[Frontiers in Bioscience S2, 764-771, January 1, 2010]

Functional and comparative assessements of the octopus learning and memory system

Binyamin Hochner

Department of Neurobiology, Institute of Life Sciences, and Interdisciplinary Center for Neural Computation, Edmond J Safra Campus, Givat Ram, Hebrew University, Jerusalem 91904, Israel

TABLE OF CONTENTS

1. Abstract
2. Why study complex nervous systems in invertebrates?
3. The vertical lobe of cephalopods and the insect mushroom body are unique brain structures involved in the advanced behavior of these animals
4. The morphological organization of the octopus nervous system
5. The learning and memory system of Octopus vulgaris 5.1. Morphological organization of the octopus VL-MSF syste
5.2. Electrophysiological characterization of the MSF and VL neurons
5.3. Characterization of the MSF-to-VL synaptic connections
5.4. Long term potentiation (LTP) of the MSF-VL synaptic input 6. How the VL and its LTP are involved in behavioral learning and memory?
7. Summary
7.1. Neurophysiological reflections arising from the comparison with the insect mushroom body
8. Acknowledments
9. References

1. ABSTRACT

The octopus and its close relatives the cuttlefish and squid are the most advanced of the invertebrates, possessing the largest brains both in weight and cell numbers. Here I review recent studies of the neurophysiological properties of the vertical lobe system (VL) in the cephalopod brain, a system already thought to be dedicated to learning and memory. Summarizing from the point of view of comparative evolution, I relate these results to other systems where anatomical and electrophysiological data are available, mainly the insect mushroom bodies and the mammalian hippocampus. The emerging results suggest that a convergent evolutionary process has resulted in similar neural organization and activity-dependent long-term synaptic plasticity in all these learning and memory systems, even though the invertebrate systems conserve their typical anatomical and electrophysiological features. And finally, functional inferences based on the comparison with the insect mushroom