Until recently anatomists were convinced that humans are born with all the neurons they are ever going to own. In the first years of life, some of theses neurons are then pruned due to a dynamic selection process. From then on, the only serious change to the brains was thought to come from cell death or inflicted lesions.
Not so. The brain actually continues to rebuild itself throughout life. For instance, new cells are born in the hippocampus. And a new study from a group at MIT demonstrates that adult dendrites of non-pymidal neurons are able to expand their branches. Here’s the abstract:
Despite decades of evidence for functional plasticity in the adult brain, the role of structural plasticity in its manifestation remains unclear. To examine the extent of neuronal remodeling that occurs in the brain on a day-to-day basis, we used a multiphoton-based microscopy system for chronic in vivo imaging and reconstruction of entire neurons in the superficial layers of the rodent cerebral cortex. Here we show the first unambiguous evidence (to our knowledge) of dendrite growth and remodeling in adult neurons. Over a period of months, neurons could be seen extending and retracting existing branches, and in rare cases adding new branch tips. Neurons exhibiting dynamic arbor rearrangements were GABA-positive non-pyramidal interneurons, while pyramidal cells remained stable. These results are consistent with the idea that dendritic structural remodeling is a substrate for adult plasticity and they suggest that circuit rearrangement in the adult cortex is restricted by cell type–specific rules.
The paper was published in PLoS Biology which means it is open-access. Go grap it!
Lee, WCA. et al. (2006): Dynamic remodeling of dendritic arbors in GABAergic interneurons of adult visual cortex. PLoS Biol 4(2): e29.