Isolation rearing affects sequential organization of motor behavior in post-pubertal but not pre-pubertal Lister and Sprague-Dawley rats.

OBJECTIVE Dopaminergic and serotonergic modulation potently influences the sequential organization of rat movements in a simple unconditioned motor paradigm. Rats reared in social isolation post-weaning differ profoundly from their socially reared litter mates on behavioral, neurochemical, and neuroanatomical measures. This investigation examined (1) whether social isolation significantly affects the sequential organization of rat movements, (2) whether these changes occur at different ages, and (3) whether these changes differ across strains. METHOD male Lister and Sprague Dawley rats reared in isolation post-weaning and socially reared controls were tested at 2 and 8 weeks post-weaning, in the Behavioral Pattern Monitor for 30-min sessions. The amount of activity and the spatial patterns of movements as measured by both the spatial scaling exponent and the fluctuation spectrum of local spatial scaling exponents were assessed in 10-min intervals. RESULTS Habituation of locomotor activity was significantly attenuated in isolation reared rats during the 30-min sessions irrespective of strain. Spatial patterns of movements were significantly affected by isolation rearing in movements in post-pubertal but not pre-pubertal Lister and Sprague-Dawley rats. The spatial scaling exponent and the fluctuation spectrum analysis revealed a shift towards straight, distance-covering, and repetitive movements rather than a complex re-organization of the behavioral repertoire. CONCLUSIONS Isolation rearing profoundly affects the sequential organization of movements in post-pubertal rats, suggesting that emerging behavioral dysfunctions parallel developmentally those found in patients with schizophrenia.