Fig. 2: Soft ABI placement and validation both intra- and post-operatively.
From: High-resolution prosthetic hearing with a soft auditory brainstem implant in macaques
a, Recording setup for ABRs and eABRs, showing the position of ground and reference electrodes. b, Post-surgery ABRs for both implanted (left) and control (right) sides. Traces show responses from 20 to 100 dB SPL. Graph displays wave II and IV amplitude depending on stimulation amplitude. c, Intra-operative eABR responses to ABI monopolar stimulation (elec1) at increasing stimulation amplitude. Waves I, II, III, IV and V are labelled. The first 1 ms of the trace was removed because of contamination with the stimulus artefact. d, 3D reconstruction based on CT images of NHP cranium. The FlexComb connector22 is visible on CT and highlighted in light brown. The ABI imaging marker is highlighted in red as it enters the posterior fossa craniotomy. Orientation is indicated. e, Magnified view of CT 3D reconstruction focusing on the electrode array (in red). The reconstruction shows the flexibility of the soft array. f, Co-registered CT and MRI images taken post surgery, showing the ABI artefact from the imaging marker. The bone is shown in purple colour and soft tissue of the brainstem is shown in green colour in two different imaging planes (sagittal, coronal; a, anterior; p, posterior; l, left; r, right; s, superior; i, inferior). g, Histological brainstem coronal cross-section showing the electrode array in place after 17 months of implantation. The black line is the imaging marker, and the full pad is delimited by the dashed red line. This image reveals the in situ conformability of the soft ABI at the surface of the brainstem. The radius curvature of the tip of the soft ABI in this image was measured as 7.3 mm.
