Olfactory Imprinting: A Worm's Memory of Things Past

Behavioral adaptations of Caenorhabditis elegans against pathogenic threats

This review examines the behavioral adaptation mechanisms of Caenorhabditis elegans in response to pathogenic bacterial threats, emphasizing their ecological significance. It systematically explores how mechanisms such as avoidance behavior, transgenerational learning, and forgetting enable C. elegans to optimize its survival and reproductive strategies within dynamic microbial environments. C. elegans detects harmful signals through chemosensation and initiates avoidance behaviors. Simultaneously, it manages environmental adaptation and energy allocation through transgenerational memory and forgetting, allowing C. elegans to cope with selective pressures from environmental fluctuations. In contrast, pathogenic bacteria such as Pseudomonas aeruginosa and Salmonella influence C. elegans behavior through strategies such as toxin release and biofilm formation, highlighting the complex co-evolutionary dynamics between hosts and pathogens. Additionally, these pathogens employ "Trojan Horse-like" and "Worm Star" mechanisms to kill C. elegans, further complicating host-pathogen interactions. These processes are driven by behavioral adaptations, biochemical signaling, and evolutionary pressures, which emphasize the ecological niche of C. elegans within microbial ecosystems. C. elegans serves as a valuable model for studying host-pathogen interactions. This study provides crucial theoretical insights into adaptive evolution and ecosystem dynamics, offering valuable guidance for the development of biocontrol strategies and the effective management of microbial ecosystems.

Olfactory Critical Periods: How Odor Exposure Shapes the Developing Brain in Mice and Flies

Neural networks have an extensive ability to change in response to environmental stimuli. This flexibility peaks during restricted windows of time early in life called critical periods. The ubiquitous occurrence of this form of plasticity across sensory modalities and phyla speaks to the importance of critical periods for proper neural development and function. Extensive investigation into visual critical periods has advanced our knowledge of the molecular events and key processes that underlie the impact of early-life experience on neuronal plasticity. However, despite the importance of olfaction for the overall survival of an organism, the cellular and molecular basis of olfactory critical periods have not garnered extensive study compared to visual critical periods. Recent work providing a comprehensive mapping of the highly organized olfactory neuropil and its development has in turn attracted a growing interest in how these circuits undergo plasticity during critical periods. Here, we perform a comparative review of olfactory critical periods in fruit flies and mice to provide novel insight into the importance of early odor exposure in shaping neural circuits and highlighting mechanisms found across sensory modalities.