Neural Filtering of Physiological Tremor Oscillations to Spinal Motor Neurons Mediates Short-Term Acquisition of a Skill Learning Task.

The acquisition of a motor skill involves adaptations of spinal and supraspinal pathways to alpha motoneurons. In this study, we estimated the shared synaptic contributions of these pathways to understand the neural mechanisms underlying the short-term acquisition of a new force-matching task. High-density surface electromyography (HDsEMG) was acquired from the first dorsal interosseous (FDI; 7 males and 6 females) and tibialis anterior (TA; 7 males and 4 females) during 15 trials of an isometric force-matching task. For two selected trials (pre- and post-skill acquisition), we decomposed the HDsEMG into motor unit spike trains, tracked motor units between trials, and calculated the mean discharge rate and the coefficient of variation of interspike interval (COVISI). We also quantified the post/pre ratio of motor units' coherence within delta, alpha, and beta bands. Force-matching improvements were accompanied by increased mean discharge rate and decreased COVISI for both muscles. Moreover, the area under the curve within alpha band decreased by ∼22% (TA) and ∼13% (FDI), with no delta or beta bands changes. These reductions correlated significantly with increased coupling between force/neural drive and target oscillations. These results suggest that short-term force-matching skill acquisition is mediated by attenuation of physiological tremor oscillations in the shared synaptic inputs. Supported by simulations, a plausible mechanism for alpha band reductions may involve spinal interneuron phase-cancelling descending oscillations. Therefore, during skill learning, the central nervous system acts as a matched filter, adjusting synaptic weights of shared inputs to suppress neural components unrelated to the specific task.

Social support, depression, and heart disease: a ten year literature review.

BACKGROUND: Coronary heart disease is the major cause of morbidity and mortality in the world. Psychosocial factors such as depression and low social support are established risk factors for poor prognosis in patients with heart disease. However, little is known about the hypothetical relationship pattern between them. PURPOSE: The purposes of this narrative review are (1) to appraise the 2002-2012 empirical evidence about the multivariate relationship between depression, social support and health outcomes in patients with heart disease; (2) to evaluate the methodological quality of included studies. METHOD: PubMed and PsychINFO were searched for quantitative studies assessing the multiple effects of low social support and depression on prognosis outcomes in patients with heart disease. The following search terms were used: social relation(*), cardiac disease, support quality, relationship, and relational support. RESULTS: Five studies (three prospective cohort studies, one case-control study, and one randomization controlled trial) were selected and coded according to the types of support (social and marital). The majority of findings suggests that low social support/being unmarried and depression are independent risk factors for poor cardiac prognosis. However, all analyzed studies have some limitations. The majority of them did not focus on the quality of marital or social relationships, but assessed only the presence of marital status or social relationship. Moreover, some of them present methodological limitations. CONCLUSION: Depressive symptoms and the absence of social or marital support are significant risk factors for poor prognosis in cardiac patients and some evidence supports their independence in predicting adverse outcomes. Cardiac rehabilitation and prevention programs should thus include not only the assessment and treatment of depression but also a specific component on the family and social contexts of patients.

In Sickness and in Health: a Literature Review about Function of Social Support within Anxiety and Heart Disease Association.

A narrative review of the major evidence concerning the relationship between anxiety, social support and cardiac disease was conducted. Literature demonstrates that a strict relationship between anxiety, social support and cardiac disease outcomes subsists. However, the function of social support within anxiety and heart disease association remains unclear and needs to further researches to be established. Moreover evidence suggests that it's the quality of close relationships to play an important role in affecting psychological and physiological health status. The main components that the literature suggests for a better quality of social support and close relationship, and the main assessment measure are presented. Evidence about cardiac rehabilitation programs and the need to assess and intervene on psychological and psychosocial factors is discussed.