LEARNING IMPAIRMENT IN 1-2-DAY-OLD EPILEPTIC CHICKS

The cause of learning impairment in children with seizure disorders is obscure, in part because of the lack of adequate animal models of lea rning deficiencies that can be used for study. The discriminating pass ive avoidance test has been used extensively to study learning behavio r in chicks. In the present study, we applied the passive avoidance te st to epileptic chicks to determine if learning deficiencies could be demonstrated in this epileptic model. Epileptic fowl have a hereditary form of primary generalized epilepsy characterized by tonic-clonic se izures. The seizures occur spontaneously and can also be induced by ph otic stimulation. The epileptic phenotype is the result of an autosoma l recessive mutation. Heterozygotes do not have seizures and were used as age-matched controls. The discriminating passive avoidance test us ed in the present study was based on the observation that chicks readi ly peck at bright shiny beads. Once chicks taste a colored bead coated with a bitter chemical (methylanthranilate), they refuse to peck the bead on subsequent presentations. In addition, chicks can discriminate between colored beads and will continue to peck at a bead of differen t color than the methylanthranilate (MeA)-coated bead. Compared to car riers, epileptic chicks demonstrated significantly less ability to dis criminate between colored beads. Furthermore, this learning impairment was observed in epileptic chicks treated with phenobarbital(PB), indi cating that the learning impairment in epileptic chicks is an inherent neurological problem and not a consequence of seizure activity.