Statistical argument for a presynaptic origin of the second positive component of somesthetic primary cortex evoked...

The positive components 1 and 2 of the averaged field response induced in the somesthetic S1 cortex by submaximal stimulation of cortical radiation and supramaximal stimulation of lemniscus medialis showed non-existent amplitude variability whereas the dispersion was significant for components 3, 4 and 5. The same stimulus delivered at a short intershock interval only induced waves 1 and 2 without any amplitude variability, the three following ones being under complete refractoriness. These results suggest a presynaptic origin of component 2.