X-Message-Number: 13070
Date: Fri, 07 Jan 2000 21:57:48 -0500
From: Jan Coetzee <>
Subject: A Look at Memory

A Look at Memory
Friday, January 07, 2000

      [By Sally Squires in the Washington Post.]

       Without memory, people would be unable to read this sentence or
their way home tonight or grasp the jokes on their favorite television
sitcom. Memory provides the foundation for learning throughout life,
it's to explore emotions through psychotherapy, become fluent in a
language or master snowboarding.
       All animals, from the lowly sea snail to humans, have some form
memory. But people possess the remarkable ability to make a nearly
number of memory associations. It's why the loss of memory - due to
aging, illnesses such as Alzheimer's disease or accidents - is so
And it's why, as the Decade of the Brain draws to a close,
are pressing to better understand this still mysterious process.
      "Every thought we have, every word we speak, every action we
in - indeed, our very sense of self and our sense of connectedness to
others - we owe to our memory, to the ability of our brains to record
store our experiences," explain neuroscientists Larry R. Squire and Eric

Kandel in their book, "Memory: From Mind to Molecules." "Memory is the
that binds our mental life, the scaffolding that holds our personal
and that makes it possible to grow and change throughout life."
      Researchers, using a variety of sophisticated new imaging devices,

beginning to understand some of neuroscience's most central questions:
are memories organized in the brain? Is there a particular location in
brain for the seemingly mindless daily habits, from climbing out of bed
brushing your teeth or making coffee? How does the brain recall vivid
details from a movie, a book or a painting? Where does the memory for
recognizing a face exist?
      "It's a very difficult thing to find the anatomic parts of memory
the brain," said Daniel Alkon, director of the Laboratory of Adaptive
Systems at the National Institute of Neurological Disorders and Stroke
(NINDS). " ... We see a picture of our father's face and hear his name
recall our relationship with him. But to find where that is stored [in
brain] is an incredibly difficult task."
      Until recently, memory research was largely confined to animals
those individuals in whom memory had begun to unravel. People suffering
amnesia, the aftermath of a stroke and various forms of dementia gave
scientists rare glimpses into the mysteries of memory.
      One of the most fascinating cases was of a 9-year-old boy who
his head on the sidewalk after being knocked down by a bicycle. His
misfortune turned into a lengthy, classic study that provided the first
riveting proof that memory is not one single process in the brain.
      The child suffered debilitating seizures and frequent blackouts.
age 27, he was so incapacitated that neurosurgeons removed part of his
brain - the hippocampus and two areas known as the medial temporal
      The operation in the mid-1950s cured the man's seizures, but it
him unable to retain new information. Meals eaten, people met, even
of himself as he aged held no meaning because he could not transfer them
his long-term memory. The man retained enough knowledge of language and
to hold a normal conversation. What he couldn't recall - even a few
afterward - was having the conversation.
      Yet the man could vividly remember events that occurred before the

accident and he could even learn some new skills. In a standard
test, he was asked to trace the figure of a star. His tracings improved
day, just as they would in normal subjects. The difference was that the
had no memory of his previous drawings.
      McGill University psychologist Brenda Milner, who has studied this

for 40 years, concluded that he couldn't retain new memories because he
longer had the medial temporal lobes and the hippocampus in his brain to

store them. Yet since the man could recall events before his injury,
and her team determined that neither the temporal lobes nor the
could be the final storage sites in the brain for longer term memories.
      The fact that the man could learn to trace a star and
improve at doing so - even if he didn't remember it - helped scientists
understand that memory is divided into two major forms, declarative and
      The surgery destroyed the man's declarative memory, or the
recognition of facts and events," according to Squire, research career
scientist at the Veterans Affairs Medical Center in San Diego.
      Left intact was his nondeclarative memory, which includes the
subconscious recall of motor skills and the ability to identify familiar

objects more quickly with experience.
      In healthy individuals, the hippocampus and the medial temporal
are at the heart of declarative memory. But the process of capturing and

recalling information spreads throughout the brain, often in
      Each memory seems to be a compilation of tiny bits of information
stored in a vast network of different cells. Just the simple ability to
recall a phone number is believed to involve the activation of several
thousand nerve cells, called neurons, distributed throughout the brain.
      "Humans are in a class by themselves," said NINDS's Alkon. "The
inside the brain is designed to allow us at the flip of a coin or the
of fingers to connect or associate any bits of information with any
bit. We can do it lightning fast. In terms of learning new associations,

most of what we do can be formed in fractions of a second."
      And the potential for storing long-term memories is thought to be
nearly endless, given the multiple associations between cells. Each
brain contains an estimated 100 billion neurons, each capable of making
to 10,000 connections with other brain cells. The number of possible
memories starts to approach the number of molecules in the universe,
      There are, of course, highly skilled individuals who aptly
the vast capacity for declarative, long-term memory. The Olympic gymnast
gold medal ice skater who moves nonstop in intricate ways through a long

routine relies on long-term memory. So does the concert pianist who
entire concerto by heart.
      At Carnegie Mellon University in Pittsburgh, psychologists Herbert

Simon and William Chase studied chess players and found that practice -
than exceptional memories - could account for differences between
      In the study, each player was asked to spend five seconds
examining a
chessboard with 26 pieces arranged in game positions. The players were
told to reproduce what they had seen on an empty board. On average,
chess players - including some grandmasters - correctly replaced 16 of
26 pieces, while beginners only positioned four pieces correctly. But
differences between skilled chess players and beginners disappeared when

Simon and Chase randomly positioned chess pieces on the board.
      Simon and Chase concluded that the grandmaster chess players had
trained so much that they had stored thousands of game position
in their brains but were no better than the beginner players in
random positions on the board.
      Modern imaging techniques are enabling scientists to study the
in ways once unimaginable and providing an understanding of the chemical

processes that make memories.
      With positron emission tomography (PET) and functional magnetic
resonance imaging (fMRI), for example, neuroscientists can pinpoint
activity during different memory tasks. At NIMH, Alex Martin, chief of
section on cognitive neuropsychology, and colleagues James Haxby, chief
the section on functional brain imaging, and Leslie Ungerleider, chief
the Laboratory of Brain and Cognition, use these techniques to explore
the brain stores information. They begin with such simple objects as
animals, houses, chairs, pencils and tools. "We can now see this whole
network, this whole cascade that is going on in milliseconds within the
brain," Martin said.
      The findings reveal a brain organized around the processes of
learning, not the objects themselves, and by the way in which these
are used. "A hammer, for instance, is stored in an area that involves
motion, while the image of a cat is placed in a part of the brain that
contains other visual shapes," Martin said.
      To identify an object, he said, "we instantly retrieve information
the features that define it. What does it look like? What color is it?
does it move or how do we manipulate it, if it's a tool?"
      For example, the studies found that verbs are stored in areas of
brain just in front of regions involved in the perception of motion.
of objects - the memory of a bright yellow hue of a pencil, for example
are stored next to the perception of color.
      Thus a hammer is stored three ways in the brain: once for its
once for its use or motion and once for the memory of the motor skill
to use it. "We store these bits of information about objects near their
features," Martin said. " ... It's all very logical."
      These findings also support clinical observations made by British
researchers Elizabeth Warrington and Rosaleen McCarthy, who noticed a
selective loss in the ability to name or retrieve objects in some
brain-damaged patients. Depending on where the injury occurred in the
some patients lost the ability to name small inanimate objects, such as
mops, forks and chairs, but retained the ability to recall living things

large objects, such as kittens, autos and clouds.
      "It looks like how we store information is not randomly scattered,

follows a plan and the plan is organized the same way our sensory and
systems are organized," Martin said. "Color goes with color, form goes
form, motor information with motor information."
      But scientists are searching even deeper, seeking to unravel how
individual brain cells store and share information. Last month,
at the University of Geneva in Switzerland announced that they had
what appears to be the first electron micrograph image of the cellular
changes involved in long-term memory. Reporting in the journal Nature,
team showed how the connections between two nerve cells in a rat's brain

change significantly when long-term memory is established.
      In an alteration that is believed to occur across nearly all
from rat to human, the team found significant changes in the spiny
that form at gaps between nerve cells called synapses. Scientists
that this change allows for a host of associations to be made linking a
particular memory with experiences, thoughts, emotions, sights, sounds
       Copyright 1999 The Washington Post Company

Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=13070