Effect of muscle length on the modulation of H reflex and inhibitory mechanisms of Ia afferent discharges during passive muscle lengthening - Archive ouverte HAL
Article Dans Une Revue Journal of Neurophysiology Année : 2024

Effect of muscle length on the modulation of H reflex and inhibitory mechanisms of Ia afferent discharges during passive muscle lengthening

Résumé

The effectiveness of activated Ia afferents to discharge ᵯC-motoneurons is decreased during passive muscle lengthening compared with static and shortening muscle conditions. Evidence suggests that these regulations are explained by (1) greater post-activation depression induced by homosynaptic post-activation depression (HPAD) and (2) primary afferent depolarization (PAD). It remains uncertain whether muscle length impacts the muscle lengthening-related aspect of regulation of the effectiveness of activated Ia afferents to discharge ᵯC-motoneurons, HPAD, PAD and heteronymous Ia facilitation (HF). We conducted a study involving 15 healthy young individuals. We recorded conditioned or non-conditioned soleus Hoffmann (H) reflex with electromyography (EMG) to estimate the effectiveness of activated Ia afferents to discharge ᵯC-motoneurons, HPAD, PAD and HF during passive lengthening, shortening and static muscle conditions at short, intermediate and long lengths. Our results show that the decrease of effectiveness of activated Ia afferents to discharge ᵯC-motoneurons and increase of post-activation depression during passive muscle lengthening occur at all muscle lengths. For PAD and HF, we found that longer muscle length increases the magnitude of regulation related to muscle lengthening. To conclude, our findings support an inhibitory effect (resulting from increased post-activation depression) of muscle lengthening and longer muscle length on the effectiveness of activated Ia afferents to discharge α-motoneurons. The increase in post-activation depression associated with muscle lengthening can be attributed to the amplification of Ia afferents discharge.
Fichier non déposé

Dates et versions

hal-04690419 , version 1 (06-09-2024)

Licence

Identifiants

Citer

Julian Colard, Marc Jubeau, Marion Crouzier, Julien Duclay, Thomas Cattagni. Effect of muscle length on the modulation of H reflex and inhibitory mechanisms of Ia afferent discharges during passive muscle lengthening. Journal of Neurophysiology, 2024, ⟨10.1152/jn.00142.2024⟩. ⟨hal-04690419⟩
12 Consultations
0 Téléchargements

Altmetric

Partager

More