Chronic alteration of Ca²⁺ and hemodynamic signals induced by intracortical microstimulation in the visual cortex of awake mice.

events emerged in nearly half of mice, predominantly under 25-Hz ICMS. HRF peak amplitude increased between day 0 and days 7-21, with latency decreasing. Spontaneous neural and hemodynamic activity near the probe was suppressed acutely but recovered over weeks. Chronic ICMS induces progressive potentiation of neuronal and vascular responses alongside local neurovascular uncoupling on day 0 and sustained silencing of spontaneous activity near the implant. These dynamics stabilized 6-7 weeks after implantation. The frequency-dependent epileptiform susceptibility, coupled with persistent focal neurovascular deficits, underscores the need for adaptive stimulation strategies during the pre-stabilization period and electrode designs that mitigate local suppression to ensure long-term stability of cortical neuroprostheses.