Publication: Procesamiento de la información en los núcleos principal e interpolar del complejo sensorial del trigémino de la rata
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2018-01-09
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Universidad Complutense de Madrid
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Abstract
La información sensorial proveniente de las vibrisas alcanza la corteza somatosensorial a través de dos vías paralelas: lemniscal y paralemniscal. Varios estudios han puesto de manifiesto que este procesamiento en paralelo no es redundante sino que cada vía procesa diferentes aspectos de la información entrante. Ambas vías se originan a nivel del tronco del encéfalo en los núcleos del complejo sensorial del trigémino Principal (la vía lemniscal) y espinal Interpolar (la vía paralemniscal). El objetivo de la presente tesis fue determinar si ya en estos núcleos subtalámicos que originan cada una de las dos vías se produce un procesamiento diferencial de la información proveniente de las vibrisas. Desde principios del siglo XX se conoce la importancia que suponen los bigotes para los roedores, por ser una entrada sensorial altamente desarrollada (Vincent 1912). El órgano de los bigotes-vibrisas de la rata está ubicado en su hocico y está formado por una matriz de unos 30 bigotes largos que el animal mueve para localizar e identificar objetos, diferenciar texturas y propiedades del movimiento de los objetos (Guic-Robles, Jenkins, and Bravo 1992; Harvey, Bermejo, and Zeigler 2001), ya que obtienen poca información visual del medio que les rodea. Es un órgano que por sus características sensoriales y perceptivas y por su funcionamiento es equiparable a las yemas de los dedos de los primates (Lichtenstien, Carvell, and Simons 1990), de ahí la importancia de conocer la fisiología de los núcleos involucrados en el procesamiento de la información extraída del medio. Cada vibrisa está anclada por su base a lo que se conoce como complejo folicular o folículo vibrisal, formado por una serie de receptores altamente vascularizados o mecanorreceptores aferrados a terminaciones musculares que se activan por el movimiento y/o la vibración del bigote, transduciendo esta señal a código neuronal mediante potenciales de acción. La información táctil obtenida por las vibrisas se proyecta a través del nervio infraorbital atravesando el ganglio de Gasser (Vg) hasta los núcleos del Complejo Sensorial del Trigémino, CST, en el tronco encefálico (Waite and Tracey 1995) que constituye la primera estación de relevo de este tipo de información. Una vez aquí, esta información se bifurca pues alcanza la corteza somatosensorial primaria (S1) por medio de dos vías, la lemniscal, que hace relevo en el núcleo ventral posteromedial del tálamo (VPm), y la paralemniscal, alcanzando el núcleo posterior medial del tálamo (Pom) (Diamond, Armstrong-James, and Ebner 1992) (Figura 1)...
Sensory information gathered from vibrissae reaches the somatosensory cortex through two parallel pathways: lemniscal and paralemniscal. The data from several studies indicate that this parallel processing is not redundant since each of the given pathways processes different aspects of the incoming information. Both pathways find their origin at the level of the brainstem in the nuclei of the Trigeminal Sensory Complex, the Principal Sensory nucleus -the lemniscal pathway- and the Spinal Interpolar nucleus -the paralemniscal pathway-. The present Thesis aims to determine to which extend vibrissae information is processed differentially at these subthalamic nuclei. Since the beginning of the 20th Century the importance of whiskers for rodents has been thought as a highly developed sensory input (Vincent 1912). The somatosenrory organ of the rat (whiskers or vibrissae) is located on its snout and is composed by a matrix of about 30 long whiskers which are moved by the animal in order to locate, to identify objects and to differentiate textures and properties of the movement of objects (Guic-Robles, Jenkins, and Bravo 1992; Harvey, Bermejo, and Zeigler 2001) since the visual input obtained from their surroundings is quite reduced. The somatosensory organ in rats resembles to the fingertips of primates due to its sensorial and perceptive features (Lichtenstein, Carvell, and Simons 1990). Therefore the importance of deep comprehension of the physiology of the nuclei involved in the information that rodents gather from their environments. Each vibrissa is attached to a follicular complex or vibrissal follicle, formed by a series of highly vascularized receptors or mechanoreceptors joint to muscular endings that are activated rather by the movement and vibration of whiskers, converting this signal into a neuronal code. The tactile information gathered from vibrissae is projected by the infraorbital nerve through the ganglion of Gasser (Vg) towards the nuclei of the Trigeminal Sensory Complex (CST) in the brainstem (Waite and Tracey 1995). Once there, the data splits in order to reach the primary somatosensory cortex (S1) by two possible pathways: the lemniscal, which relays in the posteromedial ventral nucleus of the thalamus (VPm), and the paralemniscal one that meets finally the medial posterior nucleus of the thalamus (Pom) (Diamond and Armstrong-James 1992). If the two nuclei play an active role in differential information processing their neurons could display differences in their electrophysiological activity, more probably under stimulation of the whiskers...
Sensory information gathered from vibrissae reaches the somatosensory cortex through two parallel pathways: lemniscal and paralemniscal. The data from several studies indicate that this parallel processing is not redundant since each of the given pathways processes different aspects of the incoming information. Both pathways find their origin at the level of the brainstem in the nuclei of the Trigeminal Sensory Complex, the Principal Sensory nucleus -the lemniscal pathway- and the Spinal Interpolar nucleus -the paralemniscal pathway-. The present Thesis aims to determine to which extend vibrissae information is processed differentially at these subthalamic nuclei. Since the beginning of the 20th Century the importance of whiskers for rodents has been thought as a highly developed sensory input (Vincent 1912). The somatosenrory organ of the rat (whiskers or vibrissae) is located on its snout and is composed by a matrix of about 30 long whiskers which are moved by the animal in order to locate, to identify objects and to differentiate textures and properties of the movement of objects (Guic-Robles, Jenkins, and Bravo 1992; Harvey, Bermejo, and Zeigler 2001) since the visual input obtained from their surroundings is quite reduced. The somatosensory organ in rats resembles to the fingertips of primates due to its sensorial and perceptive features (Lichtenstein, Carvell, and Simons 1990). Therefore the importance of deep comprehension of the physiology of the nuclei involved in the information that rodents gather from their environments. Each vibrissa is attached to a follicular complex or vibrissal follicle, formed by a series of highly vascularized receptors or mechanoreceptors joint to muscular endings that are activated rather by the movement and vibration of whiskers, converting this signal into a neuronal code. The tactile information gathered from vibrissae is projected by the infraorbital nerve through the ganglion of Gasser (Vg) towards the nuclei of the Trigeminal Sensory Complex (CST) in the brainstem (Waite and Tracey 1995). Once there, the data splits in order to reach the primary somatosensory cortex (S1) by two possible pathways: the lemniscal, which relays in the posteromedial ventral nucleus of the thalamus (VPm), and the paralemniscal one that meets finally the medial posterior nucleus of the thalamus (Pom) (Diamond and Armstrong-James 1992). If the two nuclei play an active role in differential information processing their neurons could display differences in their electrophysiological activity, more probably under stimulation of the whiskers...
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Tesis inédita de la Universidad Complutense de Madrid, Facultad de Óptica y Optometría, Departamento de Matemática Aplicada (Biomatemática), leída el 05/06/2017