Figure 9.

Theta burst firing leads to an increase of voltage sag, an indicator of h channel activity. A, There is a small but consistent voltage sag during the response to large hyperpolarizing voltage deflections. The amplitude of this voltage sag is increased after TBF coupled with aCSF infusion. B, The amplitude of the voltage sag is quantified by the sag ratio, which increases after TBF. C, D, The voltage sag is blocked by infusion of ZD7288 following either TBF or control periods. Action potentials in A and C are truncated for clarity.