Figure 15. Effects of carbanoxolone on harmonic SCN cells .

A, instantaneous frequency plot (truncated at 60 spikes s⁻¹) of the activity of a harmonic cell in the SCN in response to i.c.v. administration of 20 μg carbenoxolone (CBX, green bar). The cell was recorded in dark conditions, and showed isoperiodic type 1 bursting that was abolished after CBX; however, the harmonic discharge patterning persisted. B, expansion of the part of the record indicated by the blue arrow to show a single type 1 burst; note that the active period ends with fractionated bursting. C, ISI distributions from 1200 s in the control period (0–1200 s; orange) and after CBX (from 2600–3800 s). There is a small increase in the fundamental frequency of harmonic discharge in this cell. D, mean ± SEM change in firing rate of six harmonic SCN cells in 5 min bins after i.c.v. injection of CBX; the numbers in parentheses show the number of cells in each 5 min interval.