The cerebral cortex, a layer of neural tissue surrounding the
cerebrum of the mammalian brain, has been known to play various
roles in memory, language, thought, attention, and
consciousness. Up until now, no invertebrate equivalent to the
cerebral cortex has been encountered, but Detlev Arendt, Raju
Tomer, and colleagues may have found an evolutionary
counterpart. The obvious answer is hidden in one simple
creature– the worm. Wait, what? Yeah, you heard me. The marine
ragworm, found at all water depths, has been shown to possess a
tissue resembling that of our mysterious cerebral cortex. Arendt
and his colleagues used a technique called cellular profiling to
determine a molecular footprint for each kind of cell in this
particular type of ragworm. By utilizing this technique, they
were able to uncover which genes were turned on and off in each
cell, providing a means for cellular categorization.
Surprisingly, mushroom bodies, regions of the ragworm’s brain
that are thought to control olfactory senses, show a