As a neurobiologist in training and someone who was raised in an art appreciative family (nearly every single member of my extended family is an art teacher, professional artist, or used to do graphic design), I love reading original research articles that identify projections to and from brain regions. Very recently, I have done some background reading on the lateral habenula, which lies in the thalamus and has been a hott brain area to study in drug addiction, sleep, and circadian rhythms research. This paper, which was published earlier this year, identified the destination and types of projections arising from and arriving to the lateral habenula in the lamprey, which is identified as the oldest (at least phylogenetically) vertebrate. Hence, the purpose of this study was to inject a tracer in the lateral habenula and other brain areas hypothesized to project on to the lateral habenula and to capture the migration of the tracings through fluorescence microscopy. Here is a collection of absolutely stunning images from the paper.
Stephenson-Jones M, Floros O, Robertson B, & Grillner S (2012). Evolutionary conservation of the habenular nuclei and their circuitry controlling the dopamine and 5-hydroxytryptophan (5-HT) systems. Proceedings of the National Academy of Sciences of the United States of America, 109 (3) PMID: 22203996