The ability of heart rate or perceived exertion to predict oxygen uptake varies across exercise modes in persons with tetraplegia.

STUDY DESIGN: Descriptive study. OBJECTIVES: To examine grouped and intra-individual relationships between 1) exercise intensity and heart rate (EI-HR); 2) EI and oxygen uptake (EI-VO2); 3) VO2 and HR (VO2-HR); and 4) perceived exertion and VO2 (PE-VO2) in persons with tetraplegia (C4/5-C8) during different modes of exercise. SETTING: Community in Winnipeg, Canada. METHODS: Participants exercised at 3 graded intensities during arm ergometry (ERG), wheeling indoors on cement (MWC), or hand-cycling outdoors (HC). EI (Watts, km/hr) and VO2, HR and PE were recorded. RESULTS: 22 persons completed ERG, 14/22 also completed MWC and 5/22 completed ERG, MWC and HC. Regression analysis of grouped data showed a significant relationship between EI-VO2 but not for EI-HR or HR-VO2. Intra-individual analyses showed a strong correlation (r or ρ > 0.7) for VO2-HR for 16/22 during ERG. In the participants completing multiple exercise modes, a strong VO2-HR relationship was present in 12/14 in ERG, but in only 6/14 in MWC. The 5 persons exercising with all 3 modes had a strong HR-VO2 relationship in 5/5 for ERG, 2/5 in MWC and 1/5 in HC. A strong relationship for PE-VO2 was observed in a higher proportion of participants (versus HR-VO2) during MWC (9/14) and HC (2/4). CONCLUSION: Within the same individual, the HR-VO2 relationship varies across modes, despite exercising over similar ranges of steady-state VO2. HR appears less able to predict VO2 compared to PE. Based on these new findings, systematic investigation of the HR-VO2 relationship across modes of exercise in tetraplegia is warranted.

Energy Expenditure as a Function of Activity Level After Spinal Cord Injury: The Need for Tetraplegia-Specific Energy Balance Guidelines.

The World Health Organization recognizes obesity as a global and increasing problem for the general population. Because of their reduced physical functioning, people with spinal cord injury (SCI) face additional challenges for maintaining an appropriate whole body energy balance, and the majority with SCI are overweight or obese. SCI also reduces exercise capacity, particularly in those with higher-level injury (tetraplegia). Tetraplegia-specific caloric energy expenditure (EE) data is scarce. Therefore, we measured resting and exercise-based energy expenditure in participants with tetraplegia and explored the accuracy of general population-based energy use predictors. Body composition and resting energy expenditure (REE) were measured in 25 adults with tetraplegia (C4/5 to C8) and in a sex-age-height matched group. Oxygen uptake, carbon dioxide production, heart rate, perceived exertion, and exercise intensity were also measured in 125 steady state exercise trials. Those with motor-complete tetraplegia, but not controls, had measured REE lower than predicted (mean = 22% less, p < 0.0001). REE was also lower than controls when expressed per kilogram of lean mass. Nine had REE below 1200 kcal/day. We developed a graphic compendium of steady state EE during arm ergometry, wheeling, and hand-cycling. This compendium is in a format that can be used by persons with tetraplegia for exercise prescription (calories, at known absolute intensities). EE was low (55-450 kcal/h) at the intensities participants with tetraplegia were capable of maintaining. If people with tetraplegia followed SCI-specific activity guidelines (220 min/week) at the median intensities we measured, they would expend 563-1031 kcal/week. Participants with tetraplegia would therefore require significant time (4 to over 20 h) to meet a weekly 2000 kcal exercise target. We estimated total daily EE for a range of activity levels in tetraplegia and compared them to predicted values for the general population. Our analysis indicated that the EE values for sedentary through moderate levels of activity in tetraplegia fall well below predicted sedentary levels of activity for the general population. These findings help explain sub-optimal responses to exercise interventions after tetraplegia, and support the need to develop tetraplegia-specific energy-balance guidelines that reflects their unique EE situation.

Randomized Controlled Trial of Online Acceptance and Commitment Therapy for Fibromyalgia.

In this study, 67 participants (95% female) with fibromyalgia (FM) were randomly assigned to an online acceptance and commitment therapy (online ACT) and treatment as usual (TAU; ACT + TAU) protocol or a TAU control condition. Online ACT + TAU participants were asked to complete 7 modules over an 8-week period. Assessments were completed at pre-treatment, post-treatment, and 3-month follow-up periods and included measures of FM impact (primary outcome), depression, pain, sleep, 6-minute walk, sit to stand, pain acceptance (primary process variable), mindfulness, cognitive fusion, valued living, kinesiophobia, and pain catastrophizing. The results indicated that online ACT + TAU participants significantly improved in FM impact, relative to TAU (P <.001), with large between condition effect sizes at post-treatment (1.26) and follow-up (1.59). Increases in pain acceptance significantly mediated these improvements (P = .005). Significant improvements in favor of online ACT + TAU were also found on measures of depression (P = .02), pain (P = .01), and kinesiophobia (P = .001). Although preliminary, this study highlights the potential for online ACT to be an efficacious, accessible, and cost-effective treatment for people with FM and other chronic pain conditions. PERSPECTIVE: Online ACT reduced FM impact relative to a TAU control condition in this randomized controlled trial. Reductions in FM impact were mediated by improvements in pain acceptance. Online ACT appears to be a promising intervention for FM.

Neuromuscular Electrical Stimulation for Treatment of Muscle Impairment: Critical Review and Recommendations for Clinical Practice.

Purpose: In response to requests from physiotherapists for guidance on optimal stimulation of muscle using neuromuscular electrical stimulation (NMES), a review, synthesis, and extraction of key data from the literature was undertaken by six Canadian physical therapy (PT) educators, clinicians, and researchers in the field of electrophysical agents. The objective was to identify commonly treated conditions for which there was a substantial body of literature from which to draw conclusions regarding the effectiveness of NMES. Included studies had to apply NMES with visible and tetanic muscle contractions. Method: Four electronic databases (CINAHL, Embase, PUBMED, and SCOPUS) were searched for relevant literature published between database inceptions until May 2015. Additional articles were identified from bibliographies of the systematic reviews and from personal collections. Results: The extracted data were synthesized using a consensus process among the authors to provide recommendations for optimal stimulation parameters and application techniques to address muscle impairments associated with the following conditions: stroke (upper or lower extremity; both acute and chronic), anterior cruciate ligament reconstruction, patellofemoral pain syndrome, knee osteoarthritis, and total knee arthroplasty as well as critical illness and advanced disease states. Summaries of key details from each study incorporated into the review were also developed. The final sections of the article outline the recommended terminology for describing practice using electrical currents and provide tips for safe and effective clinical practice using NMES. Conclusion: This article provides physiotherapists with a resource to enable evidence-informed, effective use of NMES for PT practice.

Objectif : en réponse à des demandes de conseils de physiothérapeutes pour optimiser la stimulation musculaire à l'aide de la stimulation électrique neuromusculaire (SENM), une revue, une synthèse et une extraction de données de la littérature ont été entreprises par six formateurs, cliniciens et chercheurs en physiothérapie dans le domaine des agents électrophysiques. L'objectif était de cibler des affections couramment traitées ayant fait l'objet d'une quantité suffisante d'études pour tirer des conclusions concernant l'efficacité de la SENM. Les études devaient porter sur la SENM produisant des contractions musculaires visibles et toniques. Méthodes : quatre bases de données électroniques (CINAHL, Embase, PubMed et Scopus) ont été parcourues à la recherche d'études pertinentes publiées entre la création des bases de données et mai 2015. D'autres articles ont été tirés de bibliographies de revues systématiques et de collections personnelles. Résultats : les données extraites ont été synthétisées par consensus des auteurs en vue de dresser des recommandations sur l'optimisation des paramètres et des techniques d'application de la stimulation dans le traitement de déficits musculaires associés aux affections suivantes: accident vasculaire cérébral (extrémité inférieure ou supérieure; aigu ou chronique), reconstruction du ligament croisé antérieur, syndrome fémoro-rotulien douloureux, arthrose du genou et arthroplastie totale du genou, ainsi que des maladies graves et en stade avancé. Les auteurs fournissent également un résumé des éléments clés de chaque étude incluse dans la revue. Enfin, ils recommandent une nomenclature de l'électrothérapie et présentent des conseils pour l'utilisation sécuritaire et efficace de la SENM. Conclusion : ce document constitue pour les physiothérapeutes une ressource permettant d'appuyer leur utilisation de la SENM sur des données probantes.

Correcting waveform bias using principal component analysis: Applications in multicentre motion analysis studies.

Multicentre studies are rare in three dimensional motion analyses due to challenges associated with combining waveform data from different centres. Principal component analysis (PCA) is a statistical technique that can be used to quantify variability in waveform data and identify group differences. A correction technique based on PCA is proposed that can be used in post processing to remove nuisance variation introduced by the differences between centres. Using this technique, the waveform bias that exists between the two datasets is corrected such that the means agree. No information is lost in the individual datasets, but the overall variability in the combined data is reduced. The correction is demonstrated on gait kinematics with synthesized crosstalk and on gait data from knee arthroplasty patients collected in two centres. The induced crosstalk was successfully removed from the knee joint angle data. In the second example, the removal of the nuisance variation due to the multicentre data collection allowed significant differences in implant type to be identified. This PCA-based technique can be used to correct for differences between waveform datasets in post processing and has the potential to enable multicentre motion analysis studies.

Out-Patient Pulmonary Rehabilitation Improves Medial-Lateral Balance in Subjects With Chronic Respiratory Disease: Proof-of-Concept Study.

BACKGROUND: Recent studies show balance impairment in subjects with chronic respiratory disease. The aim of this proof-of-concept study was to investigate clinical and quantitative measures of balance in people with chronic respiratory disease following participation in an out-patient pulmonary rehabilitation (PR) program to better understand features of balance improvement. A secondary aim was to probe possible mechanisms for balance improvement to provide the foundation for optimal design of future studies. METHODS: Eleven individuals with chronic respiratory disease enrolled in an 8-week out-patient PR program participated. Standing balance, measured with a force plate, in the medial-lateral and anterior-posterior directions with eyes open and closed was assessed with linear (SD and sway path length) and non-linear (diffusion analysis) center-of-pressure measures. Balance was evaluated clinically with the Timed Up and Go and Four Square Step Test. Fear of falling and balance confidence were assessed with questionnaires. RESULTS: After participation in PR, medial-lateral sway path length decreased (P = .031), and center-of-pressure diffusion in the medial-lateral direction was slower (P = .02) and traveled over less distance (P = .03) with eyes closed. This suggests greater control of medial-lateral sway. There was no change in anterior-posterior balance (P > .067). Performance improved on the Timed Up and Go (median [interquartile range] pre-PR = 9.4 [7.9-12.8] vs. post-PR = 8.1 [7.3-12.2] s, P = .003) and Four Square Step Test (median [interquartile range] pre-PR = 9.3 [7.2-14.2] vs. post-PR = 8.7 [7.4-10.2] s, P = .050). There were no changes in balance confidence (P = .72) or fear of falling (P = .57). CONCLUSIONS: Participation in an 8-week out-patient PR program improved balance, as assessed by clinical and laboratory measures. Detailed analysis of force plate measures demonstrated improvements primarily with respect to medial-lateral balance control. These data provide a basis for the development of larger scale studies to investigate the mechanisms for medial-lateral balance improvements following PR and to determine how PR may be refined to enhance balance outcomes in this population. (ClinicalTrials.gov registration NCT00864084.).

Pain management with acupuncture in osteoarthritis: a systematic review and meta-analysis.

BACKGROUND: The utility of acupuncture in managing osteoarthritis symptoms is uncertain. Trial results are conflicting and previous systematic reviews may have overestimated the benefits of acupuncture. METHODS: Two reviewers independently identified randomized controlled trials (up to May 2014) from multiple electronic sources (including PubMed/Medline, EMBASE, and CENTRAL) and reference lists of relevant articles, extracted data and assessed risk of bias (Cochrane's Risk of Bias tool). Pooled data are expressed as mean differences (MD), with 95% confidence intervals (CI) (random-effects model). RESULTS: We included 12 trials (1763 participants) comparing acupuncture to sham acupuncture, no treatment or usual care. We adjudicated most trials to be unclear (64%) or high (9%) risk of bias. Acupuncture use was associated with significant reductions in pain intensity (MD -0.29, 95% CI -0.55 to -0.02, I2 0%, 10 trials, 1699 participants), functional mobility (standardized MD -0.34, 95% CI -0.55 to -0.14, I2 70%, 9 trials, 1543 participants), health-related quality of life (standardized MD -0.36, 95% CI -0.58 to -0.14, I2 50%, 3 trials, 958 participants). Subgroup analysis of pain intensity by intervention duration suggested greater pain intensity reduction with intervention periods greater than 4 weeks (MD -0.38, 95% CI -0.69 to -0.06, I2 0%, 6 trials, 1239 participants). CONCLUSIONS: The use of acupuncture is associated with significant reductions in pain intensity, improvement in functional mobility and quality of life. While the differences are not as great as shown by other reviews, current evidence supports the use of acupuncture as an alternative for traditional analgesics in patients with osteoarthritis. SYSTEMATIC REVIEW REGISTRATION: CRD42013005405.

Sympathetic nervous system responses to acupuncture and non-penetrating sham acupuncture in experimental forearm pain: a single-blind randomised descriptive study.

OBJECTIVE: To quantify the sympathetic nervous system response to acupuncture and non-penetrating sham acupuncture in volunteers with pain. METHODS: A single-blind, randomised controlled study of 36 healthy adults with no recent participation in forearm strengthening or occupations involving repeated forceful wrist motion was carried out. A fatiguing wrist extension exercise protocol was completed to induce delayed onset muscle soreness. Group 1 received no treatment, group 2 a single session of acupuncture and group 3 a single session of sham acupuncture. Outcomes included skin conductance, skin temperature and perfusion measured for 20 min before treatment, during the 15 min treatment and for 10 min after treatment. RESULTS: The acupuncture group showed a significant increase from baseline in ipsilateral perfusion (135%) and bilateral skin conductance (144 and 146%) and a significant decrease from baseline in bilateral distal skin temperature (98%). The acupuncture and sham acupuncture groups showed decreased ipsilateral proximal skin temperature. CONCLUSIONS: Acupuncture appears to activate the sympathetic nervous system, indicated by a bilateral increase in skin conductance and a bilateral decrease in distal skin temperature after needle insertion. The unilateral increase in perfusion near the needle site seen with acupuncture treatment may be due to local circulatory, rather than systemic, control.

Functional capacity, muscle strength and falls in women with fibromyalgia.

BACKGROUND: Patients with fibromyalgia have difficulty with activities of daily living, they exhibit reduced muscle strength and high incidence of reported falls. The objective of this study was to evaluate the functional performance and lower limb muscle strength in women with fibromyalgia and determine the relationship between muscle strength and falls. METHODS: Sixteen females with fibromyalgia and 16 healthy women participated in the study. Pain intensity, fibromyalgia impact on quality of life, physical activity level and fall prevalence were assessed. The peak torque and the rate of torque development were determined in maximal voluntary isometric contraction (hip, knee and ankle joints) using a load cell. The 30s chair stand, 8 ft up and go, sit and reach, and functional reach tests were used to characterize functional performance. FINDINGS: Women with fibromyalgia showed deficits in lower limb muscle strength, balance and agility and exhibited decreased knee extension peak torque and rate of torque development. In addition, they showed lower hip adduction and extension peak torque in comparison to the control group (P>0.05). Hip extension rate of torque development, duration of fibromyalgia symptoms, overall pain, knee pain, and fibromyalgia impact were strong predictors of the number of falls in patients with fibromyalgia (R2=0.86; P<0.05), when considered collectively. INTERPRETATION: Women with fibromyalgia showed reduced functional performance and lower limb muscle strength, mostly explained by pain. There was a high prevalence of falls in this population, as explained by hip extensors rate of torque development, duration of fibromyalgia symptoms and pain.

Store-and-feedforward adaptive gaming system for hand-finger motion tracking in telerehabilitation.

This paper presents a telerehabilitation system that encompasses a webcam and store-and-feedforward adaptive gaming system for tracking finger-hand movement of patients during local and remote therapy sessions. Gaming-event signals and webcam images are recorded as part of a gaming session and then forwarded to an online healthcare content management system (CMS) that separates incoming information into individual patient records. The CMS makes it possible for clinicians to log in remotely and review gathered data using online reports that are provided to help with signal and image analysis using various numerical measures and plotting functions. Signals from a 6 degree-of-freedom magnetic motion tracking system provide a basis for video-game sprite control. The MMT provides a path for motion signals between common objects manipulated by a patient and a computer game. During a therapy session, a webcam that captures images of the hand together with a number of performance metrics provides insight into the quality, efficiency, and skill of a patient.

Kinematic Analysis of Gait Following Intra-articular Corticosteroid Injection into the Knee Joint with an Acute Exacerbation of Arthritis.

PURPOSE: The objective of this study was to examine the effects of intra-articular corticosteroid injection (ICI) on ipsilateral knee flexion/extension, ankle dorsiflexion/plantarflexion (DF/PF), and hip abduction/adduction (abd/add) during stance phase in people with an acute exacerbation of rheumatoid arthritis (RA) of the knee joint. The study also assessed the effects of ICI on spatiotemporal parameters of gait and functional status in this group. METHODS: Nine people with an exacerbation of RA of the knee were recruited. Kinematic and spatiotemporal gait parameters were obtained for each participant. Knee-related functional status was assessed using the Knee injury and Osteoarthritis Outcome Score (KOOS). Spatiotemporal gait parameters and joint angles (knee flexion, ankle DF/PF, hip abd/add) of the affected side were compared pre- and post-ICI. RESULTS: Data for eight people were available for analysis. Median values for knee flexion and ankle PF increased significantly following ICI. Gait parameters of cadence, velocity, bilateral stride length, bilateral step length, step width, double-support percentage, and step time on the affected side also showed improvement. Pain and knee-related functional status as measured by the KOOS showed improvement. CONCLUSIONS: This study demonstrated a beneficial short-term effect of ICI on knee-joint movements, gait parameters, and knee-related functional status in people with acute exacerbation of RA of the knee.

Treatment of chronic low-back pain: a 1-year or greater follow-up.

BACKGROUND: Musculoskeletal disorders are the most frequent cause of physical disability in developed countries. In particular, lower back pain is very common and represents a significant burden both in terms of patient suffering and costs. It is important to determine the most effective and efficient interventions in the treatment of this condition. PURPOSE: This article presents clinical outcomes in patients with chronic lower back pain involving ligamentous pathology treated by a physician who specializes in injection therapy for chronic musculoskeletal conditions and is able to tailor injection therapy specifically to each individual patient. DESIGN: As a retrospective case series, patients from outpatient clinics in both rural and one urban centre were assessed, treated, and had 1 year or more follow-up. METHODS: Patients were referred by their family physician for assessment for chronic lower back pain refractory to conventional medical management. OUTCOME MEASURES: Pain and quality of life (QoL) numeric (10 cm) analog scales (0 = no pain, 10 = the worst pain imaginable; 0 = best quality of life, 10 = worst quality of life) were administered pretreatment and 1 year or later after the last treatment. RESULTS: One hundred and ninety (190) patients were treated during the study period, June 1999-May 2006. Patients whose follow-up was 1 year or greater from the last treatment were included, leaving 140 patients available for data analysis. Both pain and QoL scores were significantly improved at least 1 year after the last treatment. There were no differences in outcomes as a result of age, response to Xylocaine (lidocaine) injection, insurance coverage, smoking history, or gender. CONCLUSIONS: This study suggests that prolotherapy using a variety of proliferants can be an effective treatment for low back pain from presumed ligamentous dysfunction for some patients when performed by a skilled practitioner.

Manipulation of objects with and without the use of the index finger: implications for digital amputations.

STUDY DESIGN: Clinical Measurement. PURPOSE: To evaluate changes in temporal and amplitude movement accuracy with tasks requiring fine motor manipulation with and without the use of the index finger (WIF). PARTICIPANTS: Twenty right-handed participants (10 males, 10 females, aged 24-47 years) were recruited. METHODS: Three objects, ranging in weight and size, that required the use of 2 or 3 fingers were selected for this study. Motor performance was quantified during manipulation of a pen, cork, and wine glass using a computerized visual guided tracking task. The miniBird (Ascension Technology, Burlington, VT, USA) miniature motion tracking sensor was attached to each object to measure and record the 3D linear and angular motion. RESULTS: Task performance and temporal accuracy of the pen task in the normal condition was more accurate (P=.033). During the WIF condition there was significantly more motion performing the wine task (P<.001). CONCLUSIONS: The protocol directly measures the ability of the hand to coordinate movement in response to a visual tracking target. Both temporal accuracy and amplitude consistency can be objectively evaluated. The current study evaluates the ability of the hand to manipulate 3 objects used in fine motor manipulation, using motion analysis and visual tracking. LEVEL OF EVIDENCE: 3b.

Relationship between dynamic balance measures and functional performance in community-dwelling elderly people.

BACKGROUND: Poor balance control, mobility restrictions, and fall injuries are serious problems for many older adults. OBJECTIVE: The purpose of this study was to evaluate a new dynamic standing balance assessment test for identifying individuals at risk for falling in a group of community-dwelling older adults. DESIGN: This was a cross-sectional observational study of 72 community-dwelling older adults who were receiving rehabilitation in a geriatric day hospital. METHOD: A Dynamic Balance Assessment (DBA) test protocol was developed based on the concept of the Sensory Organization Test and the Clinical Test of Sensory Interaction and Balance. The DBA consists of 6 tasks performed on a normal floor surface and repeated on a sponge surface. A flexible pressure mat was used to record the foot's center of pressure (COP) on both surfaces, and loss of balance was recorded. Balance performance also was evaluated using the Berg Balance Scale, the Timed "Up & Go" Test, gait speed, and the Six-Minute Walk Test. Participants were classified as "fallers" or "nonfallers" based on a self-report. RESULTS: No significant differences were noted between the faller group (n=47) and the nonfaller group (n=25) for demographic variables or medications. The DBA composite scores, which were derived from analysis of COP excursions of the 6 tasks performed on the sponge surface, were able to distinguish between fallers and nonfallers. Of the clinical tests, only the Timed "Up & Go" Test was able to differentiate between the faller and nonfaller groups. Limitations A prospective study is needed to confirm the current findings and to expand testing to a larger and more diverse sample. CONCLUSIONS: The findings indicate that analysis of the extent and amount of COP displacements during selected tasks and under different surface conditions is an appropriate method to assess dynamic standing balance controls and can discriminate between fallers and nonfallers among community-dwelling elderly people.

Objective evaluation of fine motor manipulation-a new clinical tool.

A new performance-based tool has been developed to accurately and precisely evaluate finger/hand function during manipulation of any object, independent of geometric and surface properties. The objectives of this study were to show test-retest reliability and evaluate criterion validity. Twenty healthy, right-handed participants were recruited. Three objects ranging in weight and size, requiring two or three fingers, were instrumented with a motion sensor that tracked 3D linear/angular motion. A computerized visual-guided tracking task was used to quantify motor performance during object manipulation. Two testing periods, one week apart were performed to evaluate test-retest reliability. Criterion validity was assessed by comparing performance with this tool to performance on commonly used clinical dexterity tests. Global performance, temporal accuracy, and amplitude consistency during manipulation of the objects compared with the reference waveform were highly reliable on the two testing occasions. Low-moderate correlations between the clinical dexterity tests and the task protocol indicate that different aspects of hand function were measured. The task protocol directly measures the ability of the hand to coordinate movement in response to a visual tracking target. Providing effective and objective ways to evaluate manual dexterity and hand function is a critical part of evidence-based practice.

Serotonin 5-HT2 receptors induce a long-lasting facilitation of spinal reflexes independent of ionotropic receptor activity.

Dorsal root-evoked stimulation of sensory afferents in the hemisected in vitro rat spinal cord produces reflex output, recorded on the ventral roots. Transient spinal 5-HT(2C) receptor activation induces a long-lasting facilitation of these reflexes (LLFR) by largely unknown mechanisms. Two Sprague-Dawley substrains were used to characterize network properties involved in this serotonin (5-HT) receptor-mediated reflex plasticity. Serotonin more easily produced LLFR in one substrain and a long-lasting depression of reflexes (LLDR) in the other. Interestingly, LLFR and LLDR were bidirectionally interconvertible using 5-HT(2A/2C) and 5-HT(1A) receptor agonists, respectively, regardless of substrain. LLFR was predominantly Abeta afferent fiber mediated, consistent with prominent 5-HT(2C) receptor expression in the Abeta fiber projection territories (deeper spinal laminae). Reflex facilitation involved an unmasking of polysynaptic pathways and an increased receptive field size. LLFR emerged even when reflexes were evoked three to five times/h, indicating an activity independent induction. Both the NMDA and AMPA/kainate receptor-mediated components of the reflex could be facilitated, and facilitation was dependent on 5-HT receptor activation alone, not on coincident reflex activation in the presence of 5-HT. Selective blockade of GABA(A) and/or glycine receptors also did not prevent reflex amplification and so are not required for LLFR. Indeed, a more robust response was seen after blockade of spinal inhibition, indicating that inhibitory processes serve to limit reflex amplification. Overall we demonstrate that the serotonergic system has the capacity to induce long-lasting bidirectional changes in reflex strength in a manner that is nonassociative and independent of evoked activity or activation of ionotropic excitatory and inhibitory receptors.

Serotonin alters multi-segmental convergence patterns in spinal cord deep dorsal horn and intermediate laminae neurons in an in vitro young rat preparation.

Each spinal neuron has a receptive field that corresponds to stimulation of a specific area of skin or subcutaneous tissue. Receptive fields are plastic and can be altered during development and injury but the actions of neuromodulators, such as serotonin (5-hydroxytryptamine, 5-HT) on receptive field properties are not well known. We used stimulation of multiple adjacent dorsal root spinal segments as a measure of "receptive field size" to determine the effects of 5-HT on multi-segmental convergent input onto neurons in laminae IV-VII. Whole-cell patch-clamp recordings were undertaken in the in vitro hemisected thoracolumbar spinal cord of rats aged 8-10 days old. Based on synaptic responses, neurons could be divided into two predominant groups and 5-HT exerted different effects on these groups. The first group received excitatory post-synaptic potentials (EPSPs) from the homonymous dorsal root but inhibitory post-synaptic potentials (IPSPs) with increasing amplitude from more distant dorsal roots. In this group, 5-HT preferentially depressed the IPSPs from adjacent nerve roots while leaving the EPSP intact. The second group received short-latency EPSPs from all segments stimulated and 5-HT potently depressed all synaptic input. In both populations the depressant actions of 5-HT increased with dose (0.1-10.0 microM). Bicuculline and strychnine did not affect the 5-HT induced short-latency synaptic depression. These results suggest that descending serotonergic systems depress spinal sensory convergence in a graded and differentiated manner. The findings are discussed in relation to the modulation of nociceptive signaling.