The epileptiform seizures mutant(epi) was discovered in 1963 in the Fayoumi breed of domestic fowl. The condition is caused by a single autosomal recessive gene, Seizures consist of three phases. They can be induced by intermittent photic stimulation(IPS) within the range of 10 to 40 flashes per sec. Seizure occur throughout the life of the bird. Incidence is very high at hatching, it declines very markedly by 3 days of age, and by 7 days of age it has returned to a high level where it remains, Susceptible birds can respond to repeated stimulations if a few minutes of rest are given between exposures. The sexes do not react differently to seizure inducement, but seizures in males may be more prolonged than those in females.
The resting awake electroencephalograms(EEGs) of epi mutant chickens were markedly different from those of their normal hatch mates, being characterized by high voltage slow activity(HVSA) with occasional spikes and spike-wave complexes. Although similar patterns have been observed in the EEGs of chickens on Vitamin-deficient diets, the abnormal EEGs of epi mutant chickens were not related to any dietary deficiencies. On exposure to effective rates of IPS, the HVSA diappeared and the EEGs exhibited typical $quot;arousal$quot; patterns. As stimualtion continued, following waves became evidnet in the EEGs.
These following waves increased in amplitude, eventually evolving into large-amplitude spikes just prior to the onset of epileptiform convulsions.
|