Development of paw preference in rats following unilateral cortical ablations in infancy

Rats which received unilateral anterior cortical lesions in infancy manifested a preference for the paw contralateral to the intact hemisphere when tested at 5 wk. and at 10 wk. of age. That this effect was locus specific and was not due to a change in the over-all balance of activity between the hemispheres was indicated by the fact that similar lesions made in the posterior cortex did not influence which paw the animals subsequently preferred. The posterior lesions, however, may have lowered the frequency of ambidexterity, a finding interpreted in terms of theoretical arguments concerning bilateral symmetry and the discrimination and memory of left and right.