Effect of midbrain raphe lesion on avoidance learning in aggressive mice.

Lesion of the midbrain ventral raphe nucleus greatly improves the avoidance-learning efficiency of normal and isolated-aggressive Albino Swiss mice. Since the lesion of this brain area selectivity lowers the forebrain concentration of 5-hydroxytryptamine (5-HT), implications of the role of brain 5-HT in avoidance-learning acquisition are discussed.