Figure 2. Histology at tip of implant shows microfibers splayed throughout the target region.

A 100 μm thick brain section showing the tips of a bundle of 530 optical microfibers implanted at a depth of 2.95 mm. Before insertion, the bundle had a diameter of 570 μm. This section was collected four months after implant, and the brain sectioned perpendicularly to the insertion angle. The cross sectional area of tissue displaced by the microfibers (annotated in green) is 26,640 μm² (pink circle).