The University of Texas at Dallas

Rats implanted with microwire arrays showed an exponential-like fall in intracortical microstimulation (ICMS) perception thresholds from weeks 5 to 12, then held near a fitted asymptote of about 1.1 nC/ph per electrode across 10 stimulating electrodes through week 30 in animals that retained detectable percepts. Correct responses to the conditioned stimulus stabilized at roughly 90%. Neither the arrays' electrophysiological nor their electrochemical properties explained the threshold trend across animals. Gene expression in implanted tissue showed elevated Gfap and Cd68 alongside reduced NeuN and Bdnf, consistent with earlier neuroinflammation findings. Two animals lost sensation over the 30-week period.

The study uses spatial proteomics to assess tissue around non-functional intracortical microelectrodes implanted for four weeks in mice, measuring neuronal integrity, immune-cell activation and local cytokine expression around probes coated with drug-loaded, controlled-release titanium dioxide nanotube array (TNA) coatings. The authors note that blood-brain barrier disruption can translocate gut-derived bacteria to the implant site and sustain chronic inflammation, and that the TNA coating's therapeutic loading and controlled release further damp residual neuroinflammation. They conclude that TNA offers a multifunctional, tunable interface for locally regulating the neuroimmune microenvironment, a step toward long-term reliable intracortical recordings.

Researchers evaluated ruthenium-oxide-coated amorphous silicon-carbide microelectrode arrays during 25 weeks of intracortical microstimulation in rodents. Perception thresholds stabilized at about 0.4 nC per phase per electrode by week nine, behavioral performance remained around 91%, and reliable sensation persisted through week 25.

The study shows mouse primary motor cortex encodes locomotion speed through a sigmoidal state-transition mechanism carried by two functionally distinct spiking populations, a framework that also extends to local field potential (LFP) band power. Using chronic 32-channel laminar arrays in 8 mice, the team recorded 5,889 single units across 384 channels and clustered them into speed-positively related (70.8%) and speed-inversely related (29.2%) groups sharing a speed threshold of about 2.3 m/min. The minority speed-inversely related population decoded speed more accurately via inverse-sigmoid transformation, generalizing across animals. The authors say the findings point toward stable, calibration-light brain-machine interface design.