Fig. 5.

Similar effects of 5-HT and NA on responses evoked by coQ and from ipsilateral Q afferents or RF. Responses of two commissural interneurons are shown, one (A–C) activated by RF and the other (D–F) monosynaptically activated by ipsilateral group II afferents. A and D show responses evoked by stimulation of coQ at 5 × T during ionophoresis (two stimuli in A, two in D). B and E show responses of the same neurons following stimulation of the ipsilateral reticulospinal tract fibres and ipsilateral Q at 5 × T, respectively. (C) Superimposed cumulative sums of responses, from RF (black) and from coQ (grey) show the number of responses evoked before (control) during (2 min of ionophoresis) and after ionophoresis of 5-HT. Cumulative sums were constructed from the bin values of PSTHs like those in Figs 2 and 3. Note that stimulation of coQ did not evoke responses before the ionophoresis began, and that the number of responses was greatly reduced and the latency increased 5 min after the ionophoresis ended. (F), as (C), showing superimposed cumulative sums of responses from the ipsilateral Q (black) and the contralateral Q (grey). Dotted horizontal line indicates the discrimination level; only spikes crossing this line were used for constructing the histograms.