title: Synaptic effects in lumbar alpha-motoneurones evoked from group II muscle afferents via two different interneuronal pathways in the cat.
abstract: Conditioning of monosynaptic reflexes was used to investigate group II excitation from quadriceps (Q) and sartorius (Sart) in posterior biceps-semitendinosus (PBSt) motoneurones and different lesions were made to analyze the interneuronal pathways. The purpose of the investigation was to find if the excitation from group II Q and Sart afferents, which enter the spinal cord in L4-L6, is relayed to motoneurones by interneurones located in these segments and/or in the same segments (L7-S1) as the PBSt motoneurones. In some experiments a transection of the dorsal column in L6, which interrupts the group II input from Sart and Q to interneurones in the L7-S1 segments, resulted in a marked decrease (by about 2/3) of group II excitation from these nerves. In other experiments the same lesion did not reduce the group II effect. In the latter cases the effect could be abolished by a second lesion of the lateral funiculus (LF) in L5-L6. It is postulated that potent effects from Q and Sart group II afferents can be evoked by interneurones located in L7-S1, i.e. in the same segments as the PBSt motoneurones (L7-S1), and/or via interneurones in more rostral segments. The axons of the more rostrally located group II interneurones appear to descend mainly in the middle part of the LF.
authors.affiliation: Department of Physiology, University of Göteborg, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Cavallari
authors.forename: L G
authors.initials: LG
authors.lastname: Pettersson
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology; D002415:Cats; D003655:Decerebrate State / Q000503:physiopathology; D009046:Motor Neurons / Q000502:physiology*; D009132:Muscles / Q000294:innervation*; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology*; D013569:Synapses / Q000502:physiology*