Browsing by Author "Crossley Karmelic, Nicolas Andrés"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Complexity and 1/f slope jointly reflect brain states
    (Nature Research, 2023) Medel, Vicente; Irani, Martín; Crossley Karmelic, Nicolas Andrés; Ossandon Valdés, Tomas; Boncompte Lezaeta, Gonzalo Nicolas
    Characterization of brain states is essential for understanding its functioning in the absence of external stimuli. Brain states differ on their balance between excitation and inhibition, and on the diversity of their activity patterns. These can be respectively indexed by 1/f slope and Lempel–Ziv complexity (LZc). However, whether and how these two brain state properties relate remain elusive. Here we analyzed the relation between 1/f slope and LZc with two in-silico approaches and in both rat EEG and monkey ECoG data. We contrasted resting state with propofol anesthesia, which directly modulates the excitation-inhibition balance. We found convergent results among simulated and empirical data, showing a strong, inverse and non trivial monotonic relation between 1/f slope and complexity, consistent at both ECoG and EEG scales. We hypothesize that differentially entropic regimes could underlie the link between the excitation-inhibition balance and the vastness of the repertoire of brain systems.
  • Thumbnail Image
    Item
    Prevalence of depressive disorder in the adult population of Latin America: a systematic review and meta-analysis
    (Elsevier Ltd, 2023) Errázuriz Concha, Antonia; Avello-Vega, Dalia; Ramírez Mahaluf, Juan P.; Torres Barrenechea, Rafael; Crossley Karmelic, Nicolas Andrés; Undurraga Fourcade, Eduardo Andrés; Jones, Peter B.; Department of Psychiatry, School of Medicine, Pontificia Universidad Católica de Chile
    © 2023 The Author(s)Background: Depressive disorder is one of the leading causes of disability worldwide; however its prevalence and association with inequality and crime is poorly characterised in Latin America. This study aimed to: i. systematically review population-based studies of prevalence of ICD/DSM depressive disorder in Latin America, ii. report pooled regional, country, and sex-specific prevalence estimates, and iii. test its association with four country-level development indicators: human development (HDI), income (Gini) and gender inequality (GII), and intentional homicide rate (IHR). Methods: We conducted a systematic review and meta-analysis of population-based studies reporting primary data on the prevalence of ICD/DSM depressive disorder in Latin America from 1990 to 2023, irrespective of language. We searched PubMed, PsycINFO, Cochrane Library, SciELO (regional database), LILAC (regional database), and available grey literature. Study quality was assessed using JBI's critical appraisal tools. We generated pooled estimates using random-effects meta-analysis; heterogeneity was assessed using the I2 statistic. Meta-regression analyses were used to test associations of depression prevalence with indicators of inequality and human development. The study was registered with PROSPERO (CRD42019143054). Findings: Using data from 40 studies in Latin America, lifetime, 12-month, and current prevalence of ICD/DSM depressive disorder were calculated at 12.58% (95% CI 11.00%–14.16%); 5.30% (4.55–6.06%), and 3.12% (2.22–4.03), respectively. Heterogeneity was high across lifetime, 12-month, and current prevalence, sex, and countries. 12-month and current prevalence was associated with higher Gini and GII, 12-month prevalence with lower HDI, and current prevalence with higher IHR. Interpretation: We found a high prevalence of ICD/DSM depressive disorders in Latin America, and a statistically significant association with inequality and development indicators. The high heterogeneity found across prevalence periods and the major gaps in country representation underscore the need to escalate efforts to improve mental health access and research capabilities in Latin America. Systematic, comparable prevalence estimates would inform more effective decision-making in the region. Funding: Pfizer Independent Medical Education Grant.
  • Thumbnail Image
    Item
    The ascending arousal system promotes optimal performance through mesoscale network integration in a visuospatial attentional task
    (The Mit Press, 2021) Wainstein Bezamat Gabriel; Rojas Libano, Daniel; Medel Sierralta, Vicente Nicolas; Alnaes, Dag; Kolskar, Knut K.; Endestad, Tor; Laeng, Bruno; Ossandon Valdes Tomas; Crossley Karmelic, Nicolas Andrés; Matar, Elie; Shine, James M.
    In our daily lives, it is usual to encounter highly demanding cognitive tasks. They have been traditionally regarded as challenges that are solved mainly through cerebral activity, specifically via information-processing steps carried by neurons in the cerebral cortex. Activity in cortical networks thus constitutes a key factor for improving our understanding of cognitive processes. However, recent evidence has shown that evolutionary older players in the central nervous system, such as brain stem's ascending modulatory systems, might play an equally important role in diverse cognitive mechanisms. Our article examines the role of the ascending arousal system on large-scale network dynamics by combining pupillometry, functional MRI, and graph theoretical analysis.