C. elegans worms demonstrate left-right brain asymmetry in processing smell-based memories, with distinct neural pathways controlling whether an odor becomes attractive or repulsive based on past experience. The lateralized circuitry allows the same chemical stimulus to trigger opposite behaviors depending on environmental context and learning history. This neurological asymmetry represents a fundamental mechanism for adaptive behavior that likely extends across species. The discovery challenges the assumption that simple organisms rely on symmetric neural processing and suggests that brain lateralization evolved as an early solution to complex decision-making. For humans, this illuminates how our own lateralized brain architecture might have ancient evolutionary origins in basic survival circuits. The research provides a tractable model for studying how sensory memories form and switch valence, potentially informing therapeutic approaches for conditions where smell-memory associations become dysfunctional, such as PTSD or eating disorders. While conducted in a millimeter-long worm, the core principles of asymmetric sensory processing and context-dependent plasticity appear conserved across nervous systems, offering insights into the foundational logic of adaptive behavior.