ABSTRACT
Abstract Objective: To show the relation between the four parameters associated to bursting discharges of the thalamic reticular cells (TRNn): the maximum firing frequency (fmax) and the temperature at which it occurs (Tfmax), the range of temperatures defined as the full width at half maximum (∆Th) and the maximum specific low threshold calcium conductance (GT). Materials and Methods: In order to simulate the TRNn bursting activity, a computational simulation model was implemented using the NEURON software, which incorporates morphological and electrophysiological data, and stimuli properties closely related to reality. Results: It was found that there are nonlinear relations between the parameters. The fmax frequency follows a quadratic growth with temperature and tends asymptotically towards a limit value with the maximum calcium conductance. In the same manner, ∆Th increases until reaching a limit value as function of fmax and GT. However, the increment per frequency unit is bigger than the increment per conductance unit. Conclusions: Four equations were obtained that model the relations between the parameters associated to bursting discharges of the TRNn in rats and other neurons with similar characteristics in different animal species.
Resumen Objetivo: Mostrar la relación entre los cuatro parámetros asociados a las descargas en ráfaga de las neuronas del núcleo reticular del tálamo (TRNn): la frecuencia máxima de descarga (fmax) y la temperatura a la cual se produce (Tfmax), el rango de temperaturas definido como ancho a media altura (∆Th) y la conductancia máxima de calcio de bajo umbral (GT). Materiales y métodos: Para simular las descargas en ráfaga de las TRNn se implementó un modelo de simulación computacional usando el software NEURON, que incorpora datos morfológicos, electrofisiologicos y las propiedades de los estímulos en estrecha relación con la realidad. Resultados: Se encontraron relaciones no lineales entre los parámetros. La frecuencia fmax crece de forma cuadrática con la temperatura y tiende asintóticamente a un valor límite con la conductancia. Así mismo, ∆Th también se incrementan hasta alcanzar un valor límite en función de fmax y GT. No obstante, es mayor el incremento por cada unidad de frecuencia que por cada unidad de conductancia. Conclusiones: Se obtuvieron cuatro ecuaciones que modelan las relaciones entre los pará- metros asociados a las descargas en ráfaga de las neuronas TRN en ratas y otras neuronas con características similares en diferentes especies animales.
ABSTRACT
BACKGROUND: We present a software tool called SENB, which allows the geometric and biophysical neuronal properties in a simple computational model of a Hodgkin-Huxley (HH) axon to be changed. The aim of this work is to develop a didactic and easy-to-use computational tool in the NEURON simulation environment, which allows graphical visualization of both the passive and active conduction parameters and the geometric characteristics of a cylindrical axon with HH properties. RESULTS: The SENB software offers several advantages for teaching and learning electrophysiology. First, SENB offers ease and flexibility in determining the number of stimuli. Second, SENB allows immediate and simultaneous visualization, in the same window and time frame, of the evolution of the electrophysiological variables. Third, SENB calculates parameters such as time and space constants, stimuli frequency, cellular area and volume, sodium and potassium equilibrium potentials, and propagation velocity of the action potentials. Furthermore, it allows the user to see all this information immediately in the main window. Finally, with just one click SENB can save an image of the main window as evidence. CONCLUSIONS: The SENB software is didactic and versatile, and can be used to improve and facilitate the teaching and learning of the underlying mechanisms in the electrical activity of an axon using the biophysical properties of the squid giant axon.
