Does this dramatic difference in physiology imply a difference in function? Not necessarily. We show that the physiological properties of the VL neurons, particularly the linear input-output relations of the intermediate layer neurons, allow the two different networks to perform the same computation. The convergence of different networks to the same computational capacity indicates that it is the computation, not the specific properties of the network, that is self-organized or selected for by evolutionary pressure.

SUMMARYIt is now well established that prenatal sensory experience affects development itself and has long-term consequences in terms of postnatal behavior. This study focused on the functionality of the sensory system in cuttlefish in ovo. Embryos of stage 23, 25 and 30 received a tactile, chemical or visual stimulus. An increase of mantle contraction rhythm was taken to indicate a behavioral response to the stimulus. We clearly demonstrated that tactile and chemical systems are functional from stage 23, whereas the visual system is functional only from stage 25. At stage 25 and 30, embryos were also exposed to a repeated light stimulus. Stage 30 embryos were capable of habituation, showing a progressive decrease in contractions across stimulations. This process was not due to fatigue as we observed response recovery after a dishabituation tactile stimulus. This study is the first to show that cuttlefish embryos behaviorally respond to stimuli of different modalities and that the visual system is the last to become functional during embryonic development, as in vertebrate embryos. It also provides new evidence that the memory system develops in ovo in cuttlefish.

This study aims to analyze the effects of electrolytic lesion, restricted to either the ventral or the dorsal parts of the vertical lobe (VL), on the behavior of cuttlefish (Sepia officinalis). Two behavioral tests were performed on sham-operated and lesioned cuttlefish: assessment of locomotor activity in an open field and determination of spatial learning abilities in a T maze. The results showed that ventral lesions of the VL led to marked impairment in the acquisition of spatial learning, whereas dorsal lesions of the VL increased locomotor activity in the open field and impaired long-term retention of spatial learning. This study establishes for the first time the existence of distinct functions in the ventral and the dorsal parts of the VL in cephalopods.

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