Decoding the task specificity of post-error adjustments: Features and determinants.

Errors typically trigger post-error adjustments aimed at improving subsequent reactions within a single task, but little work has focused on whether these adjustments are task-general or task-specific across different tasks. We collected behavioral and electrophysiological (EEG) data when participants performed a psychological refractory period paradigm. This paradigm required them to complete Task 1 and Task 2 separated by a variable stimulus onset asynchrony (SOA). Behaviorally, post-error slowing and post-error accuracy exhibited task-general features at short SOAs but some task-specific features at long SOAs. EEG results manifest that task-general adjustments had a short-lived effect, whereas task-specific adjustments were long-lasting. Moreover, error awareness specifically conduced to the improvement of subsequent sensory processing and behavior performance in Task 1 (the task where errors occurred). These findings demonstrate that post-error adjustments rely on both transient, task-general interference and longer-lasting, task-specific control mechanisms simultaneously, with error awareness playing a crucial role in determining these mechanisms. We further discuss the contribution of central resources to the task specificity of post-error adjustments.

Differential effects of stimulation frequency on isometric and concentric isotonic contractile function in human quadriceps.

Electrically evoked contractions are used to assess the relationship between frequency input and contractile output to characterize inherent muscle function, and these have been done mostly with isometric contractions (i.e., no joint rotation). The purpose was to compare the electrically stimulated frequency and contractile function relationship during isometric (i.e., torque) with isotonic (i.e., concentric torque, angular velocity, and mechanical power) contractions. The knee extensors of 16 (5 female) young recreationally active participants were stimulated (∼1-2.5 s) at 14 frequencies from 1 to 100 Hz. This was done during four conditions, which were isometric and isotonic at loads of 0 (unloaded), 7.5%, and 15% isometric maximal voluntary contraction (MVC), and repeated on separate days. Comparisons across contractile parameters were made as a % of 100 Hz. Independent of the load, the mechanical power-frequency relationship was rightward shifted compared with isometric torque-frequency, concentric torque-frequency, and velocity-frequency relationships (all P ≤ 0.04). With increasing load (0%-15% MVC), the isotonic concentric torque-frequency relationship was shifted leftward systematically from 15 to 30 Hz (all P ≤ 0.04). Conversely, the same changes in load caused a rightward shift in the velocity-frequency relationship from 1 to 40 Hz (all P ≤ 0.03). Velocity was leftward shifted of concentric torque in the unloaded isotonic condition from 10 to 25 Hz (all P ≤ 0.03), but concentric torque was leftward shifted of velocity at 15% MVC isotonic condition from 10 to 50 Hz (all P ≤ 0.03). Therefore, isometric torque is not a surrogate to evaluate dynamic contractile function. Interpretations of evoked contractile function differ depending on contraction type, load, and frequency, which should be considered relative to the specific task.NEW & NOTEWORTHY In whole human muscle, we showed that the electrically stimulated power-frequency relationship was rightward shifted of the stimulated isometric torque-frequency relationship independent of isotonic load, indicating that higher stimulation frequencies are needed to achieve tetanus. Therefore, interpretations of evoked contractile function differ depending on contraction type (isometric vs. dynamic), load, and frequency. And thus, isometric measures may not be appropriate as a surrogate assessment when evaluating dynamic isotonic contractile function.

Assessing the effectiveness of serious game training designed to assist in upper limb prothesis rehabilitation.

Introduction: Controlling a myoelectric upper limb prosthesis is difficult, therefore training is required. Since training with serious games showed promising results, the current paper focuses on game design and its effectivity for transfer between in-game skill to actual prosthesis use for proportional control of hand opening and control of switching between grips. We also examined training duration and individual differences. Method: Thirty-six participants were randomly assigned to one of three groups: a task-specific serious game training group, a non-task-specific serious game training group and a control group. Each group performed a pre-test, mid-test and a post-test with five training sessions between each test moment. Test sessions assessed proportional control using the Cylinder test, a test designed to measure scaling of hand aperture during grabbing actions, and the combined use of proportional and switch control using the Clothespin Relocation Test, part of the Southampton Hand Assessment Procedure and Tray Test. Switch control was assessed during training by measuring amplitude difference and phasing of co-contraction triggers. Results: Differences between groups over test sessions were observed for proportional control tasks, however there was lack of structure in these findings. Maximum aperture changed with test moment and some participants adjusted maximum aperture for smaller objects. For proportional and switch control tasks no differences between groups were observed. The effect of test moment suggests a testing effect. For learning switch control, an overall improvement across groups was found in phasing of the co-contraction peaks. Importantly, individual differences were found in all analyses. Conclusion: As improvements over test sessions were found, but no relevant differences between groups were revealed, we conclude that transfer effects from game training to actual prosthesis use did not take place. Task specificity nor training duration had effects on outcomes. Our results imply testing effects instead of transfer effects, in which individual differences played a significant role. How transfer from serious game training in upper limb prosthesis use can be enhanced, needs further attention.

Proceedings of the 2022 annual meeting of the Fetal Alcohol Spectrum Disorders study group.

The 2022 Fetal Alcohol Spectrum Disorders Study Group (FASDSG) meeting was held in coordination with the 45th annual Research Society on Alcoholism conference on June 25th, 2022. The theme of the meeting was "Enhancing the Relevance of Research for the Community." The program began with a moderated panel discussion on the value of community-engaged research, which included two self-advocates and a clinical and pre-clinical researcher. Invited plenary speakers included Jill Locke, Ph.D., who provided an engaging introduction to implementation science, and Jared Young, Ph.D., who discussed cross-species domain task specificity. The meeting also included updates from three government agencies, short presentations by junior and senior investigators showcasing late-breaking FASD research, trainee award winners, and a presentation on the Toward Health Outcomes intervention roadmap by Jacqueline Pei, Ph.D.

Temporal Signature of Task-Specificity in Isolated Focal Laryngeal Dystonia.

BACKGROUND AND OBJECTIVE: Laryngeal dystonia (LD) is focal task-specific dystonia, predominantly affecting speech but not whispering or emotional vocalizations. Prior neuroimaging studies identified brain regions forming a dystonic neural network and contributing to LD pathophysiology. However, the underlying temporal dynamics of these alterations and their contribution to the task-specificity of LD remain largely unknown. The objective of the study was to identify the temporal-spatial signature of altered cortical oscillations associated with LD pathophysiology. METHODS: We used high-density 128-electrode electroencephalography (EEG) recordings during symptomatic speaking and two asymptomatic tasks, whispering and writing, in 24 LD patients and 22 healthy individuals to investigate the spectral dynamics, spatial localization, and interregional effective connectivity of aberrant cortical oscillations within the dystonic neural network, as well as their relationship with LD symptomatology. RESULTS: Symptomatic speaking in LD patients was characterized by significantly increased gamma synchronization in the middle/superior frontal gyri, primary somatosensory cortex, and superior parietal lobule, establishing the altered prefrontal-parietal loop. Hyperfunctional connectivity from the left middle frontal gyrus to the right superior parietal lobule was significantly correlated with the age of onset and the duration of LD symptoms. Asymptomatic whisper in LD patients had not no statistically significant changes in any frequency band, whereas asymptomatic writing was characterized by significantly decreased synchronization of beta-band power localized in the right superior frontal gyrus. CONCLUSION: Task-specific oscillatory activity of prefrontal-parietal circuitry is likely one of the underlying mechanisms of aberrant heteromodal integration of information processing and transfer within the neural network leading to dystonic motor output. © 2023 International Parkinson and Movement Disorder Society.

Embouchure Dystonia as a Network Disease.

While the pathophysiology of embouchure dystonia, a sub-entity of musician's dystonia, is still not fully understood, recent research has shown that it involves alterations of several brain functions and networks. Maladaptive plasticity in sensorimotor integration, sensory perception, and deficient inhibitory mechanisms at cortical, subcortical, and spinal level seem to contribute to its pathophysiology. Furthermore, functional systems of the basal ganglia and the cerebellum are involved, clearly pointing toward a network disorder. We therefore propose a novel network model, based on electrophysiological and recent neuroimaging studies highlighting embouchure dystonia.

Oromotor Nonverbal Performance and Speech Motor Control: Theory and Review of Empirical Evidence.

This position paper offers a perspective on the long-standing debate concerning the role of oromotor, nonverbal gestures in understanding typical and disordered speech motor control secondary to neurological disease. Oromotor nonverbal tasks are employed routinely in clinical and research settings, but a coherent rationale for their use is needed. The use of oromotor nonverbal performance to diagnose disease or dysarthria type, versus specific aspects of speech production deficits that contribute to loss of speech intelligibility, is argued to be an important part of the debate. Framing these issues are two models of speech motor control, the Integrative Model (IM) and Task-Dependent Model (TDM), which yield contrasting predictions of the relationship between oromotor nonverbal performance and speech motor control. Theoretical and empirical literature on task specificity in limb, hand, and eye motor control is reviewed to demonstrate its relevance to speech motor control. The IM rejects task specificity in speech motor control, whereas the TDM is defined by it. The theoretical claim of the IM proponents that the TDM requires a special, dedicated neural mechanism for speech production is rejected. Based on theoretical and empirical information, the utility of oromotor nonverbal tasks as a window into speech motor control is questionable.

Comparing the Effects of Two Perturbation-Based Balance Training Paradigms in Fall-Prone Older Adults: A Randomized Controlled Trial.

INTRODUCTION: There is increasing evidence that perturbation-based balance training (PBT) is highly effective in preventing falls at older age. Different PBT paradigms have been presented so far, yet a systematic comparison of PBT approaches with respect to feasibility and effectiveness is missing. Two different paradigms of PBT seem to be promising for clinical implementation: (1) technology-supported training on a perturbation treadmill (PBTtreadmill); (2) training of dynamic stability mechanisms in the presence of perturbations induced by unstable surfaces (PBTstability). This study aimed to compare both program's feasibility and effectiveness in fall-prone older adults. METHODS: In this three-armed randomized controlled trial, seventy-one older adults (74.9 ± 6.0 years) with a verified fall risk were randomly assigned into three groups: PBTtreadmill on a motorized treadmill, PBTstability using unstable conditions such as balance pads, and a passive control group (CG). In both intervention groups, participants conducted a 6-week intervention with 3 sessions per week. Effects were assessed in fall risk (Brief-BEST), balance ability (Stepping Threshold Test, center of pressure, limits of stability), leg strength capacity, functional performance (Timed Up and Go Test, Chair-Stand), gait (preferred walking speed), and fear of falling (Short FES-I). RESULTS: Fifty-one participants completed the study. Training adherence was 91% for PBTtreadmill and 87% for PBTstability, while no severe adverse events occurred. An analysis of covariance with an intention-to-treat approach revealed statistically significant group effects in favor of PBTstability in the Brief-BEST (p = 0.009, η2 = 0.131) and the limits of stability (p = 0.020, η2 = 0.110) and in favor of PBTtreadmill in the Stepping Threshold Test (p < 0.001, η2 = 0.395). The other outcomes demonstrated no significant group effects. CONCLUSION: Both training paradigms demonstrated high feasibility and were effective in improving specific motor performances in the fall-prone population and these effects were task specific. PBTtreadmill showed higher improvements in reactive balance, which might have been promoted by the unpredictable nature of the included perturbations and the similarity to the tested surface perturbation paradigm. PBTstability showed more wide-ranging effects on balance ability. Consequently, both paradigms improved fall risk-associated measures. The advantages of both formats should be evaluated in light of individual needs and preferences. Larger studies are needed to investigate the effects of these paradigms on real-life fall rates.

Task-Specific Lingual Dystonia During Japanese Religious Services.

INTRODUCTION: Lingual dystonia is a subtype of oromandibular dystonia characterized by involuntary contractions of the tongue muscles, often provoked by speaking or eating. METHODS: This study reports six Japanese cases (four female and two male, mean age at onset of 49.5 years) with task-specific lingual dystonia during praying. In the early phase, all patients experienced lingual protrusion exclusively during Japanese religious services. When the patients start speaking, the tongues protrude forward, making it difficult to pronounce words. The patients were treated with multimodal treatment, including muscle afferent block (MAB) therapy comprising local anesthetic injection, botulinum toxin (onabotulinumtoxinA) injection, and a sensory trick splint. RESULTS: MAB therapy was conducted in five patients (mean time: 5.8), and botulinum toxin injection was administered in four patients (mean time: 8). The injected muscles were the genioglossal muscles and, in one case, the lateral pterygoid muscle. Sensory trick splints were inserted in three patients. After the multimodal therapy, the patients were able to pronounce words smoothly and clearly. Oromandibular Dystonia Rating Scale scores improved significantly (P<0.005) from baseline (187 points) to endpoint (47 points) with a mean follow-up of 4.7 years. CONCLUSION: Although this entity is rare, medical and dental professionals should be aware of this peculiar symptom. Multimodal therapy is required to ensure effective treatment of praying-induced lingual dystonia.

On the Spatial Distribution of Temporal Complexity in Resting State and Task Functional MRI.

Measuring the temporal complexity of functional MRI (fMRI) time series is one approach to assess how brain activity changes over time. In fact, hemodynamic response of the brain is known to exhibit critical behaviour at the edge between order and disorder. In this study, we aimed to revisit the spatial distribution of temporal complexity in resting state and task fMRI of 100 unrelated subjects from the Human Connectome Project (HCP). First, we compared two common choices of complexity measures, i.e., Hurst exponent and multiscale entropy, and observed a high spatial similarity between them. Second, we considered four tasks in the HCP dataset (Language, Motor, Social, and Working Memory) and found high task-specific complexity, even when the task design was regressed out. For the significance thresholding of brain complexity maps, we used a statistical framework based on graph signal processing that incorporates the structural connectome to develop the null distributions of fMRI complexity. The results suggest that the frontoparietal, dorsal attention, visual, and default mode networks represent stronger complex behaviour than the rest of the brain, irrespective of the task engagement. In sum, the findings support the hypothesis of fMRI temporal complexity as a marker of cognition.

The construct of balance control in primary school-aged children: Unidimensional and task-specific.

The aim of this study was to determine the dimensionality and task-specificity of balance control by investigating the relationships between different tasks and the degree to which these tasks belong to the same construct in primary school-aged children. Seventy-four South African children were randomly selected from a sample of convenience. They performed 18 different balance tasks that were grouped into four balance scales: the Performance and Fitness (PERF-FIT) static balance score, the PERF-FIT dynamic balance score, the PERF-FIT moving cans balance score and the Balance Sensory score. Spearman rank correlations were calculated between the scores. Principal component analysis (PCA) was used to investigate the number of factors within the construct. Moderate to good correlations were found between: i) PERF-FIT Moving cans balance score and the Balance Sensory score (r = 0.605, p < 0.001); ii) PERF-FIT static balance score and the PERF-FIT Moving cans (r = 0.586, p < 0.001); iii) PERF-FIT static balance score and the Balance Sensory score (r = 0.541, p < 0.001). All other correlations were low to fair. The PCA revealed one component. The three PERF-FIT items (moving cans-, static- and dynamic balance score) and the Balance Sensory score explained 59.4% of the variance of total balance performance.

Brain Structural Changes in Focal Dystonia-What About Task Specificity? A Multimodal MRI Study.

BACKGROUND: The neural basis of task specificity in dystonia is still poorly understood. This study investigated gray and white matter (WM) brain alterations in patients with task-specific dystonia (TSD) and non-task-specific dystonia (NTSD). METHODS: Thirty-six patients with TSD (spasmodic dysphonia, writer's cramp), 61 patients with NTSD (blepharospasm, cervical dystonia), and 83 healthy controls underwent 3D T1-weighted and diffusion tensor magnetic resonance imaging (MRI). Whole brain cortical thickness and voxel-based morphometry; volumes of basal ganglia, thalamus, nucleus accumbens, amygdala, and hippocampus; and WM damage were assessed. Analysis of variance models were used to compare MRI measures between groups, adjusting for age and botulinum toxin (BoNT) treatment. RESULTS: The comparison between focal dystonia patients showed cortical thickness and gray matter (GM) volume differences (ie, decreased in NTSD, increased in TSD) in frontal, parietal, temporal, and occipital cortical regions; basal ganglia; thalamus; hippocampus; and amygdala. Cerebellar atrophy was found in NTSD patients relative to controls. WM damage was more severe and widespread in task-specific relative to NTSD patients. TSD patients receiving BoNT, relative to nontreated patients, had cortical thickening and increased GM volume in frontoparietal, temporal, and occipital regions. NTSD patients experiencing pain showed cortical thickening of areas involved in pain-inhibitory mechanisms. CONCLUSIONS: TSD and NTSD are characterized by opposite alterations of the main cortical and subcortical sensorimotor and cognitive-controlling brain structures, suggesting the possible presence of different pathophysiological and/or compensatory mechanisms underlying the complexity of the two clinical phenotypes of focal dystonia. © 2020 International Parkinson and Movement Disorder Society.

Interference of balance tasks revisited: Consolidation of a novel balance task is impaired by subsequent learning of a similar postural task.

BACKGROUND: Interference effects have repeatedly been demonstrated for simple motor tasks but not for the complex whole-body task of balancing. It was therefore assumed that different balance tasks are so specific that they do not elicit interacting adaptations; neither in a positive (contextual interference) nor in a negative way (disruption of motor consolidation). RESEARCH QUESTION: Is a novel balancing task susceptible to interference if a similar balance task is learned shortly afterwards? METHODS: The common A1-B-A2 interference intervention design was applied. Participants were assigned to one of four intervention groups that differed with respect to task B. All four groups performed postural task A on a rocker board device (6 series of 8 trials of 8 s). Shortly after completion of task A, participants performed their respective task B (postural wobble board (P-WB), ballistic force, accuracy) or rested (control group). 24 h later, all groups performed a retention test of task A consisting of one series of 8 trials. To test for interference, we calculated repeated mixed design analysis of covariance (ANCOVA). RESULTS: For the retention test, the ANCOVA revealed a significant TIME*GROUP interaction (p = .010), which was followed up by separate Bonferroni-corrected post-hoc tests for each group. These tests showed a significant performance decrease for the P-WB group (p = .016) but no change in performance for the other three groups. SIGNIFICANCE: In contrast to previous findings, our results indicate that the complex whole-body task of balancing is susceptible to interference, but only, when task B consists of a similar balance task. This is of great functional relevance as for example fall prevention programs incorporate many different balance tasks to prepare participants for all sorts of situations. In such interventions, it seems therefore advisable to apply a random instead of a blocked practice design.

Verbal memory in children with temporal lobe epilepsy: Exploring task-specificity.

RATIONALE: This study explored the applicability of the adult model of task-specificity of memory to children with temporal lobe epilepsy (TLE). METHOD: Retrospective clinical audit; 38 children and adolescents (6-16 years) with lesional TLE (n = 22 mesial; n = 16 lateral) treated at tertiary pediatric hospitals completed two types of verbal memory paradigms: arbitrary associative (Verbal Paired Associates - Hard Pairs) and semantically related (Verbal Paired Associates - Easy Pairs; Stories). RESULTS: Children with mesial TLE performed more poorly than their lateral TLE counterparts on both types of memory paradigms: arbitrary associative and semantically related (Stories only). Groups with left and right TLE performed comparably on all verbal memory measures. CONCLUSIONS: Our findings suggest that the adult model of task-specificity may not be completely applicable to children with TLE. Consideration of the developmental context is critical in research and clinical work with pediatric populations.

Idiopathic Non-task-Specific Upper Limb Dystonia, a Neglected Form of Dystonia.

OBJECTIVE: The objective of this study was to describe the clinical and demographic features of idiopathic non-task-specific upper limb dystonia compared with the task-specific form. METHODS: In this retrospective study, adult patients with idiopathic upper limb dystonia, either focal or as part of a segmental/multifocal dystonia, from the Italian Dystonia Registry were enrolled. In patients with focal upper limb dystonia, dystonia spread was estimated by survival analysis. RESULTS: Of the 1522 patients with idiopathic adult-onset dystonia included in the Italian Dystonia Registry, we identified 182 patients with upper limb dystonia. Non-task-specific dystonia was present in 61.5% of enrolled cases. Women predominated among non-task-specific patients, whereas men predominated in the task-specific group. Peak age of upper limb dystonia onset was in the sixth decade in the non-task-specific group and in the fourth decade in the task-specific group. In both groups, upper limb dystonia started as focal dystonia or as part of a segmental dystonia. Segmental onset was more frequent among non-task-specific patients, whereas focal onset predominated among task-specific patients. Dystonic action tremor was more frequent among non-task-specific patients. No significant differences between groups emerged in terms of sensory trick frequency, rest tremor, or family history of dystonia. In patients with focal upper limb dystonia, dystonia spread was greater in the non-task-specific group. CONCLUSION: Novel information on upper limb dystonia patients suggests that non-task-specific and task-specific upper limb dystonia have different demographic and clinical features. However, it remains to be determined whether these differences also reflect pathophysiological differences. © 2020 International Parkinson and Movement Disorder Society.

Selective perception in probing by foot: Perceiving the length of a probe and the distance of a probed surface.

Perception of properties of object wielded by means of muscular effort exhibits both task specificity and anatomical independence. A person can perceive different properties of an object wielded by a given anatomical component and can perceive a given property of an object wielded by different anatomical components. Task-specificity and anatomical independence are fundamental characteristics of the haptic system described a biotensegrity system embedded in lawfully structured energy arrays. We investigate whether both characteristics are also exhibited when a person attempts to perceive properties by means of a wielded object. Participants used a foot-wielded rod to probe a surface and reported the length of the rod and the distance of the surface probed (on separate sets of trials). The ability to differentiate these properties generalized across anatomical components, and perception of each property by foot was supported by sensitivities to the same invariant mechanical parameters that support perception of each property by hand. The results suggest that the biotensegrity hypothesis applies to perception both of and by means an object attached to the body.

Adaptive Ankle Resistance from a Wearable Robotic Device to Improve Muscle Recruitment in Cerebral Palsy.

Individuals with cerebral palsy can have weak and poorly coordinated ankle plantar flexor muscles that contribute to inefficient walking patterns. Previous studies attempting to improve plantar flexor function have had inconsistent effects on mobility, likely due to a lack of task-specificity. The goal of this study was to develop, validate, and test the feasibility and neuromuscular response of a novel wearable adaptive resistance platform to increase activity of the plantar flexors during the propulsive phase of gait. We recruited eight individuals with spastic cerebral palsy to walk with adaptive plantar flexor resistance provided from an untethered exoskeleton. The resistance system and protocol was safe and feasible for all of our participants. Controller validation demonstrated our ability to provide resistance that proportionally- and instantaneously-adapted to the biological ankle moment (R = 0.92 ± 0.04). Following acclimation to resistance (0.16 ± 0.02 Nm/kg), more-affected limbs exhibited a 45 ± 35% increase in plantar flexor activity (p = 0.02), a 26 ± 24% decrease in dorsiflexor activity (p < 0.05), and a 46 ± 25% decrease in co-contraction (tibialis anterior and soleus) (p = 0.02) during the stance phase. This adaptive resistance system warrants further investigation for use in a longitudinal intervention study.

Training-, muscle- and task-specific up- and downregulation of cortical inhibitory processes.

Motor cortical contribution was shown to be important for balance control and for ballistic types of movements. However, little is known about the role of cortical inhibitory mechanisms and even less about long(er)-term adaptations of these inhibitory processes. Therefore, the aim of the present study was to investigate the role of intracortical inhibition before and after four weeks of explosive or balance training. Two groups of subjects participated for four weeks either in an explosive training programme of the plantar flexor muscles or in a balance training programme on unstable devices. Adaptations in short-interval intracortical inhibition (SICI) were assessed by applying paired-pulse TMS to the soleus muscle during dynamic plantar flexions, balance perturbations and at rest. Furthermore, SICI was assessed for the untrained tibialis anterior muscle. The results show task-, muscle- and group-specific adaptations in SICI after the training (p = .021) with significantly increased SICI after balance training in the balance task and decreased SICI after explosive training in the ballistic task. The training also caused task- and group-specific behavioural adaptations indicated by improved balance performance after balance training and increased ballistic performance after explosive training. There were no changes in SICI when measured at rest or in the untrained tibialis anterior muscle. This study shows that long(er)-term training improves the ability to modulate cortical inhibitory processes in a task- and muscle-specific manner.

The recovery of standing and locomotion after spinal cord injury does not require task-specific training.

After complete spinal cord injury, mammals, including mice, rats and cats, recover hindlimb locomotion with treadmill training. The premise is that sensory cues consistent with locomotion reorganize spinal sensorimotor circuits. Here, we show that hindlimb standing and locomotion recover after spinal transection in cats without task-specific training. Spinal-transected cats recovered full weight bearing standing and locomotion after five weeks of rhythmic manual stimulation of triceps surae muscles (non-specific training) and without any intervention. Moreover, cats modulated locomotor speed and performed split-belt locomotion six weeks after spinal transection, functions that were not trained or tested in the weeks prior. This indicates that spinal networks controlling standing and locomotion and their interactions with sensory feedback from the limbs remain largely intact after complete spinal cord injury. We conclude that standing and locomotor recovery is due to the return of neuronal excitability within spinal sensorimotor circuits that do not require task-specific activity-dependent plasticity.