Deciphering compromised speech-in-noise intelligibility in older listeners: the role of cochlear synaptopathy.

Speech intelligibility declines with age and sensorineural hearing damage (SNHL). However, it remains unclear whether cochlear synaptopathy (CS), a recently discovered form of SNHL, significantly contributes to this issue. CS refers to damaged auditory-nerve synapses that innervate the inner hair cells and there is currently no go-to diagnostic test available.

Isolating auditory-nerve contributions to electrocochleography by high-pass filtering: A better biomarker for cochlear nerve degeneration?

In search of biomarkers for cochlear neural degeneration (CND) in electrocochleography from humans with normal thresholds, we high-pass and low-pass filtered the responses to separate contributions of auditory-nerve action potentials (N) from hair-cell summating potentials (SP). The new N measure is better correlated with performance on difficult word-recognition tasks used as a proxy for CND. Furthermore, the paradoxical correlation between larger SPs and worse word scores, observed with classic electrocochleographic analysis, disappears with the new metric.

Model-based hearing-enhancement strategies for cochlear synaptopathy pathologies.

It is well known that ageing and noise exposure are important causes of sensorineural hearing loss, and can result in damage of the outer hair cells or other structures of the inner ear, including synaptic damage to the auditory nerve (AN), i.e., cochlear synaptopathy (CS).

Predicting neural deficits in sensorineural hearing loss from word recognition scores.

The current gold standard of clinical hearing assessment includes a pure-tone audiogram combined with a word recognition task. This retrospective study tests the hypothesis that deficits in word recognition that cannot be explained by loss in audibility or cognition may reflect underlying cochlear nerve degeneration (CND). We collected the audiological data of nearly 96,000 ears from patients with normal hearing, conductive hearing loss (CHL) and a variety of sensorineural etiologies including (1) age-related hearing loss (ARHL); (2) neuropathy related to vestibular schwannoma or neurofibromatosis of type 2; (3) Ménière's disease; (4) sudden sensorineural hearing loss (SSNHL), (5) exposure to ototoxic drugs (carboplatin and/or cisplatin, vancomycin or gentamicin) or (6) noise damage including those with a 4-kHz "noise notch" or reporting occupational or recreational noise exposure.

Energy and frequency ripple in devices with inertial excitation of oscillations.

We consider vibration devices that consist of softly vibration-isolated rigid bodies subjected to vibrations transmitted by means of inertial vibration exciters (unbalanced rotors) driven into rotation by electric motors. Typically, when designing such devices, it is assumed that the rotors rotate uniformly with a certain circular frequency and the body performs small harmonic oscillations with the same frequency. The present work, using a second-order approximation of their nonlinear coupled differential equations, shows that the rotor and the oscillating body keep exchanging energy.

Envelope following responses predict speech-in-noise performance in normal-hearing listeners.

Permanent threshold elevation after noise exposure or aging is caused by loss of sensory cells; however, animal studies show that hair cell loss is often preceded by degeneration of the synapses between sensory cells and auditory nerve fibers. Silencing these neurons is likely to degrade auditory processing and may contribute to difficulties understanding speech in noisy backgrounds. Reduction of suprathreshold ABR amplitudes can be used to quantify synaptopathy in inbred mice.

Enhancing the sensitivity of the envelope-following response for cochlear synaptopathy screening in humans: The role of stimulus envelope.

Auditory de-afferentation, a permanent reduction in the number of inner-hair-cells and auditory-nerve synapses due to cochlear damage or synaptopathy, can reliably be quantified using temporal bone histology and immunostaining. However, there is an urgent need for non-invasive markers of synaptopathy to study its perceptual consequences in live humans and to develop effective therapeutic interventions. While animal studies have identified candidate auditory-evoked-potential (AEP) markers for synaptopathy, their interpretation in humans has suffered from translational issues related to neural generator differences, unknown hearing-damage histopathologies or lack of measurement sensitivity.

The derived-band envelope following response and its sensitivity to sensorineural hearing deficits.

The envelope following response (EFR) has been proposed as a non-invasive marker of synaptopathy in animal models. However, its amplitude is affected by the spread of basilar-membrane excitation and other coexisting sensorineural hearing deficits. This study aims to (i) improve frequency specificity of the EFR by introducing a derived-band EFR (DBEFR) technique and (ii) investigate the effect of lifetime noise exposure, age and outer-hair-cell (OHC) damage on DBEFR magnitudes.

Computational modeling of the human auditory periphery: Auditory-nerve responses, evoked potentials and hearing loss.

Models of the human auditory periphery range from very basic functional descriptions of auditory filtering to detailed computational models of cochlear mechanics, inner-hair cell (IHC), auditory-nerve (AN) and brainstem signal processing. It is challenging to include detailed physiological descriptions of cellular components into human auditory models because single-cell data stems from invasive animal recordings while human reference data only exists in the form of population responses (e.g.

[Local synchronized activity of neurons of different classes in cat primary visual cortex].

The goal of the present study was to investigate the local synchronized neuronal activity in the cat visual cortex and the role of different classes of neurons in neural synchrony. Four classes of neurons were identified on the basis of electrophysiological properties of extracellular recorded cells: RS, FS, IB and FRB. It was revealed that neurons with short spikes and FRB type of activity were first engaged in synchronization.

[Modeling of localization phenomena of the auditory image caused by brain regions dysfunctions].

This paper focuses on the modeling of the neural representations of subjective auditory image motion characters that can be induced by bilateral brain dysfunctions. The modeling is based on a biologically inspired computational model that simulates the behavior of bilaterally located populations of binaural auditory neurons. To assess neural model responses in terms of psychophysical data, a special method is designed.

Accurate detection of interaural time differences by a population of slowly integrating neurons.

For localization of a sound source, animals and humans process the microsecond interaural time differences of arriving sound waves. How nervous systems, consisting of elements with time constants of about and more than 1 ms, can reach such high precision is still an open question. In this Letter we present a hypothesis and show theoretical and computational evidence that a rather large population of slowly integrating neurons with inhibitory and excitatory inputs (EI neurons) can detect minute temporal disparities in input signals which are significantly less than any time constant in the system.

[Role of disrupting the antioxidant status of the body in forming the endogenous intoxication syndrome in patients with toxic and terminal stages of peritonitis].

Fifty-one patients with diffuse peritonitis were treated. 40 of these presented with the toxic stage and 11 had terminal stage with lethal outcomes. Studies of the antioxidant status showed an important role of lipid peroxidation metabolites in the formation of endogenous intoxication during the early postoperative period, manifesting, among other things, by decreased albumin transporting function.

[Liver function and the lipid metabolic status of patients before and after a surgical intervention on the gastrointestinal tract].

Local hepatic bloodflow (LHB) and metabolic processes were examined in patients with abdominal diseases during intensive transfusion and infusion therapy attended by incomplete parenteral feeding. A reduction of LHB and disorders of lipid metabolism were observed before surgery. After surgery LHB was still reduced on days 1-3.

[Hyperbaric oxygenation and current methods of detoxication in multimodal intensive therapy of diffuse peritonitis].

The course of diffuse peritonitis has been followed up in 219 patients, 20 of these with the reactive, 165 with toxic, and 34 with the terminal stages of the condition. Multiple-modality intensive care included, besides routine therapy, local abdominal hypothermia, UV irradiation of autoblood (UVIAB), and, if indicated, hyperbaric oxygenation (HBO) and hemoperfusion. In addition to clinical tests, immunobiochemical monitoring of medium-molecular peptide fractions MM1 and MM2 and index of their distribution, as well as of circulating immune complexes CIC1 and CIC2 and the levels of immunoglobulins IgA, IgM, and IgG were the criteria for assessing the severity of intoxication and efficacy of intensive care and for predicting the course and outcome of the disease.

[Changes in the cerebral blood flow in neurosurgical patients during general anesthesia using antihypoxic agents].

Cerebral blood flow (CBF) and central hemodynamics (CH) have been studied during anesthesia and after surgery in patients with tumours located in brain hemispheres. CBF and CH were determined by radiography. GOBA, diazepam and sodium thiopental were used for anesthesia.

[Complications of anesthesia and means of lowering their frequency].

Retrospective analysis of 9262 formalized case histories has been made to compile a protocol of anesthesia. Each blank contains 223 items describing the patient and is intended for retrospective computer analysis of the information. Phases of the complications onset have been established and a working classification of complications has been suggested.

[Local abdominal hypothermia in the intensive treatment of children with diffuse suppurative peritonitis].

Local abdominal hypothermia in intensive therapy of peritonitis in children checked abdominal inflammation, prevented the onset of hyperthermic reactions, promoted early stabilization of central hemodynamic parameters and early normalization of humoral immunity and led to certain clinical improvement. Taking into consideration the above data as well as possible indications and contraindications one can recommend local abdominal hypothermia for intensive therapy of generalized suppurative peritonitis in children.