Neurogenesis in Protracted Abstinence from Alcohol. Nixon, K., Crews, F.T. Journal of Neuroscience 2004, 24(43):9714-9722 http://www.jneurosci.org/cgi/content/full/24/43/9714 Here's article number 3. My testing shows that it should be available freely to all, let me know if you have problems. I selected this article for several reasons. First, it describes one of the most interesting revelations to come out of neuroscience in recent years. It has always been the dogma in neuroscience that once the brain is mature and fully developed then there are no new neurons formed and regeneration of injured neurons does not occur. What you got is what you get and there is no central nervous system neurogenesis once the plan is complete. This concept was so entrenched into every neuroscientist's brain that even when the initial experiments, performed by Altman in the 1960s, demonstrated neurogenesis in discrete regions of the adult rat brain, it was basically ignored for almost 40 years. There were scattered paper along the way that also showed adult neurogenesis, but it wasn't until the '90s that this field really came into its own. Thus, we currently know that there are specific regions of the brain where thousands of new neurons are created daily. This discovery of adult neural stem cells has dramatically changed the way neuroscientists think about learning and memory, disease states and numerous other brain specific processes. Now, just so I don't get too "neuro-centric" here, stem cells have been a hot topic for many years and continue to be a growing field in many different disciplines, not just neuroscience. This brings me to my second reason, I am currently working outside the brain looking at the role of the aryl hydrocarbon receptor and environmental toxicants on hematopoietic stem cells (HSC). These HSCs reside in bone and produce all the blood cells and mature/precursor cells for the immune system. To say that they are important is an understatement, but no less so than the neuronal precursors in this discussion. In very general respects stem cells share common traits and characteristics, so I might learn something from this discussion that could ultimately prove important for my HSC work (don’t blame me for being selfish, Moonbear did the same thing). The third reason I choose this paper, rather than one of the referenced papers that initially discovered adult neurogenesis, is that it goes on to examine adult neurogenesis in the context of a toxicological challenge, i.e., alcohol (ethanol) exposure. As alluded to above I am a toxicologist by training thus I thought I could bring a little of that particular flavor of science into our discussion as well. Having said that, I am not an "alcohol toxicologist" (maybe they're called intoxicologists); I study substances like dioxin, PCBs, and other halogenated aromatic hydrocarbons. While these do affect brain function, this paper gives me an opportunity to discuss (and learn about) another aspect of neurotoxicology that the general public is probably more familiar with. By way of a brief introduction, the paper focuses mainly on the neuronal precursors in the hippocampus, a region of the brain believed to be the center of learning and memory. Originally it was thought that learning processes and memory consolidation was based in the plasticity of the resident neurons. Mechanisms such as increasing dendritic arborization and synaptic contacts were thought to play a role, however in addition to the mechanisms, it is now thought that the constant production of new neurons in this brain region also plays a significant role. So what's with the alcohol? We all know that it is bad from pregnant women to drink. One aspect of fetal alcohol syndrome is alterations in brain anatomy and function. Thus if exposing growing fetal neurons to alcohol is deemed bad, then it logically follows that exposing growing neurons in the adult could also have deleterious effects. Thus the researchers set out to study the process of new neuron growth, using an adult rat model that was exposed to alcohol, to determine if there was an impact on neurogenesis. Their previous work has established that alcohol intoxication alters hippocampal neurogenesis, thus the next question they sought to address was what happens when you stop drinking alcohol? Are the effects reversible or have you permanently altered the system? Read on and find out.