Fig. 2: In vivo single-unit electrophysiology to assess IME performance over 8 weeks.

A Schematic of the IME showing active ( ≥ 1 unit, green dot) and inactive (no unit, red dot) channels. Active electrode yield (AEY) is the number of active channels divided by the total number of usable channels per treatment per week⁹⁵. B Weekly AEY for each treatment, with DEXSPPIN demonstrating significantly improved recording performance over PIN, DILUENT, and Free DEXSP. C Statistical comparisons (Two-way ANOVA (Mixed Model) with post hoc Tukey) of weekly AEY among groups, with significance levels indicated. D Proportion of active electrodes grouped by phase (W1–4 vs. W5–8), showing DEXSPPIN enhances recording stability in both early and late phases. E Active units per channel across treatments and phases. DEXSPPIN significantly outperforms other groups in W1–4; no significant difference from PIN in W5–8. The solid black line represents the median, and the colored dot indicates the interquartile range (25th to 75th percentile). Sample sizes: For B, determined by number of channels × number of animals: DEXSPPIN = 107, PIN = 104, DILUENT = 104, Free DEXSP = 118. For D, based on channels × weeks per phase × number of animals: DEXSPPIN = 428, PIN = 416, DILUENT = 416, Free DEXSP = 472. For E, based on total active channels per group per phase: DEXSPPIN W1–4 = 93, W5–8 = 51; PIN W1–4 = 77, W5–8 = 43; DILUENT W1–4 = 81, W5–8 = 38; Free DEXSP W1–4 = 86, W5–8 = 30. Malfunctioning channels from the outset were excluded. Significance: p < 0.05=*, p < 0.01=**, p < 0.001=***, p < 0.0001=****.