Browsing by Author "Silva, Claudio"

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    A real-time fMRI neurofeedback system for the clinical alleviation of depression with a subject-independent classification of brain states: A proof of principle study
    (2022) Pereira, Jaime A.; Ray, Andreas; Rana, Mohit; Silva, Claudio; Salinas, Cesar; Zamorano, Francisco; Irani, Martin; Opazo, Patricia; Sitaram, Ranganatha; Ruiz, Sergio
    Most clinical neurofeedback studies based on functional magnetic resonance imaging use the patient's own neural activity as feedback. The objective of this study was to create a subject-independent brain state classifier as part of a real-time fMRI neurofeedback (rt-fMRI NF) system that can guide patients with depression in achieving a healthy brain state, and then to examine subsequent clinical changes. In a first step, a brain classifier based on a support vector machine (SVM) was trained from the neural information of happy autobiographical imagery and motor imagery blocks received from a healthy female participant during an MRI session. In the second step, 7 right-handed female patients with mild or moderate depressive symptoms were trained to match their own neural activity with the neural activity corresponding to the "happiness emotional brain state" of the healthy participant. The training (4 training sessions over 2 weeks) was carried out using the rt-fMRI NF system guided by the brain-state classifier we had created. Thus, the informative voxels previously obtained in the first step, using SVM classification and Effect Mapping, were used to classify the Blood-Oxygen-Level Dependent (BOLD) activity of the patients and converted into real-time visual feedback during the neurofeedback training runs. Improvements in the classifier accuracy toward the end of the training were observed in all the patients [Session 4-1 Median = 6.563%; Range = 4.10-27.34; Wilcoxon Test (0), 2-tailed p = 0.031]. Clinical improvement also was observed in a blind standardized clinical evaluation [HDRS CE2-1 Median = 7; Range 2 to 15; Wilcoxon Test (0), 2-tailed p = 0.016], and in self-report assessments [BDI-II CE2-1 Median = 8; Range 1-15; Wilcoxon Test (0), 2-tailed p = 0.031]. In addition, the clinical improvement was still present 10 days after the intervention [BDI-II CE3-2_Median = 0; Range -1 to 2; Wilcoxon Test (0), 2-tailed p = 0.50/ HDRS CE3-2 Median = 0; Range -1 to 2; Wilcoxon Test (0), 2-tailed p = 0.625]. Although the number of participants needs to be increased and a control group included to confirm these findings, the results suggest a novel option for neural modulation and clinical alleviation in depression using noninvasive stimulation technologies.
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    Determinant factors of excess of weight in school children: a multilevel study
    (SOC MEDICA SANTIAGO, 2007) Amigo, Hugo; Bustos, Patricia; Erazo, Marcia; Cumsille, Patricio; Silva, Claudio
    Background: Rates of obesity reach high levels in Chile, with geographic, social and school variations. Aim: To identify factors at two levels associated with excessive weight in school children: child-family characteristics and school-neighborhood. Material and methods: Using a cross-sectional and multi-step design, seven counties with the highest prevalence of obesity were identified, and schools were randomly chosen from within the 1(st), 3(rd) and 5(th) quintiles of the school strata (same level of obesity prevalence). Within each school, twelve 2(nd) grade children were randomly chosen, (n =42 schools and 504 students). Nutritional status, food intake, eating habits and physical activity were measured. Socio demographic, economic characteristics and nutritional status of the parents were assessed. Home size and facilities for children physical activities were assessed, as well as school infrastructure and management. Results: Most of the explained variance (97%) in the Body Mass index (BMI) was due to individual-level factors: sedentary children behaviour (beta coefficient 1.6, standard error (SE) 0.052), maternal obesity (beta 0.94; SE 0.25), paternal obesity (beta 0.83; SE 0.28) and hours watching television (beta 0.789, SE 0-297). The same risk factors were predictive if obesity: child sedentary behaviours odds ratio (OR): 3.98, 95% confidence interval (CI): 2.44-6.48, maternal obesity (OR: 1.91, CI 1.2.7-3.02) and being woman (OR 1.75, CI: 1.0.1-2.76). Conclusions: BMI and obesity are associated with children behaviour or biological and cultural conditions of their families and not with school characteristics.
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    Patients recovering from COVID-19 who presented with anosmia during their acute episode have behavioral, functional, and structural brain alterations
    (2024) Kausel, Leonie; Figueroa-Vargas, Alejandra; Zamorano, Francisco; Stecher, Ximena; Aspe-Sanchez, Mauricio; Carvajal-Paredes, Patricio; Marquez-Rodriguez, Victor; Martinez-Molina, Maria Paz; Roman, Claudio; Soto-Fernandez, Patricio; Valdebenito-Oyarzo, Gabriela; Manterola, Carla; Uribe-San-Martin, Reinaldo; Silva, Claudio; Henriquez-Ch, Rodrigo; Aboitiz, Francisco; Polania, Rafael; Guevara, Pamela; Munoz-Venturelli, Paula; Soto-Icaza, Patricia; Billeke, Pablo
    Patients recovering from COVID-19 commonly exhibit cognitive and brain alterations, yet the specific neuropathological mechanisms and risk factors underlying these alterations remain elusive. Given the significant global incidence of COVID-19, identifying factors that can distinguish individuals at risk of developing brain alterations is crucial for prioritizing follow-up care. Here, we report findings from a sample of patients consisting of 73 adults with a mild to moderate SARS-CoV-2 infection without signs of respiratory failure and 27 with infections attributed to other agents and no history of COVID-19. The participants underwent cognitive screening, a decision-making task, and MRI evaluations. We assessed for the presence of anosmia and the requirement for hospitalization. Groups did not differ in age or cognitive performance. Patients who presented with anosmia exhibited more impulsive alternative changes after a shift in probabilities (r = - 0.26, p = 0.001), while patients who required hospitalization showed more perseverative choices (r = 0.25, p = 0.003). Anosmia correlated with brain measures, including decreased functional activity during the decision-making task, thinning of cortical thickness in parietal regions, and loss of white matter integrity. Hence, anosmia could be a factor to be considered when identifying at-risk populations for follow-up.
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    Use of Real-Time Functional Magnetic Resonance Imaging-Based Neurofeedback to Downregulate Insular Cortex in Nicotine-Addicted Smokers
    (2020) Rana, Mohit; Ruiz, Sergio; Sanchez Corzo, Andrea; Muehleck, Axel; Eck, Sandra; Salinas, Cesar; Zamorano, Francisco; Silva, Claudio; Rea, Massimiliano; Batra, Anil; Birbaumer, Niels; Sitaram, Ranganatha
    It has been more than a decade since the first functional magnetic resonance imaging (fMRI)-based neurofeedback approach was successfully implemented. Since then, various studies have demonstrated that participants can learn to voluntarily control a circumscribed brain region. Consequently, real-time fMRI (rtfMRI) provided a novel opportunity to study modifications of behavior due to manipulation of brain activity. Hence, reports of rtfMRI applications to train self-regulation of brain activity and the concomitant modifications in behavioral and clinical conditions such as neurological and psychiatric disorders [e.g., schizophrenia, obsessive compulsive Disorder (OCD), stroke] have rapidly increased.