Isolation-induced social behavioral deficit: a proposed model of hyperreactivity with a behavioral inhibition

The behavior of mice isolated for 7-9 days (isolated mice) was compared to that of mice reared in groups (grouped mice). The method consisted of counting the number of escape attempts of the mice placed under an inverted beaker. When individually observed the isolated mice attempted to escape slightly but significantly more often than the grouped mice. When a pair of mice (one isolated + one grouped) were tested together, the number of escape attempts of the isolated mice was half of that of the grouped mice: this phenomenon was named the isolation-induced social behavioral deficit. These opposed behaviors may mean the same thing: an hyperreactivity to the novelty. In a variety of new situations under the beaker (presence of a lifeless object, of a grouped mouse or of an isolated mouse), the isolated mice were more reactive than the grouped mice. In conclusion, the social behavioral deficit test may be seen as a model of hyperreactivity with a behavioral inhibition.