Browsing by Author "Lopez, Vladimir"

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    Allostatic-interoceptive anticipation of social rejection
    (2023) Migeot, Joaquin; Hesse, Eugenia; Fittipaldi, Sol; Mejia, Jhonny; Fraile, Matias; Garcia, Adolfo M.; Garcia, Maria del Carmen; Ortega, Rodrigo; Lawlor, Brian; Lopez, Vladimir; Ibanez, Agustin
    Anticipating social stress evokes strong reactions in the organism, including interoceptive modulations. However, evidence for this claim comes from behavioral studies, often with inconsistent results, and relates almost solely to the reactive and recovery phase of social stress exposure. Here, we adopted an allostatic-interoceptive predictive coding framework to study interoceptive and exteroceptive anticipatory brain responses using a social rejection task. We analyzed the heart -evoked potential (HEP) and task-related oscillatory activity of 58 adolescents via scalp EEG, and 385 human intracranial recordings of three patients with intractable epilepsy. We found that anticipatory interoceptive signals increased in the face of unexpected social outcomes, reflected in larger negative HEP modulations. Such signals emerged from key brain allostatic-interoceptive network hubs, as shown by intracranial recordings. Exteroceptive signals were characterized by early activity between 1-15 Hz across conditions, and modulated by the probabilistic anticipation of reward-related outcomes, observed over distributed brain regions. Our findings suggest that the anticipation of a social outcome is characterized by allostatic-interoceptive modulations that prepare the organism for possible rejection. These results inform our understanding of interoceptive processing and constrain neurobiological models of social stress.
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    Another in need enhances prosociality and modulates frontal theta oscillations in young adults
    (2023) Lavin, Claudio; Soto-Icaza, Patricia; Lopez, Vladimir; Billeke, Pablo
    IntroductionDecision-making is a process that can be strongly affected by social factors. Evidence has shown how people deviate from traditional rational-choice predictions under different levels of social interactions. The emergence of prosocial decision-making, defined as any action that is addressed to benefit another individual even at the expense of personal benefits, has been reported as an example of such social influence. Furthermore, brain evidence has shown the involvement of structures such as the prefrontal cortex, anterior insula, and midcingulate cortex during decision settings in which a decision maker interacts with others under physical pain or distress or while being observed by others. MethodsUsing a slightly modified version of the dictator game and EEG recordings, we tested the hypothesis that the inclusion of another person into the decision setting increases prosocial decisions in young adults and that this increase is higher when the other person is associated with others in need. At the brain level, we hypothesized that the increase in prosocial decisions correlates with frontal theta activity. Results and DiscussionThe results showed that including another person in the decision, setting increased prosocial behavior only when this presence was associated with someone in need. This effect was associated with an increase in frontocentral theta-oscillatory activity. These results suggest that the presence of someone in need enhances empathy concerns and norm compliance, raising the participants' prosocial decision-making.
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    Arousal dysregulation and executive dysfunction in attention deficit hyperactivity disorder (ADHD)
    (2024) Isaac, Valeria; Lopez, Vladimir; Escobar, Maria Josefina
    Attention deficit/hyperactivity disorder (ADHD) is a heterogeneous neurodevelopmental condition, that continues to have an elusive etiological background. A number of extant models and theories have historically intended to explain the many factors contributing to ADHD behaviors. One of the most accepted hypotheses has been the executive dysfunction theory associating reduction in executive control to abnormalities in structure and operational dysfunction of dopaminergic signaling networks. Nevertheless, executive functions are not always impaired in ADHD, and the literature describes other symptoms commonly reported suggesting individuals with ADHD would appear to suffer from a more general deficit. Another existing line of research, that has gained much attention recently, establishes that ADHD would have dysregulated states of brain arousal that would account for its commonly observed cognitive deficits and behavioral symptoms, described as the state regulation theory, which has now included measures of autonomic function. This article describes some important aspects that compose and challenge these two most influential theoretical constructs, executive dysfunction and state-regulation, based on their empirical evidence, implying the need to reevaluate the norms used to classify individuals and establish ADHD diagnosis. Large number of controversial results continue to exist within the study of ADHD biological and/or performance markers, possibly due to such heterogeneity and variability within the same diagnosis. The need to resolve these issues and establish newly revised diagnostic criteria for ADHD is critical, as therapeutic success depends on having accurately identified underlying neurophysiological factors in order to appropriately address them in treatment.
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    Beta Oscillations Distinguish Between Two Forms of Mental Imagery While Gamma and Theta Activity Reflects Auditory Attention
    (2018) Villena González, Mario; Palacios García, Ismael José; Rodriguez, Eugenio; Lopez, Vladimir
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    Electrophysiological evidence of different interpretative strategies in irony comprehension
    (2007) Cornejo, Carlos; Simonetti, Franco; Aldunate, Nerea; Ibanez, Agustin; Lopez, Vladimir; Melloni, Lucia
    We explore the hypothesis that induction of holistic or analytic strategies influences comprehension and processing of highly contextualized expressions of ordinary language, such as irony. Twenty undergraduate students were asked to categorize as coherent or incoherent a group of sentences. Each sentence completed a previous story, so that they could be ironical, literal or nonsensical endings. Participants were asked to evaluate whether each sentence was coherent or incoherent. Half of them were initially instructed to consider whether the sentences made sense (holistic condition); the other half were instructed to consider whether the sentences were congruent or incongruent (analytic condition). Behavioral responses and Event Related Potentials were registered during the experiment. Both behavioral and electrophysiological results allow clearly distinguishing between the holistic and the analytic strategies. The fact that the same set of stimuli elicits different ERP waveforms, depending on the strategy with which they are analyzed, suggests that different cognitive processes and different areas of the brain are operating in each case.
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    ERPs and contextual semantic discrimination: Degrees of congruence in wakefulness and sleep
    (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2006) Ibanez, Agustin; Lopez, Vladimir; Cornejo, Carlos
    This study explores whether the brain can discriminate degrees of semantic congruency during wakefulness and sleep. Experiment 1 was conducted during wakefulness to test degrees of congruency by means of N400 amplitude. In Experiment 2, the same paradigm was applied to a different group of participants during natural night sleep. Stimuli were 108 sentences (definitions with two attributes) with four possible degrees of congruence as ending targets. In both studies, the amplitude of N400-like effect showed modulation according to the degree of congruency. The results indicate that the brain can accomplish sentential semantic discriminations not only in wakefulness but also in sleep. (c) 2006 Elsevier Inc. All rights reserved.
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    Gesture and metaphor comprehension: Electrophysiological evidence of cross-modal coordination by audiovisual stimulation
    (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2009) Cornejo, Carlos; Simonetti, Franco; Ibanez, Agustin; Aldunate, Nerea; Ceric, Francisco; Lopez, Vladimir; Nunez, Rafael E.
    In recent years, studies have suggested that gestures influence comprehension of linguistic expressions, for example, eliciting an N400 component in response to a speech/gesture mismatch. In this paper, we investigate the role of gestural information in the understanding of metaphors. Event related potentials (ERPs) were recorded while participants viewed video clips of an actor uttering metaphorical expressions and producing bodily gestures that were congruent or incongruent with the metaphorical meaning of such expressions. This modality of stimuli presentation allows a more ecological approach to meaning integration. When ERPs were calculated using gesture stroke as time-lock event, gesture incongruity with metaphorical expression modulated the amplitude of the N400 and of the late positive complex (LPC). This suggests that gestural and speech information are combined online to make sense of the interlocutor's linguistic production in an early stage of metaphor comprehension. Our data favor the idea that meaning construction is globally integrative and highly context-sensitive. (C) 2008 Elsevier Inc. All rights reserved.
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    Humor Improves Women's but Impairs Men's Iowa Gambling Task Performance
    (2019) Flores-Torres, Jorge; Gomez-Perez, Lydia; McRae, Kateri; Lopez, Vladimir; Rubio, Ivan; Rodriguez, Eugenio
    The Iowa Gambling Task (IGT) is a popular method for examining real-life decision-making. Research has shown gender related differences in performance, in that men consistently outperform women. It has been suggested that these performance differences are related to decreased emotional control in women compared to men. Given the likely role of emotion in these gender differences, in the present study, we examine the effect of a humor induction on IGT performance and whether the effect of humor is moderated by gender. IGT performance and parameters from the Expectancy Valence Model (EVM) were measured in 68 university students (34 men; mean age 22.02, SD = 4.3 and 34 women; mean age 22.3, SD = 4.1) during a 100 trial-IGT task. Participants were exposed to a brief video before each of the IGT decisions available; one half of the samples (17 men and 17 women) was exposed to 100 humor videos, while the other half was exposed to 100 non-humor videos during the task. We observed a significant interaction between gender and humor, such that under humor, women's performance during the last block (trials 80-100) improved (compared to women under non-humor), whereas men's performance during the last block was worse (compared to men under non-humor). Consistent with previous work, under non-humor, men outperformed women in the last block. Lastly, our EVM results show that humor impacts the learning mechanisms of decision-making differently in men and women. Humor impaired men's ability to acquire knowledge about the payoff structure of the decks, and as a consequence, they were stuck in suboptimal performance. On the other hand, humor facilitated women's ability to explore and to learn from experience, improving performance. These findings deepen our understanding of the mechanisms underlying IGT decision-making and differential effects of humor in men and women.
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    Influence of violent contexts on facial reactions elicited by angry and neutral faces
    (2020) Aldunate, Nerea; Lopez, Vladimir; Barramuno, Mauricio; Galvez-Garcia, German
    This study focuses on determining whether violent contexts influence the perception of aggressiveness in faces analysing spontaneouscorrugator superciliiactivity. Participants viewed pictures of neutral and angry faces preceded by a contextual sentence describing either violent or neutral actions. They were instructed to judge each face according to whether it was aggressive or non-aggressive. Results show a higher level of perceived aggressiveness for neutral faces preceded by violent contexts, accompanied by longer reaction times, and a significant increase of corrugator activity. Angry faces preceded by neutral contexts were judged as less aggressive and elicited less corrugator activity. In conclusion, our results provide evidence that facial reactions and aggressiveness judgment for faces are context-dependent. With this work, we contribute to the view that contextual cues guide the face's emotional meaning, under top-down processing.
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    Methodological considerations related to sleep paradigm using event related potentials
    (SOC BIOLGIA CHILE, 2008) Ibanez, Agustin M.; San Martin, Rene; Hurtado, Esteban; Lopez, Vladimir
    In the last few decades, several works on event related potentials (ERPs hereafter) during sleep have been reported. In Spite of numerous Studies, clear methodological rules for this kind Of Study are often missing, making it difficult to valorize the scope of these results. We propose here a description of methodological aspects to be considered when evaluating ERPs during sleep. The use of Rechtschaffen and Kales rules versus automatic methods is assessed, Plus the additional use of certain quantitative rneasures. Additionally, two topics are discussed which Must be controlled in ERPs sleep studies: the First Night Effect, and sleep disturbances. Better control of experimental paradigms is relevant for the growth of (lie neuroscience of sleep.
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    Neural Processing of Emotional Facial and Semantic Expressions in Euthymic Bipolar Disorder (BD) and Its Association with Theory of Mind (ToM)
    (2012) Ibanez, Agustin; Urquina, Hugo; Petroni, Agustin; Baez, Sandra; Lopez, Vladimir; do Nascimento, Micaela; Herrera, Eduar; Guex, Raphael; Hurtado, Esteban; Blenkmann, Alejandro; Beltrachini, Leandro; Gelormini, Carlos; Sigman, Mariano; Lischinsky, Alicia; Torralva, Teresa; Torrente, Fernando; Cetkovich, Marcelo; Manes, Facundo
    Background: Adults with bipolar disorder (BD) have cognitive impairments that affect face processing and social cognition. However, it remains unknown whether these deficits in euthymic BD have impaired brain markers of emotional processing.
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    The medial olivocochlear reflex strength is modulated during a visual working memory task
    (2021) Marcenaro, Bruno; Leiva, Alexis; Dragicevic, Constantino; Lopez, Vladimir; Delano, Paul H.
    Top-down modulation of sensory responses to distracting stimuli by selective attention has been proposed as an important mechanism by which our brain can maintain relevant information during working memory tasks. Previous works in visual working memory (VWM) have reported modulation of neural responses to distracting sounds at different levels of the central auditory pathways. Whether these modulations occur also at the level of the auditory receptor is unknown. Here, we hypothesize that cochlear responses to irrelevant auditory stimuli can be modulated by the medial olivocochlear system during VWM. Twenty-one subjects (13 males, mean age 25.3 yr) with normal hearing performed a visual change detection task with different VWM load conditions (high load = 4 visual objects; low load = 2 visual objects). Auditory stimuli were presented as distractors and allowed the measurement of distortion product otoacoustic emissions (DPOAEs) and scalp auditory evoked potentials. In addition, the medial olivocochlear reflex strength was evaluated by adding contralateral acoustic stimulation. We found larger contralateral acoustic suppression of DPOAEs during the visual working memory period (n = 21) compared with control experiments (n = 10), in which individuals were passively exposed to the same experimental conditions. These results show that during the visual working memory period there is a modulation of the medial olivocochlear reflex strength, suggesting a possible common mechanism for top-down filtering of auditory responses during cognitive processes.
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    Voluntary modulations of attention in a semantic auditory-visual matching Task: an ERP study
    (SOC BIOLGIA CHILE, 2008) Ortega, Rodrigo; Lopez, Vladimir; Aboitiz, Francisco
    The present study explores the neural correlates of voluntary modulations of attention in an auditory-visual matching task. Visual stimuli (a female or a male face) were preceded in close temporal proximity by auditory stimuli consisting of the Spanish word for "man" and "woman" ("hombre" or "mujer"). In 80% of the trials the gender of the two stimuli coincided. Participants were asked to mentally count the specific instances in which a female face appeared after hearing the word "man" (10 % of the trials). Our results show attention-related amplitude modulation of the early visual ERP components NI and anterior P2, but also amplitude modulations of (i) the N270 potential usually associated with conflict detection, (ii) a P300 wave related to infrequency, and (iii) an N400 potential related to semantic incongruence. The elicitation of these latter components varied according to task manipulations, evidencing the role of voluntary allocation of attention in fine-tuning cognitive processing, which includes basic processes like detection of infrequency or semantic incongruity often considered to be volition-independent.