p2pnet news view | Cool:- Can bad memories be erased?

And if they can, should they be?

Toronto researchers can, they say, selectively delete fear memories from mice.

“Through an ingenious set of experiments, a group of researchers at Toronto’s Hospital for Sick Children have not only located these terror-laden brain cells in mice, but erased them – along with the frightening memories they stored,” says the Toronto Star.

In a study led by Sheena Josselyn, assistant professor of Physiology, Canada Research Chair in Molecular and Cellular Cognition and a Sick Kids scientist, the team removed the small portion of neurons thought to be involved in a specific memory, says the story.

Says the abstract to the team’s resultant paper, published in Science »»»

Memories are thought to be encoded by sparsely distributed groups of neurons. However, identifying the precise neurons supporting a given memory (the memory trace) has been a long-standing challenge. We have shown previously that lateral amygdala (LA) neurons with increased cyclic adenosine monophosphate response element–binding protein (CREB) are preferentially activated by fear memory expression, which suggests that they are selectively recruited into the memory trace. We used an inducible diphtheria-toxin strategy to specifically ablate these neurons. Selectively deleting neurons overexpressing CREB (but not a similar portion of random LA neurons) after learning blocked expression of that fear memory. The resulting memory loss was robust and persistent, which suggests that the memory was permanently erased. These results establish a causal link between a specific neuronal subpopulation and memory expression, thereby identifying critical neurons within the memory trace.

Explains ScienceNOW Daily News »»»

First, Sheena Josselyn, a neuroscientist at the University of Toronto in Canada and colleagues put mice through fear training. When a tone played, the mice received an electrical shock to their feet. After several rounds, the mice froze in fear at the sound. Then the team flipped a genetically engineered switch that killed CREB-making neurons. When the researchers played the tone again 2, 5, even 12 days later, the mice didn’t freeze — they forgot their fear.

But, “You wouldn’t want to completely get rid of all aspects of a memory,” the Start has Dr Michael Salter, head of the Neurosciences & Mental Health program at the hospital, saying, going on:

“To help people with these kinds of post-traumatic stress disorders … you might just want to minimize the emotional association between the memory and the highly disruptive and negative emotions that people have in this context.”

Adds the story:

” ‘The elegance in this one, which goes orders of magnitude beyond other studies, is that now they didn’t do something that was global to all neurons in the lateral nucleus,’ said Karim Nader, professor of neuroscience at McGill University. ‘They can kill only the neurons that they think express the memory’.”

Toronto Star – Should painful memories be erased?, March 13, 2009
Science – Selective Erasure of a Fear Memory, March 13, 2009

ScienceNOW Daily News – Eternal Sunshine of the Murine Mind, March 12, 2009

---

Use free p2pnet newsfeeds for your site. It’s really easy!
Subscribe to p2pnet.net | | rss feed: http://p2pnet.net/p2p.rss | | Mobile – http://p2pnet.net/index-wml.php

---

Net access blocked by government restrictions? Use Psiphon from the Citizen Lab at the University of Toronto. Go here for details.

This entry was posted on Saturday, March 14th, 2009 at 1:33 pm and is filed under Cool Stuff. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

HOME

Viewed 2880 times