[The preference for one limb in rats--the result of learning in an experiment or an individual characteristic?]

The problem was studied whether an initial preference of one limb exists in rats connected with interhemispheric asymmetry or it appears during the procedure of testing (the first successful movement of one limb becomes consolidated). The work consisted in obtaining experimental retrograde amnesia after preliminary determination of the preferred limb and in the following testing of the preference after a definite time interval. In this case the trace of preceding learning must not influence the following choice of the limb. It is shown that the preference in rats is not a result of accidental learning in the experiment but initially exists before testing procedure. Retaining of memory trace for a long time (2-4 weeks) is also shown even after a very short learning (one-three successful movements).