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Τετάρτη 27 Απριλίου 2016
Firefighter - Lebanon Fire District
Neurophysiological analytics for all! Free open-source software tools for documenting, analyzing, visualizing, and sharing using electronic notebooks
Neurophysiology requires an extensive workflow of information analysis routines, which often includes incompatible proprietary software, introducing limitations based on financial costs, transfer of data between platforms, and the ability to share. An ecosystem of free open-source software exists to fill these gaps, including 1000's of analysis and plotting packages written in Python and R, which can be implemented in a sharable and reproducible format, such as the Jupyter electronic notebook. This tool chain can largely replace current routines by importing data, producing analyses, and generating publication quality graphics. An electronic notebook, like Jupyter, allows these analyses, along with documentation of procedures, to display locally or remotely in an internet browser, which can be saved as an HTML, PDF, or other file format for sharing with team members and the scientific community. The current report illustrates these methods using data from electrophysiological recordings of the musk shrew vagus - a model system to investigate gut-brain communication, for example, cancer chemotherapy-induced emesis. We show methods for spike sorting (including statistical validation), spike train analysis, and analysis of compound action potentials in notebooks. Raw data and code are available from notebooks in Data Supplements or from an executable online version, which replicates all analyses without installing software - an implementation of reproducible research. This demonstrates the promise of combining disparate analyses into one platform, along with the ease of sharing this work. In an age of diverse, high-throughput computational workflows, this methodology can increase efficiency, transparency, and the collaborative potential of neurophysiological research.
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Assessment of the expression and role of the {alpha}1 nAChR subunit in efferent cholinergic function during the development of the mammalian cochlea
Hair cell (HC) activity in the mammalian cochlea is modulated by cholinergic efferent inputs from the brainstem. These inhibitory inputs are mediated by calcium-permeable nicotinic acetylcholine receptors (nAChRs) containing α9 and α10 subunits and by subsequent activation of calcium-dependent potassium channels. Intriguingly, mRNAs of α1 and nAChRs, subunits of the 'muscle-type' nAChR have also been found in developing HCs (Cai et al. 2015; Scheffer et al. 2007; Sinkkonen et al. 2011) prompting proposals that another type of nAChR is present and may be critical during early synaptic development. Mouse genetics, histochemistry, pharmacology and whole-cell recording approaches were combined to test the role of α1 nAChR subunit in HC efferent synapse formation and cholinergic function. The onset of α1 mRNA expression in mouse HCs was found to coincide with the onset of the ACh response and efferent synaptic function. However, in mouse inner hair cells (IHCs) no response to the muscle-type nAChR agonists (±)-anatoxin A, (±)-epibatidine, (-)-nicotine or DMPP was detected, arguing against the presence of an independent functional α1-containing muscle-type nAChR in IHCs. In α1 deficient mice, no obvious change of IHC efferent innervation was detected at E18, contrary to the hyperinnervation observed at the neuromuscular junction. Additionally, ACh response and efferent synaptic activity were detectable in α1 deficient IHCs, suggesting that α1 is not necessary for assembly and membrane targeting of nAChRs, or for efferent synapse formation in IHCs.
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Saccadic adaptation to a systematically varying disturbance
Saccadic adaptation maintains the correct mapping between eye movements and their targets, yet the dynamics of saccadic gain changes in the presence of systematically varying disturbances has not been extensively studied. Here, we assessed changes in the gain of saccade amplitudes induced by continuous and periodic post-saccadic visual feedback. Observers made saccades following a sequence of target steps either along the horizontal meridian (Two-way adaptation) or with unconstrained saccade directions (Global adaptation). An intra-saccadic step-following a sinusoidal variation as a function of the trial number (with three different frequencies tested in separate blocks)-consistently displaced the target along its vector. The oculomotor system responded to the resulting feedback error by modifying saccade amplitudes in a periodic fashion with similar frequency of variation but lagging the disturbance by a few trials. This periodic response was superimposed on a drift towards stronger hypometria with similar asymptotes and decay rates across stimulus conditions. The magnitude of the periodic response decreased with increasing frequency and was smaller and more delayed for Global than Two-way adaptation. These results suggest that-in addition to the well-characterized return-to-the-baseline response observed in protocols using constant visual feedback-the oculomotor system attempts to minimize the feedback error by integrating its variation across trials. This process resembles a convolution with an internal response function, whose structure would be determined by coefficients of the learning model. Our protocol reveals this fast learning process in single short experimental sessions, qualifying it for the study of sensorimotor learning in health and disease.
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Maintaining balance against force perturbations: impaired mechanisms unresponsive to levodopa in Parkinson's disease.
There is evidence that postural instability associated with Parkinson's disease (PD) is not adequately improved by levodopa, implying involvement of non-dopaminergic pathways. However, the mechanisms contributing to postural instability have yet to be fully identified and tested for their levodopa responsiveness. Here we investigate balance processes that resist external forces to the body when standing. These include in-place responses, and the transition to protective stepping. Forward and backward shoulder pulls were delivered using two force-feedback-controlled motors and were randomised for direction, magnitude and onset. Sixteen PD patients were tested OFF and ON levodopa and 16 healthy controls were tested twice. Response behaviour was quantified from 3-D ground reaction forces and kinematic measurements of body segments and total body centre of mass (CoM) motion. In-place responses resisting the pull were significantly smaller in PD as reflected in reduced horizontal antero-posterior ground-reaction force and increased CoM displacement. Ankle, knee and hip moments contributing to this resistance were smaller in PD, with the knee extensor moment to backward pulls being the most affected. The threshold force needed to evoke a step was also smaller for PD in the forward direction. Protective steps evoked by supra-threshold pulls showed deficits in PD in the backward direction, with steps being shorter and more steps being required to arrest the body. Levodopa administration had no significant effect on either in-place or protective-stepping deficits. We conclude that processes employed to maintain balance in the face of external forces show impairment in PD consistent with disruption to non-dopaminergic systems.
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Accommodation to hyperpolarization of human axons assessed in the frequency domain
Human axons in vivo were subjected to subthreshold currents with a threshold-"ZAP" profile (Impedance [Z] Amplitude Profile) to allow the use of frequency domain techniques to determine the propensity for resonant behavior, and to clarify the relative contributions of different ion channels to their low-frequency responsiveness. Twenty-four studies were performed on the motor and sensory axons in 6 subjects. The response to oscillatory currents was tested between 'DC' and 16 Hz. A resonant peak at ~2 to 2.5 Hz was found in the response of hyperpolarized axons, but there was only a small broad response in axons at resting membrane potential (RMP). A mathematical model of axonal excitability developed using DC pulses provided a good fit to the frequency response for human axons, and indicated that the hyperpolarization-activated current Ih, and the slow potassium current IKs are principally responsible for the resonance. However the results indicate that if axons are hyperpolarized more than -60% of resting threshold, the only conductances that are appreciably active are Ih and the leak conductance - i.e., that the activity of these conductances can be studied in vivo virtually in isolation at hyperpolarized membrane potentials. Given that the leak conductance dampens resonance it is suggested that the -60% hyperpolarization used here is optimal for Ih. As expected differences between the frequency responses of motor and sensory axons were present and best explained by reduced GKs, up-modulation of Ih and increased persistent Na+ current, INaP (due to depolarization of RMP) in sensory axons.
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Computational modeling indicates that surface pressure can be reliably conveyed to tactile receptors even amidst changes in skin mechanics
Distinct patterns in neuronal firing are observed between classes of cutaneous afferents. Such differences may be attributed to end organ morphology, distinct ion-channel complements, and skin microstructure, among other factors. Even for just the slowly adapting type I afferent, the skin's mechanics for a particular specimen might impact the afferent's firing properties, especially given the thickness and elasticity of skin can change dramatically over just days. Here, we show computationally that the skin can reliably convey indentation magnitude, rate and spatial geometry to the locations of tactile receptors even amidst changes in skin's structure. Using finite element analysis and neural dynamics models, we considered the skin properties of six mice that span a representative cohort. Modeling the propagation of the surface stimulus to the interior of the skin demonstrated that there can be large variance in stresses and strains near the locations of tactile receptors, which can lead to large variance in static firing rate. However, variance is significantly reduced when the stimulus tip is controlled by surface pressure and compressive stress is measured near the end organs. This particular transformation affords the least variability in predicted firing rates compared to others derived from displacement, force, strain energy density or compressive strain. Amidst changing skin mechanics, stimulus control by surface pressure may be more naturalistic and optimal and underlie how animals actively explore the tactile environment.
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Response Properties of MST Parafoveal Neurons during Smooth Pursuit Adaptation
Visual motion neurons in the posterior parietal cortex play a critical role in the guidance of smooth pursuit eye movements. Initial pursuit (open-loop period) is driven, in part, by visual motion signals from cortical areas, such as the medial superior temporal areas (MST). The purpose of this study was to determine whether adaptation of initial pursuit gain arises due to altered visual sensitivity of neurons at the cortical level. It is well known that the visual motion response in MST is suppressed following exposure to a large-field visual motion stimulus, showing visual motion adaptation. One hypothesis is that foveal motion responses in MST are associated with the smooth pursuit adaptation using a small target spot. We used a step-ramp tracking task with two steps of target velocity (double-step paradigm), which induces gain-down or gain-up adaptation. We found that following gain-down adaptation, 58% of our MST visual neurons showed a significant decrease in firing rate. This was the case even though visual motion input (before the pursuit onset) from target motion was constant. Therefore, repetitive visual stimulation during the gain-down paradigm could lead to adaptive changes in the visual response. However, the timecourse of adaptation did not show a correlation between the visual response and pursuit behavior. These results indicate the visual response in MST may not directly contribute to the adaptive change in pursuit initiation.
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Neuronal Hyperexcitability in the Ventral Posterior Thalamus of Neuropathic Rats: Modality Selective Effects of Pregabalin
Neuropathic pain represents a substantial clinical challenge; understanding the underlying neural mechanisms and back-translation of therapeutics could aid targeting of treatments more effectively. The ventral posterior thalamus (VP) is the major termination site for the spinothalamic tract and relays nociceptive activity to the somatosensory cortex, however under neuropathic conditions, it is unclear how hyperexcitability of spinal neurones converges onto thalamic relays. This study aimed to identify neural substrates of hypersensitivity, and the influence of pregabalin on central processing. In vivo electrophysiology was performed to record from VP wide dynamic range (WDR) and nociceptive-specific (NS) neurones in anaesthetised spinal nerve-ligated (SNL), sham-operated and naïve rats. In neuropathic rats, WDR neurones had elevated evoked responses to low and high intensity punctate mechanical stimuli, dynamic brushing, innocuous and noxious cooling, but less so to heat stimulation of the receptive field. NS neurones in SNL rats also displayed increased responses to noxious punctate mechanical stimulation, dynamic brushing, noxious cooling and noxious heat. Additionally, WDR, but not NS, neurones in SNL rats exhibited substantially higher rates of spontaneous firing, which may correlate with ongoing pain. The ratio of WDR:NS neurones was comparable between SNL and naïve/sham groups suggesting relatively few NS neurones gain sensitivity to low intensity stimuli leading to a 'WDR phenotype'. After neuropathy, the proportion of cold sensitive WDR and NS neurones increased, supporting that changes in frequency dependent firing and population coding underlie cold hypersensitivity. In SNL rats, pregabalin inhibited mechanical and heat responses but not cold evoked or elevated spontaneous activity.
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A comparison of computational methods for detecting bursts in neuronal spike trains and their application to human stem cell-derived neuronal networks
Accurate identification of bursting activity is an essential element in the characterization of neuronal network activity. Despite this, no one technique for identifying bursts in spike trains has been widely adopted. Instead, many methods have been developed for the analysis of bursting activity, often on an ad hoc basis. Here, we provide an unbiased assessment of the effectiveness of eight of these methods at detecting bursts in a range of spike trains. We suggest a list of features that an ideal burst detection technique should possess, and use synthetic data to assess each method in regards to these properties. We further employ each of the methods to re-analyze microelectrode array (MEA) recordings from mouse retinal ganglion cells, and examine their coherence with bursts detected by a human observer. We show that several common burst detection techniques perform poorly at analyzing spike trains with a variety of properties. We identify four promising burst detection techniques, which are then applied to MEA recordings of networks of human induced pluripotent stem cell (hiPSC)-derived neurons, and used to describe the ontogeny of bursting activity in these networks over several months of development. We conclude that no current method can provide 'perfect' burst detection results across a range of spike trains, however two burst detection techniques, the MaxInterval and logISI methods, outperform compared to others. We provide recommendations for the robust analysis of bursting activity in experimental recordings using current techniques.
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Brain potentials evoked by intraepidermal electrical stimuli reflect the central sensitization of nociceptive pathways
Central sensitization (CS), the increased sensitivity of the central nervous system to somatosensory inputs, accounts for secondary hyperalgesia, a typical sign of several painful clinical conditions. Brain potentials elicited by mechanical punctate stimulation using flat-tip probes can provide neural correlates of CS, but their signal-to-noise ratio is limited by poor synchronisation of the afferent nociceptive input. Additionally, mechanical punctate stimulation does not activate nociceptors exclusively. In contrast, low-intensity intra-epidermal electrical stimulation (IES) allows selective activation of type-II A mechano-heat nociceptors (II-AMHs), and elicits reproducible brain potentials. However, it is unclear whether hyperalgesia from IES occurs and co-exists with secondary mechanical punctate hyperalgesia, and whether the magnitude of the EEG responses evoked by IES within the hyperalgesic area is increased. To address these questions, we explored the modulation of the psychophysical and EEG responses to IES by intra-epidermal injection of capsaicin in healthy human subjects. We obtained three main results. First, the intensity of the sensation elicited by IES was significantly increased in participants who developed robust mechanical punctate hyperalgesia after capsaicin injection (i.e., responders), indicating that hyperalgesia from IES co-exists with punctate mechanical hyperalgesia. Second, the N2 peak magnitude of the EEG responses elicited by IES were significantly increased after the intra-epidermal injection of capsaicin in responders only. Third, a receiver-operator characteristics analysis showed that the N2 peak amplitude is clearly predictive of the presence of CS. These findings suggest that the EEG responses elicited by IES reflect secondary hyperalgesia, and therefore represent an objective correlate of CS.
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A motor planning stage represents the shape of upcoming movement trajectories
Interactions with our environment require curved movements that depend not only on the final position of the hand but on the path used to achieve it. Current studies in motor control, however, largely focus on point-to-point movements and do not consider how movements with specific desired trajectories might arise. Here, we examined intentionally curved reaching movements that navigate paths around obstacles. We found that the preparation of these movements incurred a large reaction-time cost. This cost could not be attributed to non-motor task requirements (e.g., stimulus perception), and was independent of the execution difficulty (i.e., extent of curvature) of the movement. Additionally, this trajectory-representation cost was not observed for point-to-point reaches (but could be optionally included if the task encouraged consideration of straight trajectories). Therefore, when the path of a movement is task relevant, the shape of the desired trajectory is overtly represented as a stage of motor planning. This trajectory-representation ability may help explain the vast repertoire of human motor behaviors.
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Measurement of Intra-individual Airway Tone Heterogeneity and its Importance in Asthma
While airways have some degree of baseline tone, the level and variability of this tone is not known. It is also unclear whether there is a difference in airway tone or in the variability of airway tone between asthmatic and healthy individuals. This study examined airway tone and intra-individual airway tone heterogeneity (variance of airway tone) in vivo in 19 individuals with asthma compared to 9 healthy adults. All participants underwent spirometry, body plethysmography and HRCT at baseline and after maximum bronchodilation with albuterol. Airway tone was defined as the percent difference in airway diameter after albuterol at total lung capacity compared to baseline. The amount of airway tone in each airway varied both within and between subjects but the difference between the two groups did not reach statistical significance (p=0.09). In contrast, the two groups differed in intra-individual airway tone heterogeneity (p=0.016). Intra-individual airway tone heterogeneity was strongly correlated with airway tone (r= 0.78, p<0.0001). Also, it was negatively correlated with the magnitude of the distension of the airways from FRC to TLC at both baseline (r= -0.49, p= 0.03) and after maximum bronchodilation (r= -0.51, p= 0.02) in the asthma, but not the healthy group. We did not find any relationship between intra-individual airway tone heterogeneity and lung function. Intra-individual airway tone heterogeneity may be an important marker of airway pathophysiology in asthma.
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Central command generated prior to arbitrary motor execution induces muscle vasodilatation at the beginning of dynamic exercise
The purpose of this study was to examine the role of central command, generated prior to arbitrary motor execution, in cardiovascular and muscle blood flow regulation during exercise. Thirty two subjects performed 30-s of two-legged cycling or 1-min of one-legged cycling (66 ± 4% and 35% of the maximal exercise intensity, respectively), which was started arbitrarily or abruptly by a verbal cue (arbitrary vs. cued start). We measured the cardiovascular variables during both exercises and the relative changes in oxygenated-hemoglobin concentration (Oxy-Hb) of non-contracting vastus lateralis muscles as index of tissue blood flow, and femoral blood flow to non-exercising leg during one-legged cycling. Two-legged cycling with arbitrary start caused a decrease in total peripheral resistance (TPR), which was smaller during the exercise with cued start. The greater reduction of TPR with arbitrary start was also recognized at the beginning of one-legged cycling. Oxy-Hb of non-contracting muscle increased by 3.6 ± 1% (P<0.05) during one-legged cycling with arbitrary start, whereas such increase in Oxy-Hb was absent with cued start. The increases in femoral blood flow and vascular conductance of non-exercising leg were evident (P<0.05) at 10 s from the onset of one-legged cycling with arbitrary start, whereas those were smaller or absent with cued start. It is likely that when voluntary exercise is started arbitrarily, central command is generated prior to motor execution and then contributes to muscle vasodilatation at the beginning of exercise. Such centrally-induced muscle vasodilatation may be weakened and/or masked in the case of exercise with cued start.
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Force Steadiness As A Predictor Of Time To Complete A Pegboard Test Of Dexterity In Young Men And Women
The purpose of the study was to evaluate the capacity of an expanded set of force steadiness tasks to explain the variance in the time it takes young men and women to complete the grooved pegboard test. In a single experimental session, 30 participants (24.2 ± 4.0 yrs; 15 women) performed the grooved pegboard test, two tests of hand speed, measurements of muscle strength, and a set of submaximal, steady contractions. The steadiness tasks involved single and double actions requiring isometric contractions in the directions of wrist extension, a pinch between the index finger and thumb, and index finger abduction. Time to complete the grooved pegboard test ranged from 41.5 to 67.5 s. The pegboard times (53.9 ± 6.2 s) were not correlated with any of the strength measurements or the reaction-time test of hand speed. A stepwise, multiple-regression analysis indicated that much of the variance (R2 = 0.70) in pegboard times could be explained by a model that comprised two predictor variables derived from the steadiness tasks: time to match the target during a rapid force-matching task and force steadiness (coefficient of variation for force) during a single-action task. Moreover, the pegboard times were significantly faster for women (51.7 ± 6.8 s) than men (56.1 ± 4.9 s). Participants with slower pegboard times seemed to place a greater emphasis on accuracy than speed as they had longer times to match the target during the rapid force-matching task and exhibited superior force steadiness during the single-action task.
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Hyperoxia and hypergravity are independent risk factors of atelectasis in healthy sitting humans: a pulmonary ultrasound and SPECT/CT study.
Aero-atelectasis has developed in aircrew flying routine peacetime flights on the latest generation high-performance aircraft, when undergoing excessive oxygen supply. To single out the effects of hyperoxia and hypergravity on lung tissue compression, and on ventilation and perfusion, eight subjects were studied before and after 1h15 min exposure to 1-3.5Gz in a human centrifuge. They performed the protocol three times, breathing air, 44.5%O2 or 100%O2 and underwent functional and topographical imaging of the whole lung by ultrasound and SPECT/CT. Ultrasound lung comets (ULC) and atelectasis both increased after exposure. The number of ULC was <1 pre-protocol (i.e. normal lung) and larger post-100%O2 (22 ± 3, mean ± SD) than in all other conditions (P<0.001). Post-44.5%O2 differed from air (P <0.05). Seven subjects showed low to medium grade atelectasis post-100%O2. There was an effect on grade of gas mixture and hypergravity, with interaction (P < 0.001 respectively). 100%O2, 44.5% O2 and air differed from each other (P < 0.05). SPECT ventilation and perfusion was always normal. Ultrasound concurred with CT for showing normal lung in the upper third and ULC/atelectasis in posterior and inferior areas, not for other localizations. In conclusion, hyperoxia and hypergravity are independent risk factors of reversible atelectasis formation. Ultrasound is a useful screening tool. Together with electrical impedance tomography measurements (reported separately), these findings show that zones with decreased ventilation prone to transient airway closure are present above atelectatic areas.
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Lack of correlation between cerebral vasomotor reactivity and dynamic cerebral autoregulation during stepwise increases in inspired CO2 concentration
Cerebral vasomotor reactivity (CVMR) and dynamic cerebral autoregulation (CA) are measured extensively in clinical and research studies. However, the relationship between these measurements of cerebrovascular function is not well understood. In this study, we measured changes in cerebral blood flow velocity (CBFV) and arterial blood pressure (BP) in response to stepwise increases in inspired CO2 concentrations of 3% and 6% to assess CVMR and dynamic CA in 13 healthy young adults (2 women, 32±9 yrs). CVMR was assessed as percentage changes in CBFV (CVMRCBFV) or cerebrovascular conductance index (CVCi, CVMRCVCi) in response to hypercapnia. Dynamic CA was estimated by performing transfer function analysis between spontaneous oscillations in BP and CBFV. Steady-state CBFV and CVCi both increased exponentially during hypercapnia; CVMRCBFV and CVMRCVCi were greater at 6% (3.85±0.90 and 2.45±0.79%/mmHg) than 3% CO2 (2.09±1.47 and 0.21±1.56%/mmHg, p=0.009 and 0.005, respectively). Furthermore, CVMRCBFV was greater than CVMRCVCi during either 3% or 6% CO2 (p=0.017 and p<0.001, respectively). Transfer function gain and coherence increased in the very low frequency range (0.02-0.07Hz) and phase decreased in the low frequency range (0.07-0.20Hz) when breathing 6%, but not 3% CO2. There were no correlations between the measurements of CVMR and dynamic CA. These findings demonstrated influences of inspired CO2 concentrations on assessment of CVMR and dynamic CA. The lack of correlation between CVMR and dynamic CA suggests that cerebrovascular responses to changes in arterial CO2 and BP are mediated by distinct regulatory mechanisms.
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Shape-independent object category responses revealed by MEG and fMRI decoding
Neuroimaging research has identified category-specific neural response patterns to a limited set of object categories. For example, faces, bodies, and scenes evoke activity patterns in visual cortex that are uniquely traceable in space and time. It is currently debated whether these apparently categorical responses truly reflect selectivity for categories or instead reflect selectivity for category-associated shape properties. In the present study, we used a cross-classification approach on functional MRI (fMRI) and magnetoencephalographic (MEG) data to reveal both category-independent shape responses and shape-independent category responses. Participants viewed human body parts (hands and torsos) and pieces of clothing that were closely shape-matched to the body parts (gloves and shirts). Category-independent shape responses were revealed by training multivariate classifiers on discriminating shape within one category (e.g., hands versus torsos) and testing these classifiers on discriminating shape within the other category (e.g., gloves versus shirts). This analysis revealed significant decoding in large clusters in visual cortex (fMRI) starting from 90 ms after stimulus onset (MEG). Shape-independent category responses were revealed by training classifiers on discriminating object category (bodies and clothes) within one shape (e.g., hands versus gloves) and testing these classifiers on discriminating category within the other shape (e.g., torsos versus shirts). This analysis revealed significant decoding in bilateral occipitotemporal cortex (fMRI) and from 130 to 200 ms after stimulus onset (MEG). Together, these findings provide evidence for concurrent shape and category selectivity in high-level visual cortex, including category-level responses that are not fully explicable by two-dimensional shape properties.
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Saccades create similar mislocalizations in visual and auditory space
Orienting our eyes to a light, a sound, or a touch occurs effortlessly, despite the fact that sound and touch have to be converted from head- and body-based coordinates to eye-based coordinates to do so. We asked whether the oculomotor representation is also used for localization of sounds even when there is no saccade to the sound source. To address this, we examined whether saccades introduced similar errors of localization judgments for both visual and auditory stimuli. Sixteen subjects indicated the direction of a visual or auditory apparent motion seen or heard between two targets presented either during fixation or straddling a saccade. Compared with the fixation baseline, saccades introduced errors in direction judgments for both visual and auditory stimuli: in both cases, apparent motion judgments were biased in direction of the saccade. These saccade-induced effects across modalities give rise to the possibility of shared, cross-modal location coding for perception and action.
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Electroencephalographic detection of respiratory-related cortical activity in humans: from event-related approaches to continuous connectivity evaluation
The presence of a respiratory-related cortical activity during tidal breathing is abnormal and a hallmark of respiratory difficulties, but its detection requires superior discrimination and temporal resolution. The aim of this study was to validate a computational method using EEG covariance (or connectivity) matrices to detect a change in brain activity related to breathing. In 17 healthy subjects, EEG was recorded during resting unloaded breathing (RB), voluntary sniffs, and breathing against an inspiratory threshold load (ITL). EEG were analyzed by the specially developed covariance-based classifier, event-related potentials, and time-frequency (T-F) distributions. Nine subjects repeated the protocol. The classifier could accurately detect ITL and sniffs compared with the reference period of RB. For ITL, EEG-based detection was superior to airflow-based detection (P < 0.05). A coincident improvement in EEG-airflow correlation in ITL compared with RB (P < 0.05) confirmed that EEG detection relates to breathing. Premotor potential incidence was significantly higher before inspiration in sniffs and ITL compared with RB (P < 0.05), but T-F distributions revealed a significant difference between sniffs and RB only (P < 0.05). Intraclass correlation values ranged from poor (–0.2) to excellent (1.0). Thus, as for conventional event-related potential analysis, the covariance-based classifier can accurately predict a change in brain state related to a change in respiratory state, and given its capacity for near "real-time" detection, it is suitable to monitor the respiratory state in respiratory and critically ill patients in the development of a brain-ventilator interface.
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Associative plasticity in the human motor cortex is enhanced by concurrently targeting separate muscle representations with excitatory and inhibitory protocols
Paired associative stimulation (PAS) induces changes in the excitability of human sensorimotor cortex that outlast the procedure. PAS typically involves repeatedly pairing stimulation of a peripheral nerve that innervates an intrinsic hand muscle with transcranial magnetic stimulation over the representation of that muscle in the primary motor cortex. Depending on the timing of the stimuli (interstimulus interval of 25 or 10 ms), PAS leads to either an increase (PAS25) or a decrease (PAS10) in excitability. Both protocols, however, have been associated with an increase in excitability of nearby muscle representations not specifically targeted by PAS. Based on these spillover effects, we hypothesized that an additive, excitability-enhancing effect of PAS25 applied to one muscle representation may be produced by simultaneously applying PAS25 or PAS10 to a nearby representation. In different experiments prototypical PAS25 targeting the left thumb representation [abductor pollicis brevis (APB)] was combined with either PAS25 or PAS10 applied to the left little finger representation [abductor digiti minimi (ADM)] or, in a control experiment, with PAS10 also targeting the APB. In an additional control experiment PAS10 targeted both representations. The plasticity effects were quantified by measuring the amplitude of motor evoked potentials (MEPs) recorded before and after PAS. As expected, prototypical PAS25 was associated with an increase in MEP amplitude in the APB muscle. This effect was enhanced when PAS also targeted the ADM representation but only when a different interstimulus timing (PAS10) was used. These results suggest that PAS-induced plasticity is modified by concurrently targeting separate motor cortical representations with excitatory and inhibitory protocols.
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Frontal and motor cortex contributions to response inhibition: evidence from electrocorticography
Changes in the environment require rapid modification or inhibition of ongoing behavior. We used the stop-signal paradigm and intracranial recordings to investigate response preparation, inhibition, and monitoring of task-relevant information. Electrocorticographic data were recorded in eight patients with electrodes covering frontal, temporal, and parietal cortex, and time-frequency analysis was used to examine power differences in the beta (13–30 Hz) and high-gamma bands (60–180 Hz). Over motor cortex, beta power decreased, and high-gamma power increased during motor preparation for both go trials (Go) and unsuccessful stops (US). For successful stops (SS), beta increased, and high-gamma was reduced, indexing the cancellation of the prepared response. In the middle frontal gyrus (MFG), stop signals elicited a transient high-gamma increase. The MFG response occurred before the estimated stop-signal reaction time but did not distinguish between SS and US trials, likely signaling attention to the salient stop stimulus. A postresponse high-gamma increase in MFG was stronger for US compared with SS and absent in Go, supporting a role in behavior monitoring. These results provide evidence for differential contributions of frontal subregions to response inhibition, including motor preparation and inhibitory control in motor cortex and cognitive control and action evaluation in lateral prefrontal cortex.
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Synaptic refinement during development and its effect on slow-wave activity: a computational study
Recent evidence suggests that synaptic refinement, the reorganization of synapses and connections without significant change in their number or strength, is important for the development of the visual system of juvenile rodents. Other evidence in rodents and humans shows that there is a marked drop in sleep slow-wave activity (SWA) during adolescence. Slow waves reflect synchronous transitions of neuronal populations between active and inactive states, and the amount of SWA is influenced by the connection strength and organization of cortical neurons. In this study, we investigated whether synaptic refinement could account for the observed developmental drop in SWA. To this end, we employed a large-scale neural model of primary visual cortex and sections of the thalamus, capable of producing realistic slow waves. In this model, we reorganized intralaminar connections according to experimental data on synaptic refinement: during prerefinement, local connections between neurons were homogenous, whereas in postrefinement, neurons connected preferentially to neurons with similar receptive fields and preferred orientations. Synaptic refinement led to a drop in SWA and to changes in slow-wave morphology, consistent with experimental data. To test whether learning can induce synaptic refinement, intralaminar connections were equipped with spike timing-dependent plasticity. Oriented stimuli were presented during a learning period, followed by homeostatic synaptic renormalization. This led to activity-dependent refinement accompanied again by a decline in SWA. Together, these modeling results show that synaptic refinement can account for developmental changes in SWA. Thus sleep SWA may be used to track noninvasively the reorganization of cortical connections during development.
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Long-latency reflexes of elbow and shoulder muscles suggest reciprocal excitation of flexors, reciprocal excitation of extensors, and reciprocal inhibition between flexors and extensors
Postural corrections of the upper limb are required in tasks ranging from handling an umbrella in the changing wind to securing a wriggling baby. One complication in this process is the mechanical interaction between the different segments of the arm where torque applied at one joint induces motion at multiple joints. Previous studies have shown the long-latency reflexes of shoulder muscles (50–100 ms after a limb perturbation) account for these mechanical interactions by integrating information about motion of both the shoulder and elbow. It is less clear whether long-latency reflexes of elbow muscles exhibit a similar capability and what is the relation between the responses of shoulder and elbow muscles. The present study utilized joint-based loads tailored to the subjects' arm dynamics to induce well-controlled displacements of their shoulder and elbow. Our results demonstrate that the long-latency reflexes of shoulder and elbow muscles integrate motion from both joints: the shoulder and elbow flexors respond to extension at both joints, whereas the shoulder and elbow extensors respond to flexion at both joints. This general pattern accounts for the inherent flexion-extension coupling of the two joints arising from the arm's intersegmental dynamics and is consistent with spindle-based reciprocal excitation of shoulder and elbow flexors, reciprocal excitation of shoulder and elbow extensors, and across-joint inhibition between the flexors and extensors.
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Visual ecology and potassium conductances of insect photoreceptors
Voltage-activated potassium channels (Kv channels) in the microvillar photoreceptors of arthropods are responsible for repolarization and regulation of photoreceptor signaling bandwidth. On the basis of analyzing Kv channels in dipteran flies, it was suggested that diurnal, rapidly flying insects predominantly express sustained K+ conductances, whereas crepuscular and nocturnally active animals exhibit strongly inactivating Kv conductances. The latter was suggested to function for minimizing cellular energy consumption. In this study we further explore the evolutionary adaptations of the photoreceptor channelome to visual ecology and behavior by comparing K+ conductances in 15 phylogenetically diverse insects, using patch-clamp recordings from dissociated ommatidia. We show that rapid diurnal flyers such as the blowfly (Calliphora vicina) and the honeybee (Apis mellifera) express relatively large noninactivating Kv conductances, conforming to the earlier hypothesis in Diptera. Nocturnal and/or slow-moving species do not in general exhibit stronger Kv conductance inactivation in the physiological membrane voltage range, but the photoreceptors in species that are known to rely more on vision behaviorally had higher densities of sustained Kv conductances than photoreceptors of less visually guided species. No statistically significant trends related to visual performance could be identified for the rapidly inactivating Kv conductances. Counterintuitively, strong negative correlations were observed between photoreceptor capacitance and specific membrane conductance for both sustained and inactivating fractions of Kv conductance, suggesting insignificant evolutionary pressure to offset negative effects of high capacitance on membrane filtering with increased conductance.
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Weak signal amplification and detection by higher-order sensory neurons
Sensory systems must extract behaviorally relevant information and therefore often exhibit a very high sensitivity. How the nervous system reaches such high sensitivity levels is an outstanding question in neuroscience. Weakly electric fish (Apteronotus leptorhynchus/albifrons) are an excellent model system to address this question because detailed background knowledge is available regarding their behavioral performance and its underlying neuronal substrate. Apteronotus use their electrosense to detect prey objects. Therefore, they must be able to detect electrical signals as low as 1 μV while using a sensory integration time of <200 ms. How these very weak signals are extracted and amplified by the nervous system is not yet understood. We studied the responses of cells in the early sensory processing areas, namely, the electroreceptor afferents (EAs) and pyramidal cells (PCs) of the electrosensory lobe (ELL), the first-order electrosensory processing area. In agreement with previous work we found that EAs cannot encode very weak signals with a spike count code. However, PCs can encode prey mimic signals by their firing rate, revealing a huge signal amplification between EAs and PCs and also suggesting differences in their stimulus encoding properties. Using a simple leaky integrate-and-fire (LIF) model we predict that the target neurons of PCs in the midbrain torus semicircularis (TS) are able to detect very weak signals. In particular, TS neurons could do so by assuming biologically plausible convergence rates as well as very simple decoding strategies such as temporal integration, threshold crossing, and combining the inputs of PCs.
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Viral vector-based tools advance knowledge of basal ganglia anatomy and physiology
Viral vectors were originally developed to deliver genes into host cells for therapeutic potential. However, viral vector use in neuroscience research has increased because they enhance interpretation of the anatomy and physiology of brain circuits compared with conventional tract tracing or electrical stimulation techniques. Viral vectors enable neuronal or glial subpopulations to be labeled or stimulated, which can be spatially restricted to a single target nucleus or pathway. Here we review the use of viral vectors to examine the structure and function of motor and limbic basal ganglia (BG) networks in normal and pathological states. We outline the use of viral vectors, particularly lentivirus and adeno-associated virus, in circuit tracing, optogenetic stimulation, and designer drug stimulation experiments. Key studies that have used viral vectors to trace and image pathways and connectivity at gross or ultrastructural levels are reviewed. We explain how optogenetic stimulation and designer drugs used to modulate a distinct pathway and neuronal subpopulation have enhanced our mechanistic understanding of BG function in health and pathophysiology in disease. Finally, we outline how viral vector technology may be applied to neurological and psychiatric conditions to offer new treatments with enhanced outcomes for patients.
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Comparison of blood pressure in sitting with different arm position
2016-04-27T09-19-40Z
Source: International Journal of Therapies and Rehabilitation Research
SHAH SWEETY, PAREKH NAMRATA.
comparison of blood pressure in sitting with different arm position. 1.arm at chair level 2.arm at heart level any significant changes present or not?
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Comparison of the Selected Treatment Modalities of Carpal Tunnel Syndrome Depending on Severity of Condition
2016-04-27T09-19-40Z
Source: International Journal of Therapies and Rehabilitation Research
Waleed Salah El-din Mahmoud.
Background: A number of treatments are used for carpal tunnel syndrome, with considerable controversy surrounding optimal management of the disorder. Purpose: Compare which of the selected treatment modalities was effective regarding the pain level and functional status depending on severity of condition. Method: Forty patients (40 wrists) were randomly assigned to one of the four groups: group I (n = 10), patients with mild symptoms who received LLLT, group II (n = 10), patients with mild symptoms who received US, and group III (n = 10), patients with moderate symptoms who received LLLT, and group IV (n = 10), patients with moderate symptoms who received US. Symptoms were evaluated by the (SSS) symptom-severity scale. Pain level and functional status were measured by visual analogue scale (VAS) and functional status scale (FSS) respectively. Results: LLLT and US have the same effect on pain level (p=0.342) and functional status (p=0.367) in mild symptoms. However, LLLT was more effective than US of pain reduction (p
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Role of Pilates in Rehabilitation: A Literature Review
2016-04-27T09-19-40Z
Source: International Journal of Therapies and Rehabilitation Research
Dr.Chintan Munjal Parikh, Prof. Maneesh Arora.
Introduction Pilates was the brainchild of Joseph H Pilates. Pilates appeared during World War I to rehabilitate those injured by the war. Recently, the method started to be used by health professionals with the objective of integrating body and mind, because it improves fitness, flexibility, strength, posture, balance and body awareness. Exercises, first gained recognition among professional dancers, actors and choreographers but has become more popular and is now regularly applied in sport, fitness and physiotherapy. Pilates works by combining breathing techniques with special stretches. It is a method of exercise which focuses on improving bodys core by making the body more flexible & stronger. Objective To establish evidence based role of pilates exercises in wide range of rehabilitation programmes. Design review of literature Data collection: Relevant articles in English were retrieved through a search of MEDLINE and PubMed. Key search terms were lower back muscle endurance & core muscle assessment test. The principal criterion for inclusion was as follows: any study that discussed or tested lower trunk & core muscle endurance test. The tests used for rehabilitation protocol & test using stability ball related articles were excluded. Thirty-seven of the initial studies are included in this review. Data Synthesis: Recent research, meta analysis, clinical oriented first thirty literatures taken in the study. Results Pilates commonly used in low back pain prevention & rehabilitation, balance, strength, flexibility, body composition & relaxation enhancement programmes. Pilates is a uniquely precise and intelligent approach to exercise and body-conditioning, which gives you a leaner, suppler, more toned body and a calmer, more relaxed mind& its role not limited to Low back pain rehabilitation. Conclusion Pilates have wide range of application in rehabilitation. But more systemic research required which focus on the components of blinding, concealed allocation, subject adherence, intentionto- treat analysis, and follow-up designs.
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Associations Between Body Anthropometric Measures and Severity of Carpal Tunnel Syndrome
Publication date: Available online 26 April 2016
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Mauro Mondelli, Stefania Curti, Stefano Mattioli, Alessandro Aretini, Federica Ginanneschi, Giuseppe Greco, Andrea Farioli
ObjectiveTo assess the associations between carpal tunnel syndrome (CTS) severity and selected anthropometric and obesity indexes.DesignWe performed a case-control study. Clinical and electrophysiological severity of CTS was classified as mild, moderate or severe based on validated scales. Body and hand anthropometric characteristics were measured at the time of the electrodiagnostic study. We estimated the relative risk ratios (RRR) of CTS severity by fitting multinomial logistic regression models adjusted by age and sex. In addition we fitted multivariable models including age, sex, wrist ratio, hand ratio, body mass index (BMI), and waist-stature ratio.SettingConsecutive patients referred to three electromyography laboratories.ParticipantsWe enrolled 370 cases and 747 controls.InterventionsN/AMain Outcome MeasuresAssociations between CTS severity and selected anthropometric and obesity indexes.ResultsWe observed associations between many anthropometric indexes and CTS severity. Among obesity indexes the waist-stature ratio and among hand anthropometric indexes the wrist-palm ratio showed the highest RRR for clinical and electrophysiological severity scale. RRR of severe CTS (adjusted for age and sex) for the wrist-palm ratio were 3.5 for clinical scale and 2.4 for electrophysiological scale. RRR of severe CTS for waist-stature ratio were 2.3 for clinical scale and 2.0 for electrophysiological scale. In the multivariable models, both BMI and waist-stature ratio were associated with the outcomes.ConclusionsDifferent configurations of the body and, in particular, the hand and wrist system may influence the occurrence and severity of CTS. Multiple obesity indexes, possibly including waist-stature ratio, should be considered when investigating the association between body composition and CTS. Future studies should determine whether in obese subjects with CTS the weight and waist circumference loss may produce an improvement in CTS symptoms and recovery of distal conduction velocity of the median nerve.
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Rehabilitation of swallowing and cough functions following stroke: an expiratory muscle strength training trial
Publication date: Available online 26 April 2016
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Karen Wheeler Hegland, Paul W. Davenport, Alexandra E. Brandimore, Floris F. Singletary, Michelle S. Troche
ObjectiveTo determine the effect of expiratory muscle strength training on both cough and swallow function in stroke patients.DesignProspective pre-post intervention trial with one participant group.SettingTwo outpatient rehabilitation clinicsParticipantsFourteen adults with a history of ischemic stroke in the preceding 3 – 24 months participated in this study.InterventionExpiratory muscle strength training (EMST). The training program was completed at home and consisted of 25 repetitions per day, 5 days per week, for 5 weeks.Main outcome measuresBaseline and post-training measures were: maximum expiratory pressure, voluntary cough airflows, reflex cough challenge to 200μM capsaicin, sensory perception of urge-to-cough, and fluoroscopic swallow evaluation. Repeated measures and one-way analyses of variance were used to determine significant differences pre/post training.ResultsMaximum expiratory pressure increased in all participants by an average of 30cmH2O post training. At baseline, all participants demonstrated a blunted reflex cough response to 200 μM capsaicin. Following 5 weeks of training, measures of urge to cough and cough effectiveness increased for reflex cough, however voluntary cough effectiveness did not increase. Swallow function was minimally impaired at baseline, and there were no significant changes in the measures of swallow function post training.ConclusionsExpiratory muscle strength training improves both expiratory muscle strength, reflex cough strength and urge-to-cough. Voluntary cough and swallow measures were not significantly different post training. It may be that stroke patients benefit from the training for up-regulation of reflex cough and thus improved airway protection.
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Braden Scale (Pressure Ulcer)
Link to instrument: Measure available on the bradenscale.com website (other languages available below)
Acronym:
BS
Purpose:
Assesses the likelihood of developing pressure ulcers.
Description:
Braden total scores range from 6 to 23 points with lower scores indicating a higher risk for presses ulcers.
Braden scale subscales include:
- Sensory subscale measures the ability to feel and relieve discomfort
- Moister subscale assesses the degree to which skin is exposed to moisture
- Mobility subscale assesses one's ability to relieve pressure
- Activity subscale the ability to get out of bed and/or ambulate
- Nutrition subscale assesses the amount of food intake
- Friction and shear subscale measures the patient's ability to assist with movement or be able to move in a way that keeps the skin free of contact with underlying surfaces
Area of Assessment: General Health
Body Part: Upper Extremity, Back, Lower Extremity
ICF Domain: Body Structure
Domain: General Health
Assessment Type: Observer
Length of Test: 06 to 30 Minutes
Time to Administer:
20 to 30 minutes
Number of Items: 6
Equipment Required:
None
Training Required:
None
Type of training required: No Training
Cost: Free
Actual Cost:
- Free
- For permission refer to the Braden Scale website
Age Range: Preschool Child: 2-5 years, Child: 6-12 years, Adolescent: 13-17 years, Adult: 18-64 years, Elderly adult: 65+
Administration Mode: Paper/Pencil
Diagnosis: Acquired Brain Injury, Cardiac Conditions, Cerebral Palsy, Geriatrics, Movement Disorders, Multiple Sclerosis, Parkinson's Disease, Spinal Cord Injury, Stroke, Traumatic Brain Injury
Populations Tested:
- Stroke
- SCI
- TBI
- Home Care
- Critical Care
Standard Error of Measurement (SEM):
Home care: (Kottner et al, 2009; 2007: n = 352 home care clients who took part in the prevalence study were assessed twice, 288 of which completed the Braden Scale; sex = 68% female, 32% male; mean age = 77.8 (11.8) years; 2008: n = 339 home care clients who took part in the prevalence study were assessed twice, 292 of which completed the Braden Scale; sex = 62.8% female; mean age = 77.4 (13.4) years)
| Interrater reliability and agreement coefficients for the Braden Scale and its items | ||||
| Year | Items | p | ICC (1,1) (95% CI) | SEM |
| 2007 (n=288) | Sensory Perception | 0.87 | 0.71 (0.65-0.76) | 0.34 |
| Moisture | 0.88 | 0.81 (0.77-0.85) | 0.36 | |
| Activity | 0.87 | 0.91 (0.89-0.93) | 0.26 | |
| Mobility | 0.82 | 0.86 (0.83-0.89) | 0.34 | |
| Nutrition | 0.83 | 0.78 (0.73-0.82) | 0.35 | |
| Friction & Shear | 0.91 | 0.89 (0.87-0.92) | 0.24 | |
| Total score | 0.66 | 0.90 (0.88-0.92) | 1.00 | |
| 2008 (n=292) | Sensory perception | 0.85 | 0.74 (0.69-0.79) | 0.34 |
| Moisture | 0.85 | 0.64 (0.57-0.71) | 0.40 | |
| Activity | 0.87 | 0.88 (0.85-0.90) | 0.27 | |
| Mobility | 0.81 | 0.82 (0.78-0.85) | 0.38 | |
| Nutrition | 0.84 | 0.79 (0.75-0.83) | 0.29 | |
| Friction & Shear | 0.90 | 0.83 (0.79-0.86) | 0.25 | |
| Total score | 0.63 | 0.88 (0.85-0.91) | 0.98 | |
Minimal Detectable Change (MDC):
Not Established
Minimally Clinically Important Difference (MCID):
Not Established
Cut-Off Scores:
Home Health: (Kelly et al, 2010; n = 2120 patients aged 60 years and older who were admitted for intermittent skilled home health care and had a documented admission Braden score; mean age = 77.5(8.803) years)
- For a cut off score of 18, the sensitivity was 73.30% and the specificity was 65.50%
- The percentage of patients that were correctly classified was 65.61%
Home Health: (Bergquist et al, 2001; n = 1711 nonhospice patients aged 60 or older who did not have pressure ulcers at the beginning of home healthcare; this was a secondary analysis of data from a retrospective cohort study of risk factors for pressure ulcer development in older adults receiving home health care; mean age for patients with incident pressure ulcers = 78.78 (8.38) years; mean age for patients without pressure ulcers = 76.28 (8.56) years)
- Cut off score of 19 or less
- 61% sensitivity
- 68% specificity
| Cut-off Score over Time | |||||
| Week | Cut-off Score | Sensitivity (%) | Specificity (%) | PVP (%) | PVN (%) |
| 1 | 19 | 70 | 62 | 9 | 97 |
| 2 | 20 | 62 | 52 | 8 | 95 |
| 3 | 18 | 60 | 84 | 17 | 97 |
| 4 | 20 | 83 | 65 | 25 | 97 |
| 5 | 18 | 67 | 82 | 17 | 98 |
| 6 | 19 | 100 | 76 | 11 | 100 |
| 7 | 17 | 60 | 95 | 50 | 97 |
| 8 | 18 | 80 | 79 | 27 | 98 |
| PVN = Predictive Value Negative PVP = Predictive Value Positive | |||||
Home Care: (Ramundo et al, 1995; n = 48 home care patients, 7 of which aquired a pressure ulcer)
- Cut-off scores for sensitivity:
- Cut-off score of 11-15: Sensitivity = 14%
- Cut-off score of 16: Sensitivity = 25%
- Cut-off score of 17: Sensitivity = 43%
- Cut-off score above 18: Sensitivity = 100%
- Cut-off scores for specificity:
- Cut-off score 11 or below: Specificity = 98%
- Cut-off score of 12-13: Specificity = 95%
- Cut-off score of 14-16: Specificity = 80-90%
- Cut-off score of 17: Specificity = 63%
- Cut-off score above 18: Specificity = 0-34%%
Traumatic Injury: (Baldwin et al, 1998; n = 36; mean age = 31.7 (10.9) years; blunt trauma accounted for 66% of the sample; mean length of stay was 26.5 days)
- A cut-off score for pressure ulcer risk of 10 yielded a sensitivity of 91% and specificity of 96%
Skilled Nursing Facility: (Braden and Bergstrom, 1994; n = 102 subjects over the age of 19 free of pressure sore development and admitted within the previous 72 hours to a skilled nursing facility)
- Cut-off score of 18: Sensitivity = 79% and Specificity = 74%
Critical Care Patients: (Letícia et al, 2011; n = 72 patients admitted to ICUs with a Braden Score of less than 18 and without a pressure ulcer; mean age = 60.9 (16.5) years; mean length of stay = 17.1 (9.0) days)
- A cut-off score 12 was identified in the first assessment, which showed 85.7% sensitivity and 64.6% specificity
- A cut-off score 13 was identified in the second assessment, which showed 71.4% sensitivity and 81.5% specificity
- A cut-off score 13 was identified in the third assessment, which showed 71.4% sensitivity and 83.1% specificity
- The third assessment showed the best predictive performance in critical care patients
Inpatient care: (VandenBosch et al, 1996, n = 103 subjects hospitalized for a minimum of 7 days and randomly selected from routine hospital admissions; 29 subjects developed pressure ulcers; mean age = 67.0 (13.8) years)
- Cut-off score was 17, with a sensitivity of 59% and a specificity of 59%
Inpatient Care: (Lindgren et al, 2002; n = 530 patients without pressure sores on admission were assessed over a 12 week period; mean age = 69.25 (14.39) years)
| Cut-off Scores, Sensitivity, and Specificity for the Entire Sample | ||
| Cut-off Point | Sensitivity | Specificity |
| ≤ 38 | 77.8% | 34.8% |
| ≤ 37 | 70.4% | 46.5% |
| ≤ 36 | 57.4% | 57.6% |
| ≤ 35 | 50.0% | 64.3% |
| ≤ 34 | 46.3% | 69.4% |
| ≤ 33 | 38.9 % | 75.3% |
| ≤ 32 | 33.3% | 80.2% |
| ≤ 31 | 31.5 % | 84.6% |
Normative Data:
Inpatient care: (VandenBosch et al, 1996)
- Braden pressure ulcer negative mean score = 18.2 (2.4)
- Braden pressure ulcer positive mean score = 16.6 (3.0)
Test-retest Reliability:
Not Established
Interrater/Intrarater Reliability:
ICU Patients: (Kottner and Dassen, 2010; ICU 1: n = 21 ICU patients and 22 nurse raters; mean age = 69.7 (8.3) years; ICU 2: n = 24 ICU patients and 31 nurse raters; mean age = 67.2 (11.3) years)
| Interrater Reliability and SEM for Braden Scale: | |||
| Scale Item (Score Range) | Strength | ICC (95% CI) | SEM |
| Braden scale sum score (6–23) | Adequate | 0.72 (0.52–0.87) | 1.67 |
| 1. Sensory perception (1–4) | Adequate | 0.64 (0.40–0.81) | 0.58 |
| 2. Moisture (1–4) | Adequate | 0.49 (0.22–0.73) | 0.78 |
| 3. Activity (1–4) | Poor | 0.08 (-0.16 to 0.39) | 0.43 |
| 4. Mobility (1–4) | Adequate | 0.53 (0.27–0.76) | 0.46 |
| 5. Nutrition (1–4) | Adequate | 0.56 (0.31–0.78) | 0.49 |
| 6. Friction and shear (1–3) | Adequate | 0.48 (0.21–0.72) | 0.40 |
Inpatient Care: (Lindgren et al, 2002)
- Excellent intrarater reliability (ICC = 0.83)
Acute Care Hospital: (Magnan et al, 2009; n = 102 patients in an acute care hospital)
| Posttest Comparison of New Users to Regular Users on RN-to-Expert Agreements/Disagreements on Braden Subscale Ratings | ||||
| Braden Subscale | New Users Count (% within group) | Regular Users (% within group) | X^2 | P |
| Sensory-perception | | |||
| Agreements | 55 (82.1%) | 58 (63.7%) | ||
| Disagreements | 12 (17.9%) | 33 (36.3%) | 6.38 | .012 |
| Moisture | ||||
| Agreements | 49 (73.1%) | 37 (40.7%) | ||
| Disagreements | 18 (26.9%) | 54 (59.3%) | 16.41 | <.001 |
| Activity | ||||
| Agreements | 60 (89.6%) | 56 (61.5%) | ||
| Disagreements | 7 (10.4%) | 35 (38.5%) | 15.52 | <.001 |
| Mobility | ||||
| Agreements | 54 (80.6%) | 57 (62.6%) | ||
| Disagreements | 13 (19.4%) | 34 (37.4%) | 5.96 | .015 |
| Nutrition | ||||
| Agreements | 50 (74.6%) | 36 (39.6%) | ||
| Disagreements | 17 (25.4%) | 55 (60.4%) | 19.13 | <.001 |
| Friction-shear | ||||
| Agreements | 56 (83.6%) | 53 (58.2%) | ||
| Disagreements | 11 (16.4%) | 38 (41.8%) | 11.58 | .001 |
Internal Consistency:
Not established
Criterion Validity (Predictive/Concurrent):
- The Sensitivity (ranges from 83% to 100%) and specificity (ranges from 64% to 90%) of the Braden scale suggests the instruments predictive validity (Bergstrom et al, 1987)
- Nurses were able to predict the development of pressure ulcers in 51.7% of subjects, while they incorrectly predicted the likelihood of developing a pressure ulcer in 41.1% of patients (Bergstrom et al, 1987)
- Sensitivity, specificity and predictive values for medical and surgical patients were also calculated. (Lindgren et al, 2002)
- The predictive validity was especially good for medical patients and those with infectious diseases at a cut-off point of ≤ 31. (Lindgren et al, 2002)
Construct Validity (Convergent/Discriminant):
Spinal Cord Injury: (Mortenson & Miller, 2008; A literature review of seven scales that assess the development of pressure ulcers, including the Braden Scale)
- Poor construct validity in terms of stage of the first pressure ulcer (r = 0.03)
- Adequate concurrent validity with the Norton Scale (r = 0.48)
- Poor concurrent validity with the Waterlow Scale (r = -0.06)
ICU Patients: (Kottner and Dassen, 2010)
ICU 1:
- Excellent correlation between Braden and VAS (r = -0.77)
- Excellent correlation between Braden and Waterlow (r = -0.71)
ICU 2:
- Excellent correlation between Braden and VAS (r = -0.60)
- Excellent correlation between Braden and Waterlow (r = -0.72)
Content Validity:
Not Established
Face Validity:
Not Established
Floor/Ceiling Effects:
Not Established
Responsiveness:
Traumatic Injury: (Baldwin et al, 1998)
| Sensitivity and Specificity for Braden Total Scores | ||
| Braden Score | Sensitivity | Specificity |
| 16 | 9% | 71% |
| 15 | 9% | 71% |
| 14 | 27% | 76% |
| 13 | 45% | 81% |
| 12 | 64% | 86% |
| 11 | 73% | 89% |
| 10 | 91% | 96% |
| 9 | 100% | 100% |
Home Health: (Kelly et al, 2010)
| Sensitivity and Specificity for Braden Total Scores | |||
| *Braden Score | Incidence | Sensitivity | Specificity |
| 9 | 1 | 3.33 | 98.63 |
| 10 | 2 | 6.66 | 98.68 |
| 11 | 2 | 6.66 | 98.67 |
| 12 | 4 | 13.33 | 98.77 |
| 13 | 4 | 16.66 | 98.81 |
| 14 | 7 | 23.33 | 98.89 |
| 15 | 7 | 23.33 | 98.86 |
| 16 | 11 | 36.66 | 99.00 |
| 17 | 16 | 53.33 | 99.19 |
| 18 | 22 | 73.30 | 99.40 |
| 19 | 25 | 83.33 | 99.50 |
| 20 | 29 | 96.66 | 99.82 |
| 21 | 29 | 96.66 | 99.60 |
| 22 | 29 | 96.66 | 98.25 |
| 30 | 100 | 0.00 | 0.00 |
| *Patients whose Braden Scale score was less than or equal to the stated number in column | |||
Considerations:
- Prior research suggest that nurses may be more effective in predicting the development of pressure ulcers than the Braden scale (Salvadalena et al, 1992)
-
Technology-assisted Braden Scale training led to statistically significant improvements in the IRR on 3 of the 6 Braden subscales and yielded better than 80% RN-to-expert agreement on 4 subscales (sensory-perception, activity, mobility, and friction-shear) among new users only (Magnan et al, 2009)
Braden Scale translations:
Chinese:
http://ift.tt/26ulffz
Danish:
http://ift.tt/24k2Q31
French:
http://ift.tt/26ulffD
German:
http://ift.tt/24k2Q33
Italian (p15-16):
http://ift.tt/26ulh7b
Japanese:
http://ift.tt/24k2Q35
Korean:
http://ift.tt/26ulffG
Spanish:
http://ift.tt/24k2Q3b
Portuguese:
http://ift.tt/26ulffI
These translations, and links to them, are subject to the Terms and Conditions of Use of the Rehab Measures Database. RIC is not responsible for and does not endorse the content, products or services of any third-party website, and does not make any representations regarding its quality, content or accuracy. If you would like to contribute a language translation to the RMD, please contact us at rehabmeasures@ric.org.
Do you see an error or have a suggestion for this instrument summary? Please e-mail us!
Bibliography:
Baldwin, K. M. and Ziegler, S. M. (1998). "Pressure ulcer risk following critical traumatic injury." Adv Wound Care 11(4): 168-173. Find it on PubMed
Bergquist, S. and Frantz, R. (2001). "Braden scale: validity in community-based older adults receiving home health care." Appl Nurs Res 14(1): 36-43. Find it on PubMed
Kottner, J. and Dassen, T. (2008). "An interrater reliability study of the Braden scale in two nursing homes." Int J Nurs Stud 45(10): 1501-1511. Find it on PubMed
Kottner, J. and Dassen, T. (2010). "Pressure ulcer risk assessment in critical care: interrater reliability and validity studies of the Braden and Waterlow scales and subjective ratings in two intensive care units." Int J Nurs Stud 47(6): 671-677. Find it on PubMed
Mortenson, W. and Miller, W. (2007). "A review of scales for assessing the risk of developing a pressure ulcer in individuals with SCI." Spinal Cord 46(3): 168-175. Find it on PubMed
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