Effects of rearing complexity on dendritic branching in frontolateral and temporal cortex of the rat

Dendritic branching was studied in Golgi-stained neurons from frontolateral and temporal cortex of rats reared for 30 days after weaning in complex, social, or isolated environments. In temporal cortex, layer-4 pyramidal neurons from rats reared in complex environments had significantly more basal dendritic branches than those from littermates reared socially or in isolation. Layer-5 pyramidal neurons showed similar rearing effects. In contrast, no significant differences due to rearing were detected in frontal cortex. In both regions, there was a high degree of concordance within litters. These results amplify those of previous studies and indicate that: the effects of environmental complexity on dendritic branching are not restricted to those previously seen in visual cortex; the effects are not seen in all cortical areas or neuronal populations as might be expected if they reflected a general hormonal or nutritional difference; and both the non-universality of the effects and the relative concordance within litters suggest that equivalent neuronal populations are stained in the different environmental groups.