a standard “parts list” of the brain.
While some scientists are hard at work
categorizing all these different cells, others are thinking about what such diversity
means for living, breathing animals. New
results suggest, for instance, that a population of nerve cells in which individual
responses to an electrical poke differ can
process more information than a group
in which responses are the same. Others
think that variety might help the brain
cope with a changing environment.
Accounting for all of the individual
brain components — a task as daunting
as finding out every New Yorker’s favorite color, credit score and whether they
cry at sad movies — isn’t just a tedious
sorting job. A deeper knowledge of the
brain’s inhabitants might lead to new
treatments for brain-related disorders.
If particular cells are more vulnerable to
diseases such as dementia, schizophrenia and autism, therapies that protect
or target these cell populations may be
effective. More broadly, knowing who
is doing what in the brain will help scientists understand the inner workings
of the impossibly complex three-pound
hunk of flesh that sits in the skull.
Brain census
Yuste is a collector. Instead of Broadway
ticket stubs or rare butterflies, he and
his colleagues sift through nerve cells in
the brain, meticulously cataloging each
cell’s appearance, behavior and habitat.
Yuste believes that before scientists can
understand the boroughs of the brain,
they must know who lives there. “People
like us are interested in studying how the
brain works by taking it apart,” he says.
Current classes neuroscientists catalog nerve cells in many ways. one simple distinction is to sort neurons structurally by the number
of long, thin extensions that send and receive messages from other cells. though helpful, these groups represent the very tip of the classification iceberg. scientists are finding vast diversity among neurons in the brain and are trying to make sense of what the differences mean.
Unipolar neurons have just one long
projection that carries information. one
job of these neurons is to collect sensory
information from the skin and send the
message to the brain.
Bipolar neurons have one message-receiving dendrite and one message-sending axon. bipolar neurons in the eye
collect information from rods or cones
and pass it along to other nerve cells.
Multipolar neurons have one axon and
many dendrites, which collect information from lots of different places. this
class includes interneurons, which carry
signals within the brain and spinal cord.
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july 30, 2011 | SCIENCE NEWS | 23
