Assessment of Motor Function in Rodents: Behavioral Models Sharing Simplicity and Multifaceted Applicability

The open-field test was originally described by Hall (1934) for the study of emotionality in rats. As reviewed by Prut and Belzung (2003), the procedure consists of subjecting an animal, usually a rodent, to an environment from which escape is prevented by surrounding walls. Hall’s apparatus consisted of a brightly illuminated circular arena of about 1.2 m diameter closed by a wall of 0.45 m high. Hall used defecation and urination in the above-described open-field to measure individual differences in rats’ emotionality. Thenceforth, the use of this test has diversified enormously, differing, for example, in shape of the environment (circular, square, or rectangular), lighting, subjects, and mainly in the behavioral parameters quantified (see Walsh and Cummins 1976; Belzung 1999; Prut and Belzung 2003 for review). This concern notwithstanding, during the last 70 years, the open-field test has become one of the most (likely the most) widely used test in neuropsychobiology and neuropsychopharmacology. Indeed, even nowadays, studies using this very simple method have been published in the best periodicals of biological psychiatry (Abilio et al. 1999, for example), neurobiology of aging (Silva et al. 1996, for example), and neuropsychopharmacology (Chinen et al. 2006, for example).