Effets de la stimulation du nerf fémoral sur l'activité volontaire du muscle soléaire chez des sujets hémiparétiques

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Stimulation électrique de la moelle épinière lombaire pour déclencher la marche chez le chat spinal

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Stimulation de la survie et de la régénération des cellules ganglionnaires de la rétine par inactivation de la GTPase Rho après lésion du nerf optique du rat adulte

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Analyse des mécanismes d'échec des endoprothèses couvertes et stimulation de la formation néointimale in vitro : vers un meilleur traitement des anévrismes de l'aorte abdominale

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Efetividade das correntes TENS (Transcutaneous Electrical Nerve Stimulation) na promoção do processo de cicatrização de feridas crónicas: revisão sistemática

Introdução: As feridas crónicas têm um impacto bastante significativo em várias componentes, tais como a física, psicológica e financeira. Estudos efetuados no âmbito da estimulação elétrica (EE) na cicatrização de feridas crónicas mostraram que as correntes bidirecionais, como o TENS (transcutaneous electrical nerve stimulation), parecem ser promissoras. Objetivo: Descrever analiticamente os efeitos das correntes TENS na promoção da cicatrização de feridas crónicas. Métodos: O estudo que efetuámos trata-se de uma revisão sistemática. As bases de dados utilizadas foram: MEDLINE/PubMed, Cochrane Central Register of Controlled Trials, B-on, PEDro. Foram incluídos estudos realizados em humanos com idades superiores ou iguais a 18 anos, podendo ser randomizados ou não. Estes estudos deviam de ter como outcome a taxa de cicatrização. A qualidade dos artigos foi avaliada pela escala PEDro. Resultados: Dos 2505 artigos encontrados, incluímos 14 estudos (7 randomizados e 7 não-randomizados). Destes estudos, 5 focam-se nas feridas diabéticas, 3 incidem nas úlceras de pressão, 1 inclui úlceras venosas e 5 englobam mais do que um tipo de feridas crónicas. A média de idades em todos os estudos varia de 31,1 e 73,1 anos, sendo que o número da amostra varia de 20 a 214 indivíduos. Todos os artigos apresentaram resultados positivos na taxa de cicatrização aquando da aplicação das correntes TENS em qualquer tipo de feridas crónicas. O estudo apresenta algumas limitações na qualidade metodológica e no processo de seleção dos ensaios. Conclusão: A terapia TENS parece ser uma modalidade terapêutica efetiva na promoção do processo de cicatrização de feridas crónicas.

Localising the auditory N1m with event-related beamformers:localisation accuracy following bilateral and unilateral stimulation

The auditory evoked N1m-P2m response complex presents a challenging case for MEG source-modelling, because symmetrical, phase-locked activity occurs in the hemispheres both contralateral and ipsilateral to stimulation. Beamformer methods, in particular, can be susceptible to localisation bias and spurious sources under these conditions. This study explored the accuracy and efficiency of event-related beamformer source models for auditory MEG data under typical experimental conditions: monaural and diotic stimulation; and whole-head beamformer analysis compared to a half-head analysis using only sensors from the hemisphere contralateral to stimulation. Event-related beamformer localisations were also compared with more traditional single-dipole models. At the group level, the event-related beamformer performed equally well as the single-dipole models in terms of accuracy for both the N1m and the P2m, and in terms of efficiency (number of successful source models) for the N1m. The results yielded by the half-head analysis did not differ significantly from those produced by the traditional whole-head analysis. Any localisation bias caused by the presence of correlated sources is minimal in the context of the inter-individual variability in source localisations. In conclusion, event-related beamformers provide a useful alternative to equivalent-current dipole models in localisation of auditory evoked responses.

Pupillary shapes in response to electrical stimulation of the sclera of peripheral cornea in cats and porcines

Purpose: We have reported that the changes in the pupillary shape in response to electrical stimulation of the branches of the ciliary nerves in cats. (Miyagawa et al. PLoS One, 2014). This study investigates the changes in the pupillary shapes in response to electrical stimulations of the sclera of peripheral cornea in cats and porcines. Methods: Two enucleated eyes of two cats and three enucleated porcine eyes were studied. Trains of biphasic pulses (current, 3 mA; duration, 2 ms/phase; frequency, 40 Hz) were applied using a tungsten electrode (0.3mm diameter). The stimulation was performed at every 45 degree over the entire circular region on the sclera near the cornea. The pupillary images were recorded before and 4 s (cat) and 10 s (pig) after the stimulation and the change in the pupil diameter (Δr) was quantified. The pupillary images were obtained with a custom-built compact wavefront aberrometer (Uday et al. J Cataract Refract Surg, 2013). Results: In a cat eye, the pupil was dilated by the electrical stimulation at six out of eight orientations (before stimulation pupil diameter r=10.10±0.49 mm, Δr=0.33±0.12 mm). The pupil dilated only toward the electrode (relative eccentricity of the pupil center to the pupil diameter change amount rdec=1.15±0.28). In the porcine eyes, the pupils were constricted by the electrical stimulations at the temporal and nasal orientations (r=10.04±0.57 mm, Δr=1.52±0.70 mm). The pupils contracted symmetrically (rdec=0.30±0.12). Conclusions: With electrical stimulation in the sclera of the peripheral cornea, asymmetric mydriasis in cat eyes and symmetrical miosis in porcine eyes were observed. Under the assumption that the electrical stimulation stimulated both muscles that contribute to the pupil control, our hypothesis proposed here is that the pupil dilator is stronger than the pupil sphincter in cat, and pupil sphincter is stronger than pupil dilator in porcine.

Accommodative response to electrical stimulation of the sclera of peripheral cornea in cats and porcines

Purpose: We have reported that the changes in the accommodative response to electrical stimulation of the branches of the ciliary nerves in cats. (Miyagawa et al, PLoS One, 2014). We have also reported that no robust accommodative responses to the electrical stimulations of the sclera of peripheral cornea (SSPC) were observed in enucleated porcine eyes (Mihashi et al, VPOptics, 2014). In this study, accommodative responses to SSPC stimulation in cats and porcines were investigated. Methods: Two eyes of two cats under anesthesia and after they were sacrificed were studied. Three enucleated porcine eyes obtained from a local slaughterhouse were also studied. Trains of biphasic pulses (current, 3 mA; duration, 2 ms/phase; frequency, 40 Hz) were applied using a tungsten electrode (0.3mm diameter) from several orientations. Wavefront sensing with a compact wavefront aberrometer (Uday et al J Cataract Refract Surg, 2013) were performed before and 4 s (cat) and 10 s (pig) after the stimulations and wavefront aberrations including spherical errors were analyzed over a 4-mm pupil area. Results: In the first cat under anesthesia, at three out of seven stimulus positions, 0.2 D hyperopic accommodative responses were observed and in two orientations, myopic responses were observed. For the other cat, weak accommodative responses including astigmatic changes were observed. In the sacrificed condition of the second cat, 0.1 D myopic response was observed for one stimulus orientation and the smaller responses were observed at six out of eight stimulus positions. No accommodative responses were elicited for the enucleated porcine eyes. Conclusions: In the anesthetized cats, electrical stimulation of the SSPC induced accommodative responses; the responses were unstable and weaker than the responses by the ciliary nerve stimulations we observed in our previous study. Small accommodative responses were observed after one of two cats had been sacrificed, but no accommodative responses were detected in the enucleated porcine eyes. Further studies are needed to confirm difference in the accommodation functions in the two species.

Stimulation of GABAergic neurons of the lateral septum and its effect on movement speed

The lateral septum is associated with the regulation of innate behavior, motivation, and locomotion. Its complex interconnections with cognitive and affective regions such as the hippocampus, hypothalamus, and medial septum have made it an attractive region for studying how motivation regulates behavior in context-specific settings. This GABAergic brain region’s main output is the lateral hypothalamus, which provides downstream signaling of motor commands. Even though stimulation of lateral septum projections to the hypothalamus have shown to decrease running speed in free behaving mice, characterizing movement kinematics due to LS activation has not been studied. GABAergic medium spiny neurons of the lateral septum were selectively activated through the use of optogenetic techniques in transgenic mice. Photostimulation of the lateral septum at theta frequencies caused a non-significant decrease in head and back speed. 3D motion analysis of body movement under photostimulation was quantified, revealing a slow, linear decrease of body speed as photostimulation progressed. These results support the role of lateral septum activation in movement regulation and shed light on the specific manner in which stimulation of the LS gradually decreases movement speed.

Effets de la stimulation du nerf fémoral sur l'activité volontaire du muscle soléaire chez des sujets hémiparétiques

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Stimulation électrique de la moelle épinière lombaire pour déclencher la marche chez le chat spinal

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Stimulation de la survie et de la régénération des cellules ganglionnaires de la rétine par inactivation de la GTPase Rho après lésion du nerf optique du rat adulte

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Analyse des mécanismes d'échec des endoprothèses couvertes et stimulation de la formation néointimale in vitro : vers un meilleur traitement des anévrismes de l'aorte abdominale

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Effects of Altered Prenatal Sensory Stimulation on Postnatal Contingency Learning in Bobwhite Quail Neonates (Colinus Virginianus)

Preterm infants are exposed to high levels of modified early sensory experience in the Neonatal Intensive Care Unit (NICU). Reports that preterm infants show deficits in contingency detection and learning when compared to full-term infants (Gekoski, Fagen, & Pearlman, 1984; Haley, Weinberg, & Grunau, 2006) suggest that their exposure to atypical amounts or types of sensory stimulation might contribute to deficits in these critical skills. Experimental modifications of sensory experience are severely limited with human fetuses and preterm infants, and previous studies with precocial bird embryos that develop in ovo have proven useful to assess the effects of modified perinatal sensory experience on subsequent perceptual and cognitive development. In the current study, I assessed whether increasing amounts of prenatal auditory or visual stimulation can interfere with quail neonates’ contingency detection and contingency learning in the days following hatching. Results revealed that augmented prenatal visual stimulation prior to hatching does not disrupt the ability of bobwhite chicks to recognize and prefer information learned in a contingent fashion, whereas augmented prenatal auditory stimulation disrupted the ability of chicks to benefit from contingently presented information. These results suggest that specific types of augmented prenatal stimulation that embryos receive during late prenatal period can impair the ability to learn and remember contingently presented information. These results provide testable developmental hypotheses, with the goal of improving the developmental care and management of preterm neonates in the NICU setting.