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Introduction: In recent decades there has been a special interest in theories that could explain the regulation of motor control, and their applications. These theories are often based on models of brain function, philosophically reflecting different criteria on how movement is controlled by the brain, each being emphasised in different neural components of the movement. The concept of motor learning, regarded as the set of internal processes associated with practice and experience that produce relatively permanent changes in the ability to produce motor activities through a specific skill, is also relevant in the context of neuroscience. Thus, both motor control and learning are seen as key fields of study for health professionals in the field of neurorehabilitation. Development: The major theories of motor control are described, which include, motor programming theory, systems theory, the theory of dynamic action, and the theory of parallel distributed processing, as well as the factors that influence motor learning and its applications in neurorehabilitation. Conclusions: At present there is no consensus on which theory or model defines the regulations to explain motor control. Theories of motor learning should be the basis for motor rehabilitation. The new research should apply the knowledge generated in the fields of control and motor learning in neurorehabilitation. Resumen: Introducción: En las últimas décadas ha existido un especial interés por las teorías que podrían explicar el gobierno del control motor y sus aplicaciones. Estas teorías suelen basarse en mode-los de función cerebral, reflejando criterios filosóficamente diferentes sobre la forma en la que el movimiento es controlado por el cerebro, enfatizando cada una de ellas en los distintos componentes neurales del movimiento. Asimismo, en el contexto de las neurociencias, toma relevancia el concepto de aprendizaje motor, considerado como el conjunto de procesos inter-nos asociados a la práctica, y la experiencia, que producen cambios relativamente permanentes en la capacidad de producir actividades motoras, a través de una habilidad específica. Por lo que ambos, control y aprendizaje motor, se posicionan como campos de estudio fundamentales para los profesionales sanitarios en el campo de la neurorrehabilitación. Desarrollo: Se describen las principales teorías de control motor como la teoría de la programa-ción motora, la teoría de sistemas, la teoría de la acción dinámica o la teoría del procesamiento de distribución en paralelo, así como los factores que influyen en el aprendizaje motor y sus aplicaciones en neurorrehabilitación. Conclusiones: En la actualidad no existe un consenso sobre qué teoría o modelo es definitorio en dar explicación al gobierno del control motor. Las teorías sobre el aprendizaje motor deben ser la base para la rehabilitación motora. Las nuevas líneas de investigación deben aplicar los conocimientos generados en los campos del control y aprendizaje motor en neurorrehabilita-ción. Keywords: Models, Motor control, Motor learning, Neurological diseases, Neuro-rehabilitation, Theories, Palabras clave: Aprendizaje motor, Control motor, Modelos, Neurorrehabilitación, Patología neurológica, Teorías

Background: This study aimed to analyse the effects of a plank-based strength training programme on muscle activation in patients with long COVID., Subjects and Methods: Case series study that included patients with long COVID who participated in a 12-week trunk and pelvic muscle strength training programme. Clinical variables and the modified fatigue impact scale (MFIS) were used to assess fatigue levels. Percentage of muscle activation during a core muscle plank was measured via surface electromyography. Pre- and post-intervention results were compared using the Wilcoxon signed-rank test and evaluated with Cohen's D effect size (ES)., Results: Twenty-one subjects participated in the study; 81% female, mean age 47.5 years (range: 28-55 years), and median duration of symptoms 21 months (range: 5-24 months); 90.5% of the participants experienced fatigue (MFIS score = 38). Muscle activation during plank exercises improved across all muscles after the intervention, with significant increases in the left (p = 0.011, medium ES) and right external oblique (p =0.039, small ES) muscles and the right latissimus dorsi muscle (p = 0.039, small ES). Additionally, significant reductions in fatigue were observed in the total MFIS score (p = 0.004, medium ES) and in the physical (p < 0.001, large ES) and psychosocial subscales (p = 0.033, small ES)., Conclusions: Results suggest that a plank-based strength training programme may be effective in enhancing trunk and pelvic muscle activation in individuals with long COVID.

Background: The efficacy of transcranial direct current stimulation (tDCS) has been studied extensively. The cathodic (c-tDCS), anodic (a-tDCS), and bihemispheric stimulation have demonstrated efficacy in the management of the paretic upper extremity (UE) after stroke, but it has not been determined which stimulation polarity has, so far, shown the best results., Objective: To evaluate the available evidence to determine which tDCS polarity has the best results in improving UE motor function after stroke., Methods: PubMed, PEDro, Web of Science, EMBASE, and SCOPUS databases were searched. Different Medical Subject Headings (MeSH) terms were combined for the search strategy, to cover all studies that performed a comparison between different tDCS configurations focused on UE motor rehabilitation in people with lived experience of stroke., Results: Fifteen studies remained for qualitative analysis and 12 for quantitative analysis. Non-significant differences with a 95% confidence interval (CI) were obtained for c-tDCS versus a-tDCS (g = 0.10, 95% CI = -0.13; 0.33, p = .39, N = 292), for a-tDCS versus bihemispheric (g = 0.02, 95% CI = -0.46; 0.42, p = .93, N = 81), and for c-tDCS versus bihemispheric (g = 0.09, 95% CI = -0.84; .66, p = .73, N = 100). No significant differences between the subgroups of the meta-analysis were found., Conclusions: The results of the present meta-analysis showed no evidence that a stimulation polarity is superior to the others in the rehabilitation of UE motor function after stroke. A non-significant improvement trend was observed toward c-tDCS compared to a-tDCS., (© 2023 American Academy of Physical Medicine and Rehabilitation.)

Although advances in obstetric and neonatal care have improved the survival of preterm infants, many studies document the increased risk of motor and sensory neurodevelopmental abnormalities that can hinder school progress. The aim of this study was to analyze the differences in gross and fine motor development in children born preterm and full term aged 3 to 6 years using the Peabody Developmental Motor Scales 2 (PDMS-II). Fifteen preterm and fifteen term children, matched for age and sex, participated in this study. They were evaluated with the PDMS-II scale. The scores obtained in the PDMS-II scale showed statistically significant differences ( p < 0.05) in all subscales except for the "grasping" subscale. No dissimilarities were found between children who attended an early intervention program and those who did not participate, nor was there any correlation between week of gestation and birth weight and motor development in preschool. The results obtained show that differences are found with respect to motor development, with lower scores for those born preterm compared to children born at term. No statistically significant difference was found between preterm children who attended early intervention and those who did not. No correlation was found between motor development at preschool age and birth weight and gestational age.

Introduction: Transcranial direct current stimulation (tDCS) is a promising technique for brain modulation after a cerebrovascular accident (CVA). This treatment modality has been previously studied in the recovery of patients. The aim of this review is to analyse the evidence for the application of tDCS in the recovery of gait disturbance in stroke patients., Methods: This review was conducted according to the recommendations of the PRISMA statement. Three different electronic databases were searched for relevant results: PubMed, Scopus, and Cochrane, from 2015 to January 2022. We included reviews and meta-analyses that only considered randomised controlled trials (RCTs) that investigated the effects of transcranial direct current stimulation, in combination or not with other physiotherapy treatments, compared to no treatment, usual care, or alternative treatment on gait recovery. Our primary outcomes of interest were walking speed, mobility, and endurance; secondary outcomes included motor function., Results: Thirteen studies with a total of 195 RCTs were included. Data on population, outcome measures, protocols, and outcomes were extracted. The Amstar-2 scale and the GRADE system of certainty of evidence were used. Only one study received high certainty of evidence, 5 received low certainty of evidence, and 7 received critically low certainty of evidence. Moderate to low-quality evidence showed a beneficial effect of tDCS on gait parameters, but not significantly., Conclusions: Although the tDCS produces positive changes in gait recovery in spatio-temporal parameters such as mobility, endurance, strength, and motor function, there is insufficient evidence to recommend this treatment. Higher-quality studies with larger sample sizes are needed for stronger conclusions.

Multiple sclerosis (MS) is a chronic autoimmune disease that affects the central nervous system. Gait abnormalities, such as altered joint kinematics, are common in people with MS (pwMS). Traditional clinical gait assessments may not detect subtle kinematic alterations, but advances in motion capture technology and analysis methods, such as statistical parametric mapping (SPM), offer more detailed assessments. The aim of this study was to compare the lower-limb joint kinematics during gait between pwMS and healthy controls using SPM analysis. Methods: A cross-sectional study was conducted involving pwMS and healthy controls. A three-dimensional motion capture system was used to obtain the kinematic parameters of the more affected lower limb (MALL) and less affected lower limb (LALL), which were compared using the SPM analysis. Results: The study included 10 pwMS with mild disability (EDSS ≤ 3) and 10 healthy controls. The results showed no differences in spatiotemporal parameters. However, significant differences were observed in the kinematics of the lower-limb joints using SPM. In pwMS, compared to healthy controls, there was a higher anterior pelvis tilt (MALL, p = 0.047), reduced pelvis elevation (MALL, p = 0.024; LALL, p = 0.044), reduced pelvis descent (MALL, p = 0.033; LALL, p = 0.022), reduced hip extension during pre-swing (MALL, p = 0.049), increased hip flexion during terminal swing (MALL, p = 0.046), reduced knee flexion (MALL, p = 0.04; LALL, p < 0.001), and reduced range of motion in ankle plantarflexion (MALL, p = 0.048). Conclusions : pwMS with mild disability exhibit specific kinematic abnormalities during gait. SPM analysis can detect alterations in the kinematic parameters of gait in pwMS with mild disability.

ASD patients include a variety of motor deficits; however, these issues have received less scientific attention than other ASD symptoms. Due to understanding and behavioral difficulties, it might be difficult to administer motor assessment measures to children and adolescents with ASD. To evaluate motor challenges in this population, including gait and dynamic balance issues, the timed up and go test (TUG) may be a simple, easy to apply, quick, and inexpensive tool. This test measures in seconds the time it takes for an individual to get up from a standard chair walk 3 m, turn around, walk back to the chair, and sit down again. The study purpose was to evaluate the inter- and intra-rater reliability of TUG test in children and teenagers with ASD. A total of 50 children and teenagers with ASD (43 boys and 7 girls) between 6 and 18 years were included. Reliability was verified by the intraclass correlation coefficient, standard error of measurement, and minimum detectable change. The agreement was analyzed by the Bland-Altman method. A good intra-rater reliability (ICC = 0.88; 95% CI = 0.79-0.93) and an excellent inter-rater reliability (ICC = 0,99; 95% CI = 0.98 to 0.99) were observed. Additionally, Bland-Altman plots demonstrated that there was no evidence of bias in either the replicates or between examiners. Furthermore, the limits of agreement (LOAs) between the testers and test replicates were close, indicating that there was little variation between measurements.       Conclusions: The test TUG showed strong intra- and inter-rater reliability values, low proportion of measurement errors, and lack of significant bias based on by test repetition in children and teenagers with ASD. These results could be clinically useful for assessing balance and the risk of falls in children and teenagers with ASD. However, the present study is not free of limitations, such as the use of a non-probabilistic sampling. What is Known: • People with ASD have a variety of motor deficits that have a prevalence rate almost as common as intellectual disability. In our knowledge, there are no studies that provide data on the reliability of the use of scales or assessment tests in children and adolescents with ASD to measure motor difficulties, such as gait and dynamic balance, in children and teenagers with ASD. • Timed up and go test (TUG) could be a possible tool to measure this motor skills. What is New: • The reliability and agreement of the Timed up and go test in 50 children and teenagers with autism spectrum disorder showed strong intra- and inter-rater reliability values, low proportion of measurement errors, and lack of significant bias based on by test repetition., (© 2023. The Author(s).)

Background: Multiple sclerosis (MS) is a progressive neurodegenerative disease characterized by axonal degeneration and demyelination. Changes in gait, related to joint kinematics and kinetics, especially at the ankle and knee, have been observed in people with MS (pwMS). Muscle coactivation plays an important role in joint stabilization; however, excessive coactivation may interfere with gait. The aim of this study was to analyze the differences in muscle activation during gait in pwMS compared to healthy individuals., Methods: A cross-sectional study was conducted involving pwMS and healthy controls. Surface electromyography was used to record muscle activity during gait. The main outcome measures were the coactivation index (CI) and the area under the curve (AUC), which were calculated for several pairs of lower extremity muscles., Results: Nine pwMS and nine healthy controls were included. When comparing the MS group to the control group, the AUC was significantly higher in the lateral gastrocnemius ( p = 0.023) and the CI for the lateral gastrocnemius-anterior tibialis ( p = 0.022) and gluteus maximus-lateral gastrocnemius ( p = 0.047)., Conclusion: Mildly affected pwMS have altered muscle coactivation patterns during gait, especially in the most affected limb. The results highlight the importance of muscle coactivation in pwMS and its possible role in the early detection of gait abnormalities.

People with Down syndrome (DS) have gait deficits because motor milestones are usually reached later. Decreased gait speed or reduced stride length are some of the main deficits. The main objective of the present work was to assess the reliability of the 10-Meter Walk Test (10MWT) in adolescents and young adults with DS. The objective has been to analyze the construct validity of the 10MWT with the Timed up and go (TUG) test. A total of 33 participants with DS were included. Reliability was verified by intraclass correlation coefficient (ICC). The agreement was analyzed by the Bland-Altman method. Finally, construct validity was evaluated through Pearson correlation coefficient. The 10MWT intra-rater and inter-rater reliability were good (ICC between 0.76 until 0.9) and excellent (ICC > 0.9), respectively. The minimal detectable change for intra-rater reliability was 0.188 m/s. Also, it has demonstrated moderate construct validity (r > 0.5) considering the TUG test. The 10MWT has shown high intra- and inter-rater reliability and validity in adolescent and adults with SD and a moderate construct validity between TUG test and 10MWT.

The central nervous system (CNS) of preterm infants might have some peculiarities which distinguish it from that of full term infants. The difficulties associated with prematurity are the main cause of deaths all over the world during the new-born period after community-acquired pneumonia, and the second cause of deaths worldwide in children under five years old. Early recognition of signs indicating fragile postural control in premature infants can support understanding and help prevent and early intervention on possible future neuromotor dysfunctions in these subjects. The purpose of this paper is to determine if there is a qualitatively different development of postural control in premature infants without neurological involvement and infants born at term. We conducted a systematic review of longitudinal and cross-sectional case-control studies published between 2010 and March 2020 on this topic. The evaluation of parameters related to postural control was also included. The methodological quality of the selected works was evaluated using the CASPe critical reading programme for cases and controls. PRISMA guidelines for systematic reviews were followed for prematurity and postural control. 16 articles were included. The total sample amounted to 3,460 participants, of which 1,860 in the preterm group, and 1,600 in the control group. All the studies found show a poorer postural control by the group of children born preterm compared to the group of children born at term and one study indicating more limited postural control with higher prematurity. Regarding the methodological quality according to CASPe, those studies exceeding half of the total score were considered of adequate quality., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2022 Tuñón-Domínguez, Cuesta-Gómez, Molina-Rueda, Juárez-Vela, Ruiz de Viñaspre-Hernández, Santolalla-Arnedo, Sánchez-González and Carratalá-Tejada.)

Introduction: Phantom limb pain (PLP) after amputation is a frequent entity that conditions the life of those who suffer it. Current treatment methods are not sufficiently effective for PLP management. We aim to analyze the clinical application of transcranial direct current (tDCS) in people with amputation suffering from PLP., Evidence Acquisition: The following databases were consulted in September 2021: MEDLINE, EMBASE, The Web of Science, PEDro, SCOPUS and SciELO. Randomized controlled trials investigating the use of tDCS in people with amputation undergoing PLP were selected. Demographic data, type and cause of amputation, time since amputation, stimulation parameters, and outcomes were extracted., Evidence Synthesis: Six articles were included in this review (seven studies were considered because one study performed two individual protocols). All included studies evaluated PLP; six evaluated the phantom limb sensations (PLS) and two evaluated the psychiatric disorders. In all included studies the intensity and frequency of PLP was reduced, in three PLS were reduced, and in none study psychiatric symptoms were modified., Conclusions: Anodic tDCS over the contralateral M1 to the affected limb, with an intensity of 1-2 mA, for 15-20 minutes seems to significantly reduce PLP in people with amputation. Single-session treatment could modify PLP intensity for hours, and multi-session treatment could modify PLP for months. Limited evidence suggests that PLS and psychiatric disorders should be treated with different PLP electrode placements. Further studies with larger sample size and longer follow-up times are needed to establish the priority of tDCS application in the PLP management.

Background: Parkinson's disease (PD) causes postural instability and gait abnormalities that may be associated with an arm swing reduction., Objective: To conduct systematic review and meta-analysis to determine the kinematic patterns of arm-swing during gait in people with PD METHODS: A computer literature search of the PubMed, EMBASE, WOS, PEDro, SCOPUS and SciELO databases was conducted. Terms related to PD and arm-swing were combined to find studies that performed a free walking evaluation of the arm-swing of PD patients on or off medication compared to healthy controls. After a standardized evaluation by three examiners, fifteen articles met inclusion criteria. Random effects meta-analysis models were utilized to quantify (1) the arm-swing range of motion (RoM); (2) the arm-swing amplitude; (3) the arm-swing velocity; and (4) the arm-swing asymmetry., Results: On average, arm-swing RoM (7.07°), amplitude (0.8 cm), and velocity (0.31 m/s) were significantly decreased in PD compared to healthy controls. Healthy subjects had significantly more symmetrical arm-swing (8.16%) than people with PD. Effect sizes were moderate-large., Conclusions: People with PD have significant differences in RoM, amplitude, velocity, and asymmetry of arm-swing during gait compared to the healthy control group. Medication phase does not significantly influence arm-swing characteristics. Further studies will be needed to determine whether different disease characteristics influence the biomechanics of arm-swing during gait., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Upper extremity involvement is one of the most common motor impairments in children with unilateral spastic cerebral palsy (CP). One tool for the assessment of manual function in CP is the Nine Hole Peg Test (NHPT). However, the reliability of the NHPT in patients with unilateral CP is unknown. This study aimed to analyze the intra-rater inter-session reliability of the NHPT in unilateral spastic CP, for its use in clinical practice and research. A total of 27 participants with spastic unilateral CP were included. Reliability was verified by the intraclass correlation coefficient (ICC), standard error of measurement, and minimum detectable change. The agreement was analyzed by the Bland-Altman method. An excellent intra-rater reliability was observed for the non-affected side (ICC = 0.94) and the affected side (ICC = 0.96). The minimal detectable change was 4 and 12 s for the non-affected and affected side, respectively. There were no significant biases between repetitions.   Conclusions: The NHPT showed excellent intra-rater inter-session reliability in patients with spastic unilateral CP. In addition, the test shows adequate agreement and proportionally small errors to assess manual dexterity. What is Known: • The Nine Hole Peg Test (NHPT) is widely used to assess dexterity in patients with neurological conditions. • The NHPT has demonstrated appropriate measurement properties in healthy children and adults with neurological conditions. What is New: • The NHPT presents excellent reliability, small measurement errors, and adequate agreement for the assessment of patients with cerebral palsy. • The measurement error of the NHPT in unilateral cerebral palsy may be up to 13% of the total time to perform it., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study aimed to evaluate walking in multiple sclerosis (MS) patients with mild disability. A case control study with 8 mild disability MS patients and 10 controls was conducted. This study analyzed spatiotemporal, kinematic, and kinetic parameters. We also analyzed the timing of these parameters, as a percentage of the gait cycle. The MS patients and controls walked with a similar gait pattern. However, there were differences in the timing of the biomechanical parameters. The timing of toe-off was at 62-63% of gait cycle in MS subjects while in controls it was at 59.94% ( p = 0.009 to 0.027 vs. to controls). The peak of knee flexion during swing was at 74-76% of gait cycle in MS subjects while in controls was at 72% ( p = 0.027 to 0.034). While the peak of ankle dorsiflexion during stance occurred at 48-50% in MS subjects, while in controls it was at 46% ( p = 0.001 to 0.009), and the peak of plantar flexion during pre-swing was at 66% in MS subjects vs. 64% in controls ( p = 0.001). At the kinetic pattern, the first peak of the vertical ground reaction force occurred at 14% of gait cycle in controls while in MS patients it was at 17-20% ( p = 0.012 to 0.021). MS subjects with mild disability walked with similar spatiotemporal parameters, joint angles and moments compared to controls. However, our results suggest that those changed the temporal occurrences, expressed as percentage of the gait cycle, of the kinematic and kinetic parameters.

This systematic review evaluated psychomotor differences between children with and without siblings who have autism spectrum disorder (ASD), as well as the most reliable psychomotor skills that can help predict ASD and its associated language disorders. Literature from 2005 to 2020 was searched using the following databases: PubMed, Trip Medical Database, Cochrane, Web of Science, Science Direct, and Brain. A total 11 papers were included. Fine motor skills and joint attention displayed reliable results in order to predict ASD and its associated language disorders. The period between the first and the second year of life was considered the most appropriate one for the assessment of psychomotor skills. The best period to predict language disorders and ASD diagnosis is around 36 months old.

This study evaluates the effects of a rehabilitation program based on reflex locomotion therapy (RLT) on balance, gait, and fatigue in patients with multiple sclerosis (MS). Twenty-three patients diagnosed with MS participated in this study. Reversal design was carried out. The assessment tools included the Berg Balance Scale (BBS), the Performance Oriented Mobility Assessment (POMA), the Fatigue Severity Scale (FSS) and the instrumental analysis of the gait recorded by Vicon Motion System ® . We analyzed spatio-temporal parameters and kinematic variables of the hip, knee, and ankle joints. Additionally, the Client Satisfaction Questionnaire (CSQ-8) was administrated. We did find a significant improvement in balance and gait tools after the RLT period. Regarding instrumental analysis, the statistical analysis of spatio-temporal parameters showed a significant improvement in stride length, double support, and velocity after the RLT period. Concerning kinematic parameters, the analysis showed improvements in hip and knee range of motion (ROM) after RLT period. RLT could improve gait and balance in patients with MS. The patients reported a high level of satisfaction with the therapy received.

Background : Although the median frequency is used as a basis to assess the presence of muscular fatigue, some studies have found that it is not a good estimator for this purpose. Physiotherapists often deal with patients with movement issues related to fatigue. A new objective estimator that is easy to obtain and interpret can help with the management of such patients. Objective and Purpose : The aim of this study was to identify the frequency bands most affected by fatigue and propose a protocol to obtain such information. Methods : Thirty healthy subjects (age 22.05 ± 2.42 years, height 1.71 ± 0.08 m, and weight 68.75 ± 11.42 kg) were recruited to measure the rectus femoris electromyography (EMG) of both legs during gait, before and after a fatiguing protocol. Four frequency bands were studied: high frequency (107-250 Hz), midfrequency (65-94 Hz), 40 Hz (34-53 Hz), and low frequency (< 25 Hz). Each frequency band is related to different aspects of the muscular contraction. Results : The main finding is that the ratios of the 40-Hz frequency and low-frequency bands showed significant differences in both legs between pre-fatigue and post-fatigue recordings. Critical thresholds F* 4.86 and 4.93 were exceeded at 4.5-8.7%, 30.64-46%.38, 63.75-66.8%, and 83.69-90.79% and at 0-2.53%, 4.7-15.21%, 18.15-54.65%, and 55.81-99.95% of the gait cycle, respectively, with p values < .05. Conclusions : The low-frequency band constitutes the best indicator to assess fatigue in gait.

Background: The effectiveness of transcranial direct current stimulation (tDCS) in the upper limb (UL) motor rehabilitation of stroke has been widely studied. However, the long-term maintenance of its improvements has not yet been proven., Methods: A systematic search was conducted in MEDLINE/Pubmed, Web of Science, PEDRo, and Scopus databases from inception to April 2021. Randomized controlled trials were included if they performed a tDCS intervention combined with UL rehabilitation in stroke patients, performed several sessions (five or more), and assessed long-term results (at least three-month follow-up). Risk of bias and methodological quality were evaluated with the Cochrane RoB-2 and the Oxford quality scoring system., Results: Nine studies were included, showing a high methodological quality. Findings regarding UL were categorized into (1) functionality, (2) strength, (3) spasticity. All the studies that showed significant improvements retained them in the long term. Baseline functionality may be a limiting factor in achieving motor improvements, but not in sustaining them over the long term., Conclusion: It seems that the improvements achieved during the application of tDCS combined with UL motor rehabilitation in stroke were preserved until the follow-up time (from 3 months to 1 year). Further studies are needed to clarify the long-term effects of tDCS.

Background: The effectiveness of transcranial direct current stimulation (tDCS) together with conventional physiotherapy in motor rehabilitation after stroke has been widely studied. Despite this, few studies have focused on its application in gait and balance rehabilitation. This review aimed to determine the efficacy of transcranial direct current stimulation combined with conventional physiotherapy on gait, balance, and the functionality of the lower limb after stroke., Methods: This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Four electronic databases were systematically searched for relevant articles. Randomized clinical trials in English or Spanish that evaluated the use of the transcranial direct current stimulation, combined with physiotherapy, to improve gait, balance, and lower limb functionality after stroke were included., Main Results: 10 articles were included, with a total of 222 subjects. Data about population, assessment tools, protocols, sessions, and results were extracted. The methodological quality of the included studies ranged between 3 and 5., Conclusion: The use of transcranial direct current stimulation combined with physiotherapy improves gait parameters, static and dynamic balance, and lower limb functionality in stroke patients. Long-term effects have not yet been demonstrated.

The aim of the present systematic review was to describe the gait pattern in people with multiple sclerosis (MS) by compiling the main findings obtained from studies using three-dimensional capture systems of human movement. The search was carried out in PubMed, Web of Science, Physiotherapy Evidence Database (PEDro), and the Cumulative Index to Nursing and Allied Health (CINAHL) databases. Studies that used three-dimensional gait analysis systems and that analyzed spatiotemporal, kinematic, kinetic, or electromyographic parameters, were included. The quality of the studies was assessed using the Critical Review Form-Quantitative Studies scale. 12 articles were included with 523 (342 women and 181 men) people with a diagnosis of MS. The present work suggests that people with MS have a decrease in speed and stride length, as well as an increase in double-stance intervals during gait. Likewise, it is common to observe a decrease in hip extension during the stance period, a decrease in knee flexion in the swing period, a decrease in ankle dorsiflexion in the initial contact and a decrease in ankle plantar flexion during the pre-swing phase. The subjects with MS decrease the hip extensor moment and the ankle power during the stance period of walking.

The aim of this study was to evaluate the test-retest reliability of a conventional gait model (CGM), the Plug-in Gait model, to calculate the angles of the hip, knee, and ankle during initial contact (IC) and toe-off (TO). Gait analysis was performed using the Vicon Motion System ® (Oxford Metrics, Oxford, UK). The study group consisted of 50 healthy subjects. To evaluate the test-retest reliability, the intraclass correlation coefficient (ICC), the standard error of measurement (SEM), the minimal detectable change (MDC), and the Bland-Altman analysis with 95% limits of agreement were calculated. The ICC for the joint angles of the hip, knee, and ankle was higher than 0.80. However, the ankle angle at IC had an ICC lower than 0.80. The SEM was <5° for all parameters. The MDC was large (>5°) for the hip angle at IC. The Bland-Altman analysis indicated that the magnitude of divergence was between ±5° and ±9° at IC and around ±7° at TO. In conclusion, the ICC for the plug-in gait model was good for the hip, knee, and ankle angles during IC and TO. The plots revealed a disagreement between measurements that should be considered in patients' clinical assessments.

Background: The study of the signal in the frequency domain has shown to be a good tool to identify muscular fatigue. Previous research has shown that the low frequency band and 40 Hz frequency band increase their relative intensity with the onset of fatigue. These findings were obtained in rectus femoris, but the behaviours of other muscles of the lower limb are unknown. In this article we explored the changes in the low frequency and 40 Hz frequency band of lower limb muscles with respect to fatigue., Methods: Thirty healthy subjects were recruited to analyse the electromyography (EMG) of biceps femoris, tibialis anterior and gastrocnemius medialis and lateralis of both legs during gait. Four two-minutes walks at a self-selected speed were recorded, the first two walks with a normal muscular function and the last two walks after a fatigue protocol. All the signals were decomposed using wavelet transformations. The signals were normalized in time and spectral intensities normalized to the sum of intensities in the frequency domain. Two frequency bands were studied in each walk: the 40-Hz (34-53 Hz) and the low frequency (< 25 Hz) bands. A ratio of the spectral intensities of those frequency bands at each walk was obtained by dividing the 40-Hz frequency band spectral intensity by the low frequency band spectral intensity. Statistical parametric mapping techniques were used to compare the ratios of the prefatigue walks against the postfatigue walks., Results: The results of the Statistical Non-Parametric Mapping (SnPM) analysis of all muscles depict a higher relative spectral intensity in the low frequency band in the comparison of fatigue versus prefatigue recordings except for the right gastrocnemius lateralis. The critical thresholds F* were exceeded by multiple suprathreshold clusters with p values <0.05, showing that the low frequency band increased its relative spectral intensity in the case of fatigue., Conclusion: The obtained results suggest that the low frequency band increases its relative spectral intensity in all the studied muscles when fatigue onsets. This increase in relative spectral intensity may be linked to an increase in motor unit synchronization promoted by the central nervous system to ensure good motor control., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Objective: To study postural control and muscle activity during the limit of stability test (LOS) in subjects with chronic ankle instability., Design: Observational study., Setting: University laboratory., Participants: 10 healthy subjects were included in the control group and 10 subjects in the CAI group (age between 18 and 30 years, with history of the multiple ankle "giving way" episodes in the last six months and score ≤24 in the Cumberland Ankle Instability Tool)., Main Outcome Measures: A computerized dynamic posturography equipment was used for assessing the LOS. The electromyography activity of tibialis anterior (TA), soleus (SOL), medial gastrocnemius (MG) and peroneus longus (PL) was registered., Results: Subjects with CAI had a greater activation in TA to forward (p < .01), forward affected (p = .001), backward affected (p = .007) and backward directions (p < .01); in PL to forward affected (p < .01) and affected directions (p = .001); in MG to forward (p = .023) and affected directions (p < .01) and in SOL to the affected direction (p = .009). We observed restricted excursions and less directional control in subjects with CAI., Conclusions: Subjects with CAI exhibited poorer ability to move their center of gravity within stability limits. In addition, they have an altered ankle muscle activity during LOS test toward the affected ankle joint., Competing Interests: Declaration of competing interest We affirm that we have no financial affiliation or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript. Any other conflict of interest is also disclosed in an attachment., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Gait analysis is necessary to diagnose movement disorders. In order to reduce the costs of three-dimensional motion capture systems, new low-cost methods of motion analysis have been developed. The purpose of this study was to evaluate the inter- and intra-rater reliability of Kinovea ® and the agreement with a three-dimensional motion system for detecting the joint angles of the hip, knee and ankle during the initial contact phase of walking. Fifty healthy subjects participated in this study. All participants were examined twice with a one-week interval between the two appointments. The motion data were recorded using the VICON Motion System ® and digital video cameras. The intra-rater reliability showed a good correlation for the hip, the knee and the ankle joints (Intraclass Correlation Coefficient, ICC > 0.85) for both observers. The ICC for the inter-rater reliability was >0.90 for the hip, the knee and the ankle joints. The Bland-Altman plots showed that the magnitude of disagreement was approximately ±5° for intra-rater reliability, ±2.5° for inter-rater reliability and around ±2.5° to ±5° for Kinovea ® versus Vicon ® . The ICC was good for the hip, knee and ankle angles registered with Kinovea ® during the initial contact of walking for both observers (intra-rater reliability) and higher for the agreement between observers (inter-rater reliability). However, the Bland-Altman plots showed disagreement between observers, measurements and systems (Kinovea ® vs. three-dimensional motion system) that should be considered in the interpretation of clinical evaluations.

Background: Although there are studies that have examined brain functional reorganization following upper-limb amputation, understanding of the brain changes that occur in people with lower-limb amputation is limited., Objective: To investigate modifications in the brain following lower-limb amputation., Methods: We included case-control studies that evaluate neuroplasticity in the central nervous system using neuroimaging techniques. A literature search was conducted using MEDLINE, CINAHL, Web of Science, Scopus, and Cochrane., Results: Eleven articles were included (total n = 204 people with unilateral lower-limb amputation). These studies showed an increase in cerebellar gray matter volume in prosthesis users, as well as a decrease in thickness of the premotor cortex, orbitofrontal cortex, temporo-occipital junction, precentral gyrus, visual areas, and somatosensory cortex. Regarding white matter, the trials observed a decrease in the integrity at the corona radiata, the connections between the premotor areas, the fronto-occipital fasciculus and the corpus callosum. In addition, a decreased functional connectivity between cortical and subcortical areas has been described., Conclusions: Lower-limb amputation causes changes in several brain structures that may occur in the absence of pain and regardless of prosthesis use. The modifications observed include thinning or loss of gray matter volume, decrease in the integrity of the white matter connections between brain structures and changes in the functional connectivity between cortical and subcortical areas., Level of Evidence: I., (© 2019 American Academy of Physical Medicine and Rehabilitation.)

Background: Non-immersive video games are currently being used as technological rehabilitation tools for individuals with Parkinson's disease (PD). The aim of this feasibility study was to evaluate the effectiveness of the Leap Motion Controller® (LMC) system used with serious games designed for the upper limb (UL), as well as the levels of satisfaction and compliance among patients in mild-to-moderate stages of the disease., Methods: A non-probabilistic sampling of non-consecutive cases was performed. 23 PD patients, in stages II-IV of the Hoehn & Yahr scale, were randomized into two groups: an experimental group (n = 12) who received treatment based on serious games designed by the research team using the LMC system for the UL, and a control group (n = 11) who received a specific intervention for the UL. Grip muscle strength, coordination, speed of movements, fine and gross UL dexterity, as well as satisfaction and compliance, were assessed in both groups pre-treatment and post-treatment., Results: Within the experimental group, significant improvements were observed in all post-treatment assessments, except for Box and Blocks test for the less affected side. Clinical improvements were observed for all assessments in the control group. Statistical intergroup analysis showed significant improvements in coordination, speed of movements and fine motor dexterity scores on the more affected side of patients in the experimental group., Conclusions: The LMC system and the serious games designed may be a feasible rehabilitation tool for the improvement of coordination, speed of movements and fine UL dexterity in PD patients. Further studies are needed to confirm these preliminary findings.

Background: Recovery of motor function following stroke is essential to restore adequate functionality. The use of functional electrical stimulation (FES) technology as a neuroprosthesis to enhance the motor function of the UL, and thus facilitate the performance of ADL, could lead to a stroke patient's greater activity and participation in daily life., Objective: The aim of the present study was to establish whether the application of FES in patients who have suffered a stroke with UL motor impairment is able to modify and facilitate their reaching patterns, measured by a three-dimensional motion capture system., Methods: 20 patients with chronic stroke participated in this study. For muscle stimulation, the electrical stimulator Compex® was used. Motion analysis was performed using the VICON Motion System®. Joint movements of the thorax, shoulder and elbow were analyzed in the sagittal plane, during the reaching movement under two different conditions of stimulation: FES condition and placebo condition., Results: Differences between FES condition and placebo condition were observed. In the FES condition it was recorded: an increased shoulder flexion and elbow extension in the reaching movement., Conclusions: Functional electrical stimulation improved reaching movement in stroke patients with upper limb impairment.

The Gait Assessment and Intervention Tool (GAIT) has been recently developed for gait assessment in patients with stroke, and it is considered as a tool that may identify clinically relevant deviations from normal gait and quantifies relevant changes in gait because of an intervention. The objective was to analyze the GAIT psychometric properties in participants with stroke. A convenience sample of 15 adults with stroke was selected (58.15±7.8 years; 5.38±3.3 years from injury). We used the GAIT for evaluating the gait in patients with stroke. GAIT scoring is based on observations of anterior/posterior and lateral-view video documents. Inter-rater reliability of the GAIT between trained raters was good (intraclass correlation coefficient=0.762; P=0.008; 95% confidence interval=0.749-0.926). The minimal detectable change was 7.68 points (12.39%). Inter-rater reliability for the hip, knee, and ankle items was also good. In conclusion, the current study demonstrated that GAIT has good inter-rater reliability and good internal consistency.

Objective: This work sought to evaluate the precision and repeatability of a telepathology prototype based on open software and hardware., Materials and Methods: A prototype was designed with application in telepathology and telemicroscopy. Accuracy and prototype precision were evaluated by calculating the mean absolute error and the intraclass and repeatability correlation coefficients for a series of 190 displacements at 10, 25, 50, 75, and 100 μm., Results and Conclusions: This work developed a low-cost prototype that is accessible, easily reproducible, implementable, and scalable; based on the use of technology created under principles of open software and hardware. A pathologist reviewed the obtained images and found them to be of diagnostic quality. Its excellent repeatability, coupled with its good accuracy, allows for its application in telemicroscopy and static, dynamic, and whole-slide imaging pathology systems.

The aim of the study was to investigate the differences in the stability limits between patients with vascular and nonvascular unilateral transtibial amputation (UTA) and patients without amputation. Eighteen patients with UTA who used a prosthesis were divided into two groups: vascular (n=9) and nonvascular (n=9). Twenty-four patients without amputation served as the control group. Computerized dynamic posturography Smart EquiTest System, version 8.0 was used for measuring stability limits. The limits of stability test was used to assess the participants' ability to voluntarily sway to various locations in space. The measured parameters were maximum centre of gravity (COG) excursion, endpoint COG excursion and directional control. Single-factor analysis of variance and Bonferroni adjustment a posteriori tests was performed to investigate the differences between groups. The patients with vascular UTA had significantly lower endpoint COG excursion to oblique and forward direction compared with controls (P=0.017). In addition, the patients with vascular UTA had significantly lower maximum COG excursion to oblique and forward and to oblique and backward directions (P=0.031; 0.019). Patients with vascular UTA had significantly lower endpoint and maximum COG excursion to oblique and backward direction compared with patients with nonvascular UTA (P=0.30; 0.029). To summarize, patients with vascular UTA have substantially reduced limits of stability compared with patients without amputation and the patients with nonvascular UTA.

Background: The association between motor-related cortical activity and peripheral stimulation with temporal precision has been proposed as a possible intervention to facilitate cortico-muscular pathways and thereby improve motor rehabilitation after stroke. Previous studies with patients have provided evidence of the possibility to implement brain-machine interface platforms able to decode motor intentions and use this information to trigger afferent stimulation and movement assistance. This study tests the use a low-latency movement intention detector to drive functional electrical stimulation assisting upper-limb reaching movements of patients with stroke. Methods: An eight-sessions intervention on the paretic arm was tested on four chronic stroke patients along 1 month. Patients' intentions to initiate reaching movements were decoded from electroencephalographic signals and used to trigger functional electrical stimulation that in turn assisted patients to do the task. The analysis of the patients' ability to interact with the intervention platform, the assessment of changes in patients' clinical scales and of the system usability and the kinematic analysis of the reaching movements before and after the intervention period were carried to study the potential impact of the intervention. Results: On average 66.3 ± 15.7% of trials (resting intervals followed by self-initiated movements) were correctly classified with the decoder of motor intentions. The average detection latency (with respect to the movement onsets estimated with gyroscopes) was 112 ± 278 ms. The Fügl-Meyer index upper extremity increased 11.5 ± 5.5 points with the intervention. The stroke impact scale also increased. In line with changes in clinical scales, kinematics of reaching movements showed a trend toward lower compensatory mechanisms. Patients' assessment of the therapy reflected their acceptance of the proposed intervention protocol. Conclusions: According to results obtained here with a small sample of patients, Brain-Machine Interfaces providing low-latency support to upper-limb reaching movements in patients with stroke are a reliable and usable solution for motor rehabilitation interventions with potential functional benefits.

Background: Subjects with lower limb amputation develop new motor control strategies to preserve balance when they experience unexpected perturbations. Most studies performed thus far have not aimed to discuss the possible differences in postural control between subjects with vascular unilateral transtibial amputation (UTA) and subjects with traumatic UTA., Objective: To analyze the automatic postural reaction in response to unexpected surface perturbations in a sample of subjects with traumatic and vascular UTA and to compare these observations with those for a group of healthy subjects., Setting: University department., Design: Observational study., Participants: A total of 9 men with traumatic UTA, 7 men with vascular UTA, and 10 control subjects without amputation., Intervention: Computerized dynamic posturography Smart EquiTest System version 8.0 was used to measure automatic postural responses in both groups., Main Outcome Measures: The motor control test was used to assess the participants' automatic postural responses to unexpected surface perturbations., Results: Latency scores showed that subjects with traumatic UTA coped with faster latencies under their sound limb than did the subjects with vascular UTA in medium backward and forward perturbations (medium-backward: P = .004; medium-forward: P = .037). In addition, the subjects with traumatic UTA also managed faster responses to medium-backward (P = .017 versus right control limb; P = .046 versus left control limb) and large-backward (P = .021 versus right control limb) and medium-forward (P = .012 versus right control limb; P = .043 versus left control limb) perturbations in their sound limb in contrast to control subjects. Weight symmetry showed that the subjects with traumatic UTA bore significantly more weight through their sound limb compared with the control subjects during medium and large backward translations (P = .028 and P = .045, respectively)., Conclusions: The subjects with traumatic UTA had a greater reliance on their sound limb, and they had faster latencies and more weight in the sound limb upon experiencing unexpected perturbations compared with the control subjects. Conversely, persons with vascular UTA experienced slower latency responses in the sound limb compared with persons with traumatic UTA., (Copyright © 2016 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.)

Objective: To analyze the clinical and psychometric properties of observational gait assessment scales in people with neurological disorders., Data Sources: The databases used for the literature search were MEDLINE, the Cochrane Central Register of Controlled Trial, Web of Science, and the Cumulative Index to Nursing and Allied Health. The search was conducted between September 15 and November 30, 2014., Study Selection: Studies that investigate and validate observational gait assessment scales in people with central nervous system disorders., Data Extraction: General characteristics of the studies, including number of patients and observational gait assessment scales analyzed and their psychometric properties, were extracted., Data Synthesis: After the literature search, 15 articles were included in this review. Seven of the 15 articles studied the Tinetti Gait Scale (TGS), 2 studied the Rivermead Visual Gait Assessment (RVGA), 1 studied the Gait Assessment and Intervention Tool (G.A.I.T.), 3 studied the Wisconsin Gait Scale, and one of them compared the TGS and the G.A.I.T., Conclusions: The scale that appears to be the most suitable for both clinical practice and research is the G.A.I.T. because it has shown to be valid, reliable, and sensitive to change, homogeneous, and comprehensive, containing a large number of items that assess most components of the gait pattern. The RVGA was studied in those with diverse neurological disorders, including multiple sclerosis. For those with Parkinson disease, the TGS showed sensitivity and the Tinetti Performance-Oriented Mobility Assessment (POMA) showed predictive capability for falls and mortality as well as intra- and interrater reliability. The Tinetti POMA was also studied in those with normal pressure hydrocephalus, showing sensitivity and in those with Huntington disease, showing reliability and validity. More research is needed to more comprehensively analyze the psychometric properties of the RVGA, Wisconsin Gait Scale, TGS, and G.A.I.T. in patients with diverse neurological disorders, other than stroke., (Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Introduction: In recent decades there has been a special interest in theories that could explain the regulation of motor control, and their applications. These theories are often based on models of brain function, philosophically reflecting different criteria on how movement is controlled by the brain, each being emphasised in different neural components of the movement. The concept of motor learning, regarded as the set of internal processes associated with practice and experience that produce relatively permanent changes in the ability to produce motor activities through a specific skill, is also relevant in the context of neuroscience. Thus, both motor control and learning are seen as key fields of study for health professionals in the field of neuro-rehabilitation., Development: The major theories of motor control are described, which include, motor programming theory, systems theory, the theory of dynamic action, and the theory of parallel distributed processing, as well as the factors that influence motor learning and its applications in neuro-rehabilitation., Conclusions: At present there is no consensus on which theory or model defines the regulations to explain motor control. Theories of motor learning should be the basis for motor rehabilitation. The new research should apply the knowledge generated in the fields of control and motor learning in neuro-rehabilitation., (Copyright © 2011 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.)

Objective: To assess the clinical and psychometric properties of stroke motor assessment scales., Data Sources: The databases consulted for the literature research were MEDLINE, PEDro, ISI Web of Knowledge, and Cumulative Index to Nursing and Allied Health (CINAHL). The search was carried out between March 2011 and January 2014., Study Selection: Studies that describe and validate a measurement scale designed to assess gross motor function in stroke. The articles were classified according to the levels of evidence and grades of recommendation for diagnosis studies of the Oxford Center for Evidence-Based Medicine., Data Extraction: General characteristics of the studies, including number of patients, motor function assessment scales analyzed, and their psychometric properties, were collected., Data Synthesis: After the literature search, 19 articles were included in this review; 32 articles were excluded for not meeting the inclusion criteria. Four of the 19 articles studied the Motor Assessment Scale, 5 the Fugl-Meyer Assessment, 3 investigated the Sodring Motor Evaluation for Stroke Patients, 4 the Stroke Rehabilitation Assessment of Movement, 2 were about the Motricity Index, and 2 about the Rivermead Motor Assessment. All of them were classified as level 2b according to the levels of evidence and grades of recommendation., Conclusions: All the scales compiled in this review have been shown to be useful both in clinical practice and in terms of research. The most suitable scales to be used in the clinical field would be the short versions of the Fugl-Meyer Assessment and the Stroke Rehabilitation Assessment of Movement. A real consensus about the measurement of gross motor function in patients with stroke is not available in the recent literature., (Copyright © 2014 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Objective: The aim of this study was to quantify the motor adaptations in the frontal plane made by unilateral transtibial amputees (UTAs), with special regard to: (1) abduction/adduction moment at the hip and knee valgus moment in the frontal plane; (2) pelvic and thorax obliquity; and (3) stride length and gait speed., Methods: 15 Males with unilateral transtibial amputation comprised the subject group and 15 non-disabled individuals served as control group. Gait analysis was performed using the VICON MOTION SYSTEM(®) (Oxford Metrics, Oxford, UK)., Results: In this study, UTAs walked with a reduced hip abductor moment during the stance phase. At the knee joint, the valgus moment was reduced in the prosthetic limb compared to the sound and the control limb. The thorax range of motion in the frontal plane was increased on the prosthetic side, compared with the non amputee subjects., Conclusion: Our findings suggest that unilateral transtibial amputation patients walk with different motor control strategies in the frontal plane compared with the non-disabled subjects. These results suggest the need for specific training for this group of UTAs, focusing on exercises to stabilize and strengthen the proximal muscles as well as practicing balance and coordination in the coronal plane., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Gravity and radiation are undoubtedly the two major environmental factors altered in space. Gravity is a weak force, which creates a permanent potential field acting on the mass of biological systems and their cellular components, strongly reduced in space flights. Developmental systems, particularly at very early stages, provide the larger cellular compartments known, where the effects of alterations in the size of the gravity vector on living organisms can be more effectively tested. The insects, one of the more highly evolved classes of animals in which early development occurs in a syncytial embryo, are systems particularly well suited to test these effects and the specific developmental mechanisms affected. Furthermore, they share some basic features such as small size, short life cycles, relatively high radio-resistance, etc. and show a diversity of developmental strategies and tempos advantageous in experiments of this type in space. Drosophila melanogaster, the current biological paradigm to study development, with so much genetic and evolutionary background available, is clearly the reference organism for these studies. The current evidence on the effects of the physical parameters altered in space flights on insect development indicate a surprising correlation between effects seen on the fast developing and relatively small Drosophila embryo and the more slowly developing and large Carausius morosus system. In relation to the issue of the importance of developmental and environmental constraints in biological evolution, still the missing link in current evolutionary thinking, insects and space facilities for long-term experiments could provide useful experimental settings where to critically assess how development and evolution may be interconnected. Finally, it has to be pointed out that since there are experimental data indicating a possible synergism between microgravity and space radiation, possible effects of space radiation should be taken into account in the planning and evaluation of experiments designed to test the potential role of microgravity on biological developmental and evolution.

As an intermediate step in the development of a defined quantitative model of pattern formation during Drosophila segmentation, we present here a model capable of predicting the experimentally determined levels of gene activity and their phenotypic consequences. In its present form, the model includes only four genes: the three genes of the bithorax complex (Ubx, abd-A and Abd-B) and Antennapedia. It is shown that the model is quite robust, predicting many properties in the behavior of these genes. A previously undescribed property is that all of these genes should phenotypically exhibit some kind of haploinsufficiency when present in only a single dose in the genetic background of the animal. This is shown both by the model and by a new method of quantitatively analyzing the differences in the more obvious cuticular features of the larvae, i.e., the patterns in the ventral denticle belts. The model is also capable of dealing with a complicated genetic situation, a hybrid gene of Ubx and abd-A produced by the C1 deletion.

A quantitative model of the effect of the bithorax complex on segmentation is presented which could explain the known data of the spatiotemporal regulation of key gene complex during early Drosophila development, in relation to their effects on some of the segmentation landmarks. The model tries to put together the two different genetic levels, the genotypic and the phenotypic. At the genotypic level, a minimal cross-regulatory network of the different genes involved, Antp, Ubx, abd-A and Abd-B which explains the reported levels of expressions of these genes. At the phenotypic level, the pattern of the ventral denticle belts across the larva which are characteristics of the different segments have been compared by calculating a value of the degree of similarity in the case of the wild-type and several mutant combinations. Finally the two parts of the model are combined, showing that a satisfactory agreement between the two can be achieved. Therefore, this work is a first attempt to develop a method which will provide an explanatory solution of the old question in morphogenesis of how the phenotype is directed by the genotype of a cell or organism.