Convergence of trigeminal afferents on retractor bulbi motoneurones in the anaesthetized cat.
AUTOR(ES)
Grant, K
RESUMO
Retractor bulbi motoneurones were identified by intracellular recording of their antidromic invasion following stimulation of the motor axons. Characteristics of excitatory post-synaptic potentials (e.p.s.p.s) evoked by electrical stimulation of long ciliary nerves (corneal afferents), the supraorbital nerve and the ipsilateral or contralateral vibrissae were analysed. Comparison of the orthodromic responses induced by supra-threshold stimulation of the four trigeminal inputs showed that the most powerful excitatory effect was due to corneal afferent stimulation. Excitatory synaptic potentials were followed in some cases by a period of hyperpolarization lasting 15-20 msec. It is suggested that this is an inhibitory potential of post-synaptic origin. Interaction between condition and test e.p.s.p.s evoked by long ciliary nerve and supraorbital nerve stimulation revealed a partial blocking of test e.p.s.p.s over a longer period (more than 30 msec), and it is suggested that inhibitory mechanisms within the trigeminal nucleus may be in part responsible for the absence of facilitation at the level of the motoneurone.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1199146Documentos Relacionados
- Red nucleus inputs to retractor bulbi motoneurones in the cat.
- Convergence in segmental reflex pathways from nociceptive and non-nociceptive afferents to alpha-motoneurones in the cat.
- Reduction by baclofen of monosynaptic EPSPs in lumbosacral motoneurones of the anaesthetized cat.
- Monosynaptic EPSPs elicited by single interneurones and spindle afferents in trigeminal motoneurones of anaesthetized rats.
- The role of cutaneous afferents in the control of gamma-motoneurones during locomotion in the decerebrate cat.