The match/mismatch of visuo-spatial cues between acquisition and retrieval contexts influences the expression of response vs. place memory in rats.

Animals can perform goal-directed tasks by using response cues or place cues. The underlying memory systems are occasionally presented as competing. Using the double-H maze test (Pol-Bodetto et al.), we trained rats for response learning and, 24 h later, tested their memory in a 60-s probe trial using a new start place. A modest shift of the start place (translation: 60-cm to the left) provided a high misleading potential, whereas a marked shift (180° rotation; shift to the opposite) provided a low misleading potential. We analyzed each rat's first arm choice (to assess response vs. place memory retrieval) and its subsequent search for the former platform location (to assess the persistence in place memory or the shift from response to place memory). After the translation, response memory-based behavior was found in more than 90% rats (24/26). After the rotation, place memory-based behavior was observed in 50% rats, the others showing response memory or failing. Rats starting to use response cues were nevertheless able to subsequently shift to place ones. A posteriori behavioral analyses showed more and longer stops in rats starting their probe trial on the basis of place (vs. response) cues. These observations qualify the idea of competing memory systems for responses and places and are compatible with that of a cooperation between both systems according to principles of match/mismatch computation (at the start of a probe trial) and of error-driven adjustment (during the ongoing probe trial).
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