In this paper, Thompson and Cline seek to determine the effect of Thyroid Hormone (TH) on early brain development, including cell proliferation in neural progenitor cells, neuronal differentiation, and dendrite arbor development. In order to achieve this, the study used spatial and temporal manipulations of TH signaling, targeted DIO3 treatment, analysis of brain morphology, and time-lapse in vivo imaging of neural progenitor cell (NPC) response to T3 treatments. One interesting result from this study was even after just six days of treatment, brain morphology had significantly changed to decrease the rostrocaudal length of the brain and increase the width of the optic tectum, suggesting major neurogenesis and development. The data also suggested that both widespread and local administrations of TH increased tectal cell proliferation through the increase of NPCs. Through the results of the study, the authors concluded that the brain is sensitive to TH signaling during developmental stages because the neural circuits are forming, local TH signaling changes the fate of NPCs by expanding the tectal progenitor pool and increasing NPC differentiation into neurons, and that increased TH signaling increases dendritic arborization in neurons that had already differentiated. Overall, I think this paper could have improved in the background information, because I had to look up practically every word because there was no explanation of what things were.
I understand that this wasn’t aimed at beginning neuroscience students, however I think a key to successful research papers is being able to explain things in a way that is commonly understood. I think one of the most interesting parts of this paper was the discussion about increased dendritic arborization as a result of T3 treatments. The idea that this arborization increases synaptic connectivity in the retinotectal circuit is interesting and could imply interesting medical applications in the future for individuals with decreased synaptic connectivity. In terms of the actual research, I think it would be interesting to see this research applied to mammals. Although Thompson and Cline describe why it is difficult to examine these effects in the mammalian brain, I believe that this would be a monumental step to take for this research. To apply this work to mammals could imply a future treatment for congenital optic neurogenesis disorders. I’m curious as to how this research would be different, because in this experiment they were able to just bathe the tadpoles in the solution they wanted to test or inject it in the eye with coconut oil, however in mammals there would have to be a method to inject the solution into the animal such that it crosses the blood brain barrier.
In addition, the T3 treatment and increase of TH levels and signaling could be an interesting addition in the field of neonatology in cases of congenital neurogenesis disorders. In relation to this idea, perhaps one day this research could even be applied to congenital heart disorders, which affect many children.