Sensorimotor gating impairments induced by MK-801 treatment may be reduced by tolerance effect and by familiarization in monkeys.

Dizocilpine (MK-801) is a non-competitive NMDA antagonist that induces schizophreniclike effects. It is therefore widely used in experimental models of schizophrenia including prepulse inhibition (PPI) impairments in rodents. Nevertheless, MK-801 has never been tested in monkeys on a PPI paradigm. In order to evaluate MK-801 effects on monkeys' PPI, we tested eight capuchin monkeys (Sapajus spp.) using three different doses of MK-801 (0.01; 0.02; 0.03 mg/kg). Results show PPI impairment in acute administration of the highest dose (0.03 mg/kg). PPI impairment induced by MK-801 was reversed by re-exposure to the PPI test throughout treatment trials, in contrast with rodent studies. These results indicate that tolerance effect and familiarization with PPI test may reduce the sensorimotor gating deficits induced by MK-801 in monkeys, suggesting a drug-training interaction.

Whole-body prepulse inhibition protocol to test sensorymotor gating mechanisms in monkeys.

Prepulse inhibition (PPI) is the decrease of startle reflex amplitude when a slight stimulus is previously generated. This paradigm may provide valuable information about sensorimotor gating functionality. Here we aimed at determining the inhibited and uninhibited startle response of capuchin monkeys (Sapajus spp.), and to evaluate the role of the superior colliculus in PPI. Capuchin monkeys were tested in a whole-body protocol, to determine the best startle amplitude and interstimuli interval. Additionally we tested two subjects with bilateral superior colliculus damage in this protocol. Results show that 115 dB auditory pulse has induced the best startle response. In contrast to reports in other species, no habituation to the auditory stimuli was observed here in capuchins. Also, startle reflex inhibition was optimal after 120 msec interstimuli interval. Finally, there was a downward tendency of percentage inhibition in superior colliculus-lesioned monkeys. Our data provides the possibility of further studies with whole-body protocol in capuchin monkeys and reinforces the importance of the superior colliculus in PPI.

A role for the superior colliculus in the modulation of threat responsiveness in primates: toward the ontogenesis of the social brain.

Defense and social mechanisms in primates seem to share, at least in infancy, common neural substrata.Among these, recent research has implicated the primate superior colliculus (SC) on tasks involving visual detection and recognition of threatening stimuli, such as snakes and faces with emotional expressions. There is also evidence that both kinds of stimuli share specific characteristics and command special attention in the primate visual system. The present review focuses on the role of the SC in these seemingly overlapping functions.We present social behavioral data from capuchin monkeys in which the bilateral lesion of the SC induced a transitory impairment of social behaviors. The findings presented here are compared with previous studies, our own and others, on social behaviors and threat detection. We argue that, although the SC may participate in both systems,its role is more prominent in the detection/recognition of threat. Social interactions more likely depend on larger and more complex neural systems, where the SC may play a key role in early infancy. The implications of these recent findings are discussed under an evolutionary perspective.

Teaching embryology using models construction in practical classes / La enseñanza de embriología usando la construcción de modelos en las clases prácticas

Recently, the curriculum and the educational methodologies associated with health sciences courses are being reviewed and adapted. Pre-clinical sciences, such as anatomy and embryology are as well subjected to those changes. In human embryology courses it is common to use models to represent the different phases of development to facilitate learning, since the students can see and touch the models, obtaining knowledge by analogies. The purpose of the present study was to investigate if the construction of models by the students during practical embryology classes would improve or facilitate their learning. One year after the classes, 60 students answered a questionnaire with nine objective questions, including spaces for suggestions and observations. The student's responses suggested that the construction of models contributed to their learning.

Recientemente, el plan de estudios y las metodologías educativas asociadas a los cursos de ciencias de la salud están siendo revisados y adaptados. Ciencias pre-clínicas tales como la Anatomía y la Embriología son también sometidas a cambios. En los cursos de Embriología Humana, es común el uso de modelos para representar las diferentes fases del desarrollo, y así facilitar el aprendizaje, ya que los estudiantes pueden ver y tocar los modelos, así se realiza la obtención de conocimientos por medio de analogías. El propósito del presente estudio fue investigar si la construcción de modelos por parte de los estudiantes, durante las clases prácticas de Embriología, mejora o facilita su aprendizaje. Después de un año, 60 estudiantes respondieron a un cuestionario con nueve preguntas objetivas, incluidos los espacios para sugerencias y observaciones. De acuerdo con las respuestas de los estudiantes, la construcción de modelos han contribuido a su aprendizaje.

Superior colliculus lesions impair threat responsiveness in infant capuchin monkeys.

The ability to react fast and efficiently in threatening situations is paramount for the survival of organisms and has been decisive in our evolutionary history. Defense mechanisms in primates rely on the fast recognition of potential predators and facial expressions of conspecifics. The neural circuitry responsible for the detection of threat is generally thought to be centered on the amygdala. Although it is a pivotal structure in the processing of emotional stimuli, the amygdala does not seem necessary for the early stages of this process. Here we show that bilateral neurotoxic lesions of the superior colliculus in infant capuchins monkeys impaired the recognition of a rubber-snake in a threat-reward conflict task. Lesioned monkeys were uninhibited by a snake in a food-reward retrieval task. Lack of inhibition in the task was observed over the course of 15 weeks. The long lasting recognition impairment of a natural predator observed here is similar to the tameness aspects of Kluver-Bucy syndrome, indicating an important role of this structure in threat recognition.