Two mouse papers, one circuit and one drug pairing — and both stop at a rodent proxy.
Weekly Science Digest, 10 Oct 2026 to 16 Oct 2026.
1. Plasticity and the head twitch come apart
Two mouse studies dissociated psilocybin's synaptic remodeling from its hallucination proxy.
In Nature Neuroscience, 5-HT2A signaling in layer 5 cortical pyramidal neurons was necessary and sufficient for psilocybin's synapse formation and pruning, yet dispensable for the head-twitch response. Separately, a PDE9 inhibitor blunted psilocybin's head twitch while the antidepressant-like effect and synaptogenesis signaling survived.
The first in vivo PET measure of LSD's 5-HT2A occupancy came from seven volunteers.
Simultaneous PET-MRI showed high-affinity 5-HT2A occupancy, raised global cerebral blood flow and carotid flow, and reduced global connectivity. Plasma levels and subjective effects traced an anticlockwise hysteresis loop — effects lagging and outlasting drug concentration.
MDMA for PTSD pools to g = -0.71; psilocybin for alcohol use disorder to around SMD 0.5.
The MDMA living review covers 6 RCTs and 286 participants, all MAPS-sponsored, with response risk ratio 1.35 and remission 2.25. The alcohol meta-analysis found 6 trials and only 202 participants total, of which 3 were randomized.
Oregon's psilocybin centers screened callers carefully but charge a median $1,900.
In a mystery shopper study of 22 licensed centers, none offered unsupervised use or same-day dosing without psychiatric assessment, and none told callers to stop antidepressants. Staff interviews described centers struggling financially; 4 of 26 had already closed before calls began.
