Pump Up the Volume: Could Excessive Neural Gain Explain Tinnitus and Hyperacusis?

2015 ◽  
Vol 20 (4) ◽  
pp. 273-282 ◽  
Author(s):  
Hannah Brotherton ◽  
Christopher J. Plack ◽  
Michael Maslin ◽  
Roland Schaette ◽  
Kevin J. Munro
Keyword(s):  
Auditory System ◽  
Dynamic Range ◽  
Sensory Deprivation ◽  
Acoustic Stimulation ◽  
Neural Firing ◽  
Slow Adaptation ◽  
Health And Disease ◽  
Adaptation Processes ◽  
Perceptual Changes ◽  
Neural Gain

Naturally occurring stimuli can vary over several orders of magnitude and may exceed the dynamic range of sensory neurons. As a result, sensory systems adapt their sensitivity by changing their responsiveness or ‘gain'. While many peripheral adaptation processes are rapid, slow adaptation processes have been observed in response to sensory deprivation or elevated stimulation. This adaptation process alters neural gain in order to adjust the basic operating point of sensory processing. In the auditory system, abnormally high neural gain may result in higher spontaneous and/or stimulus-evoked neural firing rates, and this may have the unintended consequence of presenting as tinnitus and/or sound intolerance, respectively. Therefore, a better understanding of neural gain, in health and disease, may lead to more effective treatments for these aberrant auditory perceptions. This review provides a concise summary of (i) evidence for changes in neural gain in the auditory system of animals, (ii) physiological and perceptual changes in adult human listeners following an acute period of enhanced acoustic stimulation and/or deprivation, (iii) physiological evidence of excessive neural gain in tinnitus and hyperacusis patients, and (iv) the relevance of neural gain in the clinical treatment of tinnitus and hyperacusis.

Influence of the Acoustic Reflex on Vowel Recognition

1986 ◽  
Vol 29 (3) ◽  
pp. 420-424 ◽  
Author(s):  
Michael Dorman ◽  
Ingrid Cedar ◽  
Maureen Hannley ◽  
Marjorie Leek ◽  
Julie Mapes Lindholm
Keyword(s):  
Auditory System ◽  
Sound Pressure ◽  
Dynamic Range ◽  
Recognition Accuracy ◽  
Pressure Level ◽  
Acoustic Reflex ◽  
The Poor ◽  
Stapedial Reflex ◽  
Vowel Recognition ◽  
High Sound

Computer synthesized vowels of 50- and 300-ms duration were presented to normal-hearing listeners at a moderate and high sound pressure level (SPL). Presentation at the high SPL resulted in poor recognition accuracy for vowels of a duration (50 ms) shorter than the latency of the acoustic stapedial reflex. Presentation level had no effect on recognition accuracy for vowels of sufficient duration (300 ms) to elicit the reflex. The poor recognition accuracy for the brief, high intensity vowels was significantly improved when the reflex was preactivated. These results demonstrate the importance of the acoustic reflex in extending the dynamic range of the auditory system for speech recognition.

Auditory processing of complex sounds: an overview

1992 ◽  
Vol 336 (1278) ◽  
pp. 295-306 ◽  
Keyword(s):  
Auditory System ◽  
Auditory Processing ◽  
Dynamic Range ◽  
Auditory Brainstem ◽  
Frequency Selectivity ◽  
Dorsal Cochlear Nucleus ◽  
Cochlear Nerve ◽  
Complex Sounds ◽  
Wide Range ◽  
Time Coding

The past 30 years has seen a remarkable development in our understanding of how the auditory system - particularly the peripheral system - processes complex sounds. Perhaps the most significant has been our understanding of the mechanisms underlying auditory frequency selectivity and their importance for normal and impaired auditory processing. Physiologically vulnerable cochlear filtering can account for many aspects of our normal and impaired psychophysical frequency selectivity with important consequences for the perception of complex sounds. For normal hearing, remarkable mechanisms in the organ of Corti, involving enhancement of mechanical tuning (in mammals probably by feedback of electro-mechanically generated energy from the hair cells), produce exquisite tuning, reflected in the tuning properties of cochlear nerve fibres. Recent comparisons of physiological (cochlear nerve) and psychophysical frequency selectivity in the same species indicate that the ear’s overall frequency selectivity can be accounted for by this cochlear filtering, at least in band width terms. Because this cochlear filtering is physiologically vulnerable, it deteriorates in deleterious conditions of the cochlea - hypoxia, disease, drugs, noise overexposure, mechanical disturbance - and is reflected in impaired psychophysical frequency selectivity. This is a fundamental feature of sensorineural hearing loss of cochlear origin, and is of diagnostic value. This cochlear filtering, particularly as reflected in the temporal patterns of cochlear fibres to complex sounds, is remarkably robust over a wide range of stimulus levels. Furthermore, cochlear filtering properties are a prime determinant of the ‘place’ and ‘time’ coding of frequency at the cochlear nerve level, both of which appear to be involved in pitch perception. The problem of how the place and time coding of complex sounds is effected over the ear’s remarkably wide dynamic range is briefly addressed. In the auditory brainstem, particularly the dorsal cochlear nucleus, are inhibitory mechanisms responsible for enhancing the spectral and temporal contrasts in complex sounds. These mechanisms are now being dissected neuropharmacologically. At the cortical level, mechanisms are evident that are capable of abstracting biologically relevant features of complex sounds. Fundamental studies of how the auditory system encodes and processes complex sounds are vital to promising recent applications in the diagnosis and rehabilitation of the hearing impaired.

scholarly journals Magnetic Stimulation Allows Focal Activation of the Mouse Cochlea

2022 ◽  
Author(s):  
Jae-Ik Lee ◽  
Richard Seist ◽  
Stephen McInturff ◽  
Daniel J Lee ◽  
Christian Brown ◽  
...  
Keyword(s):  
Neural Coding ◽  
Magnetic Stimulation ◽  
Dynamic Range ◽  
Functional Performance ◽  
Electrode Array ◽  
Acoustic Stimulation ◽  
Profound Hearing Loss ◽  
Safety Testing ◽  
Spectral Channels ◽  
Additional Safety

Cochlear implants (CIs) strive to restore hearing to those with severe to profound hearing loss by artificially stimulating the auditory nerve. While most CI users can understand speech in a quiet environment, hearing that utilizes complex neural coding (e.g., appreciating music) has proved elusive, probably because of the inability of CIs to create narrow regions of spectral activation. Several novel approaches have recently shown promise for improving spatial selectivity, but substantial design differences from conventional CIs will necessitate much additional safety testing before clinical viability is established. Outside the cochlea, magnetic stimulation from small coils (micro-coils) has been shown to confine activation more narrowly than that from conventional micro-electrodes, raising the possibility that coil-based stimulation of the cochlea could improve the spectral resolution of CIs. To explore this, we delivered magnetic stimulation from micro-coils to multiple locations of the cochlea and measured the spread of activation utilizing a multi-electrode array inserted into the inferior colliculus; responses to magnetic stimulation were compared to analogous experiments with conventional micro-electrodes as well as to the responses to auditory monotones. Encouragingly, the extent of activation with micro-coils was ~60% narrower than that from electric stimulation and largely similar to the spread arising from acoustic stimulation. The dynamic range of coils was more than three times larger than that of electrodes, further supporting a smaller spread of activation. While much additional testing is required, these results support the notion that coil-based CIs can produce a larger number of independent spectral channels and may therefore improve functional performance. Further, because coil-based devices are structurally similar to existing CIs, fewer impediments to clinical translational are likely to arise.

Ipsilateral Electric Acoustic Stimulation of the Auditory System: Results of Long-Term Hearing Preservation

2006 ◽  
Vol 11 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Wolfgang K. Gstoettner ◽  
Silke Helbig ◽  
Nicola Maier ◽  
Jan Kiefer ◽  
Andreas Radeloff ◽  
...  
Keyword(s):  
Auditory System ◽  
Hearing Preservation ◽  
Acoustic Stimulation ◽  
Electric Acoustic Stimulation ◽  
Stimulation Of

scholarly journals Two Temporal Phases of Light Adaptation in Retinal Rods

2002 ◽  
Vol 119 (2) ◽  
pp. 129-146 ◽  
Author(s):  
Peter D. Calvert ◽  
Victor I. Govardovskii ◽  
Vadim Y. Arshavsky ◽  
Clint L. Makino
Keyword(s):  
Binding Sites ◽  
Time Course ◽  
Light Adaptation ◽  
Dynamic Range ◽  
Continuous Illumination ◽  
Slow Phase ◽  
Fast Phase ◽  
Slow Adaptation ◽  
Adaptation Phase

Vertebrate rod photoreceptors adjust their sensitivity as they adapt during exposure to steady light. Light adaptation prevents the rod from saturating and significantly extends its dynamic range. We examined the time course of the onset of light adaptation in bullfrog rods and compared it with the projected onset of feedback reactions thought to underlie light adaptation on the molecular level. We found that adaptation developed in two distinct temporal phases: (1) a fast phase that operated within seconds after the onset of illumination, which is consistent with most previous reports of a 1–2-s time constant for the onset of adaptation; and (2) a slow phase that engaged over tens of seconds of continuous illumination. The fast phase desensitized the rods as much as 80-fold, and was observed at every light intensity tested. The slow phase was observed only at light intensities that suppressed more than half of the dark current. It provided an additional sensitivity loss of up to 40-fold before the rod saturated. Thus, rods achieved a total degree of adaptation of ∼3,000-fold. Although the fast adaptation is likely to originate from the well characterized Ca2+-dependent feedback mechanisms regulating the activities of several phototransduction cascade components, the molecular mechanism underlying slow adaptation is unclear. We tested the hypothesis that the slow adaptation phase is mediated by cGMP dissociation from noncatalytic binding sites on the cGMP phosphodiesterase, which has been shown to reduce the lifetime of activated phosphodiesterase in vitro. Although cGMP dissociated from the noncatalytic binding sites in intact rods with kinetics approximating that for the slow adaptation phase, this hypothesis was ruled out because the intensity of light required for cGMP dissociation far exceeded that required to evoke the slow phase. Other possible mechanisms are discussed.

scholarly journals Improved alpha-beta power reduction via combined Electrical and Ultrasonic stimulation in a Parkinsonian Cortex-Basal Ganglia-Thalamus Computational Model

2021 ◽  
Author(s):  
Thomas Tarnaud ◽  
Wout Joseph ◽  
Ruben Schoeters ◽  
Luc Martens ◽  
Emmeric Tanghe
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Basal Ganglia ◽  
Neuronal Network ◽  
Continuous Wave ◽  
Dynamic Range ◽  
Cortical Cell ◽  
Acoustic Stimulation ◽  
Isolated Neurons ◽  
Beta Power

AbstractObjectiveTo investigate computationally the interaction of combined electrical and ultrasonic modulation of isolated neurons and of the Parkinsonian cortex-basal ganglia-thalamus loop.MethodsContinuous-wave or pulsed electrical and ultrasonic neuromodulation is applied to isolated Otsuka plateau-potential generating subthalamic nucleus (STN) and Pospischil regular, fast and low-threshold spiking cortical cells in a temporally-alternating or simultaneous manner. Similar combinations of electrical/ultrasonic waveforms are applied to a Parkinsonian biophysical cortex-basal ganglia-thalamus neuronal network. Ultrasound-neuron interaction is modelled respectively for isolated neurons and the neuronal network with the NICE and SONIC implementations of the bilayer sonophore underlying mechanism. Reduction in α—β spectral energy is used as a proxy to express improvement in Parkinson’s disease by insonication and electrostimulation.ResultsSimultaneous electro-acoustic stimulation achieves a given level of neuronal activity at lower intensities compared to the separate stimulation modalities. Conversely, temporally alternating stimulation with 50 Hz electrical and ultrasound pulses is capable of eliciting 100 Hz STN firing rates. Furthermore, combination of ultrasound with hyperpolarizing currents can alter cortical cell relative spiking regimes. In the Parkinsonian neuronal network, high-frequency pulsed separated electrical and ultrasonic deep brain stimulation (DBS) reduce pathological α — β power by entraining STN-neurons. In contrast, continuous-wave ultrasound reduces pathological oscillations by silencing the STN. Compared to the separated stimulation modalities, temporally simultaneous or alternating electro-acoustic stimulation can achieve higher reductions in α — β power for the same contraints on electrical/ultrasonic intensity.ConclusionContinuous-wave and pulsed ultrasound reduce pathological oscillations by different mechanisms. Electroacoustic stimulation further improves α— β power for given safety limits and is capable of altering cortical relative spiking regimes.Significancefocused ultrasound has the potential of becoming a non-invasive alternative of conventional DBS for the treatment of Parkinson’s disease. Here, we elaborate on proposed benefits of combined electro-acoustic stimulation in terms of improved dynamic range, efficiency, resolution, and neuronal selectivity.

16 Noninvasive deep brain stimulation via delivery of temporally interfering electric fields

2020 ◽  
Vol 91 (8) ◽  
pp. e6.3-e7
Author(s):  
Nir Grossman
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Brain Stimulation ◽  
Dynamic Range ◽  
Imperial College ◽  
Network Activity ◽  
Massachusetts Institute Of Technology ◽  
Neural Firing ◽  
Institute Of Technology ◽  
The Brain

Nir is a Lecturer (Assistant Professor) at Imperial College London and a founding fellow of the UK Dementia Research Institute (UK-DRI). The long-term goal of his research is to develop neuromodulatory interventions for neurodegenerative diseases by direct modulation of the underlying aberrant network activity. Nir received a BSc in Physics from the Israeli Institute of Technology (Technion), an MSc in Electromagnetic Engineering from the Technical University of Hamburg-Harburg, and a PhD in Neuroscience from Imperial College London. He then completed a postdoc training, as a Wellcome Trust Fellow, at the Massachusetts Institute of Technology (MIT) and Harvard University. Nir was recently awarded the prestige prize for Neuromodulation from the Science magazine for describing how temporal interfering of kHz electric fields can non-invasively stimulate focal neural structures deep in the brain.Electrical brain stimulation is a key technique in research and clinical neuroscience studies, and also is in increasingly widespread use from a therapeutic standpoint. However, to date all methods of electrical stimulation of the brain either require surgery to implant an electrode at a defined site, or involve the application of non-focal electric fields to large fractions of the brain. We report a noninvasive strategy for electrically stimulating neurons at depth. By delivering to the brain multiple electric fields at frequencies too high to recruit neural firing, but which differ by a frequency within the dynamic range of neural firing, we can electrically stimulate neurons throughout a region where interference between the multiple fields results in a prominent electric field envelope modulated at the difference frequency. We validated this temporal interference (TI) concept via modeling and physics experiments, and verified that neurons in the living mouse brain could follow the electric field envelope. We demonstrate the utility of TI stimulation by stimulating neurons in the hippocampus of living mice without recruiting neurons of the overlying cortex. Finally, we show that by altering the currents delivered to a set of immobile electrodes, we can steerably evoke different motor patterns in living mice.

An in vivo investigation of inferior colliculus single neuron responses to cochlear nucleus pulse train stimulation

2012 ◽  
Vol 108 (11) ◽  
pp. 2999-3008 ◽  
Author(s):  
Stefan J. Mauger ◽  
Mohit N. Shivdasani ◽  
Graeme D. Rathbone ◽  
Antonio G. Paolini
Keyword(s):  
Speech Perception ◽  
Brain Stem ◽  
Inferior Colliculus ◽  
Cochlear Nucleus ◽  
Acoustic Stimulation ◽  
Neural Firing ◽  
Response Properties ◽  
Stimulus Rate ◽  
Auditory Brain Stem

The auditory brain stem implant (ABI) is being used clinically to restore hearing to patients unable to benefit from a cochlear implant (CI). Speech perception outcomes for ABI users are typically poor compared with most CI users. The ABI is implanted either on the surface of or penetrating through the cochlear nucleus in the auditory brain stem and uses stimulation strategies developed for auditory nerve stimulation with a CI. Although the stimulus rate may affect speech perception outcomes with current stimulation strategies, no studies have systematically investigated the effect of stimulus rate electrophysiologically or clinically. We therefore investigated rate response properties and temporal response properties of single inferior colliculus (IC) neurons from penetrating ABI stimulation using stimulus rates ranging from 100 to 1,600 pulses/s in the rat. We found that the stimulus rate affected the proportion of response types, thresholds, and dynamic ranges of IC activation. The stimulus rate was also found to affect the temporal properties of IC responses, with higher rates providing more temporally similar responses to acoustic stimulation. Suppression of neural firing and inhibition in IC neurons was also found, with response properties varying with the stimulus rate. This study demonstrated that changes in the ABI stimulus rate results in significant differences in IC neuron response properties. Due to electrophysiological differences, the stimulus rate may also change perceptual properties. We suggest that clinical evaluation of the ABI stimulus rate should be performed.

Neurocomputational Lightness Model Explains the Appearance of Real Surfaces Viewed Under Gelb Illumination

2020 ◽  
Vol 3 (1) ◽  
pp. 10502-1-10502-16
Author(s):  
Michael E. Rudd
Keyword(s):  
Dynamic Range ◽  
Neural Model ◽  
Cell Types ◽  
Emotional Reactions ◽  
Integration Process ◽  
Dynamic Range Compression ◽  
Cell Responses ◽  
Material Surfaces ◽  
Neural Gain ◽  
Dependent Factor

Abstract One of the primary functions of visual perception is to represent, estimate, and evaluate the properties of material surfaces in the visual environment. One such property is surface color, which can convey important information about ecologically relevant object characteristics such as the ripeness of fruit and the emotional reactions of humans in social interactions. This paper further develops and applies a neural model (Rudd, 2013, 2017) of how the human visual system represents the light/dark dimension of color—known as lightness—and computes the colors of achromatic material surfaces in real-world spatial contexts. Quantitative lightness judgments conducted with real surfaces viewed under Gelb (i.e., spotlight) illumination are analyzed and simulated using the model. According to the model, luminance ratios form the inputs to ON- and OFF-cells, which encode local luminance increments and decrements, respectively. The response properties of these cells are here characterized by physiologically motivated equations in which different parameters are assumed for the two cell types. Under non-saturating conditions, ON-cells respond in proportion to a compressive power law of the local incremental luminance in the image that causes them to respond, while OFF-cells respond linearly to local decremental luminance. ON- and OFF-cell responses to edges are log-transformed at a later stage of neural processing and then integrated across space to compute lightness via an edge integration process that can be viewed as a neurally elaborated version of Land’s retinex model (Land & McCann, 1971). It follows from the model assumptions that the perceptual weights—interpreted as neural gain factors—that the model observer applies to steps in log luminance at edges in the edge integration process are determined by the product of a polarity-dependent factor 1—by which incremental steps in log luminance (i.e., edges) are weighted by the value <1.0 and decremental steps are weighted by 1.0—and a distance-dependent factor 2, whose edge weightings are estimated to fit perceptual data. The model accounts quantitatively (to within experimental error) for the following: lightness constancy failures observed when the illumination level on a simultaneous contrast display is changed (Zavagno, Daneyko, & Liu, 2018); the degree of dynamic range compression in the staircase-Gelb paradigm (Cataliotti & Gilchrist, 1995; Zavagno, Annan, & Caputo, 2004); partial releases from compression that occur when the staircase-Gelb papers are reordered (Zavagno, Annan, & Caputo, 2004); and the larger compression release that occurs when the display is surrounded by a white border (Gilchrist & Cataliotti, 1994).

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