Part of the Stanford Neurosciences curriculum is attendance at a weekly journal club wherein students take turns presenting 30 minute presentations on current or classic papers. Recently, Poh Hui Chia, a 3rd year graduate student in the laboratory of Kang Shen, presented a paper recently published in Cell that used a novel computational technique to examine the possibility that mushroom bodies and vertebrate pallium (aka cortex) could have shared a common ancestor.
Profiling by Image Registration Reveals Common Origin of Annelid Mushroom Bodies and Vertebrate Pallium, by Tomer et al, contains a methodologically complex analysis of key cellular and molecular features of both the marine annelid worm, Platynereis' mushroom bodies and the mouse pallium. Those readers with an appreciation for comparative neuroanatomy are sure to enjoy Poh Hui's discussion of the paper's unique computational methods and intriguing results.
In the introduction to their paper, Tomer et al describe the highlights of their paper as follows:
► A new protocol for cellular resolution expression profiling by image registration ► Generation of a multigene map of the developing annelid brain ► The annelid mushroom bodies and the vertebrate pallium share molecular coordinates ► Homology of sensory associative brain centers in Bilateria
JC Presentation Part 1
JC Presentation Part 2
From Tomer et al, 2010:
The evolution of the highest-order human brain center, the “pallium” or “cortex,” remains enigmatic. To elucidate its origins, we set out to identify related brain parts in phylogenetically distant animals, to then unravel common aspects in cellular composition and molecular architecture. Here, we compare vertebrate pallium development to that of the mushroom bodies, sensory-associative brain centers, in an annelid. Using a newly developed protocol for cellular profiling by image registration (PrImR), we obtain a high-resolution gene expression map for the developing annelid brain. Comparison to the vertebrate pallium reveals that the annelid mushroom bodies develop from similar molecular coordinates within a conserved overall molecular brain topology and that their development involves conserved patterning mechanisms and produces conserved neuron types that existed already in the protostome-deuterostome ancestors. These data indicate deep homology of pallium and mushroom bodies and date back the origin of higher brain centers to prebilaterian times.