Quality Controls: The Role of Self-Corrective Science in Explorations of Primate Memory Systems

Area of Science:

• Neuroscience
• Cognitive Psychology
• Animal Models

Background:

• Mort Mishkin's 1978 study established a monkey model of global amnesia using combined amygdala and hippocampus (A+H) lesions.
• The delayed nonmatching-to-sample (DNMS) task was used to assess memory deficits in this model.

Purpose of the Study:

• To investigate if visual memory impairments observed in Mishkin's model generalized to tactual stimuli.
• To re-examine the neural basis of memory impairment in the monkey model, particularly the role of the amygdala and hippocampus versus overlying cortical structures.

Main Methods:

• Surgical removal of the entorhinal and perirhinal cortex (rhinal cortex) in monkeys.
• Testing memory function using the delayed nonmatching-to-sample (DNMS) task.
• Comparison with subsequent excitotoxic A+H lesions that spared the rhinal cortex.

Main Results:

• Bilateral removal of the rhinal cortex alone caused a profound impairment on the DNMS task.
• Excitotoxic A+H lesions, which preserved the rhinal cortex, did not replicate the severe memory impairment.
• These findings indicated that the rhinal cortex, not the amygdala and hippocampus, was primarily responsible for the observed memory deficits.

Conclusions:

• The original monkey model of global amnesia requires reconsideration.
• The study highlights the critical role of the rhinal cortex in memory.
• The DNMS task may not accurately assess the type of memory loss experienced by patients like H.M.