Tye et al

While reading Tye et al., I was struck by how powerful the use of optogenetics was in clearly demonstrating the causal role of VTA dopamine neurons in the regulation of depression-related behaviors. It truly showed why this technique is so valuable for research, and the detailed conclusions it can allow us to reach.  As I read, I was extremely impressed by the ability to essentially turn on and off helplessness and anhedonia behaviors in mere minutes or less, and the possible therapeutic benefits knowledge of this could have, but then it occurred to me what a shift this study, and others like it, are forcing me to make in my view of how depression and related behaviors come to be. I suppose that is really the point of this paper, to begin deconstructing the mysterious black box that depression has been and reach a better understanding of how the disease works and how it can be treated, but it still caught me off guard on some level. In my mind, depression is something that is created over time; it isn’t an on/off light switch. This is reflected, for example, in the fact that the CMS paradigm must be carried out for weeks before depressive-like behaviors are present in lab animals, and in how antidepressants take so long to take their full effect. Having had this notion fairly ingrained in my mind, I then found it difficult to reconcile it with the finding that symptoms can be made to appear and disappear by simply activating or deactivating a relatively small (albeit important) subcategory of neurons. I certainly wouldn’t say that I don’t believe the conclusions found by Tye et al- I found their arguments to be very strong- only that they surprised and confused me. When I think of something as complex as a feeling of helplessness, I think of buildup over time of emotion, caused by repeated experiences, the memories of which eventually help guide behavior. Being shown that behaviors can come and go without altering memories or having long stretches of time go by is challenging for me to accept, but has been very interesting to think and wonder about.