Neurophysiological evaluation of convergent afferents innervating the human esophagus and area of referred pain on the anterior chest wall

Noxious stimuli in the esophagus cause pain that is referred to the anterior chest wall because of convergence of visceral and somatic afferents within the spinal cord. We sought to characterize the neurophysiological responses of these convergent spinal pain pathways in humans by studying 12 healthy subjects over three visits (V1, V2, and V3). Esophageal pain thresholds (Eso-PT) were assessed by electrical stimulation and anterior chest wall pain thresholds (ACW-PT) by use of a contact heat thermode. Esophageal evoked potentials (EEP) were recorded from the vertex following 200 electrical stimuli, and anterior chest wall evoked potentials (ACWEP) were recorded following 40 heat pulses. The fear of pain questionnaire (FPQ) was administered on V1. Statistical data are shown as point estimates of difference +/- 95% confidence interval. Pain thresholds increased between V1 and V3 [Eso-PT: V1-V3 = -17.9 mA (-27.9, -7.9) P < 0.001; ACW-PT: V1-V3 = -3.38 degrees C (-5.33, -1.42) P = 0.001]. The morphology of cortical responses from both sites was consistent and equivalent [P1, N1, P2, N2 complex, where P1 and P2 are is the first and second positive (downward) components of the CEP waveform, respectively, and N1 and N2 are the first and second negative (upward) components, respectively], indicating activation of similar cortical networks. For EEP, N1 and P2 latencies decreased between V1 and V3 [N1: V1-V3 = 13.7 (1.8, 25.4) P = 0.02; P2: V1-V3 = 32.5 (11.7, 53.2) P = 0.003], whereas amplitudes did not differ. For ACWEP, P2 latency increased between V1 and V3 [-35.9 (-60, -11.8) P = 0.005] and amplitudes decreased [P1-N1: V1-V3 = 5.4 (2.4, 8.4) P = 0.01; P2-N2: 6.8 (3.4, 10.3) P < 0.001]. The mean P1 latency of EEP over three visits was 126.6 ms and that of ACWEP was 101.6 ms, reflecting afferent transmission via Adelta fibers. There was a significant negative correlation between FPQ scores and Eso-PT on V1 (r = -0.57, P = 0.05). These data provide the first neurophysiological evidence of convergent esophageal and somatic pain pathways in humans.

Does anticholinergics drug burden relate to global neuro-disability outcome measures and length of hospital stay?

Primary objective: To assess the relationship between disability, length of stay (LOS) and anticholinergic burden (ACB) with people following acquired brain or spinal cord injury. Research design: A retrospective case note review assessed total rehabilitation unit admission. Methods and procedures: Assessment of 52 consecutive patients with acquired brain/spinal injury and neuropathy in an in-patient neuro-rehabilitation unit of a UK university hospital. Data analysed included: Northwick Park Dependency Score (NPDS), Rehabilitation complexity Scale (RCS), Functional Independence Measure and Functional Assessment Measure FIM-FAM (UK version 2.2), LOS and ACB. Outcome was different in RCS, NPDS and FIM-FAM between admission and discharge. Main outcomes and results: A positive change was reported in ACB results in a positive change in NPDS, with no significant effect on FIM-FAM, either Motor or Cognitive, or on the RCS. Change in ACB correlated to the length of hospital stay (regression correlation = −6.64; SE = 3.89). There was a significant harmful impact of increase in ACB score during hospital stay, from low to high ACB on NPDS (OR = 9.65; 95% CI = 1.36–68.64) and FIM-FAM Total scores (OR = 0.03; 95% CI = 0.002–0.35). Conclusions: There was a statistically significant correlation of ACB and neuro-disability measures and LOS amongst this patient cohort.

Segmental body composition determination through a bioelectrical very large scale integration (VLSI) system

The purpose of this investigation was to develop new techniques to generate segmental assessments of body composition based on Segmental Bioelectrical Impedance Analysis (SBIA). An equally important consideration was the design, simulation, development, and the software and hardware integration of the SBIA system. This integration was carried out with a Very Large Scale Integration (VLSI) Field Programmable Gate Array (FPGA) microcontroller that analyzed the measurements obtained from segments of the body, and provided full body and segmental Fat Free Mass (FFM) and Fat Mass (FM) percentages. Also, the issues related to the estimate of the body's composition in persons with spinal cord injury (SCI) were addressed and investigated. This investigation demonstrated that the SBIA methodology provided accurate segmental body composition measurements. Disabled individuals are expected to benefit from these SBIA evaluations, as they are non-invasive methods, suitable for paralyzed individuals. The SBIA VLSI system may replace bulky, non flexible electronic modules attached to human bodies. ^

Review of the History and Current Status of Cell-Transplant Approaches for the Management of Neuropathic Pain

Treatment of sensory neuropathies, whether inherited or caused by trauma, the progress of diabetes, or other disease states, are among the most difficult problems in modern clinical practice. Cell therapy to release antinociceptive agents near the injured spinal cord would be the logical next step in the development of treatment modalities. But few clinical trials, especially for chronic pain, have tested the transplant of cells or a cell line to treat human disease. The history of the research and development of useful cell-transplant-based approaches offers an understanding of the advantages and problems associated with these technologies, but as an adjuvant or replacement for current pharmacological treatments, cell therapy is a likely near future clinical tool for improved health care.

Potential for Cell-Transplant Therapy with Human Neuronal Precursors to Treat Neuropathic Pain in Models of PNS and CNS Injury: Comparison of hNT2.17 and hNT2.19 Cell Lines

Effective treatment of sensory neuropathies in peripheral neuropathies and spinal cord injury (SCI) is one of the most difficult problems in modern clinical practice. Cell therapy to release antinociceptive agents near the injured spinal cord is a logical next step in the development of treatment modalities. But few clinical trials, especially for chronic pain, have tested the potential of transplant of cells to treat chronic pain. Cell lines derived from the human neuronal NT2 cell line parentage, the hNT2.17 and hNT2.19 lines, which synthesize and release the neurotransmitters gamma-aminobutyric acid (GABA) and serotonin (5HT), respectively, have been used to evaluate the potential of cell-based release of antinociceptive agents near the lumbar dorsal (horn) spinal sensory cell centers to relieve neuropathic pain after PNS (partial nerve and diabetes-related injury) and CNS (spinal cord injury) damage in rat models. Both cell lines transplants potently and permanently reverse behavioral hypersensitivity without inducing tumors or other complications after grafting. Functioning as cellular minipumps for antinociception, human neuronal precursors, like these NT2-derived cell lines, would likely provide a useful adjuvant or replacement for current pharmacological treatments for neuropathic pain.

A practical system for hands-off computer interaction based on electromyogram (EMG)/eye gaze tracking (EGT)

Effective interaction with personal computers is a basic requirement for many of the functions that are performed in our daily lives. With the rapid emergence of the Internet and the World Wide Web, computers have become one of the premier means of communication in our society. Unfortunately, these advances have not become equally accessible to physically handicapped individuals. In reality, a significant number of individuals with severe motor disabilities, due to a variety of causes such as Spinal Cord Injury (SCI), Amyothrophic Lateral Sclerosis (ALS), etc., may not be able to utilize the computer mouse as a vital input device for computer interaction. The purpose of this research was to further develop and improve an existing alternative input device for computer cursor control to be used by individuals with severe motor disabilities. This thesis describes the development and the underlying principle for a practical hands-off human-computer interface based on Electromyogram (EMG) signals and Eye Gaze Tracking (EGT) technology compatible with the Microsoft Windows operating system (OS). Results of the software developed in this thesis show a significant improvement in the performance and usability of the EMG/EGT cursor control HCI.

Modelo animal da Doença de Parkinson baseado na expressão de alfa - sinucleína: caracterização comportamental, eletrofisiológica e avaliação dos efei tos da estimulação da medula espinhal

Parkinson disease (PD) is associated with motor symptoms and dopaminergic cell loss in the nigrostriatal pathway. Alpha-synuclein is the major component of the Lewy bodies, the biological hallmarks of disease, and has been associated with familial cases of PD. Recently, the spinal cord stimulation (SCS) showed to be effective to alleviate the Parkinson symptoms in animal models and human patients. In this project, we characterized the motor and electrophysiological effects of alpha-synuclein overexpression in the substantia nigra of rats. We further investigated the effects of spinal electrical stimulation, AMPT and L-dopa administration in this model. Method: Sprague-Dawley rats were injected with empty viral vector or the vector carrying the gene for alpha-synuclein in the substantia nigra, and were tested weekly for 10 weeks in the open field and cylinder tests. A separated group of animals implanted with bilateral electrode arrays in the motor cortex and the striatum were recorded in the open field, during the SCS sessions and the pharmacological experiments. Results: Alpha-synuclein expression resulted in motor asymmetry, observed as the reduction in use of contralateral forepaw in the cylinder test. Animals showed an increase of local field potential activity in beta band three and four weeks after the virus injection, that was not evident after the 5th week. AMPT resulted in a sever parkinsonian state, with reduction in the locomotor activity and significant peak of oscillatory activity in cortex and striatum. SCS was effective to alleviate the motor asymmetry at long term, but did not reduce the corticostriatal low frequency oscillations observed 24 hs after the AMPT administration. These oscillations were attenuated by L-dopa that, even as SCS, was not effective to restore the locomotor activity during the severe dopaminergic depletion period. Discussion: The alpha-synuclein model reproduces the motor impairment and the progressive neurodegenerative process of PD. We demonstrated, by the first time, that this model also presents the increase in low frequency oscillatory activity in the corticostriatal circuit, compatible with parkinsonian condition; and that SCS has a therapeutic effect on motor symptom of this model.

Trajetória de vida dos pescadores vítimas de lesão medular por mergulho: experiências, representações sociais e estresse

Spinal cord injury causes permanent disabling manifestations, affecting the anatomic integrity, bodily changes and functional limitations related to the disability state. It was aimed to analyze the social representation, stress level and experiences of fishermen victims of spinal cord injury caused by diving accident in the Northern beaches of Brazil. It is a descriptive - exploratory study with quantitative, qualitative and representational data developed i n fishermen’s villages in nine beaches of Northern shore/RN, between October 2013 to August 2014, after the approval of the Ethics Committee in Research of the Universidade Federal do Rio Grande do Norte, under the number 431.891/2013, CAAE 20818913.0.0000 .5537. The sample was composed by 44 fishermen with spinal cord injury, defined from inclusion and exclusion criteria of the participants. It was used as instrument to collect the data a semi structured interview. Quantitative data was analyzed by descrip tive statistics, showing the data through table, boxes and graphics by Microsoft Excel. Data from interviews were submitted to the software called Analyse Lexicale par Contexte d’un Ensemble de Segments de Texte (ALCESTE) using the analysis of the Social R epresentation Theory and Center Core Theory. It is shown the outcomes of the research through four articles, following the normative recommendations of the journals. Participants of the study were all male, age mean 49,6 years, elementary school (68,2%), m arried (77,3%); paraplegia sequel (50,0%). Most of them showed stress (75,0%), almost in the exhaustion stage (33,3%), prevalent insomnia symptoms (95,5%) in the last hours; hypertension (97,7%) in the last week and sexual troubles (95,5%) in the last mont h). Decompressive illness caused spinal cord injury (57,1%), occurred prevalently in low summer (75,0%), northern shore (96,4%), having as main consequences the paresthesia and pain in the upper and lower limbs (67,9%), followed by death (25,0%). Interview analysis under the understanding of Social Representation of spinal cord injury allowed the appearance of seven categories: Treatment: limitation and expectative; Spinal Cord injury: before and after; Retirement: reality yet to come; Disability: dependenc y, incapacity, vulnerability; Overcoming and autonomy; Self feelings: physics losses and new start; Life and labor: impediments, plans and changes. The center core of the representation is found in the first category by the expectative and limitation on th e treatment, meanwhile the outskirt elements are in seventh and third categories. Physics limitation for fishing activities and retirement expectative is the most outstanding of the structure. Social representation concerning spinal cord injury is found in a transaction moment between before and after with the prevented fishing activity, coping of the situation with the potential remaining. The anchoring is established in the desire for changes related to the improvements of life and health conditions exper ienced day by day through faith. This study finishes pointing out the range of the objectives, which topic is relevant for public health of fishermen. It is suggested prevention measures, promotion and health recovery of fishermen, besides safe, healthy an d worthy conditions as a compromise of social and health politics.

Estimulação transcraniana por corrente contínua (ETCC) sobre o córtex motor na modulação autonômica em pessoas com lesão medular com diferentes graus e níveis de lesão

Introduction: Transcranial Direct Current Stimulation (tDCS) has been used in studies for the treatment of chronic pain, but their effects on the autonomic nervous system (ANS) are non-existent. Therefore, the need for studies is of fundamental importance, as these individuals have autonomic imbalance and the intensity of this is dependent on the degree and level of injury. Objective: We investigated the effect of tDCS on the ANS in people with spinal cord injury (SCI) with different degrees and levels of injury. Methods: Randomized, placebo-controlled, double-blind, applied anodal tDCS or sham on the primary motor cortex (M1), bilaterally. The subjects (lower incomplete injury, n = 7; lower complete injury, n = 9; and high complete thoracic injury, n = 3) visited the laboratory three times and received active or sham tDCS for 13min. The heart rate variability (HRV) was measured before, during and after stimulation and analyzed the variables LF, HF and LF / HF. Results: The tDCS modulated the ANS in different ways among the groups. In individuals with SCI high complete thoracic the tDCS did not change the HRV. However, for individuals with SCI low incomplete, tDCS changed the HRV in order to increase sympathetic (LF, p = 0.046) and reduced parasympathetic (HF, p = 0.046). For individuals SCI low complete to tDCS changed the HRV reduction sympathetic (LF, p = 0.017) and increased parasympathetic (HF, p = 0.017). Conclusions: The present study suggests that anodal tDCS applied on the motor cortex bilaterally could modulate the ANS balance in people with spinal cord injury and that this effect is dependent on the degree and level of injury.

Quantitative Analysis of Kilohertz-Frequency Neurostimulation

Mainstream electrical stimulation therapies, e.g., spinal cord stimulation (SCS) and deep brain stimulation, use pulse trains that are delivered at rates no higher than 200 Hz. In recent years, stimulation of nerve fibers using kilohertz-frequency (KHF) signals has received increased attention due to the potential to penetrate deeper in the tissue and to the ability to block conduction of action potentials. As well, there are a growing number of clinical applications that use KHF waveforms, including transcutaneous electrical stimulation (TES) for overactive bladder and SCS for chronic pain. However, there is a lack of fundamental understanding of the mechanisms of action of KHF stimulation. The goal of this research was to analyze quantitatively KHF neurostimulation.

We implemented a multilayer volume conductor model of TES including dispersion and capacitive effects, and we validated the model with in vitro measurements in a phantom constructed from dispersive materials. We quantified the effects of frequency on the distribution of potentials and fiber excitation. We also quantified the effects of a novel transdermal amplitude modulated signal (TAMS) consisting of a non-zero offset sinusoidal carrier modulated by a square-pulse train. The model revealed that high-frequency signals generated larger potentials at depth than did low frequencies, but this did not translate into lower stimulation thresholds. Both TAMS and conventional rectangular pulses activated more superficial fibers in addition to the deeper, target fibers, and at no frequency did we observe an inversion of the strength-distance relationship. In addition, we performed in vivo experiments and applied direct stimulation to the sciatic nerve of cats and rats. We measured electromyogram and compound action potential activity evoked by pulses, TAMS and modified versions of TAMS in which we varied the amplitude of the carrier. Nerve fiber activation using TAMS showed no difference with respect to activation with conventional pulse for carrier frequencies of 20 kHz and higher, regardless the size of the carrier. Therefore, TAMS with carrier frequencies >20 kHz does not offer any advantage over conventional pulses, even with larger amplitudes of the carrier, and this has implications for design of waveforms for efficient and effective TES.

We developed a double cable model of a dorsal column (DC) fiber to quantify the responses of DC fibers to a novel KHF-SCS signal. We validated the model using in vivo recordings of the strength-duration relationship and the recovery cycle of single DC fibers. We coupled the fiber model to a model of SCS in human and applied the KHF-SCS signal to quantify thresholds for activation and conduction block for different fiber diameters at different locations in the DCs. Activation and block thresholds increased sharply as the fibers were placed deeper in the DCs, and decreased for larger diameter fibers. Activation thresholds were > 5 mA in all cases and up to five times higher than for conventional (~ 50 Hz) SCS. For fibers exhibiting persistent activation, the degree of synchronization of the firing activity to the KHF-SCS signal, as quantified using the vector strength, was low for a broad amplitude range, and the dissimilarity between the activities in pairs of fibers, as quantified using the spike time distance, was high and decreased for more closely positioned fibers. Conduction block thresholds were higher than 30 mA for all fiber diameters at any depth and well above the amplitudes used clinically (0.5 – 5 mA). KHF-SCS appears to activate few, large, superficial fibers, and the activated fibers fire asynchronously to the stimulation signal and to other activated fibers.

The outcomes of this work contribute to the understanding of KHF neurostimulation by establishing the importance of the tissue filtering properties on the distribution of potentials, assessing quantitatively the impact of KHF stimulation on nerve fiber excitation, and developing and validating a detailed model of a DC fiber to characterize the effects of KHF stimulation on DC axons. The results have implications for design of waveforms for efficient and effective nerve fiber stimulation in the peripheral and central nervous system.

Mechanisms underlying activation of neural stem cells in the adult central nervous system

À la fin du 19e siècle, Dr. Ramón y Cajal, un pionnier scientifique, a découvert les éléments cellulaires individuels, appelés neurones, composant le système nerveux. Il a également remarqué la complexité de ce système et a mentionné l’impossibilité de ces nouveaux neurones à être intégrés dans le système nerveux adulte. Une de ses citations reconnues : “Dans les centres adultes, les chemins nerveux sont fixes, terminés, immuables. Tout doit mourir, rien ne peut être régénérer” est représentative du dogme de l’époque (Ramón y Cajal 1928). D’importantes études effectuées dans les années 1960-1970 suggèrent un point de vue différent. Il a été démontré que les nouveaux neurones peuvent être générés à l’âge adulte, mais cette découverte a créé un scepticisme omniprésent au sein de la communauté scientifique. Il a fallu 30 ans pour que le concept de neurogenèse adulte soit largement accepté. Cette découverte, en plus de nombreuses avancées techniques, a ouvert la porte à de nouvelles cibles thérapeutiques potentielles pour les maladies neurodégénératives. Les cellules souches neurales (CSNs) adultes résident principalement dans deux niches du cerveau : la zone sous-ventriculaire des ventricules latéraux et le gyrus dentelé de l’hippocampe. En condition physiologique, le niveau de neurogenèse est relativement élevé dans la zone sous-ventriculaire contrairement à l’hippocampe où certaines étapes sont limitantes. En revanche, la moelle épinière est plutôt définie comme un environnement en quiescence. Une des principales questions qui a été soulevée suite à ces découvertes est : comment peut-on activer les CSNs adultes afin d’augmenter les niveaux de neurogenèse ? Dans l’hippocampe, la capacité de l’environnement enrichi (incluant la stimulation cognitive, l’exercice et les interactions sociales) à promouvoir la neurogenèse hippocampale a déjà été démontrée. La plasticité de cette région est importante, car elle peut jouer un rôle clé dans la récupération de déficits au niveau de la mémoire et l’apprentissage. Dans la moelle épinière, des études effectuées in vitro ont démontré que les cellules épendymaires situées autour du canal central ont des capacités d’auto-renouvellement et de multipotence (neurones, astrocytes, oligodendrocytes). Il est intéressant de noter qu’in vivo, suite à une lésion de la moelle épinière, les cellules épendymaires sont activées, peuvent s’auto-renouveller, mais peuvent seulement ii donner naissance à des cellules de type gliale (astrocytes et oligodendrocytes). Cette nouvelle fonction post-lésion démontre que la plasticité est encore possible dans un environnement en quiescence et peut être exploité afin de développer des stratégies de réparation endogènes dans la moelle épinière. Les CSNs adultes jouent un rôle important dans le maintien des fonctions physiologiques du cerveau sain et dans la réparation neuronale suite à une lésion. Cependant, il y a peu de données sur les mécanismes qui permettent l'activation des CSNs en quiescence permettant de maintenir ces fonctions. L'objectif général est d'élucider les mécanismes sous-jacents à l'activation des CSNs dans le système nerveux central adulte. Pour répondre à cet objectif, nous avons mis en place deux approches complémentaires chez les souris adultes : 1) L'activation des CSNs hippocampales par l'environnement enrichi (EE) et 2) l'activation des CSNs de la moelle épinière par la neuroinflammation suite à une lésion. De plus, 3) afin d’obtenir plus d’information sur les mécanismes moléculaires de ces modèles, nous utiliserons des approches transcriptomiques afin d’ouvrir de nouvelles perspectives. Le premier projet consiste à établir de nouveaux mécanismes cellulaires et moléculaires à travers lesquels l’environnement enrichi module la plasticité du cerveau adulte. Nous avons tout d’abord évalué la contribution de chacune des composantes de l’environnement enrichi à la neurogenèse hippocampale (Chapitre II). L’exercice volontaire promeut la neurogenèse, tandis que le contexte social augmente l’activation neuronale. Par la suite, nous avons déterminé l’effet de ces composantes sur les performances comportementales et sur le transcriptome à l’aide d’un labyrinthe radial à huit bras afin d’évaluer la mémoire spatiale et un test de reconnaissante d’objets nouveaux ainsi qu’un RNA-Seq, respectivement (Chapitre III). Les coureurs ont démontré une mémoire spatiale de rappel à court-terme plus forte, tandis que les souris exposées aux interactions sociales ont eu une plus grande flexibilité cognitive à abandonner leurs anciens souvenirs. Étonnamment, l’analyse du RNA-Seq a permis d’identifier des différences claires dans l’expression des transcripts entre les coureurs de courte et longue distance, en plus des souris sociales (dans l’environnement complexe). iii Le second projet consiste à découvrir comment les cellules épendymaires acquièrent les propriétés des CSNs in vitro ou la multipotence suite aux lésions in vivo (Chapitre IV). Une analyse du RNA-Seq a révélé que le transforming growth factor-β1 (TGF-β1) agit comme un régulateur, en amont des changements significatifs suite à une lésion de la moelle épinière. Nous avons alors confirmé la présence de cette cytokine suite à la lésion et caractérisé son rôle sur la prolifération, différentiation, et survie des cellules initiatrices de neurosphères de la moelle épinière. Nos résultats suggèrent que TGF-β1 régule l’acquisition et l’expression des propriétés de cellules souches sur les cellules épendymaires provenant de la moelle épinière.

The Hanging/hanged Patient and Relevance to Pre-hospital Care

Death and injury from hanging is a complex situation, which requires careful and appropriate assessment and management in the pre-hospital environment. It is arguably an area of limited understanding and therefore may not be assessed and managed in the most effective manner. Most hanged/hanging patients will be found in their homes, rather than in institutions. It could be argued that due to prevalence as a suicide method, the majority of pre-hospital ambulance service staff will be responded to at least one hanged or hanging patient within their careers, thus a greater understanding will benefit both clinician and patient. Patients who attempt or achieve suicide will rarely achieve fracturing the spine and severing the spinal cord, bringing into question the requirement for the traditional cervical collar and spinal immobilisation techniques. Death from asphyxiation and carotid/vagal reflex require consideration and management as does raised ICP, which is likely to occur.

Sonic hedgehog signaling regulates mode of cell division of early cerebral cortex progenitors and increases

The morphogen Sonic Hedgehog (SHH) plays a critical role in the development of different tissues. In the central nervous system, SHH is well known to contribute to the patterning of the spinal cord and separation of the brain hemispheres. In addition, it has recently been shown that SHH signaling also contributes to the patterning of the telencephalon and establishment of adult neurogenic niches. In this work, we investigated whether SHH signaling influences the behavior of neural progenitors isolated from the dorsal telencephalon, which generate excitatory neurons and macroglial cells in vitro. We observed that SHH increases proliferation of cortical progenitors and generation of astrocytes, whereas blocking SHH signaling with cyclopamine has opposite effects. In both cases, generation of neurons did not seem to be affected. However, cell survival was broadly affected by blockade of SHH signaling. SHH effects were related to three different cell phenomena: mode of cell division, cell cycle length and cell growth. Together, our data in vitro demonstrate that SHH signaling controls cell behaviors that are important for proliferation of cerebral cortex progenitors, as well as differentiation and survival of neurons and astroglial cells.

Restoring function after neuromuscular trauma: novel paradigms for enhancing volitional control of neural activity in untethered environments and vHAB, a gamified therapy platform

Thesis (Ph.D.)--University of Washington, 2016-08

Rôle de DSCAM dans le développement normal du cortex moteur et de la voie corticospinale

DSCAM est exprimé dans le cortex lors du développement et sa mutation altère l’arborisation dendritique des neurones pyramidaux du cortex moteur. Considérant que les souris DSCAM2J possèdent des problèmes posturaux et locomoteurs, nous émettons l’hypothèse que DSCAM est impliqué dans le fonctionnement normal du cortex moteur et de la voie corticospinale. Comparées aux souris contrôles, les souris DSCAM2J vont présenter des problèmes moteurs à basse vitesse et enjamber un obstacle presque normalement à vitesse intermédiaire. Le traçage antérograde de la voie corticospinale révèle un patron d’innervation normal dans le tronc cérébrale et la moelle épinière. Des microstimulations intracorticale du cortex moteur évoque des réponses électromyographiques dans les membres à un seuil et une latence plus élevé. Par contre, une stimulation de la voie corticospinale dans la médulla évoque des réponses électromyographies à un seuil et une latence similaire entre les deux groupes, suggérant une réduction de l’excitabilité du cortex moteur.