Forget the hype: how close are we to a 'forgetting pill'?

The neuralyzer from Men in Black

I've been a little disconcerted by the recent appearance in the popular science press of a number of articles seeming to claim that we're just around the corner from being able to erase painful or traumatic memories.  For example:

Wired: The Forgetting Pill Erases Painful Memories Forever by Jonah Lehrer

Scientific American: Erasing Painful Memories: Drug and Behavioral Therapies Will Help Us Forget Toxic Thoughts by Jerry Adler

The articles are beautifully written, full of interesting and thought-provoking questions, and obviously the product of a great deal of work.  I think good science writing is really important and greatly value the work that writers like Jonah Lehrer and Jerry Adler do. However, I can't understand how these very clever, usually marvellous writers make the huge leap in this instance from the (albeit in themselves fascinating) findings in animal models to the putative selective erasure of the complex, multidimensional, highly interconnected ensemble of neural representations that constitutes a single human autobiographical memory.

This matters because many thousands of people suffer enormous anguish every day with the dreadful effects of post-traumatic stress or related conditions, and may have their hopes raised that a "forgetting pill" is just around the corner.  It seems to me that this hype isn't justified based on current knowledge, although as this isn’t my area of specialist expertise, maybe I’m missing something.  I had an interesting email conversation with Jonah Lehrer in which he was characteristically open to a number of my (hopefully constructive) criticisms.  However, to find out whether I might have misunderstood the science, I asked someone who is an expert in this area, Dr Amy Milton from the University of Cambridge, to set things straight.  Here’s her view:

Elements of episodic memory

Keen students of memory will recognise that the title of this post is an homage to the seminal book of the same title by the great memory researcher, Endel Tulving.  To my mind, Tulving’s Elements is one of the finest books that has been written about memory, along with William James’s Principles of Psychology and Dan Schacter’s Searching for Memory. (It’s quite possible that Charles Fernyhough’s forthcoming Pieces of Light may soon join that list).

In Tulving’s book, he describes how episodic memories of experienced events are unlikely to be stored as fixed, separate, discrete “memory traces”, but rather as “bundles” of features.  It makes sense, given the enormous number of events we may have to remember over a lifetime, that our brains would have evolved a more efficient strategy than simply storing each event separately, as a bound trace comprising all its different components.  The redundancy would be huge.  Instead, it appears that we store single representations of features distributed around the brain which are then shared between different event memories via associative networks. Tulving acknowledges that “we have no idea about the number and identity of features that the human mind or its memory system has at its disposal” (p. 161).  However, he speculates that “the features of the mind correspond to discriminable differences in our perceptual environment and to the categories and the concepts that the language we use imposes on the world.” (ibid)