One of the most fundamental bifurcations in the evolution of the brain is the step from diffuse neural nets such as in jellyfish to a structured "rope-ladder" nervous system with a central and a peripheral part in bilateralians. The latter have for the first time a preferred direction of movement, which comes along with cephalization, the development of a head with an accumulation of sense organs and ganglia. The cerebral ganglia of early bilateralians might be seen as earliest predecessors of the brain.

We test the cognition of Schmidtea mediterranea, a freshwater planarian used in regeneration and developmental studies, with paradigms similar to those used to explore the intelligence of rodents. For instance, we test their spatial memory in a T-maze.

Schmidtea mediterranea
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