In the delayed non-match-to-sample task, monkeys with MTL lesions:
Group of answer choices
a. Won’t pick new object
b. Can’t remember sample object from before
c. Both a and b
d. Pick the new object after the delay
The correct answer and explanation is:
The correct answer is b. Can’t remember sample object from before.
In the delayed non-match-to-sample (DNMS) task, animals are presented with a sample object, followed by a delay, and then a choice between two objects: one being the same as the sample and the other being different. The task is designed to test memory, particularly the ability to remember the sample object over time. The correct response is to choose the object that is different from the sample, which requires the animal to recall the sample object and recognize the non-matching one after the delay.
Monkeys with lesions in the medial temporal lobe (MTL), which includes regions like the hippocampus, experience difficulties with this task. The MTL is crucial for forming and retaining memories, especially those involving new information and associations. When MTL lesions occur, monkeys typically lose the ability to remember the sample object from the initial phase of the task. This inability to recall the sample object means they cannot use it as a reference when selecting the correct object after the delay.
In a normal scenario, without MTL damage, monkeys can remember the sample object and use that memory to guide their choice of the new object after the delay. However, with MTL lesions, they fail to remember the sample object, leading to poor performance on the task. This issue highlights the role of the MTL in memory processing, particularly in tasks involving short-term memory and object recognition.