Ontogeny of spatial navigation in rats: a role for response requirements?
Three experiments investigated the role of response requirements in the Morris water maze for pre- and postweanling rats. Fischer-344N pups were required to locate a hidden platform using extramaze cues in a tank modified for the pups' immature response repertoire. Weanlings (20-22 days) displayed spatial learning in a pool 1/2 the size of the adults' (Experiment 1); by 26-28 days of age, probe performance was comparable to adults' on quadrant preference and platform-crossing measures. Preweanlings (17 days), in a pool 1/3 the original size, significantly reduced escape latencies and displayed quadrant preference and platform-crossing scores indicative of spatial navigation. These results suggest that despite its protracted postnatal development, the preweanling hippocampus allows neural integration of visual-spatial information; however, the capacity to demonstrate such learning is dependent on task parameters and the pup's response repertoire.
Carman
H M
HM
Research and Graduate Studies, University of Kentucky, Lexington 40536-0082, USA.
Mactutus
C F
CF
D000367:Age Factors; D000818:Animals; D001245:Association Learning; D003463:Cues; D004924:Escape Reaction; D005260:Female; D008297:Male; D018782:Maze Learning; D009949:Orientation; D051381:Rats; D011916:Rats, Inbred F344; D013028:Space Perception