Fig. 6. Effects of oxotremorine (100 µmol l^-1, 600 s; horizontal bars) on FWA and SWA Dahlgren cells. (A,B) Activity of individual Dahlgren cells (ii-v) extracted from multiunit recordings (i) from FWA (A) and SWA (B; same recording as Fig. 5C) CNSS. In both recordings, bursting and phasically active Dahlgren cells ceased firing, at least for the duration of the superfusion period. (C) Intracellular recording of FWA type 1 Dahlgren cell, showing hyperpolarisation of membrane potential (ca. 20 mV) in response to oxotremorine. Repolarisation (broken line) occurred in the continuing presence of the agonist. (D) Instantaneous firing frequency (top), and voltage recording (bottom) from a single, tonically active, SWA Dahlgren cell, showing a slow onset increase in firing frequency (from 1 to 3 Hz) in response to oxotremorine, accompanied by a reduction in spike amplitude (between horizontal dotted lines).