Browsing by Author "Rojas Thomas, Felipe Eduardo"

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    Emotional text messages afect the early processing of emoticons depending on their emotional congruence: evidence from the N170 and EPN event related potentials
    (2024) Aldunate Ruff Nerea Patricia; López Hernández, Vladimir; Rojas Thomas, Felipe Eduardo; Villena González, Mario; Palacios García, Ismael José; Artigas, Claudio A.; Rodríguez B., Eugenio; Bosman, Conrado A.
    Emoticons have been considered pragmatic cues that enhance emotional expressivity during computer-mediated communication. Yet, it is unclear how emoticons are processed in ambiguous text-based communication due to incongruences between the emoticon's emotional valence and its context. In this study, we investigated the electrophysiological correlates of contextual infuence on the early emotional processing of emoticons, during an emotional congruence judgment task. Participants were instructed to judge the congruence between a text message expressing an emotional situation (positive or negative), and a subsequent emoticon expressing positive or negative emotions. We analyzed early event-related potentials elicited by emoticons related to face processing (N170) and emotional salience in visual perception processing (Early Posterior Negativity, EPN). Our results show that accuracy and Reaction Times depend on the interaction between the emotional valence of the context and the emoticon. Negative emoticons elicited a larger N170, suggesting that the emotional information of the emoticon is integrated at the early stages of the perceptual process. During emoticon processing, a valence efect was observed with enhanced EPN amplitudes in occipital areas for emoticons representing negative valences. Moreover, we observed a congruence efect in parieto-temporal sites within the same time-window, with larger amplitudes for the congruent condition. We conclude that, similar to face processing, emoticons are processed diferently according to their emotional content and the context in which they are embedded. A congruent context might enhance the emotional salience of the emoticon (and therefore, its emotional expression) during the early stages of their processing.
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    Human sensory processing under acute psychosocial stress : neurophysiological correlates
    (2021) Rojas Thomas, Felipe Eduardo; López Hernández, Vladimir; Pontificia Universidad Católica de Chile. Escuela de Medicina
    The acute state of stress can alter some sensory systems by modifying the sensitivity and specificity of sensory processing. Limbic areas, like the amygdala and locus coeruleus, may have a fundamental role in this process. Most studies on sensory processing and stress, focus on pathological states or use non-social threats as stimuli. Such designs may allow the influence of unwanted variables, such as the use of drugs or the decreased response of the L-HPA axis towards the stressor. In this sense, studies that use stimuli that represent social threats and that consider both; the cognitive/behavioral performance and the neural correlates of stress, will contribute to a better understanding of this prevalent and common condition. This research is intended to take advantage of the temporal resolution afforded by ERPs to characterize the impact of psychosocial stress on early stages of processing associated with levels of sensory sensitivity, and on late stages of processing related with task-directed cognition. It could show if psychosocial stress dissimilarly affects different processing stages. Simultaneous measures of cortisol levels, heart rate, pupillary dilation response and electroencephalogram were recorded to characterize sensory sensitivity and task-directed cognition under different levels of stress. Participants resolved an auditory oddball task before and after a lab controlled acute psychosocial stress. This project provides novel information for understanding how acute psychosocial stress can modulate sensory processing in everyday life and will contribute to understanding the neurobiology of stress-cognitive disorders.
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    Impact of acute psychosocial stress on attentional control in humans. A study of evoked potentials and pupillary response
    (2023) Rojas Thomas, Felipe Eduardo; Artigas, C.; Wainstein, G.; Morales, Juan-Pablo; Arriagada, M.; Soto, D.; Dagnino-Subiabre, A.; Silva, J.; López, V.Rojas Thomas, Felipe Eduardo; Artigas, C.; Wainstein, G.; Morales, Juan-Pablo; Arriagada, M.; Soto, D.; Dagnino-Subiabre, A.; Silva, J.; López, V.
    Psychosocial stress has increased considerably in our modern lifestyle, affecting global mental health. Deficits in attentional control are cardinal features of stress disorders and pathological anxiety. Studies suggest that changes in the locus coeruleus-norepinephrine system could underlie the effects of stress on top-down attentional control. However, the impact of psychosocial stress on attentional processes and its underlying neural mechanisms are poorly understood. This study aims to investigate the effect of psychosocial stress on attentional processing and brain signatures. Evoked potentials and pupillary activity related to the oddball auditory paradigm were recorded before and after applying the Montreal Imaging Stress Task (MIST). Electrocardiogram (ECG), salivary cortisol, and subjective anxiety/stress levels were measured at different experimental periods. The control group experienced the same physical and cognitive effort but without the psychosocial stress component. The results showed that stressed subjects exhibited decreased P3a and P3b amplitude, pupil phasic response, and correct responses. On the other hand, they displayed an increase in Mismatch Negativity (MMN). N1 amplitude after MIST only decreased in the control group. We found that differences in P3b amplitude between the first and second oddball were significantly correlated with pupillary dilation and salivary cortisol levels. Our results suggest that under social-evaluative threat, basal activity of the coeruleus-norepinephrine system increases, enhancing alertness and decreasing voluntary attentional resources for the cognitive task. These findings contribute to understanding the neurobiological basis of attentional changes in pathologies associated with chronic psychosocial stress.
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    TOI-481 b and TOI-892 b : Two Long-period Hot Jupiters from the Transiting Exoplanet Survey Satellite
    (2020) Brahm, R.; Nielsen, L. D.; Wittenmyer, R. A.; Wang, S. H.; Rodríguez, J. E.; Espinoza, N.; Jones Fernández, Matías Ignacio; Rojas Thomas, Felipe Eduardo; Vanzi, Leonardo; Zapata, Abner; Jordán Colzani, Andrés Cristóbal; Henning, T.; Hobson, M.; Kossakowski, D.; Sarkis, P.; Schlecker, M.; Trifonov, T.; Shahaf, S.; Ricker, G.; Vanderspek, R.; Latham, D. W.; Seager, S.; Winn, J. N.; Jenkins, J. M.; Addison, B. C.; Bakos, G. A.; Bhatti, W.; Bayliss, D.; Berlind, P.; Bieryla, A.; Bouchy, F.; Bowler, B. P.; Briceno, C.; Brown, T. M.; Bryant, E. M.; Caldwell, D. A.; Charbonneau, D.; Collins, K. A.; Davis, A. B.; Esquerdo, G. A.; Fulton, B. J.; Guerrero, N. M.; Henze, C. E.; Hogan, A.; Horner, J; Huang, C. X.; Irwin, J.; Kane, S. R.; Kielkopf, J.; Mann, A. W.