Yves Laporte

This research, which has been carried out on several vertebrate species (notably the cat), is based mainly on electrophysiological techniques. They have often been carried out on a unitary scale (preparation of sensory or motor nerve fibers " unique "), and have often been combined with histochemical techniques (such as glycogen depletion) or histological techniques (silver impregnation of the terminal branches of a γ axon of a muscle, the tenuissimus, after elimination by degeneration of all the other α and γ motor axons of this muscle, in collaboration with D. Barker).

Spinal cord

Demonstration of the disynaptic inhibition exerted by 1b fibers from tendon organs on homonymous motoneurons. Ipsilateral flexion reflex due to amyelinic afferent fibers innervating the skin. Convergence of afferences Ia and II from the spindles on neurons of the dorsal spinal-cerebellar bundle, whose discharges were derived by intra-axonal microelectrode. Circulatory and respiratory reflex actions of various groups of afferent fibers innervating the skin or muscles. The structural basis of sensitivity, known as " recurrent " of spinal motor roots.

Motor units

Demonstration of a linear relationship between the diameter of motor axons, estimated by their conduction velocity, and the force of contraction of all the muscle fibers they innervate, suggesting that the number of terminal branches of a motor axon is a function of its caliber. Persistence of this relationship after motor nerve transection and muscle re-innervation. Comparison of the resistance to stretching of the three types of motor unit (Slow, Fast Resistant and Fast Fatigable - S, FR, FF) during contraction. Postural function of slow motor units, whose resistance to muscular stretch is proportionally the highest, contrasts with the very low tension generated by their contraction.

Neuromuscular spindles

Nature of information encoded by primary and secondary sensory endings. Evidence of β-axons innervating both intrafusal and extrafusal skeletal muscle fibers. Distribution to different types of intrafusal muscle fibers : bag 1, bag 2, chains (b1, b2, ch) and extrafusal (S, FR, FF) of γ and β axons with " dynamic " and " static " functions (activation of the former increases the sensitivity of primary endings to changes in muscle length, while activation of the latter significantly increases the frequency of discharges from primary and secondary endings). Differences in the contractions of b1, b2 and ch fibers (demonstrated by the original " frequencygrams " method) and in the properties of their neuromuscular junctions.

Identification by exclusively physiological criteria of intrafusal fibers innervated by static γ axons. Coexistence of static γ axons with specific distribution (b2 or ch) and axons with non-specific distribution (b2 and ch) in variable proportions depending on the muscle. Functional consequences of the co-activation of these two types of intrafusal fibers.
Yves Laporte has also studied the reflex activation of the " slow " muscle system in batrachians, and the post-synaptic actions (both activating and, under certain conditions, inhibiting) exerted by the pre-ganglionic fibers of the turtle's upper cervical ganglion.

Two notices on Yves Laporte's work, the first covering the period 1945-1985, the second 1985-2009, have been deposited at the archives of the Collège de France and the Académie des Sciences.