Deep brain temperature detection by hypothalamic warm-sensitive neurons (WSNs) has been proposed to provide feedback information relevant for thermoregulation. WSNs increase their action potential ...firing rates upon warming, a property that has been presumed to rely on the composition of thermosensitive ion channels within WSNs. Here, we describe a synaptic mechanism that regulates temperature sensitivity of preoptic WSNs and body temperature. Experimentally induced warming of the mouse hypothalamic preoptic area in vivo triggers body cooling. TRPM2 ion channels facilitate this homeostatic response and, at the cellular level, enhance temperature responses of WSNs, thereby linking WSN function with thermoregulation for the first time. Rather than acting within WSNs, we—unexpectedly—find TRPM2 to temperature-dependently increase synaptic drive onto WSNs by disinhibition. Our data emphasize a network-based interoceptive paradigm that likely plays a key role in encoding body temperature and that may facilitate integration of diverse inputs into thermoregulatory pathways.
Display omitted
•Temperature in the hypothalamic preoptic area (POA) tracks body temperature in mice•TRPM2 participates in warmth detection in the POA in vivo•Presynaptic TRPM2 detects temperature increases to activate warm-sensitive neurons•Warming enhances inhibitory transmitter release via TRPM2 to mediate disinhibition
Kamm, Boffi, et al. found that the ion channel TRPM2 mediates detection of warm temperatures in the mouse hypothalamus. Specifically, TRPM2 enhances the thermosensitivity of hypothalamic warm-sensitive neurons (WSNs) via a presynaptic mechanism. This study highlights the role of WSNs and TRPM2 in body temperature homeostasis under hot environments.
Desde hace unas décadas la investigación basada en el diseño de Secuencias de Enseñanza-Aprendizaje se ha convertido en una línea de investigación cada vez más aceptada con el objetivo de generar ...conocimiento sobre la naturaleza y las condiciones de la enseñanza y el aprendizaje, mediante el diseño y desarrollo de la innovación educativa en los entornos de aula. En la primera sección se realiza una breve revisión de las investigaciones centradas en estudios teóricos y empíricos de secuencias de enseñanza-aprendizaje en el entorno del aula. Así como, la relación de ésta tradición investigadora con el movimiento de las Investigaciones Basadas en el Diseño (IBD). La segunda sección se centra en el objetivo principal de este trabajo, la descripción de la IBD como una metodología de investigación, es decir como un procedimiento que proporciona pautas para desarrollo de una investigación. Finalmente, se discute sobre los elementos claves que definen la investigación basada en el diseño y se proponen ejemplo de trabajos publicados por los autores. En las conclusiones se discute sobre qué evidencias se ofrecen para apoyar los logros de este tipo de investigación y perspectivas de futuro.
We conducted a study with introductory and upper-division physics students in a Mexican university to learn how students independently recognize the electric field’s main characteristics in the ...electric field lines diagram and as a source or target representation in conversion processes. We used the theory of registers of semiotic representations and a phenomenographic approach as a framework to analyze data. The recognition and conversion abilities were explored through interpretation and construction tasks. We identified students’ main difficulties in recognition and conversion in the interpretation and construction tasks. In conversion processes, we found that when the electric field lines diagram is the source representation, students do not interpret the field lines’ density as the magnitude of the electric field. The difficulties of interpretation that arise in these conversion processes depend partially on the target representation. We also found that constructing electric field lines is especially difficult for students at both introductory and upper-division levels. Most students would prefer to draw vector field plots instead. We recommend that electricity and magnetism teachers and researchers be aware of the difficulties that the recognition and conversion in interpretation and construction tasks may represent for their students in understanding the electric field concept.
We conducted a study with introductory and upper-division level physics students in a Mexican and a Spanish university to learn how students recognize the main characteristics of the electric field ...in three of its more widely used representations, namely, algebraic notation, vector field plot, and electric field lines, and how the students do conversions of them. The students' abilities to recognize the three representations of the electric field and do conversions gave insight into their understanding of this concept. We used the "theory of registers of semiotic representations" as a framework to analyze the data. Our results showed that the direction of the conversion is an essential factor in determining the students' success in performing conversions of electrical field representations. We found close synergy between the vector field plot and the algebraic notation of the electric field. However, we found that the conversions that involve electric field lines do not present synergy. The electric field lines representation is especially difficult for students, both as a "source" and as a "target" representation, specifically, the interpretation and representation of the magnitude of the field through the density of field lines. We recommend that teachers and researchers of electricity and magnetism be more conscious of the difficulties that some conversion tasks may present to their students. We specifically invite instructors to be attentive to how they approach the representation of electric field lines and be explicit when performing conversions that involve electric field lines.
This paper is part of the Focused Collection on Qualitative Methods in PER: A Critical Examination. Inquiring about students’ learning and their difficulties understanding the concepts and models of ...physics is a familiar challenge in physics education research. Researchers have developed various methodologies, such as phenomenography, to address it. Phenomenography is an empirical approach to determining how people experience and understand aspects of their surroundings and the physical world in qualitatively different ways. Rigorous phenomenographic analysis can be used to define categories to describe general ways the students experience the research phenomenon. The phenomenographic analysis process focuses on critical aspects of the collective experience rather than the richness of individual experience, assuming that there are a limited number of categories to describe the variations of experience for a given phenomenon. The possibility of defining a limited number of categories for experiencing a phenomenon on a collective level is one characteristic that makes phenomenographic analysis particularly appropriate for research that aims to enhance teaching and learning. We shall critically examine the strengths and weaknesses of phenomenographic research in this paper. The strengths include integral and holistic descriptions of people’s conceptions. Weaknesses include the risks of equating participants’ experiences with their descriptions of their own experiences. Our contribution weighs up the literature’s warnings about the validity and reliability of phenomenographic research. To provide an overview of phenomenography in physics education research, we conducted a literature review which identified and analyzed different approaches to data collection, data analysis, rigor, presentation of the results, and scope. We conclude by considering phenomenography as a research approach to learn how students perceive a concrete learning phenomenon, thus, providing an essential teaching design and preparation guide for instructors.
En la investigación en la educación de la física es importante conocer las dificultades de comprensión de temas abstractos. Para desarrollar la comprensión del electromagnetismo, es fundamental que ...los estudiantes entiendan el concepto de campo. El objetivo del estudio es aportar una metodología que combina la fenomenografía y la teoría de representaciones semióticas para analizar las dificultades de comprensión del campo eléctrico con relación a la conversión de representaciones. Participaron 64 estudiantes universitarios por medio de dos cuestionarios de conversión entre tres representaciones de campo eléctrico: notación algebraica, diagrama de campo vectorial y diagrama de líneas de campo. Se analizaron sus explicaciones combinando el enfoque fenomenográfico y la teoría de representaciones semióticas para crear categorías. Se identificó que las dificultades de reconocimiento se relacionan con la magnitud del campo eléctrico, más que con su dirección. Se encontró un buen reconocimiento en las conversiones entre el diagrama de campo vectorial y la notación algebraica. En las conversiones que involucran líneas de campo, se observaron dificultades de reconocimiento y conversión. Como resultado de este estudio se recomienda que la enseñanza del campo eléctrico se enfoque en el reconocimiento de sus características en cada representación y la conversión entre sus representaciones.
In Physics Education Research, it is important to study the difficulties in understanding abstract concepts. To develop the understanding of electromagnetism, it is fundamental that students understand the field concept. The study aims to contribute a methodology that combines phenomenography and the theory of registers of semiotic representations to analyze students’ difficulties understanding the electric field concept in relation to the conversion between representations. We conducted a study with 64 university students using questionnaires with conversion tasks between three electric field representations: the algebraic notation, the vector field plot, and the electric field lines diagram. We analyzed students’ explanations with a phenomenographic approach and the theory of registers of semiotic representations to create the categories. We found that the difficulties of recognition are associated with the magnitude of the electric field, more than its direction. There is good recognition in the conversions between the vector field plot and the algebraic notation. In the conversions that involve electric field lines, there were difficulties of recognition and conversion. As a result of this study, we recommend that the teaching of the electric field concept should focus on the recognition of the electric field characteristics in each representation and the conversion between representations.
Textbooks play a fundamental role in teaching and learning in school science classrooms. In this paper, we investigate the presentation of the nature of the electromagnetic field in a dozen of the ...world’s most popular introductory university physics textbooks. We analyze, from an epistemologically based teaching approach, the didactic treatment of the electromagnetic field in relation to its sources, Maxwell’s laws and electromagnetic waves. With this objective, we elaborate a rational reconstruction of the developments that led to the formulation of the nature of the electromagnetic field, Maxwell’s laws and their meaning, as well as electromagnetic waves. Next, we formulate criteria based on the key aspects derived from the reconstruction that are useful in the evaluation of electromagnetism textbooks at the introductory level and apply them to the sample of selected books. In light of the results, we reflect on their consequences for teaching. Our analysis indicates the existence of certain inconsistencies in the approach to the electromagnetic field and its relationship with its sources, Maxwell’s laws and electromagnetic waves in many of the books analyzed.
Un tratamiento superficial de las ecuaciones de Maxwell puede llevar a interpretar la existencia de una relación causal entre los diferentes términos y, por ende, que un campo eléctrico variable en ...el tiempo genera un magnético y viceversa. En este artículo abordamos los problemas asociados a dichas interpretaciones y sus consecuencias para la enseñanza de la física en cursos introductorios de física universitaria. Primero desarrollamos los principales argumentos que sustentan que las densidades de carga y de corriente, constantes o variables en el tiempo son las generadoras de los campos eléctricos y magnéticos. Proponemos luego una serie de ejemplos a nivel de cursos introductorios que nos permiten discutir las razones por las cuales considerar los campos eléctrico y magnético como entidades disjuntas conduce a contradicciones. Finalmente, analizamos sus implicaciones en la enseñanza de la física.
A thoughtless treatment of Maxwell’s equations can lead to the interpretation of the existence of a causal relationship between their different terms and, therefore, that an electric field that varies in time generates a magnetic one and vice versa. In this article we address the problems associated with these interpretations and their consequences for the teaching of physics in introductory university physics courses. First, we develop the main arguments that support that charge and current densities, constant or variable in time, are the generators of electric and magnetic fields. Then, we propose a number of classroom examples at the level of introductory courses that allow us to discuss the reasons why considering the electric and magnetic fields as disjoint entities leads to contradictions. Finally, we analyze their implications in introductory physics teaching.
In this work we present the application of design based research (DBR) methodology to conduct a systematic iterative study of the design and implementation of a teaching-learning sequence (TLS) on ...emf (electromotive force). This work is the final part of a broader study that started with the analysis of students' difficulties with emf in the contexts of transitory current, direct current, and electromagnetic induction. We complete our research by investigating to what extent students see emf as a cross-cutting concept. We establish the design parameters based on an epistemological analysis and the empirical data, and describe how we devised and implemented the first version of the TLS that takes 4.5 h of classroom time. We analyze the data obtained in the first implementation and describe the redesign process that resulted in a second version of the TLS that takes 1.5 h of classroom time. We conclude that both versions of the TLS effect a similar boost in student attainment of learning objectives compared to the control group.
PDF
