Biomaterial Database

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

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

The reflex actions, elicited by graded electrical stimulation of hind-limb muscle, skin and joint nerves were studied in an extended series of experiments in extra-and intracellular recordings from 120 lumbar gamma-motoneurones of cats anaesthetized with chloralose. The present report deals with the action of group I muscle afferent fibres, which was examined in ninety-five gamma-cells. Of the gamma-cells 83% were classified as either static or dynamic by stimulation in the mesencephalic area for dynamic control. The general responsiveness (i.e. number of input nerves with effect/number of input nerves tested) of the cells was very high (89.9%). The responsiveness to stimulation of group I muscle afferent fibres was extremely low, both in flexor and extensor gamma-motoneurones and irrespective of whether they were static or dynamic. There was no difference, as regards the low incidence of group I muscle reflex action, between stimulation of autogenetic and heteronymous nerves. Among the rare reflex effects elicited from group I muscle fibres inhibition was four times as frequent as excitation. Inhibitory effects could be provoked from the autogenetic as well as from the heteronymous nerves. In contrast, excitatory effects were almost always autogenetic. The scarcity of group I muscle action on gamma-motoneurones is in striking contrast to the well known and powerful reflex actions of Ia and Ib fibres on alpha-motoneurones. These findings are discussed in relation to the concept of alpha-gamma linkage, and it is concluded that skeletomotor and fusimotor activity cannot be rigidly linked under all conditions.

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
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
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