Re: virus: Fwd: Mind's Eye Re-Creates Visual Memories

Jim (
Fri, 16 Apr 1999 11:26:47 -0500

I would like to add my thanks also Wade

>Wow Wade, thanks a lot for the Mind's Eye article. Very informative and
>worth reading for people of this interest.
>Bill Roh
>> -----Original Message-----
>> From:
>> []On Behalf
>> Of Wade T.Smith
>> Sent: Friday, April 16, 1999 9:36 AM
>> To: Church of Virus;
>> Subject: virus: Fwd: Mind's Eye Re-Creates Visual Memories
>> Mind's Eye Re-Creates Visual Memories
>> By William J. Cromie
>> Gazette Staff
>> Using magnetic fields that disrupt brain activity, researchers have
>> proved that visual memories are re-created in the brain as mental
>> pictures. Stored images are played, like videotapes, on a screenlike
>> sheet of tissue at the back of the head.
>> Brain scans previously revealed intense activity in this area of the
>> brain when people recall a familiar object, scene, or letter.
>> However,
>> scientists debated whether the area actually plays a role in handling
>> information. It's possible, some argued, that such activity is only a
>> by-product of processing that occurs elsewhere in the brain. Now, by
>> using magnetic currents to blur the "mind's-eye" screen, Harvard
>> researchers have found they can delay visual imagination,
>> strong evidence
>> that memories of what the eye once saw are replayed in this little
>> theater of the brain.
>> "Scenes that register on the retina of the eye are faithfully
>> projected
>> by patterns of nerve signals activated in the visual area of
>> the brain,"
>> explains Stephen Kosslyn, professor of psychology. "The
>> images are then
>> stored in the temporal lobes (under the temples) in a
>> compressed form not
>> unlike magnetic pulses on a videotape.
>> "To recall things like the number of windows in a house, information
>> about the geometry of the house is unpacked from memory and
>> sent back to
>> the visual area," continues Kosslyn. "Unpacking memories is what
>> visualization is all about."
>> The area where visual images are recalled or first imagined can be
>> pinpointed by a brain scanning technique known as positron emission
>> tomography, or PET. If experimenters send pulses of magnetic
>> energy to
>> this same area, the visualization is delayed, which would not
>> happen if
>> activity in this area played no role in recall or imagination.
>> "This is a new use of a technique called repetitive
>> transcranial magnetic
>> stimulation (rTMS) whereby magnetic fields are used to both map and
>> change brain activity," notes Alvaro Pascual-Leone, a Harvard Medical
>> School researcher who worked with Kosslyn on these
>> experiments. He has
>> used rTMS to treat depression, Parkinson's disease, schizophrenia,
>> obsessive- compulsive behavior, and to help blind people
>> learn Braille.
>> Magnetic Effects
>> In 1993, Kosslyn and his colleagues showed that two small
>> areas at the
>> middle of the back of the brain become active when you close
>> your eyes
>> and visualize letters of the alphabet. A few years later, he
>> found that
>> smaller objects activate areas farther back in the visual cortex than
>> larger ones. Much the same thing happens when we first view
>> objects of
>> different sizes.
>> "It's a peculiar feature of how this part of the cortex is folded,"
>> Kosslyn notes.
>> PET scans measure brain activity by how much blood flows to different
>> sites. Kosslyn and his colleagues found that people with the weakest
>> flows took the longest to use mental pictures. Once flow exceeds a
>> certain level, however, subjects respond relatively rapidly.
>> "It's not
>> clear whether the latter group sees more vivid images, but they do
>> classify parts of visualized objects quicker."
>> In their latest experiments, Kosslyn and colleagues at Harvard-
>> affiliated Massachusetts General Hospital in Boston had eight people
>> remember patterns of stripes located in four different boxes
>> presented
>> together on a single screen. Afterward, the researchers asked them
>> questions such as whether the stripes in box number one were
>> shorter or
>> longer than those in box number four. Other questions dealt
>> with whether
>> stripes were vertical or horizontal, thicker or thinner, tilted or
>> straight.
>> Later, people did the same test after Pascual-Leone waved a
>> magnetic wand
>> over their mind's eye. An electric current running through the wand
>> rapidly turns on and off, generating a magnetic field that
>> penetrates the
>> scalp. In some sessions, the coil was positioned so the
>> magnetism missed
>> the key areas where visual images are replayed. Investigators then
>> compared results with and without magnetic stimulation of the
>> key visual
>> area.
>> "Every one of the people who received magnetic stimulation of
>> that area
>> took more time to visualize and perceive the patterns of
>> stripes," notes
>> Kosslyn. "The magnetic fields were directed at the small area
>> where the
>> PET scans had registered activity during visualization."
>> The memory delay, no doubt, stems from disruption of the brain cells.
>> Other studies have shown that intense magnetic fields can impair
>> short-term memory for words and for previously learned
>> movement responses.
>> Magnetic Therapy
>> Would it be possible to wipe out memories - say, recurring traumatic
>> images of abuse or assault - with magnetism?
>> "Possibly," Kosslyn answers. "But I think you'd need to do it
>> within a
>> year, before the memory becomes consolidated."
>> Electroshock therapy is used for both memory obliteration and
>> treating
>> major depression, and physicians are starting to use magnetic
>> stimulation
>> for the same purposes. Magnetism has the advantage of not
>> shocking people
>> into convulsions.
>> In experiments at Beth Israel Deaconess Medical Center in Boston,
>> Pascual-Leone improved the moods of 11 of 17 badly depressed
>> people who
>> had not been helped by electroshock treatment or drugs.
>> "If we prolong stimulation for five to ten days, we can
>> sometimes extend
>> the benefit up to several months," Pascual- Leone notes. "I
>> hope that it
>> will eventually work well enough so that individual treatments can be
>> custom-designed for patients."
>> Kosslyn notes that images created by pure imagination share the same
>> projection equipment as actual memories. That makes it easy
>> to confuse
>> real and implanted memories of abuse, or of witnessing a crime.
>> There is, however, evidence that false and true memories can
>> be separated
>> by the amount and pattern of brain activity they produce.
>> "Real memories
>> contain more information, more detail, and thus activate the brain
>> differently," Kosslyn points out. "It's only speculation at
>> this point,
>> but we may be able to exploit these differences to verify the
>> truth of a
>> memory."
>> Copyright 1999 President and Fellows of Harvard College
>> *******************************************
>> Wade T. Smith
>> ** **