🧠 Most people assume brain implants fail gradually, a slow degradation over months as scar tissue builds up and neurons drift away. That assumption is wrong, or at least incomplete. The failure starts before the surgeon closes the incision.

🦠 The moment an electrode enters brain tissue, something remarkable happens. Microglia, the brain’s resident immune cells, extend their processes toward the insertion site within seconds to minutes. Not hours. Seconds. We watched this happen in real time using two-photon microscopy, imaging living mouse brain through a small window in the skull as the electrode descended. The microglia moved like fingers reaching toward a splinter.

⌛ This immediate response sets the stage for everything that follows. The brain doesn’t wait to see whether the device is harmful. It treats any foreign object as a threat and begins responding before any damage has even been assessed.

🚧 At the same time, nearby blood vessels, some severed during insertion, others simply compressed as tissue deforms, begin to leak. The blood-brain barrier, the brain’s carefully maintained boundary between circulation and neural tissue, is disrupted. Proteins that normally stay in the bloodstream spill into brain tissue, and this triggers a cascade of inflammatory signals.

⚠️ Here’s what this means practically: two electrodes implanted by the same surgeon, in the same brain region, with the same device, on the same day, can perform very differently. Not because of anything that happened after implantation, but because of what happened during the ten seconds it took to insert them. Which blood vessels were nicked. How much the tissue compressed. Whether the trajectory grazed an arteriole or threaded between capillaries.

🔦 We were the first to show that this insertion variability has lasting consequences for how the device performs months later. That finding helped inform image-guided surgical approaches now used in next-generation BCI systems.

📣 The engineering implication is uncomfortable: even a perfect device, perfectly fabricated, can be compromised in the operating room before it ever records a single spike.

Blood Vessels: https://lnkd.in/ekVrUTmp
Microglia: https://lnkd.in/efv-dkfr
Astrocytes: https://lnkd.in/e2wFzPCT
Oligodendrocyte Precursor Cells: https://lnkd.in/eyz34b4
Engineering: https://lnkd.in/epWswUdi