The role of genetic factors in the determination of self-stimulation behaviour in the mouse: backcross analysis.

Intracranial self-stimulation behaviour in the lateral hypothalamus was studied in male mice obtained from a backcross between the F1 generation BALB/c J × DBA/2 J and the strain BALB/c J, recessive for the majority of the self-stimulation parameters. The 48 animals of the backcross were divided into 3 groups at the 40 μ A intensity. One group of 11 mice had mean performances similar to those of the recessive parental strain BALB/c. This result suggests that the genetic determination of the difference of self-stimulation performances observed between BALB/c and DBA/2 strains is not very complex. A negative correlation appeared between the thresholds and the performances of self-stimulation. Finally, stimulation intensities above 40 μ A triggered convulsion with similar frequencies in the three backcross groups.