Scientists discover addition of new brain cells in highest brain area

Jo!hn johnhkm at
Mon Oct 18 03:44:15 EST 1999

"PRINCETON, N.J. -- In a finding that eventually could lead to new methods
for treating brain diseases and injuries, Princeton scientists have shown
that new neurons are continually added to the cerebral cortex of adult
monkeys. The discovery reverses a dogma nearly a century old and suggests
entirely new ways of explaining how the mind accomplishes its basic
functions, from problem solving to learning and memory.

Elizabeth Gould and Charles Gross report in the Oct. 15 issue of Science
that the formation of new neurons or nerve cells -- neurogenesis -- takes
place in several regions of the cerebral cortex that are crucial for
cognitive and perceptual functions. The cerebral cortex is the most complex
region of the brain and is responsible for highest-level decision making and
for recognizing and learning about the world. The results strongly imply
that the same process occurs in humans, because monkeys and humans have
fundamentally similar brain structures."


"Within the cerebral cortex, the researchers found neurogenesis in three
areas: 1) the prefrontal region, which controls executive decision making
and short-term memory; 2) the inferior temporal region, which plays a
crucial role in the visual recognition of objects and faces, and 3) the
posterior parietal region, which is important for the representation of
objects in space.

Interestingly, there was no sign of neurogenesis in a fourth area, the
striate cortex, which handles the initial, and more rudimentary, steps of
visual processing. That contrast suggests that neurogenesis may play a role
in performing higher brain functions. Virtually all theories of learning and
memory hold that memories are formed by modifications at the synapse, which
is the transmission junction between neurons. On the basis of the new
findings, it is now conceivable that the introduction of new neurons into
the circuitry of the brain may play a role in memory.

Gould and Gross emphasize that any ideas about the functions of the new
neurons are highly speculative. But the fact that there is neurogenesis in
the cognitive and executive portions of the brain opens vast new areas that
can be explored.

Gould and Gross, both faculty members in the Department of Psychology,
collaborated with graduate student Alison Reeves and research staff member
Michael Graziano. The work was supported by grants from the National
Institutes of Health and the James S. McDonnell Foundation. "

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