Biomaterial Database

[Variations of the presynaptic inhibition of Ia fibers during voluntary movements in man]. 1988

S Meunier

Laboratoire de Neurophysiologie-Clinique, Hôpital Pittié-Salpêtrière, Paris, France.

Presynaptic inhibition of Ia fibres can strongly reduce and even extinguish Ia excitatory postsynaptic potentials (e.p.s.p.). This phenomenon has been described in animal, but so far there was no method for studying presynaptic inhibition of Ia fibres in man. We have therefore firstly set up a method suitable to appreciate the amount of presynaptic inhibition of Ia fibres in man. Presynaptic inhibition is reduced for voluntary contractions, while it is enhanced for Ia fibres directed to the motoneurones innervating synergistic muscles not involved in the contraction. This control increases the motor contrast and very likely plays a role in the selectivity of movement. In the standing position, presynaptic inhibition of Ia fibres directed to soleus motoneurones is enhanced. This prevents development of an excessive soleus stretch reflex which might hinder forward progression during walking.

UI	MeSH Term	Description	Entries
D007866	Leg	The inferior part of the lower extremity between the KNEE and the ANKLE.	Legs
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
D009068	Movement	The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.	Movements
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D011187	Posture	The position or physical attitude of the body.	Postures
D006181	H-Reflex	A monosynaptic reflex elicited by stimulating a nerve, particularly the tibial nerve, with an electric shock.	H Reflex,H-Reflexes,H Reflexes,Reflex, H
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D013569	Synapses	Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.	Synapse