Published in PNAS: A brief cue leaves a day-long internal state imprint in planarians
- planarianbrain
- 2 日前
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Our paper, “A single brief cue leaves a day-long internal state imprint in planarians,” has been published in Proceedings of the National Academy of Sciences (PNAS).
A single brief event does not always end when the event itself is over. In this study, we found that a brief, weak stimulus delivered once to planarians can leave a lasting effect, altering the likelihood of later spontaneous behavior for about 24 hours.
The key point is that the animals did not simply become more active. After stimulation, planarians did not just move faster or stay active longer. Instead, the change appeared in how behavior was initiated: they became more likely to transition from a resting state to an active state. This indicates that a fleeting cue can persist as an internal state imprint and shape later behavioral output.
Planarians are flatworms with a centralized nervous system and remarkable regenerative ability. Because they retain evolutionarily ancient features of nervous system organization, findings in planarians can provide insight into core principles by which nervous systems carry past experience forward into future behavior.
To capture this long-lasting effect, we combined long-term video recording with deep-learning-based tracking and analyzed spontaneous behavior over extended periods. This approach allowed us to detect a day-scale change that would be difficult to recognize from short observations alone.
A single brief cue leaves a day-long internal state imprint in planarians Ezomo, O. F., Suzuki, R., Narahashi, M., Matsuo, S., and Inoue, T. PNAS, 123, 2026 https://www.pnas.org/doi/10.1073/pnas.2606749123
