ANALYSIS OF THE MARBLE BURYING RESPONSE - MARBLES SERVE TO MEASURE DIGGING RATHER THAN EVOKE BURYING

Marble burying has been suggested as a model of obsessive-compulsive d isorder (OCD) based on the fact that specific serotonin reuptake inhib itors selectively influenced this response. Studying the behaviour we observed that mice also exhibited intense digging activity in the abse nce of glass marbles. This digging activity showed no habituation eith er between sessions or within a session, and it could be inhibited by psychotropic drugs in a manner similar to the marble burying response. On the basis of the results a methodological and a theoretical conclu sion can be drawn. First, it is concluded that glass marbles themselve s do not necessarily provide a fear-provoking stimulus but they serve rather as a convenient means of measuring the intensity of digging act ivity. Alternative ways of measuring the intensity of digging gave hig h correlations with marble burying. Second, the behaviour observed is not burying (the marbles) but digging/burrowing (the bedding material) , which is elicited by the presence of a ''diggable'' ground. The puta tive compulsive nature of this behaviour may add support to the hypoth esis that marble burying may be a model of OCD.