دانلود رایگان مقاله انگلیسی تاثیر استرس روحی-اجتماعی به ایجاد سازگاری حسی حرکتی وابسته به فراگیری مخچه - الزویر 2018

ABSTRACT

Despite being overlooked in theoretical models of stress-related disorders, differences in cerebellar structure and function are consistently reported in studies of individuals exposed to current and early-life stressors. However, the mediating processes through which stress impacts upon cerebellar function are currently unknown. The aim of the current experiment was to test the effects of experimentally-induced acute stress on cerebellar functioning, using a classic, forward saccadic adaptation paradigm in healthy, young men and women. Stress induction was achieved by employing the Montreal Imaging Stress Task (MIST), a task employing mental arithmetic and negative social feedback to generate significant physiological and endocrine stress responses. Saccadic adaptation was elicited using the double-step target paradigm. In the experiment, 48 participants matched for gender and age were exposed to either a stress (n = 25) or a control (n = 23) condition. Saliva for cortisol analysis was collected before, immediately after, and 10, and 30 min after the MIST. Saccadic adaptation was assessed approximately 10 min after stress induction, when cortisol levels peaked. Participants in the stress group reported significantly more stress symptoms and exhibited greater total cortisol output compared to controls. The stress manipulation was associated with slower learning rates in the stress group, while control participants acquired adaptation faster. Learning rates were negatively associated with cortisol output and mood disturbance. Results suggest that experimentally-induced stress slowed acquisition of cerebellar-dependent saccadic adaptation, related to increases in cortisol output. These ‘proof-of-principle’ data demonstrate that stress modulates cerebellarrelated functions.

4. Discussion

This experiment assessed how acute experimentally induced psychosocial stress impacted upon saccadic adaptation, a putative task of cerebellar functioning. For participants in the stress group, the MIST stress manipulation was successful in maintaining a higher level of stress compared to controls, both subjectively, through mood changes, and physiologically, through greater cortisol output in the whole group. Although, both groups showed adaptation, stress modulated the rate at which adaptation was achieved. This effect became apparent toward the end of the adaptation and it was stronger in participants who demonstrated enhanced sensitivity to the stress manipulation, as indicated by the total cortisol output. Although saccadic adaptation has been used previously in different psychiatric populations (Coesmans et al., 2014; Connolly et al., 2016; Mosconi et al., 2013), it is unclear in these studies whether performance differences are due to antecedents, concomitants or consequences of the disorder or medication effects. This study is the first to demonstrate that saccadic adaptation in healthy individuals is reduced following an experimental stress induction and that this adaptation level correlated with cortisol output.