Cell type-specific connectome predicts distributed working memory activity in the mouse brain.

Recent advances in connectomics and neurophysiology make it possible to probe whole-brain mechanisms of cognition and behavior. We developed a large-scale model of the multiregional mouse brain for a cardinal cognitive function called working memory, the brain's ability to internally hold and process information without sensory input. The model is built on mesoscopic connectome data for interareal cortical connections and endowed with a macroscopic gradient of measured parvalbumin-expressing interneuron density. We found that working memory coding is distributed yet exhibits modularity; the spatial pattern of mnemonic representation is determined by long-range cell type-specific targeting and density of cell classes. Cell type-specific graph measures predict the activity patterns and a core subnetwork for memory maintenance. The model shows numerous attractor states, which are self-sustained internal states (each engaging a distinct subset of areas). This work provides a framework to interpret large-scale recordings of brain activity during cognition, while highlighting the need for cell type-specific connectomics.

Chemical ecology in conservation biocontrol: new perspectives for plant protection.

Threats to food security require novel sustainable agriculture practices to manage insect pests. One strategy is conservation biological control (CBC), which relies on pest control services provided by local populations of arthropod natural enemies. Research has explored manipulative use of chemical information from plants and insects that act as attractant cues for natural enemies (predators and parasitoids) and repellents of pests. In this review, we reflect on past strategies using chemical ecology in CBC, such as herbivore-induced plant volatiles and the push-pull technique, and propose future directions, including leveraging induced plant defenses in crop plants, repellent insect-based signaling, and genetically engineered crops. Further, we discuss how climate change may disrupt CBC and stress the importance of context dependency and yield outcomes.

Trauma de recto penetrante: revisión de tema / Penetrating rectal trauma: a comprehensive review

Introducción. En la actualidad, el trauma de recto continúa siendo una situación clínica compleja y temida por ser potencialmente mortal. Su detección y manejo temprano es la piedra angular para impactar tanto en la mortalidad como en la morbilidad de los pacientes. Hoy en día, aún existe debate sobre la aproximación quirúrgica ideal en el trauma de recto y las decisiones de manejo intraoperatorias se ven enormemente afectadas por la experiencia y preferencias del cirujano. Métodos. Se realizó una búsqueda de la literatura en las bases de datos de PubMed, Clinical Key, Google Scholar y SciELO utilizando las palabras claves descritas y se seleccionaron los artículos más relevantes publicados en los últimos 20 años; se tuvieron en cuenta los artículos escritos en inglés y español. Discusión. El recto es el órgano menos frecuentemente lesionado en trauma, sin embargo, las implicaciones clínicas que conlleva pasar por alto este tipo de lesiones pueden ser devastadoras para el paciente. Las opciones para el diagnóstico incluyen el tacto rectal, la tomografía computarizada y la rectosigmoidoscopía. El manejo quirúrgico va a depender de la localización, el grado de la lesión y las lesiones asociadas. Conclusión. El conocimiento de la anatomía, el mecanismo de trauma y las lesiones asociadas permitirán al cirujano realizar una aproximación clínico-quirúrgica adecuada que lleve a desenlaces clínicos óptimos de los pacientes que se presentan con trauma de recto.

Introduction. Currently, rectal trauma continues to be a complex clinical and potentially fatal situation. Its early detection and management is the cornerstone to avoid both mortality and morbidity of patients. Today there is still debate about the ideal surgical approach in rectal trauma, and intraoperative management decisions are greatly affected by the experience and preferences of the surgeon. Methods. A literature search was performed in the PubMed, Clinical Key, Google Scholar and SciELO databases using the keywords described. The most relevant articles published in the last 20 years were selected. Articles written in English and Spanish were considered.Discussion. The rectum is the organ less frequently injured in trauma; however, the clinical implications of overlooking this injury can be devastating for the patient. Options for diagnosis include digital rectal examination, computed tomography and rectosigmoidoscopy. Surgical management will depend on the location, degree of the injury and the associated injuries. Conclusion. Knowledge of the anatomy, the mechanism of trauma and the associated injuries will allow the surgeon to make an adequate clinical-surgical approach that leads to optimal clinical outcomes in patients presenting with rectal trauma.

Estructura factorial de la Brief Self-Control Scale en español / Factor structure of the Brief Self-Control Scale in Spanish

Resumen El objetivo del estudio fue explorar la estructura factorial de la Brief Self-Control Scale (BSCS; Tangney, Baumeister y Boone, 2004) aplicada como autorreporte a una muestra de 151 participantes en Colombia (edad promedio de 8.2 años, 50.33 % niñas y 49.66 % niños) y 115 participantes en Chile (edad promedio de 7.3 años, 53.04 % niñas y 49.95 % niños). La escala también fue respondida a modo de heterorreporte por 80 madres de los participantes colombianos y las 115 madres de los participantes chilenos. El Análisis Factorial Exploratorio (AFE) arrojó soluciones bifactoriales en todas las muestras y reportó valores de consistencia interna aceptables, aunque la composición de los factores difirió notablemente entre países y entre madres e hijos(as). Los hallazgos se discuten en términos de las diferencias culturales, en la socialización del autocontrol y el desarrollo de la capacidad de autorregulación en los primeros años de la escuela primaria. Se concluye que la medición del autoncontrol en este grupo etáreo mediante la BSCS requiere ajustes.

Abstract The aim of this study was to explore the factor structure of the Brief Self-Control Scale (BSCS; Tangney, Baumeister and Boone, 2004) used as self-report with a sample of 151 participants in Colombia (mean age 8.2 years, 50.33 % girls and 49.66 % boys) and 115 participants in Chile (mean age 7.3 years, 53.04 % girls and 49.95 % boys). The scale was also answered as a hetero-report by 80 mothers of the Colombian participants and the 115 mothers of the Chilean participants. The Exploratory Factor Analysis (EFA) revealed bifactor solutions in all samples and reported acceptable internal consistency values, although the composition of the factors differed markedly between countries and between mothers and children. The findings are discussed in terms of cultural differences, in the socialization self-control and development of self-regulation skills in the early elementary school years. According to these findings, the measurement of self-control in this age group using the BSCS requires adjustments.

Úlcera aórtica torácica e isquemia aguda de extremidad inferior debido a proyectil de bala / Thoracic aortic ulcer and acute lower limb ischemia due to bullet

La fisiopatología de la embolización arterial de una bala con la formación de una úlcera aórtica puede ser un cuadro confuso y extraordinariamente raro. Es evidente suponer daños severos de tipo vascular, cardíaco o pulmonar como consecuencia del orificio de puerta de entrada, lo que puede llevar a una hemorragia severa y, por lo tanto, representa un riesgo vital grave, pero resulta sorprendente que este traumatismo vascular se asocie a una isquemia de una extremidad. De hecho, este tipo de lesiones han sido raramente reportadas y sus complicaciones suelen subestimarse o son tardíamente diagnosticadas. Este raro suceso se describió por primera vez durante la Primera Guerra Mundial, pero ahora este fenómeno suele asociarse a violencia civil por arma de fuego, algo que va en progresivo aumento. En este caso clínico informamos de un caso que fue tratado en nuestro centro

The pathophysiology of a bullet arterial embolization with the formation of an aortic ulcer can be a confusing and extraordinarily rare picture. It is evident to suppose severe vascular, cardiac or pulmonary damage as a consequence of the point of entry, which can lead to severe bleeding and thus represents a serious life risk, however it is surprising that this vascular trauma is associated with ischemia of a limb. In fact, these types of injuries have been rarely reported and their complications are often underestimated or are late diagnosed. This rare event was described for the first time during the First World War, but now this phenomenon is usually associated with civil violence by firearm witch is gradually increasing. In this document, we report a case that was treated in our center by thoracic endoprosthesis and surgical resection of the foreign body though arterial surgery

Evaluation of Terpene-Volatile Compounds Repellent to the Coffee Berry Borer, Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae).

The coffee berry borer (CBB) is one of the main coffee pests in the world including Colombia. This pest is difficult to manage because of its cryptic habits and the continuous availability of coffee fruits. Among the new management strategies being tested is the use of volatile compounds as insect repellents. In this work, the behavioral response of female adult CBBs to terpenes previously identified in the CBB-repellent plant species Lantana camara was evaluated. α-Terpinene, (R)-limonene, farnesene and ß-caryophyllene terpenes were tested via a Y-tube olfactometer in which ripe coffee fruits were accompanied by terpenes at concentrations between 25 and 200 ppm. Only ß-caryophyllene induced a significant and consistent CBB repellent effect at all tested doses. The protective effect of microencapsulated ß-caryophyllene was then determined under laboratory conditions by incorporating the terpene in a colloidosome-gel system at 2.8 × 105 ng/h in the middle of coffee fruits with adult CBBs. The coffee fruits in turn presented a decrease in fruit infestation. Furthermore, the protection of coffee fruits when ß-caryophyllene gels were hung in coffee trees was evaluated in the field; infestations were artificially induced by the use of raisins (CBB-infested old coffee fruits) placed on the ground. Compared with unprotected trees, the trees treated with caryophyllene gels exhibited a 33 to 45% lower degree of infestation. Taken together, the results show that ß-caryophyllene is a promising compound for an integrated pest management (IPM) program in commercial coffee plantations.

Five new species of Dolichomitus Smith from the tropical Andes, with a key for the South American species (Hymenoptera, Ichneumonidae, Pimplinae).

Dolichomitus Smith is a widely distributed pimpline genus with more than seventy known species. There are eight species previously reported from South America: D. annulicornis (Cameron), D. bivittatus Townes, D. hypermeces Townes, D. jatai Loffredo & Penteado-Dias, D. longicauda Smith, D. megalourus (Morley), D. moacyri Loffredo & Penteado-Dias and D. zonatus (Cresson). In this paper, we describe five new species: D. mariajosae Araujo & Pádua, sp. nov., D. menai Araujo & Pádua, sp. nov., D. orejuelai Araujo & Pádua, sp. nov., D. pimmi Araujo & Pádua, sp. nov., and D. rendoni Araujo & Pádua, sp. nov. All have been collected in cloud forests in the Colombian tropical Andes. An illustrated key to the South American species of the genus is also provided.

Engagement of Pulvino-cortical Feedforward and Feedback Pathways in Cognitive Computations.

Computational modeling of brain mechanisms of cognition has largely focused on the cortex, but recent experiments have shown that higher-order nuclei of the thalamus participate in major cognitive functions and are implicated in psychiatric disorders. Here, we show that a pulvino-cortical circuit model, composed of the pulvinar and two cortical areas, captures several physiological and behavioral observations related to the macaque pulvinar. Effective connections between the two cortical areas are gated by the pulvinar, allowing the pulvinar to shift the operation regime of these areas during attentional processing and working memory and resolve conflict in decision making. Furthermore, cortico-pulvinar projections that engage the thalamic reticular nucleus enable the pulvinar to estimate decision confidence. Finally, feedforward and feedback pulvino-cortical pathways participate in frequency-dependent inter-areal interactions that modify the relative hierarchical positions of cortical areas. Overall, our model suggests that the pulvinar provides crucial contextual modulation to cortical computations associated with cognition.

Secuestro pulmonar en adultos: reporte de tres casos y revisión de la literatura / Adult bronchopulmonary sequestration: report of three cases and review of the literature

Resumen El secuestro pulmonar es una enfermedad congénita infrecuente caracterizada por la presencia de una porción de parénquima pulmonar que recibe vascularización independiente de la circulación sistémica. Se presentan tres casos de secuestro pulmonar intralobares, de presentación tardía, uno de ellos asociado a una malformación adenomatosa quística y en los cuales el manejo se completó por videotoracoscopia: dos de ellos con lobectomía total y uno con lobectomía sublobar. Se trata de una enfermedad de presentación clínica variable y cuyo tratamiento es, en la mayoría de los casos, quirúrgico, requiriéndose usualmente resecciones lobares, las cuales pueden llevarse a cabo de manera eficaz y segura por videotoracoscopia.

Abstract Pulmonary sequestration is an infrequent congenital disease characterized by the presence of a portion of pulmonary parenchyma that receives vascularization independent of the systemic circulation. We present three cases of intralobar pulmonary sequestration of late presentation, one of them associated with a cystic adenomatous malformation and in which the management was completed by videothoracoscopy: two of them with total lobectomy and the other with sublobar lobectomy. It is a disease of variable clinical presentation and whose treatment is, in most cases, surgical, usually requiring lobar resections, which can be carried out effectively and safely by video-assisted thoracoscopy.

Working Memory and Decision-Making in a Frontoparietal Circuit Model.

Working memory (WM) and decision-making (DM) are fundamental cognitive functions involving a distributed interacting network of brain areas, with the posterior parietal cortex (PPC) and prefrontal cortex (PFC) at the core. However, the shared and distinct roles of these areas and the nature of their coordination in cognitive function remain poorly understood. Biophysically based computational models of cortical circuits have provided insights into the mechanisms supporting these functions, yet they have primarily focused on the local microcircuit level, raising questions about the principles for distributed cognitive computation in multiregional networks. To examine these issues, we developed a distributed circuit model of two reciprocally interacting modules representing PPC and PFC circuits. The circuit architecture includes hierarchical differences in local recurrent structure and implements reciprocal long-range projections. This parsimonious model captures a range of behavioral and neuronal features of frontoparietal circuits across multiple WM and DM paradigms. In the context of WM, both areas exhibit persistent activity, but, in response to intervening distractors, PPC transiently encodes distractors while PFC filters distractors and supports WM robustness. With regard to DM, the PPC module generates graded representations of accumulated evidence supporting target selection, while the PFC module generates more categorical responses related to action or choice. These findings suggest computational principles for distributed, hierarchical processing in cortex during cognitive function and provide a framework for extension to multiregional models.SIGNIFICANCE STATEMENT Working memory and decision-making are fundamental "building blocks" of cognition, and deficits in these functions are associated with neuropsychiatric disorders such as schizophrenia. These cognitive functions engage distributed networks with prefrontal cortex (PFC) and posterior parietal cortex (PPC) at the core. It is not clear, however, what the contributions of PPC and PFC are in light of the computations that subserve working memory and decision-making. We constructed a biophysical model of a reciprocally connected frontoparietal circuit that revealed shared and distinct functions for the PFC and PPC across working memory and decision-making tasks. Our parsimonious model connects circuit-level properties to cognitive functions and suggests novel design principles beyond those of local circuits for cognitive processing in multiregional brain networks.

Children's Self-Regulation in Cultural Contexts: The Role of Parental Socialization Theories, Goals, and Practices.

Self-regulation is a complex multidimensional construct which has been approached mainly in Western cultural contexts. The present contribution examines the importance of considering the culture-sensitive nature of self-regulation by reviewing theory and research on the development of children's self-regulation in different cultural contexts. This review of theory and research allows to suggest that widely shared values in a cultural group influence parental socialization theories, goals, and practices, which in turn have an impact on how children learn to self-regulate, the forms of self-regulation they develop, and the goals associated with self-regulation. Thus, this article concludes that more specific research is required to relate both the developmental and the cultural aspects of children's self-regulation.

Phase precession: a neural code underlying episodic memory?

In the hippocampal formation, the sequential activation of place-specific cells represents a conceptual model for the spatio-temporal events that assemble episodic memories. The imprinting of behavioral sequences in hippocampal networks might be achieved via spike-timing-dependent plasticity and phase precession of the spiking activity of neurons. It is unclear, however, whether phase precession plays an active role by enabling sequence learning via synaptic plasticity or whether phase precession passively reflects retrieval dynamics. Here we examine these possibilities in the context of potential mechanisms generating phase precession. Knowledge of these mechanisms would allow to selectively alter phase precession and test its role in episodic memory. We finally review the few successful approaches to degrade phase precession and the resulting impact on behavior.

Correlation of seizure frequency and medication down-titration rate during video-EEG monitoring.

OBJECTIVE: The three important questions in video-EEG monitoring are (1) whether it is productive to monitor patients with low outpatient seizure frequency, (2) whether rapid down-titration of antiepileptic drugs (AEDs) during EMU admission helps generate more recorded seizures, and (3) how long a patient who has not yet had a seizure should be monitored in the EMU. This study aimed to answer these three questions. METHODS: Preadmission seizure frequency, times of AED administration, and times of seizure occurrence were collected on all adult patients admitted to the EMU at the Medical University of South Carolina (MUSC) between 2012 and 2014 - a total of 439 patients. The correlations between EMU seizure frequency and both (1) preadmission seizure frequency and (2) rate of antiepileptic drug (AED) down-titration were evaluated. The time of occurrence of seizures was evaluated. RESULTS: There was no correlation between patient-reported outpatient seizure frequency and EMU seizure frequency. In patients who were tapered off AEDs during monitoring, the rate of AED taper correlated with the EMU seizure frequency. Patients whose AEDs were more quickly tapered had higher EMU seizure frequencies. In order to record a first event in patients of unknown seizure type, approximately 3.5days of EMU monitoring was required. SIGNIFICANCE: Clinicians should not hesitate to admit patients with low preadmission seizure frequency to the EMU since many of these patients will have a seizure during monitoring. Faster AED down-titration in the EMU increases EMU seizure frequency. In patients who have not yet had a seizure in the EMU, monitoring should continue for at least four days.

Inheritance of Hippocampal Place Fields Through Hebbian Learning: Effects of Theta Modulation and Phase Precession on Structure Formation.

A place cell is a neuron that fires whenever the animal traverses a particular location of the environment-the place field of the cell. Place cells are found in two regions of the rodent hippocampus: CA3 and CA1. Motivated by the anatomical connectivity between these two regions and by the evidence for synaptic plasticity at these connections, we study how a place field in CA1 can be inherited from an upstream region such as CA3 through a Hebbian learning rule, in particular, through spike-timing-dependent plasticity (STDP). To this end, we model a population of CA3 place cells projecting to a single CA1 cell, and we assume that the CA1 input synapses are plastic according to STDP. With both numerical and analytical methods, we show that in the case of overlapping CA3 input place fields, the STDP learning rule leads to the formation of a place field in CA1. We then investigate the roles of the hippocampal theta modulation and phase precession on the inheritance process. We find that theta modulation favors the inheritance and leads to faster place field formation whereas phase precession changes the drift of CA1 place fields over time.

De la Epiméleia Heautu en Sócrates a la inquietud por el sujeto en psicoanálisis / From Epiméleia Heautu in Socrates to inquisitiveness for the subject in psychoanalysis

La perspectiva del pensamiento de Michel Foucault derivó de las relaciones entre el sujeto y los dispositivos de poder, a una concepción que busca reivindicar las relaciones entre el sujeto y la verdad, concepción ésta que se enmarca en un imperativo olvidado por el pensamiento moderno que llegó a su culmen bajo el aserto “pienso, luego soy”. Este imperativo, desde la perspectiva foucaultiana, se dice en términos de un “cuidado de sí” o “inquietud de sí”, el cual se constituye como una forma de ascetismo al cual hay que retornar para restablecer esa relación olvidada del sujeto con la verdad.Este texto es una reflexión sobre el psicoanálisis como esa posible práctica que retoma la inquietud de sí, teniendo en cuenta su especificidad, de tal suerte que una teoría que tiene como elemento axial al sujeto debe también tener en cuenta una pregunta fundamental: ¿qué es aquello sobre lo que el psicoanálisis se inquieta? ¿Cuál es la naturaleza de este sujeto?

Michel Foucault's thinking moved from the relationships between the subject and the apparatus of power to a conception that seeks to vindicate the relationships between the subject and truth. Such conception is in the context of an imperative forgotten by the Modern thinking that reached its apex under the assertion “I think, therefore I am.” This imperative, from a Foucauldian perspective, is in the terms of a “care of the self”, which becomes a form of asceticism where it is necessary to return in order to restore the forgotten relationship between the subject and truth.This text is a reflection on psychoanalysis as a possible practice that restores the care of the self, taking into account its specificity, so that a theory that has the subject as an axial element must also take into account a fundamental question: what is psychoanalysis concerned about? What is the nature of this subject?

La perspective de la pensée de Michel Foucault est passée des rapports entre le sujet et les dispositifs de pouvoir, à une conception qui cherche à revendiquer les rapports entre le sujet et la vérité. Cette conception rappelle un impératif oublié par la pensée moderne dont le point culminant est la proposition “je pense donc je suis”. Selon la perspective foucaldienne, cet impératif s'énonce en ces termes: “souci de soi” définit comme une manière d'ascétisme qu'il faut reprendre afin de rétablir ce rapport oublié entre le sujet et la vérité.Cet article est une réflexion sur la psychanalyse en tant que cette pratique possible qui reprend le souci de soi, en considérant sa spécificité, de telle sorte qu'une théorie dont le sujet est l'élément central doit également prendre en compte une question fondamentale: Quel est le souci de la psychanalyse? Quelle est la nature de ce sujet?

Modeling inheritance of phase precession in the hippocampal formation.

Spatial information about the environment is encoded by the activity of place and grid cells in the hippocampal formation. As an animal traverses a cell's firing field, action potentials progressively shift to earlier phases of the theta oscillation (6-10 Hz). This "phase precession" is observed also in the prefrontal cortex and the ventral striatum, but mechanisms for its generation are unknown. However, once phase precession exists in one region, it might also propagate to downstream regions. Using a computational model, we analyze such inheritance of phase precession, for example, from the entorhinal cortex to CA1 and from CA3 to CA1. We find that distinctive subthreshold and suprathreshold features of the membrane potential of CA1 pyramidal cells (Harvey et al., 2009; Mizuseki et al., 2012; Royer et al., 2012) can be explained by inheritance and that excitatory input is essential. The model explains how inhibition modulates the slope and range of phase precession and provides two main testable predictions. First, theta-modulated inhibitory input to a CA1 pyramidal cell is not necessary for phase precession. Second, theta-modulated inhibitory input on its own generates membrane potential peaks that are in phase with peaks of the extracellular field. Furthermore, we suggest that the spatial distribution of field centers of a population of phase-precessing input cells determines, not only the place selectivity, but also the characteristics of phase precession of the targeted output cell. The inheritance model thus can explain why phase precession is observed throughout the hippocampal formation and other areas of the brain.

Metas de socialización maternas: relación con edad, formación académica y zona habitacional / Mother´s socialization goals: relation with age, education level and area of residence

En este artículo analizamos como la zona de vivienda (rural/urbana), el nivel de formación académica y la edad de las madres se relacionan con sus metas de socialización. Por medio de una entrevista individual estructurada pedimos a 163 madres de la ciudad de Bogotá y varios municipios de la zona rural cundiboyacense hacer una estimación del valor atribuido a distintas metas en la socialización de sus hijos e hijas de edades entre 3 y 4 años y medio. Con esto buscábamos identificar los valores prioritarios que orientan a las madres en las prácticas educativas con sus hijos Los resultados sugieren que las madres de zonas urbanas, menor edad y mayor nivel de formación académica, se inclinan a dar mayor valor a metas de socialización relacionadas con el fomento de la independencia, mientras que las madres de mayor edad y menor nivel académico valoran más las metas de socialización vinculadas a la interdependencia. Se plantean interrogantes sobre cómo la expansión de la economía de mercado y el desarrollo de nuevas tecnologías de la comunicación podrían estar contribuyendo a cambios en los valores que inspiran las prácticas educativas maternas.

A comparative study of oral health attitudes and behavior using the Hiroshima University-Dental Behavioral Inventory (HU-DBI) between dental and civil engineering students in Colombia.

The aim of this study was to use the Hiroshima University - Dental Behavioral Inventory (HU-DBI) to compare oral health attitudes and behavior of dental and civil engineering students in Colombia. The HU-DBI's survey consisting of twenty dichotomous responses (agree-disagree) regarding tooth brushing, was completed at University Antonio Narino for the dental students and the University of Cauca for the civil engineering students. The Spanish version of the HU-DBI questionnaire was taken by 182 of 247 dental students and 411 of 762 engineering students. The data was-statistically analyzed by the chi-square test and backward logistic regression. Compared to the engineering students, the dental students were more likely to agree with questions such as "I am bothered by the color of my gums"(OR = 2.2, 95% CI: 1.3-3.7),"I think I can clean my teeth well without using toothpaste" (OR = 3.0, 95% CI: 1.5-5.9), "I have used a dye to see how clean my teeth are" (OR = 2.9, 95% CI: 1.9-4.3), and "I have had my dentist tell me that I brush very well" (OR = 2.0, 95% CI: 1.3-3.1). The dental education curriculum in a dental school compared to a civil engineering school in Colombia indicated that a three-phase curriculum in didactics and clinics increased oral health attitudes and behavior from entry to graduation.

Comprensión del significado desde Vygotsky, Bruner y Gergen / Comprehension of the meaning from Vygotsky, Bruner and Gergen

Este artículo es producto de la investigación "El significado desde Lev Semionovich Vygotsky, Jerome Bruner y Kenneth Gergen". Su pretensión es comprender los conceptos de "significado" construidos por estos autores mediante la revisión de varias de sus obras más importantes. El método de investigación utilizado fue el análisis de contenido. También se realizó una meta-observación sobre el trabajo, una vez éste estuvo concluido, lo que requirió establecer nuevas relaciones entre los autores. El análisis permitió descubrir diferencias y puntos de consenso entre los tres autores, en cuanto a la definición de significado, la explicación de su origen y evolución y la delimitación de las funciones que cumple en los seres humanos. Como idea original en Vygotsky se resalta el paso de la significación interpsicológica a la intrapsicológica; en Bruner, la constante negociación de significados entre seres humanos inmersos en una cultura; y en Gergen, la construcción relacional de los significados.

This article is a product of the investigation "The meaning from Lev Semionovich Vygotsky, Jerome Bruner and Kenneth Gergen ". The pretension is to understand the concepts of "meaning" constructed by these authors, by means of the review of some of his works. The method of investigation used was the analysis of content; in addition, there was realized a goal - observation of this work of degree that allowed to establish new relations between the authors. The realized analysis allowed to discover differences and points of consensus between three authors, as for the definition of the meanings, the explanation of his origin and evolution and the delimiting of the functions that these fulfill in the human beings. Since original idea in Vygotsky highlights the step of the interpsychological meaning to the intrapsychologica; in Bruner, the constant negotiation of meanings between human immersed beings in a culture; and in Gergen, the relational construction of the meanings.

Dental education in Colombia.

This article describes Colombia's development of formal dentistry, its dental school system, curriculum, and dental licensure, and current issues in oral health care. In 1969, there were only 4 dental schools in Colombia; at this writing there are 21. Five dental schools are public and the other 16 are private. Nearly all classes are conducted in Spanish. Undergraduate pre-dental coursework is not a prerequisite for dental school in Colombia. To obtain licensure, Colombian dental students must complete 5 years of study in dental school, earn a diploma, and work for the government for 1 year. There are approximately 41,400 dentists in Colombia, and the number is increasing quickly. However, the unemployment rate among dentists is very high, even though graduation from dental school is extremely difficult. Although the 1,100:1 ratio of citizens to dentists is considered satisfactory, access to dental care is limited due to the high rate of poverty.