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Delayed Non-Match to Sample (DNMS) is a research protocol for testing object recognition memory in experimental animals - typically monkeys or rats.

Obviously, you can't find out what the animals remember by asking them. Tying recognition to rewards such as food or intracerebral cocaine injection confuses spontaneous recognition and operant conditioning which involves distinct neuronal pathways.

The test therefore relies on the innate preference of all animals for novelty and consists of 3 phases.

SAMPLE - The subject is shown 2 identical objects.

DELAY - ...

CHOICE - The subject is shown 2 objects, one of which was shown in the sample phase and one of which is novel. The time the subject spends with the new and the old object is recorded.

The ratio of time spent with the new object : time spent with both objects is used as an index of successful recognition.

The effects of various neurophysiological challenges - typically pre-sample or in the delay phase - can thus be gauged. Examples of such fiddling might include lesion of distinct brain areas in the hippocampal formation or directed intracerebral infusion of neurotransmitter agonists or antagonists.

Our understanding of the processes of memory encoding, consolidation and retrieval is rudimentary. Such experiments, though crude, provide a means of breaking down and studying these 3 phases of memory. A better understanding of the processes of memory may allow us ultimately to improve or manipulate it.

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