Efecto de la activación adrenérgica insular en la neofobia gustatoria

Tesis (Magíster en Biotecnología)Este proyecto ha sido financiado por el Proyecto Fondecyt nº 1130724.La respuesta frente al estrés corresponde a la capacidad de un organismo de responder frente a un estímulo estresante y volver a su homeostasis. Esta respuesta es iniciada por la respuesta autonómica, mediada principalmente por actividad adrenérgica, la cual es modulada por catecolaminas, entre las cuales se destacan la norepinefrina (NE) a nivel de sistema nervioso central, y epinefrina (EPI) a nivel periférico. Se conoce una serie de áreas del cerebro asociadas a la respuesta al estrés, incluyendo la amígdala extendida, locus coeruleus, hipocampo, corteza prefrontal, entre varias. Una de las áreas del cerebro que ha sido propuesta muy recientemente como mediadora de la respuesta fisiológica frente al estrés es la corteza insular. Esta área recibe información emocional, visceral y gustatoria, y aún se desconoce por qué su actividad se ve alterada en trastornos de ansiedad. Es posible estudiar el rol de la ínsula en ansiedad usando conductas asociadas a gustos que sean sensibles al estrés y ansiedad, como la neofobia gustatoria. La neofobia gustatoria se describe como el miedo a un gusto nuevo, y es exacerbada en ambientes de estrés (hiponeofagia), siendo una medición de comportamiento tipo ansioso en animales. Este trabajo tuvo como objetivo evaluar si la actividad adrenérgica en la corteza insular media el aumento en neofobia gustatoria inducido por la presentación de un gusto nuevo en un ambiente de alta exaltación. La hipótesis que sustenta este trabajo es que la actividad adrenérgica en la corteza insular aumenta la neofobia gustatoria y modula el incremento de neofobia inducida por un ambiente de alta exaltación. Para probar la hipótesis se usó una combinación de microinyecciones de NE y propranolol intra insular y de inyecciones subcutáneas de EPI y propranolol, antes de la presentación del gusto en contextos con alta y baja exaltación. Los resultados obtenidos apoyan la hipótesis. Nuestros resultados proponen que la actividad adrenérgica periférica media la respuesta de neofobia gustatoria en ambientes de alta exaltación, efecto que es modulado por actividad adrenérgica en la corteza insular.The stress response is the ability of an organism to respond to a stressor and return to homeostasis. The first body's response to stress is the autonomic response, primarily mediated by adrenergic activity, which is modulated by catecholamines, among which norepinephrine is the predominant in the central nervous system, and epinephrine peripherally. Studies show that a dysregulation in the levels of these hormones may lead to psychiatric disorders including anxiety disorders. Among several brain areas involved in stress response, including the extended amygdala, locus coeruleus, hippocampus and prefrontal cortex, the insular cortex has been recently associated with physiological responses to stress. This area receives emotional, visceral and gustatory information, but it is still unknown why its activity is altered in anxiety disorders. It is possible to study the role of the insula in anxiety using behaviors associated with tastes which are sensitive to stress and anxiety, such as gustatory neophobia. The gustatory neophobia is the reluctance or fear to try a new taste, and is exacerbated in arousing contexts (also known as hyponeophagia), being a widely used to measure anxiety in animals. This study aimed to evaluate to which extent the adrenergic activity in the medial insular cortex increases gustatory neofobia induced by arousing novel contexts. The hypothesis behind this study is that adrenergic activity in the insular cortex increases taste neophobia and modulates the increment in neophobia induced by an arousing context. To test this hypothesis we used a combination of intrainsular microinjections of norepinephrine and propranolol and peripheral injections of epinephrine and propranolol before presentation of a novel taste in contexts of high and low arousal. Our results support the hypothesis and suggest that peripheral adrenergic activity mediates arousal induced increases in neophobia, effect that is mediated by adrenergifc activity in the insular cortex

Parasympathetic functions in children with sensory processing disorder.

The overall goal of this study was to determine if parasympathetic nervous system (PsNS) activity is a significant biomarker of sensory processing difficulties in children. Several studies have demonstrated that PsNS activity is an important regulator of reactivity in children, and thus, it is of interest to study whether PsNS activity is related to sensory reactivity in children who have a type of condition associated with sensory processing disorders termed sensory modulation dysfunction (SMD). If so, this will have important implications for understanding the mechanisms underlying sensory processing problems of children and for developing intervention strategies to address them. The primary aims of this project were: (1) to evaluate PsNS activity in children with SMD compared to typically developing (TYP) children, and (2) to determine if PsNS activity is a significant predictor of sensory behaviors and adaptive functions among children with SMD. We examine PsNS activity during the Sensory Challenge Protocol; which includes baseline, the administration of eight sequential stimuli in five sensory domains, recovery, and also evaluate response to a prolonged auditory stimulus. As a secondary aim we examined whether subgroups of children with specific physiological and behavioral sensory reactivity profiles can be identified. Results indicate that as a total group the children with severe SMD demonstrated a trend for low baseline PsNS activity, compared to TYP children, suggesting this may be a biomarker for SMD. In addition, children with SMD as a total group demonstrated significantly poorer adaptive behavior in the communication and daily living subdomains and in the overall Adaptive Behavior Composite of the Vineland than TYP children. Using latent class analysis, the subjects were grouped by severity and the severe SMD group had significantly lower PsNS activity at baseline, tones and prolonged auditory. These results provide preliminary evidence that children who demonstrate severe SMD may have physiological activity that is different from children without SMD, and that these physiological and behavioral manifestations of SMD may affect a child\u27s ability to engage in everyday social, communication, and daily living skills

How choice reveals and shapes expected hedonic outcome

Humans tend to modify their attitudes to align with past action. For example, after choosing between similarly valued alternatives, people rate the selected option as better than they originally did, and the rejected option as worse. However, it is unknown whether these modifications in evaluation reflect an underlying change in the physiological representation of a stimulus' expected hedonic value and our emotional response to it. Here, we addressed this question by combining participants' estimations of the pleasure they will derive from future events, with brain imaging data recorded while they imagined those events, both before, and after, choosing between them. Participants rated the selected alternatives as better after the decision stage relative to before, whereas discarded alternatives were valued less. Our functional magnetic resonance imaging findings reveal that postchoice changes in preference are tracked in caudate nucleus activity. Specifically, the difference in blood oxygenation level-dependent (BOLD) signal associated with the selected and rejected stimuli was enhanced after a decision was taken, reflecting the choice that had just been made. This finding suggests that the physiological representation of a stimulus' expected hedonic value is altered by a commitment to it. Furthermore, before any revaluation induced by the decision process, our data show that BOLD signal in this same region reflects the choices we are likely to make at a later time

Evidence for a Common Representation of Decision Values for Dissimilar Goods in Human Ventromedial Prefrontal Cortex

To make economic choices between goods, the brain needs to compute representations of their values. A great deal of research has been performed to determine the neural correlates of value representations in the human brain. However, it is still unknown whether there exists a region of the brain that commonly encodes decision values for different types of goods, or if, in contrast, the values of different types of goods are represented in distinct brain regions. We addressed this question by scanning subjects with functional magnetic resonance imaging while they made real purchasing decisions among different categories of goods (food, nonfood consumables, and monetary gambles). We found activity in a key brain region previously implicated in encoding goal-values: the ventromedial prefrontal cortex (vmPFC) was correlated with the subjects' value for each category of good. Moreover, we found a single area in vmPFC to be correlated with the subjects' valuations for all categories of goods. Our results provide evidence that the brain encodes a "common currency" that allows for a shared valuation for different categories of goods

The State of the Guitar in Kathmandu

The thriving guitar scene in Kathmandu is not well known outside of the country, and particularly not in the West. It has also not been the topic of much recent scholarship. It has been assumed that for Nepalis the guitar, as a foreign instrument, represents freedom and modernity; but, is this true, and what else might it signify to Nepali guitarists themselves? This article gives an overview of the history of the guitar in Kathmandu by drawing on both published scholarship and interviews conducted by the authors with twelve prominent Nepalese guitarists and guitar educators to establish the current state and future outlook of the guitar in Nepal. Findings suggest that, in addition to freedom and modernity, the guitar is connected with individualism, and is becoming naturalized and less foreign than it used to be

Objects and Types: A Tutorial

This paper is a tutorial explaining the concepts that surround abstract data types and object-oriented programming, and the relationships between these groups of concepts. These concepts include types (languagedefied, user-defied, abstract), instantiations, differences between operations and functions, overloading, objects, state, inheritance and, messages. Some of the these trems, e.g. "type", have been well defied. Many others are used in seveml contexts with multiple meanings. This paper is an attempt to identify consistent and meaningful definitions which are the most widely accepted

M2: An architectural system for computer design

The number of embedded computer systems has been growing rapidly as system costs have declined and capabilities have increased. The rationale behind design decisions for embedded systems is often informal and based on estimates of key values rather than actual measurements. Because of the small number of programs typically executed by an embedded processor, significant opportunities for optimization exist;M2 is an architectural system for computer design. It consists of language tools, architectural tools, and implementation tools. The language tools gather information about programs at compile time and at execution time. This information is used by the implementation tools to generate candidate processor implementations which are evaluated with the architectural tools. The evaluation involves comparing the size, speed, power, cost, and reliability of candidates to constraints set by the M2 user;An M2 design is based on actual program measurements and is documented so its derivation can be publicly considered. It is generated in less time and with fewer errors than manual methods;The M2 project is an extension of work being performed at Stanford University on a workbench for computer architects and of work being performed at the University of Southwestern Louisiana on plausibility-driven design