Thalamocortical synapses from "lemniscal" neurons of the dorsomedial portion of the rodent ventral posteromedial nucleus (VPMdm) are able to induce with remarkable efficacy, despite their relative low numbers, the firing of primary somatosensory cortex (S1) layer 4 (L4) neurons. To which extent this high efficacy depends on structural synaptic features remains unclear. Using both serial transmission (TEM) and focused ion beam milling scanning electron microscopy (FIB/SEM), we 3D-reconstructed and quantitatively analyzed anterogradely labeled VPMdm axons in L4 of adult mouse S1. All VPMdm synapses are asymmetric. Virtually all are established by axonal boutons, 53% of which contact multiple (2-4) elements (overall synapse/bouton ratio = 1.6). Most boutons are large (mean 0.47 μm3), and contain 1-3 mitochondria. Vesicle pools and postsynaptic density (PSD) surface areas are large compared to others in rodent cortex. Most PSDs are complex. Most synapses (83%) are established on dendritic spine heads. Furthermore, 15% of the postsynaptic spines receive a second, symmetric synapse. In addition, 13% of the spine heads have a large protrusion inserted into a membrane pouch of the VPMdm bouton. The unusual combination of structural features in VPMdm synapses is likely to contribute significantly to the high efficacy, strength, and plasticity of these thalamocortical synapses.
Rodents extract information about nearby objects from the movement of their whiskers through dynamic computations that are carried out by a network of forebrain structures that includes the thalamus and the primary sensory (S1BF) and motor (M1wk) whisker cortices. The posterior nucleus (Po), a higher order thalamic nucleus, is a key hub of this network, receiving cortical and brainstem sensory inputs and innervating both motor and sensory whisker-related cortical areas. In a recent study in rats, we showed that Po inputs differently impact sensory processing in S1BF and M1wk. Here, in C57BL/6 mice, we measured Po synaptic bouton layer distribution and size, compared cortical unit response latencies to "in vivo" Po activation, and pharmacologically examined the glutamatergic receptor mechanisms involved. We found that, in S1BF, a large majority (56%) of Po axon varicosities are located in layer (L)5a and only 12% in L2-L4, whereas in M1wk this proportion is inverted to 18% and 55%, respectively. Light and electron microscopic measurements showed that Po synaptic boutons in M1wk layers 3-4 are significantly larger (~ 50%) than those in S1BF L5a. Electrical Po stimulation elicits different areaspecific response patterns. In S1BF, responses show weak or no facilitation, and involve both ionotropic and metabotropic glutamate receptors, whereas in M1wk, unit responses exhibit facilitation to repetitive stimulation and involve ionotropic NMDA glutamate receptors. Because of the different laminar distribution of axon terminals, synaptic bouton size and receptor mechanisms, the impact of Po signals on M1wk and S1BF, although simultaneous, is likely to be markedly different.
Thalamocortical posterior nucleus (Po) axons innervating the vibrissal somatosensory (S1) and motor (MC) cortices are key links in the brain neuronal network that allows rodents to explore the environment whisking with their motile snout vibrissae. Here, using fine-scale high-end 3D electron microscopy, we demonstrate in adult male C57BL/6 wild-type mice marked differences between MC versus S1 Po synapses in (1) bouton and active zone size, (2) neurotransmitter vesicle pool size, (3) distribution of mitochondria around synapses, and (4) proportion of synapses established on dendritic spines and dendritic shafts. These differences are as large, or even more pronounced, than those between Po and ventro-posterior thalamic nucleus synapses in S1. Moreover, using single-axon transfection labeling, we demonstrate that the above differences actually occur on the MC versus the S1 branches of individual Po cell axons that innervate both areas. Along with recently-discovered divergences in efficacy and plasticity, the synaptic structure differences reported here thus reveal a new subcellular level of complexity. This is a finding that upends current models of thalamocortical circuitry, and that might as well illuminate the functional logic of other branched projection axon systems.
The TPACK model represents a high-impact advance in teacher training regarding their technological, pedagogical and content knowledge. This research presents an analysis of several publications in international databases that address the matter of the TPACK model. Accordingly, a review of the scientific literature applying the documentation as a systematization method was performed. The present study analyses 37 contributions, published between 2014 and 2017, indexed in the Web of Science (WOS) and Scopus databases, with TPACK and TPCK as the applied descriptors. Thus, the documentary analysis was based on four different criteria: public, topic, main results, and methodological design. Results show that all the reviewed publications are mainly focused on studies of basic and higher education where case studies, quantitative empirical studies, and mixed studies are predominant. Consequently, regarding the studies analyzed, there is a lack of longitudinal studies showing the teachers’ actions when applying TPACK in their daily practice.
We report a highly efficient, simple, and non-infective method for labeling individual long-range projection neurons (LRPNs) in a specific location with enough sparseness and intensity to allow complete and unambiguous reconstructions of their entire axonal tree. The method is based on the “in vivo” transfection of a large RNA construct that drives the massive expression of green fluorescent protein. The method combines two components: injection of a small volume of a hyperosmolar NaCl solution containing the Pal-eGFP-Sindbis RNA construct (Furuta et al., 2001), followed by the application of high-frequency electric current pulses through the micropipette tip. We show that, although each component alone increases transfection efficacy, compared to simple volume injections of standard RNA solution, the highest efficacy (85.7%) is achieved by the combination of both components. In contrast with the infective viral Sindbis vector, RNA transfection occurs exclusively at the position of the injection micropipette tip. This method simplifies consistently labeling one or a few isolated neurons per brain, a strategy that allows unambiguously resolving and quantifying the brain-wide and often multi-branched monosynaptic circuits created by LRPNs.
The pandemic caused by COVID-19 has generated a transformation in students’ competences and university education, especially in the use of digital tools. This study aims to analyze the use of digital tools and social networks of university students during the COVID-19 pandemic. For the collection of information, a validated Likert questionnaire (10-point scale) was adopted. The instrument consisted of a total of 66 items comprising a total of seven dimensions. The sample contained 581 students pursuing degrees in Childhood Education and Primary Education. The analysis of the available information was carried out in two different stages. First, we started by performing an exploratory factorial analysis (EFA) to determine the underlying structure of the Digital Competence of Higher Education Students (DCHES) scale factor. In the second phase, we used SEM (structural equation modeling), a statistical approach to test the relationships between observed and latent variables. More specifically, we estimated a multiple indicators multiple causes (MIMIC) model. The results showed the importance of two of the considered covariates in explaining the variability of the different dimensions of the scale analyzed (DCHES) considering the use of social networks and digital tools of university students. In this sense, both the degree to which virtual tools are used to develop teamwork and the degree of use of YouTube when communicating most fully explained the level of digital skills among the university students studied.
La universidad es un contexto de aprendizaje, en el que el alumnado es el responsable de tomar sus propias decisiones, controlar su propio proceso de aprendizaje y las interacciones que intervienen en él. En los grados como el de Educación Primaria, el progreso del aprendizaje no depende sólo de un individuo, sino del esfuerzo conjunto de un grupo de iguales, cuyo desempeño se ve reflejado en el aprendizaje individual. Así, los objetivos del presente trabajo han sido establecer cómo se desarrolla el concepto de trabajo en grupo y las estrategias que ponen en marcha para llevarlo a cabo en función de su satisfacción. Los participantes de esta investigación han sido 523 estudiantes del Grado de Educación Primaria de las Universidades de Murcia y de Jaén. Para ello se ha utilizado un cuestionario tipo Likert con cuyos resultados se ha establecido una comparación entre el alumnado que inicia el grado en Educación Primaria y aquellos que ya tienen varios años de experiencia en el ambiente universitario. Destacar como principales resultados y conclusiones que el alumnado desarrolla un concepto del trabajo en grupo que se mantiene estable en el tiempo. Sin embargo, la utilidad que creen que les reporta el trabajo en grupo sí puede cambiar, influenciados por las exigencias del contexto. Así mismo, cuando el alumnado está satisfecho con el trabajo de su grupo confían más en sus propias habilidades y capacidades para construir su conocimiento. The university is a learning context, where the students are responsible for making their own decisions and controlling their own learning process and the interactions that intervene in it. Not only that, in degrees such as Primary Education, the progress of learning does not depend only on an individual, but on the joint effort of a peer group, whose performance is reflected in the individual learning. Thus, the objectives of this paper have been to establish how the concept of group work is developed and the strategies that are put in place to carry it out according to their satisfaction. The participants of this research have been 523 students of the Degree of Primary Education of the University of Murcia and the University of Jaen. To this end, a Likert questionnaire has been used, with the results of which a comparison has been established between the students who start the degree in Primary Education and those who already have several years of experience in the university environment. The main results and conclusions confirm that the students develop a concept of group work that remains stable over time. However, the usefulness that they believe that group work brings can change, influenced by the demands of the context. Additionally, when students are satisfied with the work of their group, they rely more on their own skills and abilities to build their knowledge.
El presente trabajo ha pretendido conocer la opinión que tienen los alumnos que cursan el Trabajo Fin de Grado (TFG) en la Universidad de Jaén y en el Centro Universitario SAFA de Úbeda, en el Grado de Educación Infantil, ya que en dicho trabajo se desarrollan competencias necesarias para la consecución del Grado, aunando teoría, práctica e investigación. Para ello se ha diseñado un cuestionario que cumple con la necesaria fiabilidad y validez, estructurado en dos grandes bloques; por un lado, se pretendía caracterizar los participantes en esta investigación (género, edad, Universidad de matriculación, nota de acceso a la universidad y nota media en el Grado) y un segundo, constituido por 33 ítems acerca de las percepciones que tiene el alumnado sobre el Trabajo Fin de Grado en Educación Infantil. Se ha estructurado en cuatro dimensiones que son: Proceso de enseñanza-aprendizaje del TFG (4 ítems), Tutorización (11 ítems), Evaluación (9 ítems) y Aplicabilidad del TFG (9 ítems), posibilitando tomar en consideración las conclusiones y que ponen de manifiesto, entre otras cuestiones, la importancia de aspectos como el proceso enseñanza aprendizaje, las TIC o la Tutorización. En las conclusiones hemos detectado que el alumnado de Grado de Educación Infantil valora especialmente la tutoría, pero es necesario que el profesorado universitario redefina su rol y sea consciente de la importancia de esta asignatura y que esta se desarrolle en aras a las competencias con las que se originó.
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