New insights into behavioral evaluation of audiogenic seizures. A comparison of two ethological methods.

Wistar male rats were tested for susceptibility to audiogenic seizures (AS) and classified into sensitive (S) and resistant (R) groups by means of a severity index (SI). Susceptible animals were those which displayed wild running behavior (gyri, jumping and atonic falling) followed by generalized tonic-clonic seizures and consequently had an SI = 0.85 (maximum; n = 10). Resistant animals were considered those with no convulsive response to the acoustic stimulation having an SI = 0 (n = 10). Behavioral sequences of susceptible and resistant animals were recorded and analyzed using two ethological methods which basically considered behavior item frequency and statistical interactions of sequential patterns. Both methods include the concept of cluster analysis but do not include a simultaneous analysis of behavior frequency and time spent in each behavior. Thus, a third method is proposed to graphically display both frequency and temporal patterns in a more complex cluster analysis. The methods discussed here allow comparisons of behavioral sequences in a given experimental situation such as susceptible against resistant animals, acute and chronic seizures, comparison of pre- and postdrug effects, etc. Consequently, they may be the micro-behavioral substrate for correlation with contemporary molecular analysis of epileptic seizures.