Active Artificial Hair Cells for Use in Fluid Environments

2015 ◽  
Author(s):  
Bryan S. Joyce ◽  
Pablo A. Tarazaga
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Dynamic Range ◽  
Fluid Simulation ◽  
Fluid Loading ◽  
Fluid Inertia ◽  
Nonlinear Feedback ◽  
Flow Sensing ◽  
Nonlinear Amplifier ◽  
Nonlinear Control Law

Artificial hair cells (AHCs) are sensors inspired by biological hair cells. These devices often have lower sensitivities and poorer frequency resolutions than their biological counterparts. This is especially true when AHCs are placed in fluid. In the authors’ previous work, active AHCs were developed which used nonlinear feedback control to mimic the cochlea’s nonlinear amplifier. Incorporating this nonlinear control law can improve the AHC’s sensitivity, frequency selectivity, and dynamic range. This work examines an active artificial hair cell partially submerged in water. The fluid loading on the sensor adds inertia and significantly increases damping. A model of the sensor in air is developed and then modified to incorporate the added inertia and damping from the fluid. Simulation and experimental results show that the active artificial hair cell can overcome the added fluid inertia and damping to amplify oscillations due to low input levels and create a sharper frequency response. The resulting sensor is better suited to operate in fluid environments for flow sensing than an otherwise passive device. These sensors could potentially develop into replacements for damaged hair cells in the fluid-filled cochlea.

Active Artificial Hair Cells Using Nonlinear Feedback Control

2014 ◽  
Author(s):  
Bryan S. Joyce ◽  
Pablo A. Tarazaga
Keyword(s):  
Feedback Control ◽  
Hair Cell ◽  
Hair Cells ◽  
Dynamic Range ◽  
Control Law ◽  
Nonlinear Feedback Control ◽  
Nonlinear Feedback ◽  
Cochlear Hair Cells ◽  
Amplitude Compression ◽  
Bimorph Beam

There is interest in developing devices that mimic the sound transduction of the cochlear hair cells. Current artificial hair cell (AHC) designs have focused on passive transduction of sound into electrical signals. However, measurements inside living cochleae have revealed that a nonlinear amplification is at work in mammalian hearing. This amplification lowers the threshold for sound detection allowing mammals to hear faint sounds. The nonlinearity results in an amplitude compression whereby a large range of sound pressure levels produces a smaller range of displacements. This compressive nonlinearity gives the ear a large dynamic range. This work seeks to develop and analyze active artificial hair cells which employ a bio-inspired amplification to improve performance. This paper examines two artificial hair cell designs. The first is an 18.5 in long aluminum cantilever beam which is excited and controlled using piezoelectric actuators along the length of the beam. The second design is a one inch piezoelectric bimorph beam subject to a base excitation. In both cases a nonlinear feedback control law is implemented which reduces the beam’s linear viscous damping and introduces a cubic damping term. Model and experimental results show the control law amplified the response of the artificial hair cell to low excitation levels near the resonance frequency. Increasing input levels produced a compressive nonlinearity at resonance similar to that observed in measurements from mammalian cochleae. This work could lead to the development of new bio-inspired sensors with a lower threshold of detection, improved frequency sensitivity, and larger dynamic range.

scholarly journals Efferent Control of Hair Cell and Afferent Responses in the Semicircular Canals

2009 ◽  
Vol 102 (3) ◽  
pp. 1513-1525 ◽  
Author(s):  
Richard Boyle ◽  
Richard D. Rabbitt ◽  
Stephen M. Highstein
Keyword(s):  
Hair Cell ◽  
Brain Stem ◽  
Hair Cells ◽  
Intracellular Signaling ◽  
Dynamic Range ◽  
Reversal Potential ◽  
Semicircular Canals ◽  
Resting Potential ◽  
Efferent Neurons ◽  
The Brain

The sensations of sound and motion generated by the inner ear are controlled by the brain through extensive centripetal innervation originating within the brain stem. In the semicircular canals, brain stem efferent neurons make synaptic contacts with mechanosensory hair cells and with the dendrites of afferent neurons. Here, we examine the relative contributions of efferent action on hair cells and afferents. Experiments were performed in vivo in the oyster toadfish, Opsanus tau. The efferent system was activated via electrical pulses to the brain stem and sensory responses to motion stimuli were quantified by simultaneous voltage recording from afferents and intracellular current- and/or voltage-clamp recordings from hair cells. Results showed synaptic inputs to both afferents and hair cells leading to relatively long-latency intracellular signaling responses: excitatory in afferents and inhibitory in hair cells. Generally, the net effect of efferent action was an increase in afferent background discharge and a simultaneous decrease in gain to angular motion stimuli. Inhibition of hair cells was likely the result of a ligand-gated opening of a major basolateral conductance. The reversal potential of the efferent-evoked current was just below the hair cell resting potential, thus resulting in a small hyperpolarization. The onset latency averaged about 90 ms and latency to peak response was 150–400 ms. Hair cell inhibition often outlasted afferent excitation and, in some cases, latched hair cells in the “off” condition for >1 s following cessation of stimulus. These features endow the animal with a powerful means to adjust the sensitivity and dynamic range of motion sensation.

A study of active artificial hair cell models inspired by outer hair cell somatic motility

2016 ◽  
Vol 28 (6) ◽  
pp. 811-823 ◽  
Author(s):  
Bryan S Joyce ◽  
Pablo A Tarazaga
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Outer Hair Cell ◽  
Dynamic Range ◽  
Outer Hair Cells ◽  
Quality Factors ◽  
Control Laws ◽  
Sensor Performance ◽  
Nonlinear Amplification ◽  
Key Aspects

The cochlea displays an important, nonlinear amplification of sound-induced oscillations. In mammals, this amplification is largely powered by the somatic motility of the outer hair cells. The resulting cochlear amplifier has three important characteristics useful for hearing: an amplification of responses from low sound pressures, an improvement in frequency selectivity, and an ability to transduce a broad range of sound pressure levels. These useful features can be incorporated into designs for active artificial hair cells, bio-inspired sensors for use as microphones, accelerometers, or other dynamic sensors. The sensor consists of a cantilever beam with piezoelectric actuators. A feedback controller applies a voltage to the actuators to mimic the outer hair cells’ somatic motility. This article describes three control laws for an active artificial hair cell inspired by models of the outer hair cells’ somatic motility. The first control law is based on a phenomenological model of the cochlea while the second and third models incorporate physiological aspects of the biological cochlea to further improve sensor performance. Simulations show that these models qualitatively reproduce the key aspects of the mammalian cochlea, namely, amplification of oscillations from weak stimuli, higher quality factors, and a wider input dynamic range.

scholarly journals Hair-Cell Versus Afferent Adaptation in the Semicircular Canals

2005 ◽  
Vol 93 (1) ◽  
pp. 424-436 ◽  
Author(s):  
R. D. Rabbitt ◽  
R. Boyle ◽  
G. R. Holstein ◽  
S. M. Highstein
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Semicircular Canal ◽  
Time Course ◽  
Dynamic Range ◽  
Cell Voltage ◽  
Frequency Dependent ◽  
Adaptation Time ◽  
Phase Lead ◽  
Flat Gain

The time course and extent of adaptation in semicircular canal hair cells was compared to adaptation in primary afferent neurons for physiological stimuli in vivo to study the origins of the neural code transmitted to the brain. The oyster toadfish, Opsanus tau, was used as the experimental model. Afferent firing-rate adaptation followed a double-exponential time course in response to step cupula displacements. The dominant adaptation time constant varied considerably among afferent fibers and spanned six orders of magnitude for the population (∼1 ms to >1,000 s). For sinusoidal stimuli (0.1–20 Hz), the rapidly adapting afferents exhibited a 90° phase lead and frequency-dependent gain, whereas slowly adapting afferents exhibited a flat gain and no phase lead. Hair-cell voltage and current modulations were similar to the slowly adapting afferents and exhibited a relatively flat gain with very little phase lead over the physiological bandwidth and dynamic range tested. Semicircular canal microphonics also showed responses consistent with the slowly adapting subset of afferents and with hair cells. The relatively broad diversity of afferent adaptation time constants and frequency-dependent discharge modulations relative to hair-cell voltage implicate a subsequent site of adaptation that plays a major role in further shaping the temporal characteristics of semicircular canal afferent neural signals.

scholarly journals Neuroplastin expression is essential for hearing and hair cell PMCA expression

2021 ◽  
Author(s):  
Xiao Lin ◽  
Michael G. K. Brunk ◽  
Pingan Yuanxiang ◽  
Andrew W. Curran ◽  
Enqi Zhang ◽  
...  
Keyword(s):  
Hair Cell ◽  
White Noise ◽  
Hair Cells ◽  
Normal Development ◽  
Single Photon ◽  
Photon Emission ◽  
Auditory Brainstem ◽  
Outer Hair Cells ◽  
Emission Computed Tomography ◽  
Cell Degeneration

AbstractHearing deficits impact on the communication with the external world and severely compromise perception of the surrounding. Deafness can be caused by particular mutations in the neuroplastin (Nptn) gene, which encodes a transmembrane recognition molecule of the immunoglobulin (Ig) superfamily and plasma membrane Calcium ATPase (PMCA) accessory subunit. This study investigates whether the complete absence of neuroplastin or the loss of neuroplastin in the adult after normal development lead to hearing impairment in mice analyzed by behavioral, electrophysiological, and in vivo imaging measurements. Auditory brainstem recordings from adult neuroplastin-deficient mice (Nptn−/−) show that these mice are deaf. With age, hair cells and spiral ganglion cells degenerate in Nptn−/− mice. Adult Nptn−/− mice fail to behaviorally respond to white noise and show reduced baseline blood flow in the auditory cortex (AC) as revealed by single-photon emission computed tomography (SPECT). In adult Nptn−/− mice, tone-evoked cortical activity was not detectable within the primary auditory field (A1) of the AC, although we observed non-persistent tone-like evoked activities in electrophysiological recordings of some young Nptn−/− mice. Conditional ablation of neuroplastin in Nptnlox/loxEmx1Cre mice reveals that behavioral responses to simple tones or white noise do not require neuroplastin expression by central glutamatergic neurons. Loss of neuroplastin from hair cells in adult NptnΔlox/loxPrCreERT mice after normal development is correlated with increased hearing thresholds and only high prepulse intensities result in effective prepulse inhibition (PPI) of the startle response. Furthermore, we show that neuroplastin is required for the expression of PMCA 2 in outer hair cells. This suggests that altered Ca2+ homeostasis underlies the observed hearing impairments and leads to hair cell degeneration. Our results underline the importance of neuroplastin for the development and the maintenance of the auditory system.

scholarly journals Inner hair cell stereocilia are embedded in the tectorial membrane

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pierre Hakizimana ◽  
Anders Fridberger
Keyword(s):  
Electron Microscopy ◽  
Hair Cell ◽  
Mechanical Stimulation ◽  
Hair Cells ◽  
Viscous Drag ◽  
Tectorial Membrane ◽  
Inner Hair Cell ◽  
Inner Hair Cells ◽  
Inward Currents

AbstractMammalian hearing depends on sound-evoked displacements of the stereocilia of inner hair cells (IHCs), which cause the endogenous mechanoelectrical transducer channels to conduct inward currents of cations including Ca2+. Due to their presumed lack of contacts with the overlaying tectorial membrane (TM), the putative stimulation mechanism for these stereocilia is by means of the viscous drag of the surrounding endolymph. However, despite numerous efforts to characterize the TM by electron microscopy and other techniques, the exact IHC stereocilia-TM relationship remains elusive. Here we show that Ca2+-rich filamentous structures, that we call Ca2+ ducts, connect the TM to the IHC stereocilia to enable mechanical stimulation by the TM while also ensuring the stereocilia access to TM Ca2+. Our results call for a reassessment of the stimulation mechanism for the IHC stereocilia and the TM role in hearing.

scholarly journals Responses of hair cells to statocyst rotation.

1975 ◽  
Vol 66 (4) ◽  
pp. 507-530 ◽  
Author(s):  
D L Alkon
Keyword(s):  
Hair Cell ◽  
Centrifugal Force ◽  
Hair Cells ◽  
New Technique ◽  
Force Vector ◽  
Generator Potential ◽  
Recording Apparatus ◽  
Intracellular Potentials ◽  
A New Technique

A new technique is described for stimulating hair cells of the Hermissenda statocyst. The preparation and recording apparatus can be rotated at up to 78 rpm while recording intracellular potentials. Hair cells in front of the centrifugal force vector depolarize in response to rotation. Hair cells in back of the centrifugal force vector hypoerpolarize in response to rotation. Mechanisms by which the hair cell generator potential might arise are examined.

Hes1 is a negative regulator of inner ear hair cell differentiation

Development ◽  
2000 ◽  
Vol 127 (21) ◽  
pp. 4551-4560 ◽  
Author(s):  
J.L. Zheng ◽  
J. Shou ◽  
F. Guillemot ◽  
R. Kageyama ◽  
W.Q. Gao
Keyword(s):  
Cell Differentiation ◽  
Hair Cell ◽  
Inner Ear ◽  
Cell Fate ◽  
Hair Cells ◽  
Outer Hair Cells ◽  
Negative Regulator ◽  
Pcr Analysis ◽  
Loss Of Function ◽  
Hair Cell Differentiation

Hair cell fate determination in the inner ear has been shown to be controlled by specific genes. Recent loss-of-function and gain-of-function experiments have demonstrated that Math1, a mouse homolog of the Drosophila gene atonal, is essential for the production of hair cells. To identify genes that may interact with Math1 and inhibit hair cell differentiation, we have focused on Hes1, a mammalian hairy and enhancer of split homolog, which is a negative regulator of neurogenesis. We report here that targeted deletion of Hes1 leads to formation of supernumerary hair cells in the cochlea and utricle of the inner ear. RT-PCR analysis shows that Hes1 is expressed in inner ear during hair cell differentiation and its expression is maintained in adulthood. In situ hybridization with late embryonic inner ear tissue reveals that Hes1 is expressed in supporting cells, but not hair cells, of the vestibular sensory epithelium. In the cochlea, Hes1 is selectively expressed in the greater epithelial ridge and lesser epithelial ridge regions which are adjacent to inner and outer hair cells. Co-transfection experiments in postnatal rat explant cultures show that overexpression of Hes1 prevents hair cell differentiation induced by Math1. Therefore Hes1 can negatively regulate hair cell differentiation by antagonizing Math1. These results suggest that a balance between Math1 and negative regulators such as Hes1 is crucial for the production of an appropriate number of inner ear hair cells.

High-Voltage Electron Microscopic Study of the Inner Ear: Technique and Preliminary Results

1983 ◽  
Vol 92 (1_suppl) ◽  
pp. 3-12 ◽  
Author(s):  
Tomonori Takasaka ◽  
Hideich Shinkawa ◽  
Kozo Watanuki ◽  
Sho Hashimoto ◽  
Kazutomo Kawamoto
Keyword(s):  
Electron Microscopy ◽  
Hair Cell ◽  
Inner Ear ◽  
High Voltage ◽  
Hair Cells ◽  
Outer Hair Cells ◽  
Tectorial Membrane ◽  
Preliminary Results ◽  
Voltage Electron ◽  
Cuticular Plate

The technique and some preliminary results of the application of high-voltage electron microscopy (HVEM) to the study of inner ear morphology in the guinea pig are reported in this paper. The main advantage of HVEM is that sharp images of thicker specimens can be obtained because of the greater penetrating power of high energy electrons. The optimum thickness of the sections examined with an accelerating voltage of 1,000 kV was found to be between 500 to 800 nm. The sections below 500 nm in thickness often had insufficient contrast, while those above 800 nm were rather difficult to interpret due to overlap of images of the organelles. The whole structure of the sensory hairs from the tip to the rootlet was more frequently observed in the 800-nm thick sections. Thus the fine details of the hair attachment to the tectorial membrane as well as the hair rootlet extension into the cuticular plate could be thoroughly studied in the HVEM. In specimens fixed in aldehyde containing 2% tannic acid, the attachment of the tips of the outer hair cell stereocilia to the tectorial membrane was observed. For the inner hair cells, however, the tips of the hairs were separated from the undersurface of the tectorial membrane. The majority of the rootlets of the outer hair cells terminated at the midportion of the cuticular plate, while most of the inner hair cell rootlets traversed the entire width of the cuticular plate and extended into the apical cytoplasm. These differences in ultrastructural appearance may indicate that the two kinds of hair cells play different roles in the acoustic transduction process. The three-dimensional arrangement of the nerve endings on the hair cells was also studied by the serial thick-sectioning technique in the HVEM. In general, an entire arrangement of the nerve endings was almost completely cut in less than ten 800-nm thick sections instead of the 50- to 100-ultrathin (ie, less than 100 nm) conventional sections for transmission electron microscopy. The present study confirms an earlier report that the first row outer hair cells in the third cochlear turn are innervated by nearly equal numbers of efferent and afferent endings, the average number being nine.

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