Browsing by Author "Silva, Jaime"

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    Increase in Beta Power Reflects Attentional Top-Down Modulation After Psychosocial Stress Induction
    (Frontiers Media S.A., 2021) Palacios García, Ismael José; Silva, Jaime; Villena González, Mario Alejandro; Campos Arteaga, German Adolfo; Artigas Vergara, Claudio; Luarte, Nicolas; Rodriguez Balboa Eugenio Fernando; Bosman, Conrado A.
    Selective attention depends on goal-directed and stimulus-driven modulatory factors, each relayed by different brain rhythms. Under certain circumstances, stress-related states can change the balance between goal-directed and stimulus-driven factors. However, the neuronal mechanisms underlying these changes remain unclear. In this study, we explored how psychosocial stress can modulate brain rhythms during an attentional task and a task-free period. We recorded the EEG and ECG activity of 42 healthy participants subjected to either the Trier Social Stress Test (TSST), a controlled procedure to induce stress, or a comparable control protocol (same physical and cognitive effort but without the stress component), flanked by an attentional task, a 90 s of task-free period and a state of anxiety questionnaire. We observed that psychosocial stress induced an increase in heart rate (HR), self-reported anxiety, and alpha power synchronization. Also, psychosocial stress evoked a relative beta power increase during correct trials of the attentional task, which correlates positively with anxiety and heart rate increase, and inversely with attentional accuracy. These results suggest that psychosocial stress affects performance by redirecting attentional resources toward internal threat-related thoughts. An increment of endogenous top-down modulation reflected an increased beta-band activity that may serve as a compensatory mechanism to redirect attentional resources toward the ongoing task. The data obtained here may contribute to designing new ways of clinical management of the human stress response in the future and could help to minimize the damaging effects of persistent stressful experiences.
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    Psychosocial stress affects attentional control and neural oscillatory activity
    (2015) Palacios García, Ismael; Villena González, Mario; Campos Arteaga, German; Artigas Vergara, Claudio; Jaramillo, Karina; Silva, Jaime; Rodríguez, Eugenio
    Every day we have to divide our limited attentional resources into different external and internal demands. Considering that psychosocial stress promotes the allocation of attentional resources to threat-related stimuli such as the social evaluation, the aim of the study is (1) to investigate if psychosocial stress affects the behavioral performance in an attentional shifting task and (2) to search, under an exploratory approach, some of its neural correlates. 40 healthy participants were exposed to either an electroencephalogram-compatible version of the Trier Social Stress Test (TSST) or a control protocol. Additionally, immediately before and after these protocols, subject participated in the attentional shifting task. Manipulation checks were verified through the changes of the heart rate, salivary concentration of cortisol and the score in the anxiety scale in the “stress” condition respect the control. When we compared the behavioral performance in the attentional task prior and after both conditions, we found that the control group showed a clear improvement in performance, characterized by a relative increase of correct trials and a decrease of omissions. Analogously, after the TSST, participants showed a decreases of the correct trials and an increase of omissions. In addition to behavioral results, we found that the oscillatory activity in alpha (8–12 Hz) and gamma bands (30–70 Hz) were different in both conditions. Behavioral and electrophysiological results, suggest that psychosocial stress directs the attention internally, limiting the attentional resources for attending the external demands and inducing cognitive failures.