Browsing by Author "Billeke, Pablo"

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    Attending to the heart is associated with posterior alpha band increase and a reduction in sensitivity to concurrent visual stimuli
    (Society for Psychophysiological Research, 2017) Villena González, Mario; Moenne Vargas, Cristóbal Matías; Lagos, Rodrigo A.; Alliende Correa, Luz María; Billeke, Pablo; Aboitiz, Francisco; López Hernández, Vladimir; Cosmelli, Diego
    Attentional mechanisms have been studied mostly in specific sensory domains, such as auditory, visuospatial, or tactile modalities. In contrast, attention to internal interoceptive visceral targets has only recently begun to be studied, despite its potential importance in emotion, empathy, and self-awareness. Here, we studied the effects of shifting attention to the heart using a cue-target detection paradigm during continuous EEG recordings. Subjects were instructed to count either a series of visual stimuli (visual condition) or their own heartbeats (heart condition). Visual checkerboard stimuli were used as attentional probes throughout the task. Consistent with previous findings, attention modulated the amplitude of the heartbeat-evoked potentials. Directing attention to the heart significantly reduced the visual P1/N1 amplitude evoked by the attentional probe. ERPs locked to the attention-directing cue revealed a novel frontal positivity around 300 ms postcue. Finally, spectral power in the alpha band over parieto-occipital regions was higher while attending to the heart-when compared to the visual task-and correlated with subject's performance in the interoceptive task. These results are consistent with a shared, resource-based attentional mechanism whereby allocating attention to bodily signals can affect early responses to visual stimuli.
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    Brain state-dependent recruitment of high-frequency oscillations in the human hippocampus
    (2017) Billeke, Pablo; Ossandón, Tomás; Stockle, Marcelo; Perrone-Bertolotti, Marcela; Kahane, Philippe; Lachaux, Jean-Philippe; Fuentealba, Pablo
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    Cortical dynamics underlying social behavior in dominance hierarchy and spatial navigation
    (2020) Lara Vásquez, Ariel Fernando; Espinosa, Nelson; Morales, Cristian; Moran, Constanza; Billeke, Pablo; Gallagher, Joseph; Strohl, Joshua J.; Huerta, Patricio T.; Fuentealba, Pablo
    Rodents establish dominance hierarchy as a social ranking system in which one subject acts as dominant over all the other subordinate individuals. Dominance hierarchy regulates food access and mating opportunities, but little is known of its significance in collective behavior, for instance during navigation for foraging or migration. Here, we implemented a simplified goal-directed spatial navigation task in mice and found that the social context exerts significant influence on individual decision-making, even when efficient navigation rules leading to reward had been previously learned. Thus, decision-making and consequent task performance were strongly dependent on contingent social interactions arising during collective navigation, yet their influence on individual behavior was outlined by dominance hierarchy. Dominant animals did not behave as leaders during navigation; conversely, they were most sensitive to social context. Social ranking in turn was reflected in the neural activity and connectivity patterns of the prefrontal cortex and hippocampus, both in anesthetized and behaving mice. These results suggest that the interplay between contingent social interactions and dominance hierarchy can regulate behavioral performance, supported by the intrinsic matrix of coordinated activity in the hippocampal-prefrontal circuit.
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    Country-level gender inequality is associated with structural differences in the brains of women and men
    (National Academy of Sciences, 2023) Zugman, Andrés; Alliende, Luz María; Medel Sierralta, Vicente Nicolás; Bethlehem, Richard A. I.; Seidlitz, Jakob; Ringlein, Grace; Arango, Celso; Arnatkeviciutė, Aurina; Asmal, Laila; Bellgrove, Mark; Benegal, Vivek; Bernardo, Miquel; Billeke, Pablo; Bosch-Bayard, Jorge; Bressan, Rodrigo; Busatto, Geraldo F.; Castro, Mariana N.; Chaim-Avancini, Tiffany; Compte, Albert; Costanzi, Monise; Czepielewski, Leticia; Dazzan, Paola; Fuente-Sandoval, Camilo de la; Forti, Marta di; Díaz-Caneja, Covadonga M.; Díaz-Zuluaga, Ana María; Plessis, Stefan du; Duran, Fabio L. S.; Fittipaldi, Sol; Fornito, Alex; Freimer, Nelson B.; Gadelha, Ary; Gama, Clarissa S.; Garani, Ranjini; García-Rizo, Clemente; González Campo, Cecilia; González-Valderrama, Alfonso; Guinjoan, Salvador; Holla, Bharath; Ibáñez, Agustín; Jackowski, Andrea; Ivanovic, Daniza; León-Ortiz, Pablo; Lochner, Christine; López Jaramillo, Carlos; Luckhoff, Hilmar; Massuda, Raffael; McGuire, Philip; Miyata, Jun; Mizrahi, Romina; Murray, Robin; Ozerdem, Aysegul; Pan, Pedro M.; Parellada, Mara; Phahladira, Lebogan; Ramírez Mahaluf, Juan P.; Reckziegel, Ramiro; Marques Tiago Reis; Reyes-Madrigal, Francisco; Roos, Annerine; Rosa, Pedro; Salum, Giovanni; Scheffler, Freda; Schumann, Gunter; Serpa, Mauricio; Stein, Dan J.; Tepper, Angeles; Tiego, Jeggan; Ueno, Tsukasa; Undurraga, Juan; Undurraga, Eduardo A.; Valdés-Sosa, Pedro; Valli, Isabel; Villarreal, Mirta; Winton-Brown, Toby T.; Yalin, Nefize; Zamorano, Francisco; Zanetti, Marcus V.; Veda, C.; Winkler, Anderson M.; Pine, Daniel S.; Evans-Lacko, Sara; Crossley Karmelic, Nicolas Andrés
    Gender inequality across the world has been associated with a higher risk to mental health problems and lower academic achievement in women compared to men. We also know that the brain is shaped by nurturing and adverse socio-environmental experiences. Therefore, unequal exposure to harsher conditions for women compared to men in gender-unequal countries might be reflected in differences in their brain structure, and this could be the neural mechanism partly explaining women’s worse outcomes in gender-unequal countries. We examined this through a random-effects meta-analysis on cortical thickness and surface area differences between adult healthy men and women, including a meta-regression in which country-level gender inequality acted as an explanatory variable for the observed differences. A total of 139 samples from 29 different countries, totaling 7,876 MRI scans, were included. Thickness of the right hemisphere, and particularly the right caudal anterior cingulate, right medial orbitofrontal, and left lateral occipital cortex, presented no differences or even thicker regional cortices in women compared to men in gender-equal countries, reversing to thinner cortices in countries with greater gender inequality. These results point to the potentially hazardous effect of gender inequality on women’s brains and provide initial evidence for neuroscience-informed policies for gender equality.
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    Dominance hierarchy regulates social behavior during spatial movement
    (2024) Lara-Vasquez, Ariel; Espinosa, Nelson; Morales, Cristian; Moran, Constanza; Billeke, Pablo; Gallagher, Joseph; Strohl, Joshua J.; Huerta, Patricio T.; Fuentealba, Pablo
    Copyright © 2024 Lara-Vasquez, Espinosa, Morales, Moran, Billeke, Gallagher, Strohl, Huerta and Fuentealba.Rodents establish dominance hierarchy as a social ranking system in which one subject acts as dominant over all the other subordinate individuals. Dominance hierarchy regulates food access and mating opportunities, but little is known about its significance in other social behaviors, for instance during collective navigation for foraging or migration. Here, we implemented a simplified goal-directed spatial task in mice, in which animals navigated individually or collectively with their littermates foraging for food. We compared between conditions and found that the social condition exerts significant influence on individual displacement patterns, even when efficient navigation rules leading to reward had been previously learned. Thus, movement patterns and consequent task performance were strongly dependent on contingent social interactions arising during collective displacement, yet their influence on individual behavior was determined by dominance hierarchy. Dominant animals did not behave as leaders during collective displacement; conversely, they were most sensitive to the social environment adjusting their performance accordingly. Social ranking in turn was associated with specific spontaneous neural activity patterns in the prefrontal cortex and hippocampus, with dominant mice showing higher firing rates, larger ripple oscillations, and stronger neuronal entrainment by ripples than subordinate animals. Moreover, dominant animals selectively increased their cortical spiking activity during collective movement, while subordinate mice did not modify their firing rates, consistent with dominant animals being more sensitive to the social context. These results suggest that dominance hierarchy influences behavioral performance during contingent social interactions, likely supported by the coordinated activity in the hippocampal-prefrontal circuit.
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    Effects of acute stress on behavioral adaptation and oscillatory brain activity associated to social bargaining
    (2023) Fabar Chagay, Catalina; Ossandón, Tomás; Billeke, Pablo; Pontificia Universidad Católica de Chile. Escuela de Medicina
    El estrés agudo es una respuesta transitoria a factores estresantes físicos o fisiológicos que provoca cambios neuroendocrinos, los cuales pueden alterar el funcionamiento de diferentes áreas cerebrales, incluido el córtex prefrontal (CPF). Las funciones ejecutivas, como la toma de decisiones, la flexibilidad cognitiva, la cognición social y la monitorización de la retroalimentación, dependen de forma crucial de las redes frontales. Estas funciones cognitivas están estrechamente relacionadas con la línea media frontal theta, una banda neuronal de 4-8 Hz que se registra en las regiones frontales y aumenta tras las retroalimentaciones negativas. Se ha informado de que el estrés disminuye esta actividad. Actualmente, se debate si el estrés afecta a la compensación entre prosocialidad e interés propio, un elemento clave en situaciones de toma de decisiones sociales como el regateo. También se ha descrito ampliamente que el estrés elevado altera la flexibilidad al tiempo que disminuye la potencia theta, lo que podría repercutir en la forma en que nos adaptamos y actuamos en situaciones sociales. Sin embargo, aún no está claro cómo afecta el estrés a nuestra adaptabilidad estratégica durante contextos de creación social y cómo esto se asocia a theta como posible mecanismo neural. En este proyecto de tesis, recogimos datos neuroendocrinos, conductuales y electrofisiológicos para contribuir a este vacío de conocimiento con un enfoque integral. Utilizamos el Juego del Ultimátum (UG), un paradigma utilizado predominantemente en el campo de la teoría de juegos y la cognición social. Al utilizar una versión repetida de esta tarea en un contexto social y no social, esperábamos poder observar los cambios relacionados con la manipulación del estrés y aislar el componente social. En el primer estudio, examinamos cómo el estrés agudo afecta a las decisiones en términos de prosocialidad y flexibilidad conductual durante el regateo social. Nuestros resultados muestran que el estrés sólo tuvo efectos perjudiciales sobre el rendimiento en el contexto no social de la tarea, mientras que en el contexto social no hubo diferencias entre los participantes estresados y los no estresados. Esto sugiere que el contexto social puede actuar como un amortiguador que permite preservar la respuesta conductual y el rendimiento. En el segundo estudio, investigamos cómo afecta el estrés agudo a las decisiones en términos de flexibilidad cognitiva y conductual y la actividad de theta frontal de la línea media como posible mecanismo neural implicado en este proceso. Nuestros resultados mostraron que los participantes estresados presentaban una menor adaptación en el contexto no social, mientras que no se observaron diferencias en el contexto social. Aunque observamos una tendencia a un menor aumento de la potencia theta en el grupo de estrés tras la retroalimentación negativa, no alcanzó significación. La mayor adaptabilidad en el contexto no social entre los participantes no estresados no estuvo acompañada de un mayor aumento de la potencia theta tras los errores, que se esperaría que estuviera presente como marcador neural de la flexibilidad cognitiva. Sin embargo, observamos una mayor actividad alfa y beta en el contexto social que en el no social, lo que sugiere una mayor inhibición y reevaluación cognitiva de las emociones en los participantes no estresados.
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    Frontoparietal connectivity correlates with working memory performance in multiple sclerosis
    (2020) Figueroa Vargas, Alejandra; Carcamo, Claudia; Henriquez Ch, Rodrigo; Zamorano, Francisco; Ciampi Diaz, Ethel Leslie; Uribe San Martín, Reinaldo; Vásquez, Macarena; Aboitiz, Francisco; Billeke, Pablo
    Working Memory (WM) impairment is the most common cognitive deficit of patients with Multiple Sclerosis (MS). However, evidence of its neurobiological mechanisms is scarce. Here we recorded electroencephalographic activity of twenty patients with relapsing-remitting MS and minimal cognitive deficit, and 20 healthy control (HC) subjects while they solved a WM task. In spite of similar performance, the HC group demonstrated both a correlation between temporoparietal theta activity and memory load, and a correlation between medial frontal theta activity and successful memory performances. MS patients did not show theses correlations leading significant differences between groups. Moreover, cortical connectivity analyses using granger causality and phase-amplitude coupling between theta and gamma revealed that HC group, but not MS group, presented a load-modulated progression of the frontal-to-parietal connectivity. This connectivity correlated with working memory capacity in MS groups. This early alterations in the oscillatory dynamics underlaying working memory could be useful for plan therapeutic interventions.
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    Paradoxical Expectation : Oscillatory Brain Activity Reveals Social Interaction Impairment in Schizophrenia
    (2015) Billeke, Pablo; Armijo, Aalejandra; Castillo, Daniel; López, Tamara; Zamorano, Francisco; Cosmelli, Diego; Aboitiz, Francisco
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    The effect of a cognitive training therapy based on stimulation of brain oscillations in patients with mild cognitive impairment in a Chilean sample: study protocol for a phase IIb, 2 × 3 mixed factorial, double-blind randomised controlled trial
    (2024) Figueroa Vargas, Alejandra; Góngora, Begoña; Alonso, María F.; Ortega, Alonso; Soto Fernández, Patricio; Z-Rivera, Lucía; Ramírez, Sebastián; González, Francisca; Muñoz Venturelli, Paula; Billeke, Pablo
    Background: The ageing population has increased the prevalence of disabling and high-cost diseases, such as dementia and mild cognitive impairment (MCI). The latter can be considered a prodromal phase of some dementias and a critical stage for interventions to postpone the impairment of functionality. Working memory (WM) is a pivotal cognitive function, representing the fundamental element of executive functions. This project proposes an intervention protocol to enhance WM in these users, combining cognitive training with transcranial electrical stimulation of alternating current (tACS). This technique has been suggested to enhance the neuronal plasticity needed for cognitive processes involving oscillatory patterns. WM stands to beneft signifcantly from this approach, given its welldefined electrophysiological oscillations. Therefore, tACS could potentially boost WM in patients with neurodegenerative diseases. Methods: This study is a phase IIb randomised, double-blind clinical trial with a 3-month follow-up period. The study participants will be 62 participants diagnosed with MCI, aged over 60, from Valparaíso, Chile. Participants will receive an intervention combining twelve cognitive training sessions with tACS. Participants will receive either tACS or placebo stimulation in eight out of twelve training sessions. Sessions will occur twice weekly over 6 weeks. The primary outcomes will be electroencephalographic measurements through the prefrontal theta oscillatory activity, while the secondary efects will be cognitive assessments of WM. The participants will be evaluated before, immediately after, and 3 months after the end of the intervention. Discussion: The outcomes of this trial will add empirical evidence about the benefts and feasibility of an intervention that combines cognitive training with non-invasive brain stimulation. The objective is to contribute tools for optimal cognitive treatment in patients with MCI. To enhance WM capacity, postpone the impairment of functionality, and obtain a better quality of life. Trial registration: ClinicalTrials.gov NCT05291208. Registered on 28 February 2022. ISRCTN87597719 retrospectively registered on 15 September 2023.
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    Theta and Alpha Oscillation Impairments in Autistic Spectrum Disorder Reflect Working Memory Deficit
    (2017) Larraín Valenzuela, Josefina; Zamorano, Francisco; Soto Icaza, Patricia; Carrasco, Ximena; Herrera, Claudia; Aboitiz, Francisco; Daiber, Francisca; Billeke, Pablo
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    Validation of a Visual-Spatial Secondary Task to Assess Automaticity in Laparoscopic Skills
    (2018) Castillo, Richard; Alvarado, Juan; Moreno, Pablo; Billeke, Pablo; Martinez, Carlos; Varas, Julian; Jarufe Cassis, Nicolás