BCIwiki (bciwiki.com) — Researchers at The University of Texas at Dallas, Case Western Reserve University and the Louis Stokes Cleveland Veterans Affairs Medical Center extended a rat nose-poke go/no-go task across a 30-week implantation window to track perception thresholds evoked by intracortical microstimulation (ICMS). In rats implanted with microwire arrays, thresholds fell in an exponential-like manner from weeks 5 to 12, then approached a fitted asymptote of roughly 1.1 nC/ph per electrode across 10 stimulating electrodes and stayed stable through week 30 in animals that retained detectable percepts. Correct responses to the conditioned stimulus held at about 90%. The work was reported in Journal of Neuroscience Methods on October 6, 2026.
The team also recorded electrophysiological and electrochemical data from the arrays to look for correlates of the threshold trend, but neither property provided a robust cross-animal explanation, leaving the mechanism unresolved. Gene expression profiling of implanted tissue showed elevated Gfap and Cd68 alongside reduced NeuN and Bdnf, matching earlier neuroinflammation findings. Two animals lost sensation during the 30-week period. The authors describe the positive-reinforcement paradigm as a dependable preclinical alternative for long-term ICMS threshold assessment, with the caveat that it applies while percepts remain detectable.