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Cocaine abuse continues to be a significant problem in the USA and elsewhere. Cocaine is an indirect agonist for dopamine, norepinephrine and serotonin with numerous potential downstream effects, including processes and signals associated with adult neurogenesis. Since drug addiction is associated with brain plasticity, we hypothesized that cocaine exposure would alter cellular proliferation in two adult neurogenic regions (the subventricular and subgranular zones). We used bromodeoxyuridine (BrdU) to track newly generated cells in the brains of adult mice after chronic cocaine or saline exposures. No differences were found in the number or migration patterns of BrdU-labeled cells in the forebrain neurogenic areas. However, cocaine produced a significant increase in the number of hippocampal BrdU-labeled cells. KeywordsCocaine; subventricular zone; subgranular zone; adult neurogenesis It is well documented that both short-term and chronic exposures to recreational drugs can induce structural changes in the brain [25,34], alterations in learning and memory [29], as well as changes in mood and cognition [2,39]. Although the mechanism underlying these changes is complex, alterations in neurogenesis may be a contributing factor [13]. The process of neurogenesis is well described in the adult nervous system [28]. It predominantly occurs in the dentate gyrus of the hippocampal formation and the subventricular zone (aSVZ) of the lateral ventricles, structures that are thought to contribute to memory formation, mood regulation and olfaction [44].A number of factors influence adult neurogenesis, including aging, stress, exercise, genes, the environment, and learning as well as circulating factors such as hormones, growth factors and neurotransmitters [44]. Neurogenesis in the subgranular zone of the adult hippocampus (SGZ) is decreased by corticosteroids [17] whereas antidepressant treatment results in increased proliferation and survival of newborn hippocampal cells, possibly through serotonin (5-HT) or norepinephrine-dependent mechanisms [43]. The monoamine

This is the first investigation of the spectral tuning properties of single chemoreceptor cells of the third maxillipeds (mouthparts) of the lobster Homarus americanus. These organs are used, among other functions, for chemical recognition of food. Based upon extracellular recordings of action potentials, we report on 53 cells identified with a 15-compound equimolar mixture of mostly amino acids in an artificial seawater background (applied mixture concentration 150 {mu}M). Subsequently, all cells were tested with each compound separately. Cells were generally narrowly tuned to a single compound. Twenty-five percent of the cells sampled responded best to L-glutamate, 17% to betaine, 11% to taurine, and 9% to ammonium chloride. There was no consistent second best stimulus for these four cell populations. Two other populations were more broadly tuned: one responded best to hydroxy-L-proline and the other to L-arginine. Some cells responded to both compounds. Arginine-sensitive cells (not necessarily "arginine-best" cells) tended to respond also to a lesser degree to leucine. Hydroxy-L-proline-sensitive cells tended to respond to a lesser degree to glycine. Among the lobster's chemoreceptive organs, the tuning of the maxillipeds is the broadest of all and resembles the tuning of the walking legs more than that of the antennules or antennae.