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Un nuevo mecanismo celular para acoplar entradas que llegan a diferentes capas corticales
M E Larkum1, J J Zhu, B Sakmann
1Abt. Zellphysiologie, Max-Planck-Institut für Medizinische Forschung, Heidelberg, Germany. mlarkum@sunny.mpimf-heidelberg.mpg.de
Nature
|April 7, 1999
Resumen
Las neuronas piramidales de la capa 5 inician potenciales de acción tanto en axones como en dendritas. Un potencial de acción de propagación hacia atrás y una entrada dendrítica distal juntos permiten el inicio del potencial de acción del calcio, vinculando las entradas a través de las capas corticales.
Área de la Ciencia:
- La neurociencia es la neurociencia.
- La neurociencia computacional es una neurociencia computacional.
Sus antecedentes:
- Las neuronas piramidales en la capa 5 del neocórtex poseen sitios duales únicos para la iniciación del potencial de acción: axonal y dendrítico.
- Las entradas dendríticas distales generalmente se atenuan significativamente antes de llegar al axón, lo que requiere un umbral alto para la iniciación del potencial de acción de calcio dendrítico.
Objetivo del estudio:
- Investigar la interacción entre los potenciales de acción de propagación hacia atrás y las entradas dendríticas distales en las neuronas piramidales.
- Aclarar el mecanismo por el cual las entradas distales influyen en la generación de potencial de acción en la capa 5 de las neuronas corticales.
Principales métodos:
- Registros electrofisiológicos en la capa 5 de las neuronas piramidales.
- Protocolos de estimulación para evocar potenciales de acción de propagación hacia atrás y entradas dendríticas distales.
- Análisis de la iniciación del potencial de acción del calcio y las explosiones del potencial de acción axonal.
Principales resultados:
- Un solo potencial de acción de sodio que se propaga hacia atrás facilita la iniciación del potencial de acción de calcio dendrítico cuando coincide con la entrada excitatoria distal dentro de milisegundos.
- La entrada dendrítica inhibidora puede bloquear efectivamente la iniciación del potencial de acción del calcio dendrítico y las posteriores explosiones axonales.
- Los potenciales postsinápticos distales ejercen un mayor control sobre la iniciación del potencial de acción que el predicho por la distancia electrotónica.
Conclusiones:
- La detección de coincidencias entre los potenciales de acción de propagación hacia atrás y los potenciales postsinápticos excitatorios distales proporciona un nuevo mecanismo para el aprendizaje asociativo en las neuronas de salida corticales.
- Este mecanismo permite que las neuronas piramidales de la capa 5 integren las entradas que llegan a diferentes capas corticales, lo que influye en los cálculos de la red.
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