Now, scientists at the National Institute of Health's (NIH) National Institute of Mental Health (NIMH) have found newly born neurons that communicate via the chemical messenger GABA (gamma-aminobutyric acid) in adult rat cortex, seat of higher order "executive" functions, and in the striatum, site of habits, reward and motor skill learning. In the cortex, the new neurons appear to arise from previously unknown precursor cells native to the area, rather than from cells migrating in from another area. NIMH's Drs. Heather Cameron, Alexandre Dayer, and colleagues, report on their findings in the January 31, 2005 Journal of Cell Biology.
Their discovery adds to the scientific debate over adult neurogenesis, which has potential implications for understanding a variety of brain disorders, possibly including Alzheimer's and schizophrenia. While most researchers agree that new neurons are generated in the adult hippocampus and olfactory bulb, the existence of adult neurogenesis in other brain regions remains controversial.
The NIMH team used many more markers than previous studies to track newborn neurons as they matured and to identify the type of neurotransmitters they secreted. The markers exploited antibody affinities for specific proteins to tag particular cell types with telltale color codes, visible on brain slices under fluorescence with a laser-powered microscope.
The researchers found that the cortex and striatum were giving birth to new, widely scattered small cells, called interneurons, that make and secrete GABA, a neurotransmitter that dampens neuronal activ
Contact: Jules Asher
NIH/National Institute of Mental Health