Artículo
Dual encoding of muscle tension and eye position by abducens motoneurons
Autor/es | Davis López de Carrizosa, María América
Morado Díaz, Camilo José Miller, Joel M Rodríguez de la Cruz, Rosa María Pastor Loro, Ángel Manuel |
Departamento | Universidad de Sevilla. Departamento de Zoología Universidad de Sevilla. Departamento de Fisiología |
Fecha de publicación | 2011 |
Fecha de depósito | 2019-02-18 |
Publicado en |
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Resumen | Extraocular muscle tension associated with spontaneous eye movements has a pulse-slide-step profile similar to that of motoneuron firing rate. Existing models only relate motoneuron firing to eye position, velocity and ... Extraocular muscle tension associated with spontaneous eye movements has a pulse-slide-step profile similar to that of motoneuron firing rate. Existing models only relate motoneuron firing to eye position, velocity and acceleration. We measured and quantitatively compared lateral rectus muscle force and eye position with the firing of abducens motoneurons in the cat to determine fundamental encoding correlations. During fixations (step), muscle force increased exponentially with eccentric eye position, consistent with a model of estimate ensemble motor innervation based on neuronal sensitivities and recruitment order. Moreover, firing rate in all motoneurons tested was better related to eye position than to muscle tension during fixations. In contrast, during the postsaccadic slide phase, the time constant of firing rate decay was closely related to that of muscle force decay, suggesting that all motoneurons encode muscle tension as well. Discharge characteristics of abducens motoneurons formed overlapping clusters of phasic and tonic motoneurons, thus, tonic units recruited earlier and had a larger slide signal. We conclude that the slide signal is a discharge characteristic of the motoneuron that controls muscle tension during the postsaccadic phase and that motoneurons are specialized for both tension and position-related properties. The organization of signal content in the pool of abducens motoneurons from the very phasic to the very tonic units is possibly a result of the differential trophic background received from distinct types of muscle fibers. |
Cita | Davis López de Carrizosa, M.A., Morado Díaz, C.J., Miller, .M., Rodríguez de la Cruz, R.M. y Pastor Loro, Á.M. (2011). Dual encoding of muscle tension and eye position by abducens motoneurons. Journal of neuroscience, 31 (6), 2271-2279. |
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