BackgroundIn this study, we investigated age and hemispheric differences in transcallosal inhibition (TCI) in the context of active contraction using the ipsilateral silent period (iSP). We also examined whether age-related changes in TCI would be related to corresponding changes in manual performance with age. Participants consisted of right-handed individuals from two age groups (young adults, n=13; seniors, n=17). The iSP was measured for each hemisphere using suprathreshold TMS pulses delivered over the primary motor cortex ipsilateral to the maximally contracting hand while the homologue muscles of the opposite hand were lightly contracting (~15% of the maximum). Manual performance was assessed bilaterally for both grip strength and fine dexterity.ResultsOur results yielded two main findings. First, TCI measures derived from iSP were strongly influenced by age, whereas differences between hemispheres were only minor. Second, correlation analyses revealed that age-related variations in TCI measures were related to changes in manual performance, so that left-to-right TCI correlated with right hand performance and vice-versa for the opposite hand/hemisphere.ConclusionOverall, these results concur with other recent reports indicating that mutual inhibition between motor cortices tends to decline with age. In this respect, our observations are in line with the notion that the balance of normally predominantly inhibitory interactions between motor cortices is shifted toward excitatory processes with age.

In this study, we examined hemispheric differences in corticospinal excitability and in transcallosal inhibition in a selected group of young adults (n = 34) grouped into three handedness categories (RH: strongly right-handed, n = 17; LH: strongly left-handed, n = 10; MH: mixed-handed, n = 7) based on laterality quotients (LQ) derived from the Edinburgh Handedness Inventory. Performance measures were also used to derive a laterality index reflecting right-left asymmetries in manual dexterity (Dextli) and in finger tapping speed (Speedli). Corticospinal excitability was assessed in each hemisphere by means of transcranial magnetic stimulation (TMS) using the first dorsal interosseus as the target muscle. TMS measures consisted of resting motor threshold (rMT), motor evoked potential (MEP) recruitment curve (RC) and the contralateral silent period (cSP) with the accompanying MEP facilitation. Hemispheric interactions were assessed by means of the ipsilateral silent period (iSP) to determine the onset latency and the duration of transcallosal inhibition (i.e., LTI and DTI). Analysis of hemispheric variations in measures of corticospinal excitability revealed no major asymmetries in relation to degrees of laterality or handedness, with the exception of a rightward increase in rMTs in the LH group. Similarly, no clear asymmetries were found when looking at hemispheric variations in measures of transcallosal inhibition. However, a large group effect was detected for LTI measures, which were found to be significantly shorter in the MH group than in either the LH or RH group. MH participants also tended to show longer DTI than the other participants. Further inspection of overall variations in LTI and DTI measures as a function of LQs revealed that both variables followed a non-linear relationship, which was best described by a 2nd order polynomial function. Overall, these findings provide converging evidence for a link between mixed-handedness and more efficient interhemispheric communication when compared to either right- or left-handedness.

Introduction: Responses to neuromodulatory protocols based either on transcranial direct current stimulation (tDCS) or transcranial magnetic stimulation (TMS) are known to be highly variable between individuals. In this study, we examined whether variability of responses to anodal tDCS (a-tDCS) could be predicted from individual differences in the ability to recruit early or late indirect waves (I-waves), as reflected in latency differences of motor evoked potentials (MEPs) evoked by TMS of different coil orientation.Methods: Participants (n = 20) first underwent TMS to measure latency of MEPs elicited at different coil orientations (i.e., PA, posterior-anterior; AP, anterior-posterior; LM, latero-medial). Then, participants underwent a-tDCS (20 min @ 2 mA) targeting the primary motor cortex of the contralateral preferred hand (right, n = 18). Individual responses to a-tDCS were determined by monitoring changes in MEP amplitude at rest and in the duration of the contralateral silent period (cSP) and ipsilateral silent period (iSP) during contraction; the latter providing an index of the latency and duration of transcallosal inhibition (LTI and DTI).Results: Consistent with previous reports, individual responses to a-tDCS were highly variable when expressed in terms of changes in MEP amplitude or in cSP duration with ~50% of the participants showing either little or no modulation. In contrast, individual variations in measures of transcallosal inhibition were less variable, allowing detection of significant after-effects. The reduced LTI and prolonged DTI observed post-tDCS were indicative of an enhanced excitability of the transcallosal pathway in the stimulated hemisphere. In terms of predictions, AP-LM latency differences proved to be good predictors of responses to a-tDCS when considering MEP modulation.Conclusion: The present results corroborate the predictive value of latency differences derived from TMS to determine who is likely to express “canonical” responses to a-tDCS in terms of MEP modulation. The results also provide novel suggestive evidencethat a-tDCS can modulate the excitability of the transcallosal pathway of the stimulated hemisphere.

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ABSTRACT:Transgendered individuals are defined by having a gender identity different from their birth gender. These individuals form a prevalent distinct group within the Lesbian, Gay, Bisexual and Transsexual (LGBT) community that has specific health needs. The goal of the current work is to identify the health needs affecting transgendered individuals in order to guide potential health interventions to ameliorate their well-being. Transgendered individuals often experience elevated rates of social stigma, discrimination and prejudice, which can alienate them from other members of society including family members and health care professionals. This can have negative effects on their employment and socioeconomic status and may even render them targets of hate crimes. The combination of these factors can have significant ill effects on the physical and mental health of transgendered individuals. For example, high rates of depression and anxiety are observed within this population with a reported suicide attempt rate of over 30%. Transgendered individuals are also at high risk of being infected with HIV, with those having undergone the transition from male to female (MTF) being most affected. Although Canada is ahead of the curve in equal rights pertaining to the LGBT community compared to many countries worldwide that still have anti-homosexual legislation, there still exists a considerable amount of stigma around the transgendered community. There is a need to educate the population at large to combat social stigma in order to reduce discrimination, increase social support, improve access to health services and ultimately improve the physical and mental wellbeing of transgendered people.RÉSUMÉ:Les personnes transgenres sont définies comme ayant une identité de genre différente de leur sexe de naissance. Ces personnes forment un groupe distinct au sein de la communauté des lesbiennes, gais, bisexuels et transsexuels (LGBT), ayant des besoins de santé spécifiques. Le but du travail actuel est d’identifier les besoins de santé touchant les personnes transgenres afin de guider les interventions de santé potentielles pour améliorer leur bien-être. Les personnes transgenres éprouvent souvent des taux élevés de stigmatisation sociale, de discrimination et de préjugés, ce qui peut les aliéner des autres membres de la société y compris les membres de leur famille et des professionnels de soins de santé. Cela peut avoir des effets négatifs sur leur emploi et leur statut socioéconomique et peut même les rendre cibles de crimes haineux. La combinaison de ces facteurs peut avoir des effets néfastes importants sur la santé physique et mentale des personnes transgenres. Par exemple, des taux élevés de dépression et d’anxiété sont observés dans cette population avec un taux de tentative de suicide déclaré de plus de 30%. Les personnes transgenres sont également à risque élevé d’être infectées par le VIH, celles ayant subi la transition d’homme à femme (MTF) étant les plus touchés. Bien que le Canada soit en avance dans l’égalité des droits se rapportant à la communauté LGBT par rapport à de nombreux pays à travers le monde, il existe encore une quantité considérable de stigmatisation qui entoure la communauté transgenre. Il est nécessaire d’éduquer la population dans son ensemble à lutter contre la stigmatisation sociale afin de réduire la discrimination, d’accroître le soutien social, d’améliorer l’accès aux services de santé et, finalement, d’améliorer le bien-être physique et mental des personnes transgenres.

Supplemental Digital Content is Available in the Text. Estimated peak oxygen uptake ( ) using 6-min Walk Test distance demonstrated poor agreement with measured from a cardiopulmonary exercise test in patients with heart failure enrolled in cardiac rehabilitation.

Abstract-Transcranial direct current stimulation (tDCS) has been shown to be beneficial as a potential treatment of several disorders such as depression, addiction and chronic pain. Despite promising results reported in research, there is variability in responsiveness to tDCS among subjects. However, the source of this variability is still unknown. Creating a mechanism of determining non-responders (vs. responders) is a crucial step in order to either understand the physiology behind tDCS or increase the effectiveness of treatment. This work proposes a versatile method to predict whether a subject responds to tDCS by analyzing the voltage measured between anode and cathode during a tDCS session. Two groups of subjects are determined as responders and non-responders by assessing the effect of tDCS on their motor potential evoked by transcranial magnetic stimulation (TMS). Voltage measurements are modeled by a double Debye model and two relaxation times are extracted for each measurement. A quadratic classifier is trained to recognize responders and nonresponders based on these relaxation times. Our classification results show that there is a significant correlation between relaxation times extracted from voltage and responsiveness to tDCS determined through motor evoked potentials. These results suggest that the relative speed of polarization processes occurring in electrodes and tissue may be associated the amount of current delivered to the brain.

Objective: Ischemic stroke is a major disease causing death and permanent neurological disability with the mainstay treatment being to re-established blood flow as quickly as possible. Recent changes in the efficiency of endovascular devices performing thrombectomies have led to it now being considered the gold standard. Nevertheless, successful endovascular thrombectomy (EVT) requires access to many resources and expertise which may impact its effectiveness. The objective of the current study is to describe the application and utility of EVT in the clinical treatment of ischemic stroke at a single tertiary care hospital. Methods: This is a descriptive retrospective cohort study from a stroke database. A total of 548 patients diagnosed with an ischemic stroke affecting large cerebral arteries between January 2010 and June 2016 were included. National Institute of Health Stroke Scale (NIHSS) score was used to evaluate stroke severity upon admission. Modified Ranking Scale was used to determine the functional status of patients upon discharge. Successful reperfusion defined as a TICI score of 2B or 3, age, thrombolytic use and time- to-treatment were all considered for analysis. Results: Thrombectomies became more frequent (p<0.001) with shorter time-to-treatment in recent years (p=0.001). A successful thrombectomy has significantly improved functional status at discharge (p<0.001), even when thrombolytics were not given (p=0.003) or when patients were over 80 years old (p=0.021). Conclusion: The current work provides evidence that this single hospital has increased its frequency of application of EVT for ischemic stroke, leading to a better functional outcome at discharge independent of prior thrombolysis or age.