 16 matched healthy controls participated. General assessments of neuromotor function were gathered and included measures of reaction time (both seated and postural conditions), walking ability, balance, ankle ROM, proprioception, knee joint laxity, patellar tendon reflex latency, and quadriceps strength. Data were analyzed using mixed generalized linear models with between-subject (ie, controls, ACLR) and within-subject factors (ie, affected, unaffected limb). Individuals with an ACLR exhibited a significant slowing of their postural reaction times compared to the control individuals. The ACLR group was slower under both the simple (ACLR: 484±6.17ms, control: 399±1.95ms) and choice reaction time conditions (ACLR: 550±43ms, control: 445±43ms). No other group differences were found in any of the other measures. Overall, ACLR individuals had a reduced ability to respond quickly under more challenging postural conditions (ie, stepping response). This finding would indicate that the impact of an ACLR is not purely mechanical and restricted to the joint. Rather, injury and reconstruction of the ACL impact neural mechanisms, altering individuals' ability to respond under challenging balance tasks.

A new model of repeat mTBI in adolescent rats

Sports-related injury is frequently associated with repeated diffuse and mild traumatic brain injury (mTBI). We combined two existing models for inducing TBI in rats, the Impact Acceleration and Controlled Cortical Impact models, to create a new method relevant to the study of cognitive sequelae of repeat mTBI in adolescent athletes. Repeated mTBI, such as those incurred in sports, can result in a wide range of outcomes, with many individuals experiencing no chronic sequela while others develop profound cognitive and behavioral impairments, typically in the absence of lasting motor symptoms or gross tissue loss appreciable antemortem. It is critical to develop models of mTBI and repeat mTBI that have the flexibility to assess multiple parameters related to injury (e.g. number and magnitude of impacts, inter-injury interval, etc) that are associated with brain vulnerability compared to normal recovery. We designed a 3D-printed plastic implant to permanently secure a metal disc to the skull of adolescent rats in order to induce multiple injuries without performing multiple survival surgeries and also to minimize pre-injury anesthesia time. Rats were randomly assigned to sham injury (n = 12), single injury (n = 12; injury on P41), or repeat injury (n = 14; injuries on P35, P38, and P41) groups. Compared to single injury and sham injury, repeat injuries caused increased toe pinch reflex latency (F(2,34) = 4.126, p < .05) and diminished weight gain (F(2, 34) = 4.767, p < .05). Spatial navigation was tested using Morris water maze, beginning one week after the final injury (P48). While there were no differences between groups during acquisition, both single and repeat injuries resulted in deficits on probe trial performance (p < .01 and p < .05 respectively). Single injury animals also exhibited a deficit in working memory deficit across three days of testing (p < .05). Neither injury group had neuronal loss in the hilus or CA3, according to stereological quantification of NeuN. Therefore, by implanting a helmet we have created a relevant model of sports-related injury and repeated mTBI that results in subtle but significant changes in cognitive outcome in the absence of significant hippocampal cell death.

Learning New Feedforward Motor Commands Based on Feedback Responses.

Learning a new motor task modifies feedforward (i.e., voluntary) motor commands and such learning also changes the sensitivity of feedback responses (i.e., reflexes) to mechanical perturbations [1-9]. For example, after people learn to generate straight reaching movements in the presence of an external force field or learn to reduce shoulder muscle activity when generating pure elbow movements with shoulder fixation, evoked stretch reflex responses to mechanical perturbations reflect the learning expressed during self-initiated reaching. Such a transfer from feedforward motor commands to feedback responses is thought to take place because of shared neural circuits at the level of the spinal cord, brainstem, and cerebral cortex [10-13]. The presence of shared neural resources also predicts the transfer from feedback responses to feedforward motor commands. Little is known about such a transfer presumably because it is relatively hard to elicit learning in reflexes without engaging associated voluntary responses following mechanical perturbations. Here, we demonstrate such transfer by leveraging two approaches to elicit stretch reflexes while minimizing engagement of voluntary motor responses in the learning process: applying very short mechanical perturbations [14-19] and instructing participants to not respond to them [20-26]. Taken together, our work shows that transfer between feedforward and feedback control is bidirectional, furthering the notion that these processes share common neural circuits that underlie motor learning and transfer.

Excitatory and aversive behaviors - electrophysiological observation of anterior cingulate cortex (ACC) in rats

Increasing activities in anterior cingulate cortex (ACC) can enhance the aversion reactions associated with noxious stimuli. It has been known that opioid receptors activation can trigger endogenous analgesic effect. This study tried to explore whether opioid receptors activation in the ACC region could reduce the aversion associated with noxious stimuli. The experimental rats were randomly divided into seven groups, Complete Freund's adjuvant (CFA) + normal saline (NS) group, normal saline (NS) + normal saline (NS) group, normal saline (NS) +DAMGO ((DAla2, NMe-Phe4, Gly-ol5)enkephinlin, μ-opioid receptor agonist) group, complete Freund's adjuvant (CFA)+ 0.01/0.04/0.2/1 μg/μl DAMGO group(n=6). The experimental period was three days. The basal value was measured on the first day. The second day, 1 μl was administered through the ACC area, and then 0.08 ml of complete Freund's adjuvant (CFA) was injected into the left hind paw of the rat. CPA response, paw withdrawal reflex latency (PWL) and electrical activity in the ACC brain region of rats were observed on the third day. ①PWL was significantly decreased in rats after CFA was injected into left hind paw compared with post-injection(P＜0.05).② In the pain side of the apparatus, it took rats less residence time than that in the non-pain side. ③ 0.04/0.2/1 μg/μl DAMGO was given before CFA-injection, C-CPA reactions could be revised significantly. ④ Given 0.04/0.2/1 μg/μl DAMGO in the ACC region could decrease the increasing discharge frequency induced by CFA in ACC neurons. The activation of the mu-opioid receptor in the ACC region alleviates the aversion induced by noxious stimulation.

Cerebellar Transcranial Magnetic Stimulation Disrupts Vestibular Reflexes in Standing Balance

Despite its seemingly effortless execution, standing balance is a complex task maintained by the integration of sensory feedback from visual, somatosensory (muscle, skin, joint receptors), and vestibular (inner ear) systems. The vestibular system provides feedback about head acceleration and can be manipulated experimentally by passing an electrical current percutaneously through the mastoid processes. The cerebellum plays an important role in standing balance by integrating sensory feedback to refine activity in postural muscles. A recent study has shown that experimentally depressing cerebellar activity with repetitive transcranial magnetic stimulation can influence postural sway and muscle reflex responses following electrical vestibular stimulation. The aim of this study was to investigate the impact of acute cerebellar stimulation on vestibular muscle reflex responses in different head positions during standing balance. We applied a novel combination of stochastic electrical vestibular stimulation (SVS, ±2.5 mA, 0–20 Hz) and single‐pulse cerebellum transcranial magnetic stimulation (TMS, 60% maximum stimulator output) on fifteen healthy adults (6 males, 9 females; 21–32 years old) in two head positions: head forward and head right. Muscle reflexes were recorded bilaterally with surface electromyography (EMG) from lower leg (soleus and medial gastrocnemius) and neck (sternocleidomastoid) muscles. Time‐based cumulant density and frequency‐based coherence analyses were used to evaluate the relationship between the SVS and evoked EMG responses one second before (Pre) and one second after (Post) cerebellar TMS. 50 TMS pulses were delivered per head position. Preliminary analysis performed on left medial gastrocnemius (LMG) head right data indicated a significant reduction in the short latency (SL, P = 0.0377) and medium latency (ML, P &lt; 0.0001) reflexes following cerebellar TMS (Fig. 1). In addition, a significant drop in the coherence between the SVS and LMG Pre to Post was found using a difference of coherence test. These findings support the cerebellum to be an important center for the integration of vestibular feedback for the control of standing balance.Support or Funding InformationMount Royal University Faculty of Science and TechnologyFigure 1

Electrodiagnostic Abnormalities Associated with Fibromyalgia.

PurposeIncreasing evidence suggests that fibromyalgia most likely represents a neurological dysfunction. We previously hypothesized that at least some fibromyalgia cases may be caused by irritation of nerve root fibers and sensory neurons due to moderately increased cerebrospinal pressure. Because of the rostro-caudal hydrostatic pressure gradient, neurogenic abnormalities are expected to be most pronounced in sacral nerve roots. The purpose was to review electrodiagnostic tests of patients with fibromyalgia.MethodsA retrospective review of electrodiagnostic test results, including the lumbar and sacral nerve root myotomes of patients diagnosed with fibromyalgia according to the 1990 criteria of the American College of Rheumatology was done.ResultsAll 17 patients were female. Sural nerve responses could not be elicited in 12% and S1-Hoffmann reflex latencies were increased in 41%. In 12% of the patients, fibular motor nerve distal latency and conduction velocity were outside normal limits. Needle-EMG revealed neurogenic motor unit potentials in 0% of L2, 6% of L3, 29% of L4, 71% of L5, 47% of S1, 94% of S2, and 76% of S3-S4 myotomes. S3-S4 nerve-supplied anal reflexes were delayed in 94%.ConclusionThis is the first time that electrodiagnostic data of both lumbar and sacral nerve root myotomes in fibromyalgia patients are presented. All patients showed neurogenic abnormalities that were more pronounced in the sacral than in the lumbar myotomes with a rather patchy distribution pattern. We propose that, in addition to skin punch biopsies to assess small fiber neuropathy, assessment of the anal reflex may be a useful part of the diagnostic pathway in patients with fibromyalgia.

The effect of lycopene in egg shell membrane guidance channel on sciatic nerve regeneration in rats.

Objective(s):Peripheral nerves are commonly damaged. Although the nerve autograft still subsists the gold standard in surgery of nerve injury gaps, it has severe detriment. The egg shell membrane (ESM) is a natural material, which has a great potential in practice. The aim of this survey was to appraise the effect of lycopene and the ESM nerve guidance channel on sciatic nerve regeneration.Materials and Methods:In this study, 32 male rats were randomized into four groups: sham surgery, autograft, ESM+ dimethyl sulfoxide (DMSO), and ESM+lycopene. One centimeter of sciatic nerve was removed, and the gap was grafted by ESM channel or autograft. The sciatic function index (SFI) was evaluated at days 7, 21, 30, 49, 60 and 90 after surgery. Nerve regeneration and gastroknemius muscle fibers were evaluated at days 30 and 90 after surgery by withdrawal reflex latency (WRL), histology and immunohistology assessments.Results:At 49, 60 and 90 days after surgery, the mean SFI in ESM+lycopene group was significantly greater than ESM+DMSO group (P<0.05). On day 90, the mean muscle fiber diameters and the mean number of myelinated axons in ESM+lycopene and autograft groups were significantly greater than ESM+DMSO group (P<0.05). In addition, the mean WRL was significantly lower in ESM+lycopene group than in the ESM+DMSO group 90 days after surgery (P<0.05).Conclusion:The results of this study show that the affirmative effects of ESM+lycopene may be beneficial for treating peripheral nerve damages.