Indexed on: 04 Nov '13Published on: 04 Nov '13Published in: Psychobiology (Austin, Tex.)
Recent data have shown that, in the rat, the dorsal hippocampus exerts a stronger control on spatial learning performance than does the ventral portion. The present work was aimed at examining the respective function of the dorsal and the ventral hippocampus in two inbred strains of mice, C57BL/6 and DBA/2, providing different models of hippocampal anatomy and of spatial learning abilities. C57 and DBA mice with small dorsal (30%–40%), large ventral (70%–80%), or small ventral (30%–40%) electrolytic lesions of the hippocampus and sham lesions were examined in a nonassociative (reactivity to spatial change) and an associative (radial maze) spatial tasks. The results first confirmed strain differences in nonlesioned mice. C57 reacted more to spatial change and learned the radial maze task better than did DBA. In spite of these behavioral differences, the three hippocampal lesions produced a very similar pattern of effects in the two strains. In each task, the most severe impairment was always related to small dorsal lesions and to a lesser extent to large ventral lesions, whereas the small ventral lesions did not produce any significant effect. It is therefore apparent that, even if DBA mice are considered a genetic model of hippocampal dysfunction, their poor spatial abilities are also controlled by the dorsal subfield. These results confirm, therefore, that the dorsal area is highly specialized in the processing of spatial information, in associative as well as in nonassociative tasks, whatever the genotype considered.