A hardware model of the auditory periphery to transduce acoustic signals into neural activity

Abstract

To improve the performance of cochlear implants, we have integrated a microdevice into a model of the auditory periphery with the goal of creating a microprocessor. We constructed an artificial peripheral auditory system using a hybrid model in which polyvinylidene difluoride was used as a piezoelectric sensor to convert mechanical stimuli into electric signals. To produce frequency selectivity, the slit on a stainless steel base plate was designed such that the local resonance frequency of the membrane over the slit reflected the transfer function. In the acoustic sensor, electric signals were generated based on the piezoelectric effect from local stress in the membrane. The electrodes on the resonating plate produced relatively large electric output signals. The signals were fed into a computer model that mimicked some functions of inner hair cells, inner hair cell–auditory nerve synapses, and auditory nerve fibers. In general, the responses of the model to pure-tone burst and complex stimuli accurately represented the discharge rates of high-spontaneous-rate auditory nerve fibers across a range of frequencies greater than 1 kHz and middle to high sound pressure levels. Thus, the model provides a tool to understand information processing in the peripheral auditory system and a basic design for connecting artificial acoustic sensors to the peripheral auditory nervous system. Finally, we discuss the need for stimulus control with an appropriate model of the auditory periphery based on auditory brainstem responses that were electrically evoked by different temporal pulse patterns with the same pulse number.

A CMOS IC-based multisite measuring system for stimulation and recording in neural preparations in vitro

“…A polyvinylidene difluoride (PVDF) film and a custom-made electric circuit board (Tateno et al, 2013 ) were used to process acoustic sound and send a trigger signal to the CMOS IC system. The film was used as a piezoelectric sensor to convert acoustic sound pressures into corresponding electric signals (Shintaku et al, 2010 ).…”

Laminar responses in the auditory cortex using a multielectrode array substrate for simultaneous stimulation and recording

“…Briefly, to determine the open-skull surgery position and identify the auditory cortical area, flavoprotein autofluorescence imaging was transcranially performed [14]. To locate tonotopic maps in the AC, pure-tone bursts of different frequencies (4,8,16, and 32 kHz) were applied to mice. After observing the best frequency shift in maps, core subfields including the primary auditory cortex (A1) and anterior auditory field (AAF) were located.…”

Biomimetic Artificial Basilar Membranes for Next‐Generation Cochlear Implants

“…There are two approaches to animal testing using ABMs, depending on the target position for implantation. In studies attempting to implant the ABMs into the ear canal or middle ear cavity, the ABMs were used as acoustic sensors for recording the auditory evoked potential in animal models using an additional signal processor and electrode array . For intracochlear ABMs, the ABM is inserted into the cochlea of the animal model and the frequency selectivity is evaluated in the cochlea …”

“…Studies evaluating the performance of ABMs by recording the eABR from deafened guinea pigs were performed using PVDF membrane‐type ABMs, AlN cantilever array ABMs, and TEABMs . Figure a shows schematic illustrations of the animal test performed using the AlN cantilever‐type ABM, as reported by Jang et al When the acoustic stimulus is applied to the ABM by a loudspeaker, the ABM generates piezoelectric output depending on the SPL and the sound frequency.…”

“…Recent advances in ABMs have been made through in vivo experiments in which ABMs were applied to animal models. The auditory brainstem response (ABR) from deafened guinea pigs were measured using the electrical output induced by the ABM under sound pressure . Another approach involves implantation of the ABM into the cochlea followed by evaluation of its tonotopic characteristics .…”