The current model of adult neurogenesis in mammals suggests that adult‐born neurons are generated by stem cells that undergo long‐term self‐renewal, and that a lifetime supply of stem cells resides in the brain. In contrast, it has recently been demonstrated that adult‐born neurons in crayfish are generated by precursors originating in the immune system. This is particularly interesting because studies done many years ago suggest that a similar mechanism might exist in rodents and humans, with bone marrow providing stem cells (...) that can generate neurons. However, the relevance of these findings for natural mechanisms underlying adult neurogenesis in mammals is not clear, because of uncertainties at many levels. We argue here that the recent findings in crayfish send a strong signal to re‐examine existing data from rodents and humans, and to design new experiments that will directly test the contributions of the immune system to adult neurogenesis in mammals. (shrink)

I am in the process of refining my doctorate thesis objective, having battled through a Master’s degree in the Philosophy of Language. The doctoral issue, of course, has many facets: political, academic, locational, and financial. But the topic relevant to this paper is the issue of “interpretation” raised by Lonergan in the third section of chapter 17 of Insight . The challenge of this paper (and this volume) is to lift that section into the context of hodic conversion.