Abstract
The repeated stimulation of Group I afferent fibres induces in the spinal motoneurones a reflex discharge depression that is a function of the stimulation frequency. Since intracellular and antidromic stimulations show that the excitability of the postsynaptic membrane is not appreciably depressed, postsynaptic inhibition is not significant. The desensitization of postsynaptic receptors to the chemical transmitter seems unlikely because there was an immediate resumption of discharge on decreasing the stimulation frequency from the inhibiting values. Accommodation of postsynaptic membrane to a sustained depolarization is also unlikely as an explanation because the reflex discharge silence was obtained at stimulation frequencies so low (less than 50/sec) that there would be no fusion of the EPSPs. The hypothesis is advanced that a presynaptic mechanism is involved— either depletion of the available transmitter or presynaptic inhibition, which can both induce the reflex discharge silence as a function of the orthodromic stimulation frequency.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
