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J M Besson

Publications and source records attributed to J M Besson.

At least 181 records · Page 10Linked to original sources
PubMed1973

Spinal interneurones involved in presynaptic controls of supraspinal origin.

1. Interneurones presenting heterotopic and heterosensory convergence have been identified in laminae VI-VII of the lumbar dorsal horn in the cat. Stimulation of the hind limbs sometimes induced a bimodal response, but we considered only the late convergent discharge.2. The fact that response latencies are longer to hind limb than to forelimb stimulation at this level suggests the intervention of a supraspinal loop in the activation of spinal convergent units. This hypothesis is supported by the relationship between the excitability of supraspinal structures and the discharge intensity of convergent cells as well as by the absence of long latency responses in the spinal preparation.3. Electrophysiological and pharmacological evidence discloses a strong relationship between convergent unit discharges and the occurrence of dorsal root potentials to cortical, heterosegmental and heterosensory stimulation.4. It is suggested that convergent units receive information of supraspinal origin and exert control over sensory input to the cord via primary afferent depolarization.

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PubMed1972

Modifications of dorsal horn cell activities in the spinal cord, after intra-arterial injection of bradykinin.

1. A method is described to study the modification in the activity of the lamina IV and V cells of the dorsal horn under the intra-arterial administration of bradykinin into the hind limb of the spinal cat.2. The modifications induced by intra-arterial injection of bradykinin preferentially affected the lamina V cells (77% of the units) and produced few changes in the lamina IV cells (16% of the units showed variations).3. 52% of the lamina V cells were activated; the mean increase in the firing rate was 700%. The mean latency of the effect was 20 sec and the mean duration was 47 sec. However, there was large variance in the excitatory effect across cells. On the other hand, for the same cell, the observed effects were perfectly reproducible and injections of physiological fluid induced no response.4. 25% of the lamina V cells were inhibited. Generally, the activity of the cell was reduced to 13% of its initial value; in some cases, a total suppression of activity was observed. The mean latency of the inhibitory effect was 12 sec and its duration 28 sec. All these units had a very wide inhibitory field (activated by stimulations of low intensity) which asymmetrically surrounds the excitatory field.5. This study confirms the role played by the lamina V cells in the transmission of nociceptive messages. The existence of inhibitory phenomena is in favour of the gate control theory described by Melzack & Wall (1965) without deciding the pre- or post-synaptic nature of these mechanisms.

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