ITURRIAN, W. B., and FINK, G. B. (1960). Effect of Age and Condition-Test Interval (Days) on an Audio-conditioned
Convulsive Response i7i CF#l Mice. DEVELOPMENTAL PSYCHOBIOLOGY, l(4) 230-235. T h e initial exposure to sound provokes seizures in genetically audio-sensitive mice. I n a stock (e.g., CF# 1) generally considered audio-resistant, repeated sound exposure will under certain conditions induce seizure susceptibility. Susceptibilty is dramatically influenced by age and interval (days) between initial and subsequent exposure to sound. Previous auditory stimulation is absolutely essential for the genesis of convulsions. Selection of age and condition-test interval produced seizures of predictable incidence and severity. Incidence in 12or 45-day-old mice was about 5% at any interval. However, 18-day-old mice subjected to brief auditory stimulation (60 sec at 95 db) and tested at intervals of 1, 2, 3, 4, or 5 days resulted in a high incidence of convulsions. Clonic-tonic convulsions characterized the seizures at the 2or 3-day interval; but at 5 days only clonus was seen. Without further sound stimulation mice show a transitory audio-sensitivity lasting about 5 days. Sound-induced convulsions or repeated auditory stimulation prolong sensitivity. Important characteristics of the genetically controlled audiogenic crisis in contrast with other sound-induced convulsions include: the essential prior auditory stimulation, the brief duration of susceptibility, and the adaptation to chronic noise. age-dependent seizure susceptibility sound induced convulsions audiogenic seizures neuro-ontogenic critical period neuro-behavioral development HE RESEARCH POTENTIAL of sound-induced seizures for investigating drug action or maturation of the central nervous system has limitations due to the complexities involved in maintaining susceptible animals. Animals are considered susceptible if they exhibit a clonic-tonic seizure when exposed to sound only once (Fuller, Easier, & Smith, 1950;Vicari, 1951). Nearly all (90-100%) inbred mice of genetically susceptible strains, for example the DBA/2 strain, exhibit seizures when first subjected to sound, provided they are between 15 and 35 days of age (Vicari, 1950;Frings, Frings, & Kivert, 1951) and death usually follows the