FACTOR-ANALYSIS OF SPATIOTEMPORAL AND ETHOLOGICAL MEASURES IN THE MURINE ELEVATED PLUS-MAZE TEST OF ANXIETY

Recent research employing the elevated plus-maze to assess anxiety in rodents has incorporated a variety of behavioral elements in addition to the standard parameters of entries onto and time spent in the avers ive open arms. In the present study, we have used a large database com prising the behavioral profiles of 90 undrugged mice to examine the re lationship between the standard spatiotemporal measures and a range of specific behaviors related to the defensive repertoire of the mouse. A factor analysis applied to the standard measures revealed two factor s related to anxiety and locomotor activity. The simple addition of ce nter time (an infrequently recorded measure) to the analysis yielded a third factor, most probably related to decision making. A large-scale factor analysis applied to all measures further confirmed the existen ce of factors related to anxiety, locomotor activity, and decision mak ing, and revealed three further factors thought to represent risk asse ssment, vertical activity, and exploratory behavior. Thus, the inclusi on of ethological measures not only confirmed prior knowledge based on a very limited range of measures, but also demonstrated the existence of additional behavioral dimensions. The potential applications of th is knowledge are discussed.