We have reported that low frequency stimulation (1 Hz for 15 min), applied
after kindling stimulation of the amygdala, inhibited the development and e
xpression of amygdala-kindled seizures, an effect we termed quenching. Subs
equently we discovered that this effect could only be achieved when certain
stimulators were used that also emitted a low-level direct current (DC). T
he studies reported here indicate that DC, applied once daily for 15 min at
intensities of 5-15 mu A, produced an intensity-related attenuation of kin
dling development and an increase in the afterdischarge threshold. This eff
ect persisted in some animals for at least 1 month after discontinuation of
the DC. In fully kindled animals, a robust increase in seizure threshold a
nd persistent seizure inhibition were also observed using 10 mu A of DC adm
inistered for 14 days. These results clarify and extend our original findin
gs of a quenching effect; however, the mechanisms by which low level DC ind
uces quenching require further elucidation.