Browsing by Author "Rodríguez, María"

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    A role for the interoceptive insular cortex in the consolidation of learned fear
    (Elsevier B.V., 2016) Casanova, José; Madrid, Carlos; Contreras, Marco; Rodríguez, María; Vásquez, Mónica; Torrealba, Fernando
    A growing body of evidence suggests that learned fear may be related to the function of the interoceptive insular cortex. Using an auditory fear conditioning paradigm in rats, we show that the inactivation of the posterior insular cortex (pIC), the target of the interoceptive thalamus, prior to training produced a marked reduction in fear expression tested 24h later. Accordingly, post-training anisomycin infused immediately, but not 6h after, also reduced fear expression tested the following day, supporting a role for the pIC in consolidation of fear memory. The long-term (ca. a week) and reversible inactivation of the pIC with the sodium channel blocker neosaxitoxin, immediately after fear memory reactivation induced a progressive decrease in the behavioral expression of conditioned fear. In turn, we observed that fear memory reactivation is accompanied by an enhanced expression of Fos and Zif268, early genes involved in neural activity and plasticity. Taken together these data indicate that the pIC is involved in the regulation of fear memories.
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    An Inescapable Cat Odor Exposure Protocol for Studying Innate and Contextual Threat Conditioning in Rats
    (2021) Rodríguez, María; Contreras, Marco; Domic-Siede, Marco; Ceric, Francisco; Torrealba, Fernando
    Animals respond to threatening situations by exhibiting a number of defensive behaviors, including avoidance, freezing, and risk assessment. An animal model with an ethological approach offers a deeper insight into the biological mechanisms underlying threat responses. This paper describes a methodology to measure defensive behaviors toward both innate and learned aversive stimuli in rats. Animals were individually exposed to predator odor in an inescapable chamber to elicit a measurable, sustained, defensive state. The experimental design involved placing a rat in a familiar chamber for 10 min followed by exposure to cat odor for another 10 min in the same context. The next day, the rats were re-exposed for 10 min to the same context chamber where cat odor exposure occurred. Sessions were video-recorded and defensive behaviors were assessed on both days. The behavioral test was coupled with reversible functional inactivation and c-Fos immunohistochemistry techniques to determine the role of the interoceptive cortex in threat responses. Rats exposed to cat odor on the first day and re-exposed to the context chamber on the second day displayed higher levels of defensive behaviors, and that cat odor elicited a robust increase in the neural activity of the interoceptive cortex. Moreover, muscimol inactivation of the interoceptive cortex reduced the expression of defensive behaviors in response to cat odor and impaired contextual threat memory. These results show that this behavioral assay is a useful tool for studying neural mechanisms of defensive behaviors and may offer insight into mechanisms that mediate fear in humans and its related disorders.
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    Interoceptive Insular Cortex Mediates Both Innate Fear and Contextual Threat Conditioning to Predator Odor
    (2019) Rodríguez, María; Ceric, Francisco; Murgas, Paola; Harland, Bruce; Torrealba, Fernando; Contreras, Marco
    The insular cortex (IC), among other brain regions, becomes active when humans experience fear or anxiety. However, few experimental studies in rats have implicated the IC in threat responses. We have recently reported that inactivation of the primary interoceptive cortex (pIC) during pre-training, or the intra-pIC blockade of protein synthesis immediately after training, impaired the consolidation of auditory fear conditioning. The present study was designed to investigate the role of the pIC in innate and learned defensive responses to predator odor. Freezing behavior was elicited by single or repetitive exposures to a collar that had been worn by a domestic cat. Sessions were video-recorded and later scored by video observation. We found that muscimol inactivation of the pIC reduced the expression of freezing reaction in response to a single or repeated exposure to cat odor. We also found that pIC inactivation with muscimol impaired conditioning of fear to the context in which rats were exposed to cat odor. Furthermore, neosaxitoxin inactivation of the pIC resulted in a prolonged and robust reduction in freezing response in subsequent re-exposures to cat odor. In addition, freezing behavior significantly correlated with the neural activity of the IC. The present results suggest that the IC is involved in the expression of both innate and learned fear responses to predator odor.
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    Perfil Comunicativo en niños con Síndrome de Down mínimamente verbales de 8 a 15 años de edad en la Región Metropolitana el año 2020
    (2020) Castañeda, María; Cuadra, Margarita; Rodríguez, María
    Introducción: El Síndrome de Down presenta diferentes alteraciones asociadas, como un retraso en el desarrollo del lenguaje, siendo el lenguaje expresivo el más afectado. La prevalencia del SD es de 1 cada 1.000 - 1.100 recién nacidos vivos a nivel mundial. Conocer el tipo de perfil comunicativo de los niños con SD permitirá complementar la intervención fonoaudiológica con un Sistema de Comunicación Aumentativo Alternativo. Objetivo: Conocer el perfil comunicativo de los niños y niñas con Síndrome de Down mínimamente verbales de 8 a 15 años de edad de la Región Metropolitana durante el año 2020. Metodología: El estudio es de tipo cuantitativo, observacional y transversal. La población corresponde a niños y niñas con SD mínimamente verbales entre 8 y 15 años de edad de la RM. Se utilizó una encuesta creada por las investigadoras, que tenían preguntas sociodemográficas y preguntas relacionadas a los tipos de perfiles comunicativos. Resultados: Con un 40% el perfil comunicativo predominante es el Simbólico Emergente. Discusión: Los resultados obtenidos en el estudio relacionados a las variables sociodemográficas, son muy heterogéneos debido a la modalidad online. Las variables del tipo de perfil comunicativo lingüísticas y cognitivas concuerdan con lo que plantean estudios anteriores, mientras que las sociales y pragmáticas no concuerdan. Conclusión: En este estudio se visualiza la importancia de la intervención fonoaudiológica en la población de niños con SD mínimamente verbales, ya que favorece al pronóstico del menor en cuanto a sus habilidades comunicativas.

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