McGill University Thèses et mémoires par auteur commençant par W

The reflex behaviour of single sympathetic preganglionic neurons in response to supramaximal stimulation of the sciatic nerve was studied with extracellular microelectrodes in anaesthetized cats. In 36% of the units single shocks evoked single spike discharges with mean latencies ranging from 50 to 300 msec. In 16% of the units single shocks evoked a depression of background activity with latencies ranging from 60 to 300 msec and lasting 700 msec on the average. With repetitive stimulation over a wide range of stimulation frequencies the maximum excitatory or inhibitory effect was obtained in individual units at frequencies below 10 cps. A …  Lire la suite

It is known that CNS mechanisms for inhibition of sympathetic activity exist, but the underlying circuitry and cellular mechanisms are largely unknown. As an attempt to clarify these points, the inhibitory effect, on single antidromically identified sympathetic preganglionic neurons, of electrical stimulation of high threshold somatic and visceral afferents, descending fibres in the lateral funiculus of the spinal cord and depressor area of the medulla oblongata, near the obex, have been examined. With extracellular recording, inhibition was seen as a depression of spontaneous or glutamate-evoked firing and of antidromic soma invasion, unrelated to a previous excitation. All the inputs studied …  Lire la suite