| Summary: | 博士 === 國立清華大學 === 分子醫學研究所 === 100 === Behavioral and neural plasticity is fundamental in modern neuroscience. It is well known that environmental enrichment can affect behavioral and neural development in many animals. Particularly, visual experience plays an important role in the activity-dependent modification of visually driven behaviors and visual systems. Cuttlefish are benthic cephalopods with a complex nervous system, and most of their behaviors are visually driven. Since their embryonic and postnatal developments are continuous without metamorphosis and hatchlings are relative easy to breed in the laboratory, this group of animals provides a unique opportunity to examine the effects of early visual experience on behavioral and neural plasticity. Previous studies have shown that enriched environment is crucial for proper behavioral development in cuttlefish. However, whether visual experience alone during embryonic and postnatal developments can modify specific behaviors and neural systems remains unclear. Using cuttlefish Sepia pharaonis, the present study investigated the effects of visually impoverished and/or enriched environments on (1) camouflage body pattern maturation, (2) background preference, and (3) expression of glutamate receptors in the optic lobe, from 7 days pre-hatching to 12 weeks post-hatching. Specifically, two distinct impoverished rearing backgrounds, checkerboard (high contrast) and uniform-gray (low contrast), were used to compare the effects of different visual contrasts on behavioral and neural plasticity in long- and/or short-term exposures. The results showed that environmental enrichment in embryonic and postnatal stages is critical for the development of high contrast background preference in S. pharaonis, whereas the impoverished environment can delay or reverse their background preference. Furthermore, cuttlefish long-term reared in high and low contrast environments showed different camouflage body patterns and NMDA-like receptor expressions, whereas cuttlefish short-term exposed to checkerboard can increase their tendency of high contrast background preference. Taken together, these findings indicate that both embryonic and postnatal visual experiences can influence behavioral and neural developments in cuttlefish. It also highlights the importance of the environmental enrichment and visual contrast in affecting early cuttlefish development. The present study thus provides a good correlation between the plasticity of visual system development and the plasticity of visual behavior maturation in cephalopods.
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