Behavioral effects of lesions to the caudate nucleus or mediodorsal thalamus in neonatal, juvenile, and adult rats

Abstract

The prefrontal cortex, caudate nucleus, and mediodorsal thalamus are anatomically and behaviorally related. In the present study, the age-dependent lesion effects of caudate nucleus or mediodorsal thalamus damage were assessed using a spatial delayed alternation task known to be sensitive to prefrontal cortex damage. Bilateral electrolytic lesions were placed in the caudate nucleus or mediodorsal thalamus in rats making up three different age-at-surgery groups: neonatal (8-10 days), juvenile (25-27 days), and adult (150-160 days). All animals were allowed a 110-120-day postoperative recovery interval prior to behavioral testing. The subjects given either caudate nucleus or mediodorsal thalamus lesions as neonates were unimpaired in comparison to the juvenile or adult operates sustaining comparable brain damage. Both caudate nucleus and mediodorsal thalamus lesions produced in both juvenile and adult subjects severely retarded acquisition of the alternation task. The results are consistent with the hypothesis that the subcortical components of the prefrontothalamic system mature earlier than do the cortical components. © 1982, Psychonomic Society, Inc.. All rights reserved.