The review of data (results of the authors' investigations and data fr
om the literature) concerning neurochemical correlates of individual b
ehavior in rats is presented. The ''emotional resonance'' test was use
d for behavioral selection of rats. Individual behavior in this test i
s related to the differences in free radical mediated processes, membr
ane lipid content, nitric oxide synthase activity and cAMP pattern in
cerebral macrostructures. Behavior-related differences were revealed i
n intact animals, and in response to environmental factros. These diff
erences depend on age; they may be global or specific for selected bra
in regions and/or related to interhemisphere lateralization of biochem
ical parameters.