The human brain continues to produce new nerve cells throughout its life and these neurons may be key to learning new information. But many of these novice neurons wither and die before joining the vast signaling network of their mature peers.
Now new research seems to show that the presence or absence of new information--represented by the neurotransmitter glutamate--may determine a young neuron's survival.
Fred Gage of the Salk Institute for Biological Studies and his colleagues suspected that a lack of brain signals significantly impacted a new neuron's fate. A recently generated neuron must form synapses within three weeks or it will not survive. To test this theory, the researchers created a virus capable of blocking the receptor for glutamate--a chemical involved in transferring information between brain cells. When injected into mice, the virus effectively cut off the glutamate receptor--N-methyl-D-aspartate (NMDA)--in new neurons, which were also marked with fluorescent dye to ensure tracking. In the absence of signals from surrounding cells, these did not last more than a few weeks. "The NMDA receptor modulates synapse formation and determines what pattern of input activity new neurons receive, which in turn determines survival," Gage explains.
http://www.sciam.com/article.cfm?chanID=sa003&arti cleID=000BDA15-F772-14DC-B77283414B7F0000
Kids with learning difficulties
