Here are two bits of news, just announced via press release, about research into the function of memory (human or otherwise).
What a wonderful neurological amalgam is a brain. It seems that whenever science tries to understand the brain with the technique of compartmentalization (part of the process of reductionism), as often as not further research muddies the compartments. Case in point…
The long-held theory that our brains use different mechanisms for forming long-term and short-term memories has been challenged by new research from UCL [University College London], published today in PNAS [Proceedings of the National Academy of Sciences (USA)].
Neuroscientists formed this theory based on observation of patients with amnesia, a condition that severely disrupts the ability to form long-lasting memories. Typically, amnesia is caused by injury to the hippocampi, a pair of brain structures located in the depth of the temporal lobes.
Despite the condition devastating long-term memory, such patients are quite proficient in rehearsing a phone number over short periods of time, as long as their attention is not distracted. This led to a hypothesis that the hippocampus supports long-term but not short-term memory. However, the UCL study shows that this distinction now needs to be reconsidered.
Professor Emrah Duzel, UCL Institute for Cognitive Neuroscience, said: “As we anticipated, the patients could not distinguish the studied images from new images after 60 minutes – but performed normally at five seconds. However, a striking deficit emerged even at five seconds when we asked them to recall the detailed arrangement of objects within the scenes.
“These findings identify two distinct short-term memory networks in the brain: one that functions independently of the hippocampus and remains intact in patients with long-term memory deficits and one that is dependent on the hippocampus and is impaired alongside long-term memory.”
Nathan Cashdollar, UCL Institute of Neurology and first author of the paper, added: “Recent behavioural observations had already begun challenging the classical distinction between long-term and short-term memory which has persisted for nearly half a century. However, this is the first functional and anatomical evidence showing which mechanisms are shared between short-term and long-term memory and which are independent.”
The second piece of news on memory research involves some very preliminary but…unsettling findings. Here’s pretty much the whole press release:
It is well known that fear memories are permanent. However, a recent paper in Science, evaluated by three Faculty Members for F1000, reports an extraordinary finding that supports the use of a drug to control recollections of traumatic incidents.
The researchers demonstrated that, in mice, proteins known as extracellular matrix chondroitin sulfate proteoglycans form ‘neural nets’ in the brain that protect against the erasure of memory. They also reported that, when these mice were given a drug called chondroitinase ABC, fear memories were more likely to disappear than for those mice in the control group.
This finding has important therapeutic implications for sufferers of anxiety disorders, as it could allow doctors to erase the memories of patients who have had extremely traumatic experiences, such as survivors of war.
Announcements like this give me the heebie-jeebies (or the screaming habdabs for the Brits). For one thing, the topic of erasing memories (bad or otherwise) has enormous scope. It links to a vast amount of research at both the macro (brain scan) and micro (neurobiology) levels. So a five paragraph press release on the subject seems more than a might scanty. More importantly, selective erasure of memory is probably one of the most instantaneously controversial issues in all of neuroscience. “Brainwashing with drugs” comes to mind. Unfortunately the release blithely mentions only positive applications. Of course, the press release is not the paper itself, nor its publication in Science. However, with this kind of handling, it’s fortunate this is a tiny, tentative piece of memory research.