Neuroscience
You're nothing but a pack of neurons.
— (1994)
A fly can lose a scent and still turn back. In a virtual plume, a remembered direction helped
Tethered fruit flies repeatedly returned to an odor boundary after walking into clean air. Behavior, modeling and neural perturbations support a compact memory of direction, not a complete map. The result comes from a controlled virtual-reality assay and does not yet show the same strategy in free natural flight.
A gene that ships toxic tau out of neurons both clears it and helps it spread
Tau pathology moves from neuron to neuron in Alzheimer's disease, but how tau leaves a cell has been unclear. A Cell study finds that Arc - a neuronal gene that forms virus-like capsids - directly binds tau and packages it into extracellular vesicles that neurons release. In mice and cultured cells, deleting Arc cut the amount of seed-competent tau in those vesicles and nearly abolished cell-to-cell transmission; in human Alzheimer's brain vesicles, Arc levels tracked with phosphorylated tau. The catch is that the same packaging both removes toxic tau from a neuron and helps spread it: Arc-less mice accumulated more tau inside neurons and showed a modest early rise in cell death. This is a mechanism in models plus a human correlation - not the cause of Alzheimer's, and not a therapy.