Premotor interneurones contributing to actions of feline pyramidal tract neurones on ipsilateral hindlimb motoneurones

Stecina, K., Jankowska, E., Cabaj, A., Pettersson, L.G., Bannatyne, B.A. and Maxwell, D.J. (2008) Premotor interneurones contributing to actions of feline pyramidal tract neurones on ipsilateral hindlimb motoneurones. Journal of Physiology, 586(2), pp. 557-574. (doi: 10.1113/jphysiol.2007.145466)

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Publisher's URL: http://dx.doi.org/10.1113/jphysiol.2007.145466

Abstract

The aim of the study was to analyse the potential contribution of excitatory and inhibitory premotor interneurones in reflex pathways from muscle afferents to actions of pyramidal tract (PT) neurones on ipsilateral hindlimb motoneurones. Disynaptic EPSPs and IPSPs evoked in motoneurones in deeply anaesthetized cats by group Ia, Ib and II muscle afferents were found to be facilitated by stimulation of the ipsilateral, as well as of contralateral, PT. The ipsilateral actions were evoked by either uncrossed or double-crossed pathways. The results show that interneurones mediating reflex actions of muscle afferents; may be activated strongly enough by PT stimulation to contribute to movements initiated by ipsilateral PT neurones and that PT actions relayed by them might be enhanced by muscle stretches and/or contractions. However, in some motoneurones disynaptic IPSPs and EPSI's evoked from group Ib or II afferents were depressed by PT stimulation. In order to analyse the basis of this depression, the transmitter content in terminals of 11 intracellularly labelled interneurones excited by PT stimulation was defined inummohistochemically and their axonal projections were reconstructed. The interneurones included 9 glycinergic and 2 glutamatergic neurones. All but one of these neurones were mono- or disynaptically excited by group I and/or II afferents. Several projected to motor nuclei and formed contacts with motoneurones. However, all had terminal projections to areas outside the motor nuclei. Therefore both inhibitory and excitatory interneurones could modulate responses of other premotor interneurones in parallel with direct actions on motoneurones

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Maxwell, Professor David
Authors: Stecina, K., Jankowska, E., Cabaj, A., Pettersson, L.G., Bannatyne, B.A., and Maxwell, D.J.
Subjects:Q Science > QH Natural history > QH301 Biology
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology
Journal Name:Journal of Physiology
ISSN:0022-3751

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