gif

FIG. 1 Training on odour-odour paired associates. Each training trial consisted of two phases. In the sampling phase, the subject was presented with a cup containing a scented mixture of sand and ground rat chow with a buried reward. In the subsequent choice phase, two scented choices were presented. Both the choice items involved odours that were different from the sample, but which of them contained the bait depended on the odour of the sample. All training and tested took place in the home cage. The reward was a piece of buried sweet cereal
[page 13 of handout]

Bunsey, M & Eichenbaum, H (1996) Conservation of hippocampal memory function in rats and humans. (see below for abstract)

“If cocoa goes with coffee and coffee goes with onion, does cocoa go with onion?”
 

First Training (of rats: all discriminations for smell)

Cocoa Coffee
Salt
AND Turmeric Coffee
Salt
 

Second Training

Coffee
Onion
Nutmeg
AND Salt Onion
Nutmeg
 

Probe Test

Cocoa Onion
Nutmeg
AND Turmeric Onion
Nutmeg

Bunsey, M & Eichenbaum, H (1996) Conservation of hippocampal memory function in rats and humans. Nature, Vol.379, No.6562, Pp.255-257. (bunsey-eichenbaum.pdf)
THE hippocampus is critical to declarative memory in humans(1). This kind of memory involves associations among items or events that can be accessed flexibly to guide memory expression in various and even new situations(2-4). In animals, there has been controversy about whether the hippocampus is specialized for spatial memory(5,6) or whether it mediates a general memory function(3,4), as it does in humans. To address this issue we trained normal rats and rats with hippocampal damage on nonspatial stimulus-stimulus associations, then probed the nature of their memory representations. We report here that normal rats demonstrated two forms of flexible memory expression, transitivity, the ability to judge inferentially across stimulus pairs that share a common element, and symmetry, the ability to associate paired elements presented in the reverse of training order. Rats with neurotoxic damage limited to the hippocampus demonstrated neither form of flexible expression, indicating that non-spatial declarative processing depends specifically on the hippocampus in animals as it does in humans. (back to top | see subsequent paper using a similar “digging” procedure which suggests memory for “when” in rats)