A tot grows up speaking a different mother tongue if he is adopted
by a Parisian family than if his new family lives north of the Channel.
That’s because environment, not just genetics, is crucial for
language development. On the other hand, the chemical language that
nerve cells use to talk to one another was thought to be entirely
genetically determined. Not so, according to a study UCSD biologists published recently
in the journal Proceedings of the National Academy of Sciences.
Changing
the pattern of electrical activity in the developing nervous system
alters the nerve cells’ “mother tongue,” or more
precisely, the chemical (neurotransmitter) released by one nerve
cell and detected by a structure (receptor) on another. The finding
has implications for treating a wide range of brain disorders say
the study’s authors, Nicholas Spitzer, a professor of biological
sciences, and Laura Borodinsky, who was an assistant project scientist
working with Spitzer when she performed the research.
“Most cognitive disorders, such as depression, schizophrenia and Parkinson’s
disease, involve problems with neurotransmitters or neurotransmitter
receptors,” says Spitzer. “If modifying electrical activity
in the adult brain can alter neurotransmitters and receptors similar
to the way we have discovered in the developing frog nervous system,
it could provide a promising approach to treating these disorders.”
Spitzer and Borodinsky used drugs to increase and decrease electrical
activity in the nerve cells of frog embryos. Not only did the manipulation
change the identity of the neurotransmitter produced by the nerve
cells, the identity of the neurotransmitter receptors changed to
match. The researchers found that cells started out with many different
types of receptors, so that, like babies, the cells had the potential
to mature and were capable of understanding any one of many different
languages. The cells then eliminated the receptors that were not
being used. “It may seem wasteful to start with multiple types of receptors, and
then eliminate the ones that aren’t needed,” comments
Spitzer. “But it provides organisms with the ability to adapt
to
the environmental conditions in which they are living.”
Spitzer thinks this study provides useful information for researchers
who are developing experimental treatments involving electrical
stimulation of the brain. “If electrical stimulation shows promise as a treatment,” he
explains, “understanding the mechanism by which it works should
make it possible to be much more selective about how and where to
stimulate the brain.” 
— Sherry Seethaler
|
