Okinawa Institute

Researchers at the Okinawa Institute of Science and Technology have released Spi‑Fly, an algorithm that emulates the olfactory system of the fruit fly, which contains about 140,000 neurons. The model can identify a wide range of odors in a fraction of a second and retain the memory of each scent for an extended period. Current electronic noses are costly, detect only a narrow set of chemicals, and forget odors as soon as new ones are learned. Spi‑Fly’s design promises to overcome these limitations by providing rapid, persistent odor recognition without the need for large, expensive sensor arrays. The algorithm was published in the journal Neuromorphic Computing and Engineering.

Researchers at the Okinawa Institute of Science and Technology Graduate University in Japan have made a groundbreaking discovery about how memories are stored in the brain. By inducing a hibernation-like state in mice, they found that more than half of the mice's synapses were erased, yet the mice retained their memories. This challenges the leading hypothesis that memories are stored in strengthened connections among neurons. The study, published in Science, used a technique developed by Takeshi Sakurai to artificially activate the hibernation circuit in mice. This discovery has significant implications for our understanding of how memories are stored and retrieved in the brain.

In a new study published in *Science*, researchers at the Okinawa Institute of Science and Technology showed that mice can keep a learned fear memory even after more than half of the synapses in the engram neurons of their hippocampus disappear during an induced hibernation state. The team trained mice to associate an alcohol‑smelling chamber with mild electric shocks, then artificially slowed the animals’ metabolism with drugs and darkened the chamber for two days. Five days later, the mice still froze in the chamber, indicating the memory was intact. Brain imaging revealed that while many synapses vanished, those clustered closely on the surface of engram neurons remained, while non‑clustered synapses were lost but reappeared within a day after hibernation. Dr. Kazumasa Tanaka, the study’s lead author, said the findings suggest clustered synapses are essential for memory persistence, whereas non‑clustered ones may help access the memory. The results challenge the long‑held view that a memory requires a stable, specific synaptic pattern and open new avenues for understanding memory resilience in conditions such as amnesia or Alzheimer’s disease.