MEMORY CODE Joe Tsien Sci Am July 2007
<p class="default">07:08 PM, July 02, 2007
 
<b>Tsien, Joe: The Memory Code, Scientific American, July 2007, pp 52-59.</b>
 
(Joe Tsien is prof of pharmacol and biomed engr and the direc of the Center for Systems Neurobiology
at Boston University - major contrib. to learning and memroy - also develed techniques for
knocking out genes or proteins at a specific time and tissue. In 1999 while at Princeton he generated the smart mouse,
Doogie, which learned faster and remembered things longer ...  <b>Algernon!!!!</b>
Tsien moved to BU in 2004.
 
KEY CONCEPTS
 
"Discovery of this memory code could lead to the development of smarter computers and robots
and even new ways to peer into the human mind.
 
Brain relies on large populations of neurons acting in concert to represent and form a memory of an organism's experiences.
 
In mouse hippocampus (an area critical to memory formation), subsets of such populations - dubbed neural cliques -
have been shown to respond to different aspects of an event. Some represent abstract, genl info about a situation;
others indicate more selective features.
 
The same hierarchical organization used to lay down memories could be applied by the brain to convert collections
of electrical impulses into perception, knowledge, and behavior. If so, the memory work brngs investigators closer to
uncovering the univeral neural code: the rules the brain uses to identify and make sense of the bodys experiences.
 
The author and his colleagues have converted recordings of clique activity into binary code. Such digitization of brain signals could
create a foundation for assembling a codebook for the mind - a tool for cataloguing thoughts and experiences and comparing them
across individuals and perhaps species.
 
He records the activity of 200+ neurons simultaneously then does math analysis.
The coordinated activity of large populations of neurons is needed to represent perceptions and memories.
Flow from one neuron to another is not enough.
 
Our studies indicate that nuronal populations involved inencoding memories also extract the kind of generalized concepts
that allow us to transform daily experience into knowledge and ideas.
 
They focus on CA1 .. important for forming memories of events and places in both people and rodents.
Awake, free-moving mice. Brain lays down memories of dramatic events.
 
Fall of 1999 we generated a strain of mice engineered to have improved memory
 <b>"Build a Brainier Mouse" by Joe Z. Tsien; Sci Am, April 2000.</b>
 
Smart mouse nicknamed Doogie after Doogie Howser -- learns faster and remembers thins longer than
wild-type mice. Cover of TIME magazine ... there are pictures of both Algernon covers and Doogie mouse.
 
Scientists knew that converting perceptual experiences into long-lasting memories requires the hippocampus.
And we know what molecules are critical such as the NMDA which we altered to produce Doogie.
But no one knew exactly how the activation of nerve cells represents memory.
 
Mouse brain is not much larger than a peanut ... no one had recorded from more than 20-30 neurons simult.
(they had recorded from hundred of neurons in awake monkeys.)
 
Dramatic events ... erthquakes, terror attacks, surviving a fall.
Lab version of earthquake, a fall in a little elevator, and blowing on its back to simulate an owl attack.
 
We recorded from 260 neurons at one in CA1.
 
Used MDA multiple discrim analysis methods. Collapses a large number dimensions (260*2 -= before and after= 520)
into a space of only three dimensions.
 
Four distinct bubbles appear in this space: one for resting brain state, one for earthquake, oen for air puff, and one for elevator drop.
 
Patterns are integrated info about perceptual, emotiona, and pactual aspects of the events.
 
Did recordings every half second: they watched initial pattern develop, then return to rest then RECUR every few seconds
to minutes after the event had ended. These replays has sape shape but smaller amplitude.
 
Info in hippocampus was inscribed and could be replayed. --- corresponding to recollection.
 
Opens the door to how newly formed memory traces are consolidated into long-lasting memories
and how is it augmented in smart mice.
 
The ability to generate abstract concepts and knowledge from daily episdoes is the essence of our intelligence
and enables us to solve new problems in the ever changing world.
 
The general to specific hierarchical organization of info processing units represents a general
organizing principle throughout the brain.
 
 
 
 
 
 
 
 
 
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