Sexually dimorphic postural adjustments are used in a skilled reaching task in the rat

Sex differences occur not only in the sexual repertoire of animals but also are evident in other aspects of movement. The present study asked whether sexually dimorphic motor behavior extends to the skilled movements used in reaching for food in the rat. Because we have previously shown that males and females are sexually dimorphic in their organization of lateral and rotatory movements and because postural adjustments are incorporated into skilled movements, both body posture and limb movements were examined during a skilled reaching task. Male and female Long-Evans rats were filmed, from both the front and ventral views and their stepping patterns, postural adjustments and forelimb movements, during a successful reach were analyzed. While males and females did not differ in forelimb movements, they were significantly different in how they approached and oriented their body to the food item during a successful reach. These results are discussed in relation to the dissociation of skilled movement from postural adjustments, sex-dependent alterations following CNS injury, and the neural and evolutionary basis of sex differences in movement organization.