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Introduction: The cerebellum is a key structure for the control of movement. Here, we ask the question about its role in the learning and execution of sexual behavior in the male rat. The study focused on the fluctuation of cannabinoid receptors that are directly involved in the long-term depression, one of the neural mechanisms for learning and memory. Objective: To determine the density of CB1 type cannabinoid receptor at the cortex of the vermis cerebellum in male rats, during their training to acquire sexual experience. Materials and Methods: Sexually naive Wistar male rats were used. They received five training sessions, one each other day. At the end of each test, some rats were used to determine the levels of CB1 receptors by immunohistochemistry. Results: The vermis cerebellum has a basal density of cannabinoid receptors that showed a significant transitory reduction at the lobules 1, 6, 7 and 10. Once the subject became expert, the density returned to basal levels. Conclusions: The learning of sexual behavior requires the transitory reduction of CB1 receptors in four cerebellar lobules. It is proposed that it strengths synaptic connections through mechanisms of long-term depression and potentiation. Thus, the fluctuation of endocannabinoids at these cerebellar lobules at the vermis seems required for the establishment of neural circuits that allow the subject to get the experience for the appropriate execution of sexual behavior., Introducción: El cerebelo es una estructura clave para el control del movimiento. Aquí planteamos la pregunta sobre su papel en el aprendizaje y ejecución de la conducta sexual de la rata macho. El estudio se enfocó en las fluctuaciones de receptores a canabinoides, que están directamente implicados en la depresión a largo plazo, uno de los mecanismos neurales del aprendizaje y la memoria. Objetivos: Determinar la densidad de receptores a canabinoides tipo CB1 en la corteza del vermis cerebelar de ratas macho, durante su entrenamiento para la adquisición de experiencia sexual. Material y Métodos: Se utilizaron ratas macho Wistar, sin experiencia sexual. Se sometieron a cinco pruebas de entrenamiento, una cada tercer día. Al final de cada prueba, algunas ratas se utilizaron para determinar los niveles del receptor CB1 mediante inmunohistoquímica. Resultados: El vermis cerebelar presenta una densidad basal de receptores a canabinoides, que muestra una reducción significativa y temporal en los lóbulos 1, 6, 7 y 10. Una vez que el sujeto se vuelve experto, la densidad de los receptores regresa a su nivel basal. Conclusiones: El aprendizaje de la conducta sexual requiere de la reducción temporal de receptores CB1 en cuatro lóbulos cerebelares. Se propone que esto fortalece conexiones sinápticas a través de mecanismos de depresión y potenciación a largo plazo. Así, la fluctuación de endocanabinoides en estos lóbulos del vermis cerebelar parece indispensable para los procesos de maduración de circuitos neurales que le permiten a un sujeto adquirir la experiencia para la ejecución apropiada de la conducta sexual.

Introduction: The cerebellum is a key structure for the control of movement. Here, we ask the question about its role in the learning and execution of sexual behavior in the male rat. The study focused on the fluctuation of cannabinoid receptors that are directly involved in the long-term depression, one of the neural mechanisms for learning and memory. Objective: To determine the density of CB1 type cannabinoid receptor at the cortex of the vermis cerebellum in male rats, during their training to acquire sexual experience. Materials and Methods: Sexually naive Wistar male rats were used. They received five training sessions, one each other day. At the end of each test, some rats were used to determine the levels of CB1 receptors by immunohistochemistry. Results: The vermis cerebellum has a basal density of cannabinoid receptors that showed a significant transitory reduction at the lobules 1, 6, 7 and 10. Once the subject became expert, the density returned to basal levels. Conclusions: The learning of sexual behavior requires the transitory reduction of CB1 receptors in four cerebellar lobules. It is proposed that it strengths synaptic connections through mechanisms of long-term depression and potentiation. Thus, the fluctuation of endocannabinoids at these cerebellar lobules at the vermis seems required for the establishment of neural circuits that allow the subject to get the experience for the appropriate execution of sexual behavior., Introducción: El cerebelo es una estructura clave para el control del movimiento. Aquí planteamos la pregunta sobre su papel en el aprendizaje y ejecución de la conducta sexual de la rata macho. El estudio se enfocó en las fluctuaciones de receptores a canabinoides, que están directamente implicados en la depresión a largo plazo, uno de los mecanismos neurales del aprendizaje y la memoria. Objetivos: Determinar la densidad de receptores a canabinoides tipo CB1 en la corteza del vermis cerebelar de ratas macho, durante su entrenamiento para la adquisición de experiencia sexual. Material y Métodos: Se utilizaron ratas macho Wistar, sin experiencia sexual. Se sometieron a cinco pruebas de entrenamiento, una cada tercer día. Al final de cada prueba, algunas ratas se utilizaron para determinar los niveles del receptor CB1 mediante inmunohistoquímica. Resultados: El vermis cerebelar presenta una densidad basal de receptores a canabinoides, que muestra una reducción significativa y temporal en los lóbulos 1, 6, 7 y 10. Una vez que el sujeto se vuelve experto, la densidad de los receptores regresa a su nivel basal. Conclusiones: El aprendizaje de la conducta sexual requiere de la reducción temporal de receptores CB1 en cuatro lóbulos cerebelares. Se propone que esto fortalece conexiones sinápticas a través de mecanismos de depresión y potenciación a largo plazo. Así, la fluctuación de endocanabinoides en estos lóbulos del vermis cerebelar parece indispensable para los procesos de maduración de circuitos neurales que le permiten a un sujeto adquirir la experiencia para la ejecución apropiada de la conducta sexual.

Introduction: The cerebellum is a key structure for the control of movement. Here, we ask the question about its role in the learning and execution of sexual behavior in the male rat. The study focused on the fluctuation of cannabinoid receptors that are directly involved in the long-term depression, one of the neural mechanisms for learning and memory. Objective: To determine the density of CB1 type cannabinoid receptor at the cortex of the vermis cerebellum in male rats, during their training to acquire sexual experience. Materials and Methods: Sexually naive Wistar male rats were used. They received five training sessions, one each other day. At the end of each test, some rats were used to determine the levels of CB1 receptors by immunohistochemistry. Results: The vermis cerebellum has a basal density of cannabinoid receptors that showed a significant transitory reduction at the lobules 1, 6, 7 and 10. Once the subject became expert, the density returned to basal levels. Conclusions: The learning of sexual behavior requires the transitory reduction of CB1 receptors in four cerebellar lobules. It is proposed that it strengths synaptic connections through mechanisms of long-term depression and potentiation. Thus, the fluctuation of endocannabinoids at these cerebellar lobules at the vermis seems required for the establishment of neural circuits that allow the subject to get the experience for the appropriate execution of sexual behavior., Introducción: El cerebelo es una estructura clave para el control del movimiento. Aquí planteamos la pregunta sobre su papel en el aprendizaje y ejecución de la conducta sexual de la rata macho. El estudio se enfocó en las fluctuaciones de receptores a canabinoides, que están directamente implicados en la depresión a largo plazo, uno de los mecanismos neurales del aprendizaje y la memoria. Objetivos: Determinar la densidad de receptores a canabinoides tipo CB1 en la corteza del vermis cerebelar de ratas macho, durante su entrenamiento para la adquisición de experiencia sexual. Material y Métodos: Se utilizaron ratas macho Wistar, sin experiencia sexual. Se sometieron a cinco pruebas de entrenamiento, una cada tercer día. Al final de cada prueba, algunas ratas se utilizaron para determinar los niveles del receptor CB1 mediante inmunohistoquímica. Resultados: El vermis cerebelar presenta una densidad basal de receptores a canabinoides, que muestra una reducción significativa y temporal en los lóbulos 1, 6, 7 y 10. Una vez que el sujeto se vuelve experto, la densidad de los receptores regresa a su nivel basal. Conclusiones: El aprendizaje de la conducta sexual requiere de la reducción temporal de receptores CB1 en cuatro lóbulos cerebelares. Se propone que esto fortalece conexiones sinápticas a través de mecanismos de depresión y potenciación a largo plazo. Así, la fluctuación de endocanabinoides en estos lóbulos del vermis cerebelar parece indispensable para los procesos de maduración de circuitos neurales que le permiten a un sujeto adquirir la experiencia para la ejecución apropiada de la conducta sexual.

The distribution of vestibular neurons projecting to the flocculus and the nodulus and uvula of the caudal vermis (Larsell's lobules X and IX) was investigated with retrograde axonal transport of horseradish peroxidase and the fluorescent tracers Fast Blue, Nuclear Yellow and Diamidino Yellow. The presence of collateral axons innervating the flocculus on one hand and the nodulus and uvula on the other was studied with simultaneous injection of the different fluorescent tracers. The distribution of vestibular neurons projecting to either flocculus or caudal vermis is rather similar and has a bilateral symmetry. The projection from the magnocellular medial vestibular nucleus is very sparse, while that from the lateral vestibular nucleus is absent. The majority of labeled neurons was found in the medial, superior, and descending vestibular nuclei, in that order. Double labeled neurons were distributed in a similar way as the single labeled ones. Labeled neurons project to the nodulus and uvula, the flocculus, and to both parts of the cerebellum simultaneously in a ratio of 12:4:1. Five different populations of vestibulocerebellar neurons can be distinguished on the basis of their projection to the: (1) ipsilateral flocculus, (2) contralateral flocculus, (3) ipsilateral flocculus and nodulus/uvula, (4) contralateral flocculus and nodulus/uvula, and (5) nodulus/uvula.

Unexpected findings were obtained regarding (1) the role of nodulus and uvula of the vestibulocerebellum in vestibular-induced vomiting and (2) the existence of a readily identifiable, discretely localized 'vomiting center'. Sinusoidal electrical stimulation of the vestibular labyrinths of decerebrate cats could produce vomiting and related activity similar to that observed motion sickness. These symptoms occurred in animals with lesions of the posterior cerebellar vermis that included the nodulus and uvula, indicating, by analogy, that these structures are not essential for the development of many symptoms of motion sickness in intact animals. In a second series of experiments, electrical stimulation of the brainstem was used in an attempt to localize a vomiting center to a restricted anatomical region. Vomiting proved difficult to produce; a vomiting center, stimulation of which evoked readily reproducible results, could not be identified., This article is from 'The Aerospace Medical Panel Symposium on Motion Sickness: Mechanisms, Prediction, Prevention, and Treatment Held at Williamsburg, Virginia on 3-4 May 1984,' AD-A152 548, P21-1-21-5.