Figure 4.

Electrophysiological recordings and seizure thresholds in flies expressing eas⁺ in subsets of the nervous system. A: Recordings from the DLM muscle in 1–2-day-old male eas mutant flies expressing eas⁺ in different neuronal populations using the GAL4/UAS system. A fly expressing eas⁺ under control of the GAL4 driver elav^c155 (genotype eas elav^c155-GAL4; UAS-eas⁺) shows a high seizure threshold in the wild-type range (top two traces). Additionally, a fly expressing eas⁺ in cholinergic neurons has a seizure threshold more than double compared with controls: a seizure is triggered at 11 V (genotype eas; UAS-eas⁺/Cha-GAL4, third and fourth traces). In contrast, a fly expressing eas⁺ in GABAergic neurons (genotype eas; UAS-eas⁺/Gad1-GAL4, fifth trace) shows low seizure thresholds similar to controls, indicating mutant seizure sensitivity. B: Seizure thresholds were determined for different genotypes. Pan-neuronal expression using the elav^c155-GAL4 driver provided the strongest rescue, with seizure thresholds reaching 23 ± 3 V (n = 7), similar to wild-type thresholds. Controls in the eas mutant background containing either UAS-eas⁺ or the GAL4 showed low seizure thresholds of about 4.5 V (n > 7), *P < 0.0001 (ANOVA). The seizure threshold for flies expressing eas⁺ in cholinergic neurons using the Cha-GAL4 driver was 9.7 ± 1 V (n = 9), higher than that of control mutant flies lacking the GAL4 transgene or lacking the UAS-eas⁺ construct, which showed seizure thresholds of 4 ± 0.4 V (n = 7) and 3.8 ± 0.2 V (n = 8), respectively, P < 0.0001 (ANOVA). There was no significant difference in seizure thresholds for flies expressing eas⁺ in GABAergic neurons using the Gad1-GAL4 driver compared with controls (n > 5), P = 0.14 (ANOVA). C: Seizure thresholds do not increase in the sda mutant background. Pan-neuronal expression of eas⁺ in the sda mutant background did not change seizure thresholds significantly (n > 5), P = 0.50 (ANOVA). Error bars represent standard error.