Investigation of a New Electrode Array Technology for a Central Auditory Prosthesis

Abstract

Ongoing clinical studies on patients recently implanted with the auditory midbrain implant (AMI) into the inferior colliculus (IC) for hearing restoration have shown that these patients do not achieve performance levels comparable to cochlear implant patients. The AMI consists of a single-shank array (20 electrodes) for stimulation along the tonotopic axis of the IC. Recent findings suggest that one major limitation in AMI performance is the inability to sufficiently activate neurons across the three-dimensional (3-D) IC. Unfortunately, there are no currently available 3-D array technologies that can be used for clinical applications. More recently, there has been a new initiative by the European Commission to fund and develop 3-D chronic electrode arrays for science and clinical applications through the NeuroProbes project that can overcome the bulkiness and limited 3-D configurations of currently available array technologies. As part of the NeuroProbes initiative, we investigated whether their new array technology could be potentially used for future AMI patients. Since the NeuroProbes technology had not yet been tested for electrical stimulation in an in vivo animal preparation, we performed experiments in ketamine-anesthetized guinea pigs in which we inserted and stimulated a NeuroProbes array within the IC and recorded the corresponding neural activation within the auditory cortex. We used 2-D arrays for this initial feasibility study since they were already available and were sufficient to access the IC and also demonstrate effective activation of the central auditory system. Based on these encouraging results and the ability to develop customized 3-D arrays with the NeuroProbes technology, we can further investigate different stimulation patterns across the ICC to improve AMI performance.

Clinical applications of penetrating neural interfaces and Utah Electrode Array technologies

“…A possible alternative for some of these patients is the auditory midbrain implant (AMI), which targets the central nucleus of the inferior colliculus with a penetrating electrode array (Lenarz et al 2006, Calixto et al 2013, Stebbings et al 2014. However performance with these devices varies dramatically across patients depending on the implant location within the midbrain with the best performance still not able to achieve open set speech perception without lipreading cues.…”

Acute human brain responses to intracortical microelectrode arrays: challenges and future prospects

“…The two main dominant approaches are multiple insulated metal microwires (Nicolelis and Lebedev, 2009 ; Freire et al, 2011 ; Carmena, 2013 ) and penetrating microelectrode arrays fabricated with micro-electro-mechanical-system technologies. These devices use various substrate materials that can either be flexible and based on polymers (Rousche et al, 2001 ; Chen et al, 2009 ; Kozai and Kipke, 2009 ; Hassler et al, 2011 ) or rigid such as the Utah Electrode Array (UEA; Normann, 2007 ), the Michigan array (Seymour and Kipke, 2007 ) or the NeuroProbes arrays (Neves, 2007 ; Calixto et al, 2013 ). However today, only a few of these devices are commercially available and do not yet exist as commercial, wireless, implantable, many-channel devices that can provide reliable recording and stimulation for many years.…”

Versatile, modular 3D microelectrode arrays for neuronal ensemble recordings: from design to fabrication, assembly, and functional validation in non-human primates

“…In a recent neurophysiological work [35] carried out with the same 3D electrode arrays as used in this study and in an earlier report using similar probes [47], it has been shown that the probe technology can also be used for intracortical electrical microstimulation. This additional functionality further expands the potential versatility of the reported stacking system.…”