Biomaterial Database

Actions on gamma-motoneurones elicited by electrical stimulation of group II muscle afferent fibres in the hind limb of the cat. 1983

B Appelberg, and M Hulliger, and H Johansson, and P Sojka

The reflex effects elicited by electrical stimulation of group II muscle afferent fibres were recorded with micro-electrodes in ninety-eight hind-limb gamma-motoneurones of cats anaesthetized with chloralose. Eighty-one of the gamma-cells were classified as either static or dynamic by means of stimulation in the mesencephalic area for dynamic control known to influence dynamic gamma-motoneurones selectively. A high responsiveness to activity in group II muscle fibres was found for the whole sample of gamma-cells. Group II muscle action on dynamic gamma-motoneurones was found to be more frequent than that on static ones. Excitation from group II fibres outweighed inhibition. This was clear cut for flexor gamma-motoneurones. In extensor gamma-cells, excitation prevailed by a small margin only. However, for both static and dynamic extensor gamma-cells, excitation prevailed from both posterior biceps--semitendinosus and the gastrocnemius--soleus nerves, whereas inhibition was more frequent from the deep peroneal and quadriceps nerves. All the reflex effects studied were likely to be mediated via oligosynaptic pathways. The shortest latencies of excitatory effects were compatible with a disynaptic coupling. The fastest inhibitions were presumably trisynaptic. The present findings, supported by a parallel study of reflexes evoked by group III muscle afferents, strongly suggest that the reflexes on gamma-motoneurones are not organized in accordance with the concept of flexion reflex afferents as conceived for alpha-motoneurones. The interpretation of the results suggests a particularly independent position for dynamic gamma-cells in relation to alpha- and static gamma-motoneurones. Hence, the results also furnish an argument against the concept of alpha-gamma linkage.

UI	MeSH Term	Description	Entries
D007719	Knee Joint	A synovial hinge connection formed between the bones of the FEMUR; TIBIA; and PATELLA.	Superior Tibiofibular Joint,Joint, Knee,Joint, Superior Tibiofibular,Knee Joints,Superior Tibiofibular Joints,Tibiofibular Joint, Superior
D009046	Motor Neurons	Neurons which activate MUSCLE CELLS.	Neurons, Motor,Alpha Motorneurons,Motoneurons,Motor Neurons, Alpha,Neurons, Alpha Motor,Alpha Motor Neuron,Alpha Motor Neurons,Alpha Motorneuron,Motoneuron,Motor Neuron,Motor Neuron, Alpha,Motorneuron, Alpha,Motorneurons, Alpha,Neuron, Alpha Motor,Neuron, Motor
D009047	Motor Neurons, Gamma	Motor neurons which activate the contractile regions of intrafusal SKELETAL MUSCLE FIBERS, thus adjusting the sensitivity of the MUSCLE SPINDLES to stretch. Gamma motor neurons may be "static" or "dynamic" according to which aspect of responsiveness (or which fiber types) they regulate. The alpha and gamma motor neurons are often activated together (alpha gamma coactivation) which allows the spindles to contribute to the control of movement trajectories despite changes in muscle length.	Neurons, Fusimotor,Neurons, Gamma Motor,Gamma Motorneurons,Motor Neurons, Gamma-Efferent,Fusimotor Neuron,Fusimotor Neurons,Gamma Motor Neuron,Gamma Motor Neurons,Gamma Motorneuron,Gamma-Efferent Motor Neuron,Gamma-Efferent Motor Neurons,Motor Neuron, Gamma,Motor Neuron, Gamma-Efferent,Motor Neurons, Gamma Efferent,Motorneuron, Gamma,Motorneurons, Gamma,Neuron, Fusimotor,Neuron, Gamma Motor,Neuron, Gamma-Efferent Motor,Neurons, Gamma-Efferent Motor
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009475	Neurons, Afferent	Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.	Afferent Neurons,Afferent Neuron,Neuron, Afferent
D012018	Reflex	An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D006614	Hindlimb	Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)	Hindlimbs
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia