Stability of implants. Stability of stimulation threshold currents to elicit vocalizations and time course at chronic microstimulation probes. Electrodes were implanted at day0 of the graph A. (A) Thresholds of four chronically implanted stimulation probes (A/B and C/D) are shown. Stimulation through implant A and B (animal 1) and through implant C (animal 2) elicited echolocation calls, while stimulation through implant D (animal 2) triggered communication calls. (B) "Mean percentage above threshold"-values for all four implants (A to D) as plotted in A during the actual blockade experiments. The mean stimulation current was 20% (electrode A), 14% (electrode B), 13% (electrode C) and 14% (electrode D) above threshold to ensure a vocal answer on each stimulus within the pulse train. At threshold level, not all stimuli triggered a vocalization. The median values are indicated as numbers; additionally P25 and P75 values are shown in italics.