Tye et al., dopamine effects

         Depression is a very prevalent disease that causes many people discomfort over ranged periods of time. Whether or not dopamine neurons are relevant or not could not be tested until recent times because of a lack of necessary technology. It makes sense that the limbic region is localized for depression, considering the many mood-altering symptoms, and that the “pleasure center” nuclear accumbuns is where dopamine neuronal activity would affect mood changes.

        The methods used by Tye et al. seem to be good characterizations of their experiments and I found their time frame, as well as general methods to be more effective than Chaudhury et al. For example, the time-intensive chronic mild stress test took into account the long term clinical depression symptoms more accurately. They also establish a steady baseline of assays early on, by providing data showing that the selective inhibition of VTA dopamine neurons leads to anhedonia and other symptoms while phasic activation re-invigorates the chronic mild stress induced models. The NAc function being altered by the effects of VTA neuronal activation shows a good indication of the circuit dynamics of depressive systems.

        The results of the study could have tremendous impact on the pharmaspuetical industry. Considering that VTA dopamine neuron recruitment alters depression-related behaviors, it is a big go ahead for the industry to increase research and development into more drugs affecting the complex dopamine system.  Not only with drug development, further research into the pathway could allow a complete mapping of the downstream effects of dopamine pathways, allowing further determination of function and structure (at least in animal models). With the focus on specific targeted circuits, it seems that any significant result can lead to further research and eventually a breakthrough in the treatment of depression.  

        Additionally, the use of optogeneitcs in both studies allows us to get an idea of how important the technique is and shows how much research can progress with the use of channel rhodopsin. They also combined the technique with electrophysiology robustly.