An analysis of the neurobiology of motor control in the octopus must consider the octopus' special morphology.
I first describe octopus ‘embodiment’ using the embodied view that "… the actual behavior emerges from the interaction dynamics of agent and environment through a continuous and dynamic interplay of physical and information processes” (Pfeifer et al., Science 2007). The octopus, with its soft, flexible body and its great variety of active behaviors driven by a huge amount of sensory information, is ideal for assessing this view in a biological system. I review the motor control strategies evolved in the octopus to cope with its special morphology by first discussing the unique organization of the arm neuromuscular system. I then show that, most likely due to the difficulty of central representation of the arms’ infinitely large degrees of freedom, motor programs are represented at the higher motor centers. Indeed in goal-directed movements,such as reaching and fetching, control and computational labor are distributed between the central and the elaborate peripheral nervous system, alleviating the need for central representation of body parts in the higher motor centers. Finally, as an example of behavior involving coordination between arms, I describe how the octopus uses stereotypical arm elongations to push its body along during crawling. The octopus directs its crawling by ad hoc choice of which arms to elongate. In summary, fitting the idea of the embodied organization of behavior, our results show how the octopus'
distinctive morphology has led to the evolution and/or self-organization of special anatomical and functional organization of both the central and the peripheral nervous systems.
This work was supported by the Israel Science Foundation and by European FP7
Programme Projects OCTOPUS and STIFF-FLOP
Department of Neurobiology, Silberman Institute of Life Sciences and the
Interdisciplinary Center for Neuronal Computation. The Hebrew University of Jerusalem.