October 27, 2008

Special Brain Signal Used in Visual Reflex

U.S. scientists say they've found the nervous system uses a specific type of signal to produce stable retinal images despite vigorous head movements.

Researchers at the Salk Institute for Biological Studies said that in most nerve cells, an electrical signal reaching the end of a cell releases molecules called neurotransmitters that travel across the synapse -- the space between nerve cells -- and may or may not trigger an electrical signal in an adjacent cell.

"Most known synapses act as information filters, and both the probability and the extent of neurotransmitter release Â… depend heavily on the recent history of the synapse," said Martha Bagnall, the study's first author.

Bagnall and colleagues found signal transmission occurs differently in the vestibular-ocular reflex, or VOR, part of the brain. They found no matter how fast the sensory neuron in the VOR fires, the same amount of neurotransmitter was released. The researchers said that type of nerve transmission allows humans to rapidly and reliably produce a stable retinal image, despite eye, head and body movements.

The study, which included Associate Professor Sascha du Lac, graduate student Lauren McElvain and postdoctoral researcher Michael Faulstich, appears in the journal Neuron.