Who Needs Accurate Memories, Anyway?

Last year, Cambridge researchers stumbled across some revealing data on false memories. They were studying the effects of brain damage on memory in rats. Rats were presented with a small, elaborate object and given time to become familiar with its appearance. They were then placed in a normal cage environment, free of wacky objects, for an hour. When presented with the same object as before as well as a new object, rats without brain damage spent significantly more time exploring the new object, ignoring the one they’d seen an hour before. The researchers expected that rats with damage to the perirhinal cortex (involved in visual memory consolidation) would show no preference towards the previously shown object. The brain damaged rats took this hypothesis a step further. They actually spent LESS time investigating the new object than the normal rats, implying they had some sort of familiarity with the object, despite having never seen it before.
 

These findings propelled the research team into a new focus. They wondered if the stimuli in their regular holding environment, coupled with perirhinal damage, resulted in formation of false memories. To test this theory, a similar method was used, but rats were raised in a dark room, devoid of visual input. The visually impaired rats acted as the researchers had initially expected for rats raised in lit cages, supporting their hypothesis.

So what’s going on here? The perirhinal cortex is easily harmed in comparison to other brain areas. Damage to this area is common in diseases classified by memory impairment, such as Alzheimer’s. As it turns out, individuals with these impairments actually perform better on tests of memory if they’ve been in a dark, low-stimulus environment before testing. Connections, connections! According to the Cambridge researcher Lisa Saksida, the perirhinal cortex is responsible for formation of complex visual memories. When the area is damaged, less specialized regions will attempt to recreate memories using generalized environmental stimuli. This disadvantaged form of memory reformation produces what we know as false memories. Could the perirhinal cortex also be involved in sensations of déjà vu? Flashbulb memories? Who knows! I look forward to seeing more research emerge on this subject.

The original article can be found here: http://www.sciencemag.org/content/330/6009/1408.abstract