Papers by Cyril Schneider
Neurophysiologie Clinique, 2018
Increased evoked potentials to arousing auditory stimuli during sleep: implication for the unders... more Increased evoked potentials to arousing auditory stimuli during sleep: implication for the understanding of dream recall.
European Respiratory Journal, 2015
Http Www Theses Fr, 1999
Le passage de la jambe d'appui en phase pendulaire au cours de pas induits par une chute du c... more Le passage de la jambe d'appui en phase pendulaire au cours de pas induits par une chute du corps vers l'avant, est etudie dans le cadre general de la programmation du mouvement complexe chez l'homme. Cette transition se caracterise par la fin de l'activite motrice anti-gravitaire du soleus extenseur de la cheville d'appui (sols), le poser au sol du pied pendulaire, l'activation du tibialis anterior flechisseur dorsal de la cheville d'appui et le lever du pied d'appui. L'analyse integree des donnees biomecaniques et electromyographiques montre que le deroulement temporel de la transition est controle par un programme central posture-dependant. Les informations sensorielles pendulaires sont integrees au programme locomoteur par des boucles neuronales transcorticales, assurant l'adaptation de la commande motrice aux contraintes biomecaniques du mouvement. Le gain des afferents proprioceptifs en provenance de l'appui est module par les inhibitions presynaptiques ia et ib, ce qui evite toute activation ou modulation reflexe du patron moteur pouvant retarder ou avancer la transition. Le cortex moteur peut controler les circuits segmentaires lies a la transition : l'excitabilite des motoneurones alpha du sols est modulee par la facilitation corticospinale de l'inhibition presynaptique ia. Le systeme nerveux central est donc capable, dans une situation de rattrapage de l'equilibre, d'integrer les reafferences sensorielles au programme moteur en cours d'execution, en occultant toute intervention reflexe spinale. Deux programmes distincts assurent la compensation posturale des perturbations peripheriques et l'initiation de la transition de phase. Les controles descendants s'adaptent aux exigences fonctionnelles du mouvement, en reajustant l'intensite des decharges des muscles extenseurs si le programme postural est perturbe, et en modifiant le patron temporel de base de la transition de phase de la jambe d'appui en fonction des perturbations du programme locomoteur.
Archives of physical medicine and rehabilitation, Jan 22, 2015
This single-case research designed study explored whether intermittent theta burst stimulation (i... more This single-case research designed study explored whether intermittent theta burst stimulation (iTBS) of the right dorsolateral prefrontal cortex (rDLPFC) could improve metaphor comprehension in people with Parkinson's disease (PD) and language impairments. A right-handed participant with PD diagnosed 9 years ago, under chronic levodopa medication, and with metaphor comprehension impairment was recruited to undergo ten sessions of sham-stimulation (in two weeks), a washout period (six weeks), then ten sessions of iTBS (in two weeks). Clinical scores of metaphor comprehension and motor evaluation (UPDRS-III) and transcranial magnetic stimulation to test the excitability of the primary motor cortex (M) were used at baseline, post-sham, post-iTBS and at three follow-ups (8, 14 and 20 weeks post-iTBS). Metaphor comprehension was improved after iTBS and the highest scores were obtained 8 weeks later (p = .01). This improvement was correlated with the increase of the right M1 excitabi...
Autoimmunity reviews, 2014
Complex regional pain syndrome (CRPS) is a term used to describe a variety of disorders character... more Complex regional pain syndrome (CRPS) is a term used to describe a variety of disorders characterized by spontaneous or stimulus-induced pain that is disproportional to the inciting event and accompanied by a myriad of autonomic and motor disturbances in highly variable combinations. There are no standards which can be applied to the diagnosis and would fulfill definitions of evidence-based medicine. Indeed, there are almost as many diagnostic criteria as there are names to this disorder. The umbrella term CRPS has been subdivided into type I and type II. CRPS I is intended to encompass reflex sympathetic dystrophy and similar disorders without a nerve injury; while CRPS II occurs after damage to a peripheral nerve. There are numerous etiological pathophysiological events that have been incriminated in development of CRPS, including inflammation, autoimmune responses, abnormal cytokine production, sympathetic-sensory disorders, altered blood flow and central cortical reorganization....
Neuroscience Letters, 2011
Center for Interdisciplinary Research in Rehabilitation and Social Integration, Institut de Reada... more Center for Interdisciplinary Research in Rehabilitation and Social Integration, Institut de Readaptation en Deficience Physique de Quebec, Quebec City, Canada School of Psychology, Laval University, Quebec City, Canada Centre hospitalier de l’Universite Laval (CHUL) Research Center, Quebec City, Canada Neuroscience Dept, Laval University, Quebec City, Quebec Province, Canada Rehab Dept, Laval University, Quebec City, Quebec Province, Canada
Neuroscience Letters, 2007
We questioned whether postural phenomena associated with the coordination of pointing and steppin... more We questioned whether postural phenomena associated with the coordination of pointing and stepping resulted from the sole juxtaposition of the dynamics of each task during the overlapping time period ("juxtaposition hypothesis"). Nine subjects were involved in three experimental conditions: (1) "isolated stepping" (the stepping was performed alone), (2) "isolated pointing" (the pointing was performed alone), and (3) an "experimental sequence" (pointing and stepping were coordinated). Acceleration of centre of gravity (x G) and displacement of centre of foot pressure (xP) were recorded using a force plate. Pointing acceleration was recorded using a wrist-strapped mono-axial accelerometer. The dynamics of a "theoretical sequence" were calculated by the linear summation of x G and xP traces recorded in conditions (1) and (2). The juxtaposition hypothesis was tested by between-condition comparison of x G and xP during the anticipatory postural adjustments of stepping, i.e., at time intervals when pointing was expected to most significantly influence stepping. Results showed that x G and xP were higher (p < 0.001 and 0.01, respectively) in the experimental than in the theoretical sequence. Also, when compared to isolated stepping, the experimental sequence was performed with a higher x G (p < 0.01) while xP remained unchanged (p > 0.05). Altogether, our results suggest that the postural dynamics of pointing and stepping are not simply juxtaposed when both tasks are coordinated in a motor sequence. Conversely, the biomechanical consequences of the focal movement (pointing) on the mobility task (stepping) may be anticipated and integrated in the motor planning of quick stepping.
Human Movement Science, 2007
The present study explored whether rapid stepping is influenced by the coordination of an arm poi... more The present study explored whether rapid stepping is influenced by the coordination of an arm pointing task. Nine participants were instructed to (a) point the index finger of the dominant arm towards a target from the standing posture, (b) initiate a rapid forward step with the contralateral leg, and (c) synchronize stepping and pointing (combined task). Force plate and ankle muscle electromyography (EMG) recordings were contrasted between (b) and (c). In the combined task, the arm acceleration trace most often peaked around foot-off, coinciding with a 15% increase in the forward acceleration of the center of gravity (CoG). Backward displacement of the center of foot pressure at foot-off, duration of anticipatory postural adjustments (APAs) and ankle muscle EMG activity remained unchanged. In contrast, durations of swing phase and whole step were reduced and step length was smaller in the combined task. A reduction in the swing phase was correlated with an increased CoG forward acceleration at foot-off. Changes in the biomechanics of step initiation during the combined task might be ascribed to the postural dynamics elicited by arm pointing, and not to a modulation of the step APAs programming.
Neuroscience letters, Jan 20, 2011
Transcranial magnetic stimulation (TMS) is a neurophysiological tool that can transiently influen... more Transcranial magnetic stimulation (TMS) is a neurophysiological tool that can transiently influence brain excitability and improve cognitive performance. Facilitation effects induced by low frequency repetitive TMS on memory functions have been shown in a few studies in young and healthy participants [29] and in older individuals with memory complaints [40]. However, regions specifically involved in encoding and retrieval were not always systematically targeted. We thus aimed to facilitate episodic memory with online TMS systematically applied over the left or right dorsolateral prefrontal cortex (DLPFC) while participants were performing a recognition task. We applied online paired-pulse TMS (ppTMS) (15 ms inter-stimulus interval) either during encoding or retrieving of verbal or non-verbal material. Participants were 11 right-handed young individuals (21.33 ± 2.27 years old). Repeated measures ANOVA showed shorter reaction time when ppTMS are applied over the left DLPFC during enc...
Der Nervenarzt, 2009
In an open study the effect of repetitive peripheral magnetic stimulation (RPMS) on the spastic t... more In an open study the effect of repetitive peripheral magnetic stimulation (RPMS) on the spastic talipes equinus of various origins, degree and duration was evaluated in 53 children and adolescents. Clinical and electrophysiological investigations were designed to measure the RMPS effect on the spasticity and the functional capabilities of the spastic talipes equines. Moreover, the duration of the effect of one RPMS session should be established. The magnetic stimulation comprising 10 series of 10 s duration was applied over the first sacral radix using a frequency of 20 Hz and a 1.2-fold intensity above the motoric threshold. The RPMS significantly reduced the tonus of the spastic talipes equines and this effect lasted for 1 week. No significant changes of electrophysiological parameters measuring the F-wave, H-reflex und ASR tendon reflex could be observed. The RPMS could prove to be an effective option for the treatment of spasticity. However, this method needs further evaluation by evidence-based studies.
Comptes Rendus de l'Académie des Sciences - Series III - Sciences de la Vie, 1997
Acadkmie des sciences / Elsevier, Paris Neurosciences / Neurosciences L'augmentation de la contra... more Acadkmie des sciences / Elsevier, Paris Neurosciences / Neurosciences L'augmentation de la contraction du muscle solkaire du membre d'appui chez I'homme ne retarde pas la phase pendulaire au tours de pas dklenchks par la chute en avant Increase in the contraction of the stance soleus in man does not delay the swing phase in steps elicited by forward fall
Brain Research, 2010
Neuroimaging studies report that encoding and retrieval processes of episodic memory constantly a... more Neuroimaging studies report that encoding and retrieval processes of episodic memory constantly activate the left and right prefrontal cortex, even in the simplest memory tasks. Conversely, individuals with frontal lesions displayed impaired memory performance mainly in the most complex memory tasks. This discrepancy regarding the involvement of dorsolateral prefrontal cortex (DLPFC) may be explained by methodological divergences. Our goal was to study the critical role of the DLPFC in episodic encoding and retrieval processes according to the nature of the material (verbal or non-verbal) by using transcranial magnetic stimulation (TMS). Eighteen healthy adults performed a recognition task with words or random shapes. Paired-pulse TMS was applied (3-ms inter-pulse interval, at 90% of motor threshold) for inducing transient and safe interferences over the left or right DLPFCs during encoding or retrieval. Data analysis showed a reduced discrimination rate following TMS over the left DLPFC during encoding, as compared to a sham condition. Both hit and discrimination rates were also reduced after TMS over the right DLPFC, compared to TMS over left DLPFC, during retrieval. There was no difference between verbal and non-verbal material. Our results showed that the left and the right DLPFC play a critical role respectively in episodic encoding and retrieval processes for both verbal and non-verbal materials. Our findings are discussed in light of the findings obtained from other complementary approaches.
Brain Research, 2008
This work questioned further the influence of wrist movements on the control of precision grip. S... more This work questioned further the influence of wrist movements on the control of precision grip. Seated subjects wearing a full-arm orthosis with the wrist and hand free were instructed to maintain a thumb/index finger opposition corresponding to 15% of maximal voluntary contraction for the first dorsal interosseus (FDI). Paired-pulse transcranial magnetic stimulation eliciting conditioned MEPs of FDI was used to determine the modulation of short intracortical inhibition (SICI) during cyclic active and passive wrist flexion and extension and during a static condition (no wrist movement, hand in the neutral position). The FDI active motor threshold (AMT) and the conditioning stimulus (0.8 AMT) were assessed in each series of FDI SICI measurements and the test stimulus (TS) was adjusted to match the amplitudes of test FDI MEPs across conditions. An increase of FDI background EMG during active wrist flexion compared to extension in some subjects did not influence FDI SICI as tested at matched EMG levels in the static condition. FDI SICI was reduced during wrist flexion (whether active or passive) compared to wrist extension, the latter being of equivalent FDI SICI as in the static condition. We suggest that wrist flexion and precision grip could be linked in a functional proximo-distal synergy. Indeed, coupling the activity between M1 sites of wrist flexors and FDI muscle via cortico-cortical disinhibition of FDI site may help recruit the interjoint synergy. Also, the salience of afferent information from wrist muscles may contribute to the phase-dependent modulation of SICI in the preactivated FDI muscle.
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Papers by Cyril Schneider