Laser-engineered PRIME fiber for panoramic reconfigurable control of neural activity

Understanding the neural basis of behavior requires tools to flexibly control neural activity across distributed circuits. Optical methods enable precise, cell-type-specific control, but current fiber-based approaches deliver light to only a few fixed sites, limiting versatility. To address this, we developed 'panoramically reconfigurable illuminative' (PRIME), a single-fiber probe with over a thousand light-emitting sites distributed along its length and circumference, enabling panoramic and reconfigurable illumination from a single implant. We equipped a 160-μm multicore fiber with laser-engineered grating light emitters at designated axial and radial positions. By modulating input light patterns, PRIME dynamically switched illumination at 60 Hz among 1,200 sites spanning 5 mm and 360°. By integrating PRIME with high-density recording arrays, including Neuropixels, we demonstrated spatially targeted optogenetic activation alongside simultaneous electrophysiological recording in vivo. In freely moving mice, stimulation at different depths and locations within the superior colliculus evoked distinct defensive behaviors. PRIME's scalable and reconfigurable light delivery across large volumes offers a powerful platform for optical control of neural circuits across the brain.