DAWN TO DUSK NEWS: memory loss

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Memory lessons from a forgetful brain</h1>
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Scientists
 have just begun probing the preserved tissue from a man who, following 
brain surgery, suffered memory problems for the rest of his life.</div>
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In
 1953, a brain surgeon accidentally took away Henry Molaison’s ability 
to make new memories. The patient was only 27 years old. But Molaison’s 
loss became a major gain for science. For the rest of his life, this man
 — long referred to only as H.M. — donated much of his time to 
scientists. He wanted them to learn from his tragedy.
 When Molaison died in 2008, he donated his brain to science. And a new 
analysis of it is offering memory experts additional lessons. 
This
 study finds that the basis for Molaison’s persistent memory loss 
appears more complicated than scientists initially had thought. 
As
 a young man, Molaison suffered from severe and frequent seizures. To 
ease them, surgeon William Beecher Scoville removed parts of the man’s 
brain. The procedure worked — but had a major, unintended side effect: 
Molaison became unable to form new memories. Scientists realized they 
could link this problem to his drastically altered brain. Before long, 
scientists began publishing findings they were gleaning from their study
 of H.M. 
Indeed, “The studies on H.M. began the present era of 
research on how the brain supports memory,” notes Howard Eichenbaum. A 
neuroscientist at Boston University, he studies how the brain and other 
parts of the nervous system work. 
Recently, Jacopo Annese of the 
Brain Observatory at the University of California, San Diego and his 
colleagues decided to study Molaison’s donated brain. Their technique 
provides more detail than anything that can be used on a living patient.
 It required freezing the brain and then slicing it into 2,401 
paper-thin wisps. 
Scientists scanned a photograph of each slice 
into a computer. A computer program then reassembled the images — 
virtually — to create a 3-D model of that brain. This allowed Annese’s 
team to view every part and from any angle, inside and out. 
Then 
these researchers compared this model to drawings that Molaison’s 
surgeon had made shortly after operating on the man’s brain. The 
hippocampus is one of the primary memory-forming structures in the 
brain. Scoville had indicated he had removed the entire hippocampus. The
 new 3-D computer model shows that the surgeon actually left behind a 
surprising amount of the hippocampus. 
This wasn’t a total 
surprise. Brain scans from when Molaison was alive had shown that some 
of the hippocampus remained. But the amount seen in those brain scans 
was much less than the 3-D computer reconstruction now finds. Moreover, 
what hippocampus tissue Molaison retained still looked healthy when he 
died. Annese’s team reported its findings Jan. 28 in the research 
journal Nature Communications. 
These data indicate that 
Molaison’s severe memory problems are not solely due to a missing 
hippocampus, notes Eichenbaum, who wasn’t involved in the study. The 
loss of brain structures in addition to the hippocampus likely also 
played a role, he says. 
For instance, the surgery removed a brain 
region called the entorhinal  (EN toh RYE nul) cortex. It relays signals
 between the hippocampus and the rest of the brain. The loss of this 
entorhinal cortex probably had a big role in Molaison’s memory problems,
 Eichenbaum concludes. 
And knowing that may prove important, he 
says. Why? Comparing Molaison’s memory problems with those of people who
 lack just the hippocampus might help scientists tease apart the jobs of
 the various brain structures involved in memory, he says.  
<h3>
Power Words</h3>
computer model A program that runs on a computer that creates a model, or simulation, of a real-world feature, phenomenon or event. 
entorhinal cortex 
 A portion of the brain that serves as a relay station to transmit 
signals between the hippocampus (memory center) and the rest of the 
brain. 
hippocampus  A seahorse-shaped region of the brain. It is thought to be the center of emotion, memory and the involuntary nervous system. 
nervous system  The network of nerve cells and fibers that transmits signals between parts of the body. 
neuroscience  Science
 that deals with the structure or function of the brain and other parts 
of the nervous system. Researchers in this field are known as 
neuroscientists. 
computer program A set of instructions that a computer uses to perform some analysis or computation. 
seizure A
 sudden surge of electrical activity within the brain. Seizures are 
often a symptom of epilepsy and may cause dramatic spasming of muscles. 
virtual 
 Being almost like something. Some that is virtually real would be 
almost true or real — but not quite. The term often is used to refer to 
something that has been modeled by or accomplished by a computer using 
numbers, not by using real-world parts. So a virtual motor would be one 
that could be seen on a computer screen and tested by computer 
programming (but it wouldn’t be a three-dimensional device made from 
metal). </div>
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Memory lessons from a forgetful brain

Memory lessons from a forgetful brain Scientists have just begun probing the preserved tissue from a man who, fol...