Some doubts about the basic concept of hole-board test

Hole board test is a generally used method for screening the potential anxiolytic character of drugs. The test is based on the assumption, that head-dipping activity of the animals is inversely proportional to their anxiety state. We tested this assumption by measuring the head-dipping activity of animals in environments with different levels of aversive character (illumination). The anxiolytic chlordiazepoxide significantly elevated head-dipping activity in moderately aversive environment, it was not active in non-aversive environment, and it exhibited inhibitory activity in highly aversive environment. When the latency of the first head-dip was measured, we found that the proportion of animals with short latency was significantly increased in moderately and highly aversive environments. It is concluded, that the inverse relation between anxiety state and head-dipping activity is true only in a certain range of anxiety level. In more aversive situations, when the anxiety level of the animals is high, the holes nay represent a possible way to escape from the aversive environment instead of an explorable object. In this case the relation between anxiety state and head-dipping activity is directly and not inversely proportional.