BCIwiki (bciwiki.com) — Discrimination accuracy in rats declined in an exponential decay-like relationship (R² = 0.88) as overlap in neuronal activation volumes evoked by intracortical microstimulation (ICMS) increased, researchers at The University of Texas at Dallas reported in Frontiers in Computational Neuroscience on August 29, 2026.
The team combined simulated data from a biophysically realistic computational model of the somatosensory cortex with previously collected behavioral data from rats. ICMS patterns used in behavioral experiments were simulated, activation volumes were estimated by fitting 50–100% capture ellipsoids to the spatial distribution of activated somata, and overlap between pairs was quantified using the intersection-over-union (IoU) metric. Across both single- and four-shank microelectrode array configurations, minimal overlap (IoU < 1%) was associated with high discrimination accuracy (>70%; average of 85%), whereas IoU values exceeding 20% corresponded to near-chance performance, independent of depth versus lateral separation.
The authors suggest that ICMS-evoked activation volume overlap may provide mechanistic insight into the spatial limits of perceptual discrimination and may help guide future electrode spacing and stimulation strategies for sensory neuroprosthetic design.