An octopus has more neurons in their peripheral nervous system (PNS) than in their brain. PNS neurons could participate in forming cognitive networks with the central brain in the same way that the cerebellum is now thought to contribute to mammalian cognition. However, cephalopods lack myelinated fibres, which might decrease the ability of the PNS to participate in cognitive networks. The lack of myelinated fibres may also select for a less integrated brain, with an increased emphasis on local

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... information processing. Alternatively, integration may still occur across distant neural centers, but proceed more slowly in cephalopods than in mammals. Shelley Adamo is a professor in the Department of Psychology and Neuroscience at Dalhousie University. She focuses on invertebrate behavioural physiology. She wishes she knew how brains work, even very small ones. Website