Amygdala Kindling

Each animal was stimulated daily at the determined ADT until five, Racine Stage 5 seizures were observed. Seizures were scored as follows: Stage 1 = facial clonus, Stage 2 = head bobbing, Stage 3 = forelimb clonus, Stage 4 = forelimb clonus + rearing, Stage 5 = forelimb clonus, rearing + loss of balance (Racine, 1972). After animals were fully kindled (average of 19.4 simulations, ranging between 14-24 stimulations; 3 to 4.5 weeks after surgery), a post-kindling ADT was determined (as above) before dosing commenced. This post-surgical interval prior to testing is consistent with our prior experience using AAV-mediated expression under the hSyn promoter in rats (Soper et al., 2016). It is likewise consistent with prior studies using DREADDs for seizure control (Kätzel et al., 2014) in the neocortex and for the manipulation of the mediodorsal thalamus in behavioral studies (Parnaudeau et al., 2015, 2013).

Once animals are fully kindled, seizure responses are highly stable for months after the last stimulation (Goddard et al., 1969). In the present study, all animals displayed stable Stage 5 seizures across four separate vehicle-treated experimental sessions, which were interspersed between each drug-treated sessions.