The anterior limb of the anterior commissure is an access route to contralateral stored olfactory preference memories
Young rats learn to prefer novel odors that have been paired with reinforcers. Memories for such preference learning can be confined to one side of the olfactory system by blocking the contralateral naris during odor-reinforcer training. These memories can be accessed only from the trained naris in 6-day-old pups. But in pups 12 days of age and older, these memories, which are still stored only on one side, can be accessed from either the trained or the untrained naris. The ability of 12-day-olds to access unilaterally stored memories from the untrained side of the olfactory system permitted us to further explore the locations of olfactory memories and the routes of access to these memories. We report here that when preference memories were tested from the untrained side after selective fiber-tract transections on the trained side: (1) transection of the anterior limb of the anterior commissure at various rostral-caudal levels prevented retrieval of odor memories; (2) transection of the posterior limb did not disrupt memory access; and (3) transection of the olfactory peduncle on the trained side, thereby removing the contribution of the trained olfactory bulb, did not eliminate access to odor-preference memories. These findings suggest that access to contralateral olfactory memories is subserved by the anterior limb of the anterior commissure, probably through access to its most distal projections to the anterior olfactory nucleus and the anterior piriform cortex, and that retrieval of preference memories does not require access to the trained olfactory bulb. © 1990, Psychonomic Society, Inc.. All rights reserved.
Kucharski, D; Burka, N; Hall, WG
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