Introducing Temporal Rate Coding for Speech in Cochlear Implants: A Microscopic Evaluation in Humans and Models

2016 ◽  
Author(s):  
Anja Eichenauer ◽  
Mathias Dietz ◽  
Bernd T. Meyer ◽  
Tim Jürgens
Keyword(s):  
Cochlear Implants ◽  
Microscopic Evaluation ◽  
Rate Coding ◽  
Temporal Rate

Ovarian Dysfunction in Fetally Irradiated Beagles

1977 ◽  
Vol 35 ◽  
pp. 658-659
Author(s):  
T. M. Seed ◽  
M. H. Sanderson ◽  
D. L. Gutzeit ◽  
T. E. Fritz ◽  
D. V. Tolle ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Low Dose ◽  
Long Term Effects ◽  
Ovarian Dysfunction ◽  
Dose Rates ◽  
Highly Sensitive ◽  
Microscopic Evaluation ◽  
Ovarian Pathology ◽  
Normal Offspring

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.

Selection and Preparation of Specific Tissue Regions For Tem Using Large Epoxy-Embedded Blocks

1973 ◽  
Vol 31 ◽  
pp. 324-325 ◽  
Author(s):  
P. M. Lowrie ◽  
W. S. Tyler
Keyword(s):  
Electron Microscopy ◽  
Anatomical Structures ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Microscopic Evaluation ◽  
Embedded Blocks ◽  
Specific Tissue ◽  
Definition Of ◽  
Areas Of Interest ◽  
Selection Of

The importance of examining stained 1 to 2μ plastic sections by light microscopy has long been recognized, both for increased definition of many histologic features and for selection of specimen samples to be used in ultrastructural studies. Selection of specimens with specific orien ation relative to anatomical structures becomes of critical importance in ultrastructural investigations of organs such as the lung. The uantity of blocks necessary to locate special areas of interest by random sampling is large, however, and the method is lacking in precision. Several methods have been described for selection of specific areas for electron microscopy using light microscopic evaluation of paraffin, epoxy-infiltrated, or epoxy-embedded large blocks from which thick sections were cut. Selected areas from these thick sections were subsequently removed and re-embedded or attached to blank precasted blocks and resectioned for transmission electron microscopy (TEM).

TEM comparison of osmium vs osmium with potassium ferricyanide secondary fixatives and the impact of secondary fixative temperature on tissue preservation/contrast quality

1996 ◽  
Vol 54 ◽  
pp. 910-911
Author(s):  
J. W. Horn ◽  
B. J. Dovey-Hartman ◽  
V. P. Meador
Keyword(s):  
Osmium Tetroxide ◽  
Potassium Ferricyanide ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Microscopic Evaluation ◽  
Cacodylate Buffer ◽  
Transmission Electron Microscopic ◽  
Glutaraldehyde Solution ◽  
Temperature Impact ◽  
The Impact

Osmium tetroxide (OsO4) is a universally used secondary fixative for routine transmission electron microscopic evaluation of biological specimens. Use of OsO4 results in good ultrastructural preservation and electron density but several factors, such as concentration, length of exposure, and temperature, impact overall results. Potassium ferricyanide, an additive used primarily in combination with OsO4, has mainly been used to enhance the contrast of lipids, glycogen, cell membranes, and membranous organelles. The purpose of this project was to compare the secondary fixative solutions, OsO4 vs. OsO4 with potassium ferricyanide, and secondary fixative temperature for determining which combination gives optimal ultrastructural fixation and enhanced organelle staining/contrast.Fresh rat liver samples were diced to ∼1 mm3 blocks, placed into porous processing capsules/baskets, preserved in buffered 2% formaldehyde/2.5% glutaraldehyde solution, and rinsed with 0.12 M cacodylate buffer (pH 7.2). Tissue processing capsules were separated (3 capsules/secondary fixative.solution) and secondarily fixed (table) for 90 minutes. Tissues were buffer rinsed, dehydrated with ascending concentrations of ethanol solutions, infiltrated, and embedded in epoxy resin.

Evaluation of platelet dense granules for determining storage pool deficiencies by HVEM image and quantitative analysis

1996 ◽  
Vol 54 ◽  
pp. 770-771
Author(s):  
W.T. Gunning ◽  
J.N. Turner ◽  
K. Buttle ◽  
E.P. Calomeni ◽  
N.A. Lachant ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Platelet Function ◽  
Electron Microscopic ◽  
Von Willebrand's Disease ◽  
Dense Granules ◽  
Storage Pool ◽  
Prolonged Bleeding ◽  
Microscopic Evaluation ◽  
Storage Pools ◽  
Electron Lucent

There are a variety of conditions which have been associated with prolonged bleeding times. If other etiologies including von Willebrand's disease have been ruled out, a platelet function disorder must be considered. The best, if not only, technique to make this diagnosis is the electron microscopic evaluation of whole air dried platelets. Bull first described the presence of dense granules in whole platelets in 1968 and the technique has been utilized extensively The electron dense or delta granules are easily distinguished from the larger more numerous alpha granules which are electron lucent. The significance of the dense granules is that they are known to be “storage pools” of serotonin, calcium, adenosine di- and triphosphate, and pyrophosphate. Prolonged bleeding times may be directly related to an insufficiency of these substances. The diagnosis of a storage pool deficiency is made when either the storage content of the dense granules is abnormal or their number is diminished. We observe normal platelets to have 4-6 dense granules, which agrees with the literature.

Effects of Fundamental Frequency Contours on Sentence Recognition in Mandarin-Speaking Children With Cochlear Implants

2020 ◽  
Vol 63 (11) ◽  
pp. 3855-3864
Author(s):  
Wanting Huang ◽  
Lena L. N. Wong ◽  
Fei Chen ◽  
Haihong Liu ◽  
Wei Liang
Keyword(s):  
Cochlear Implants ◽  
Fundamental Frequency ◽  
Signal To Noise Ratio ◽  
Lexical Tone ◽  
Signal To Noise ◽  
Sentence Recognition ◽  
Test Conditions ◽  
Age Appropriate ◽  
F0 Contour ◽  
Appropriate Sentences

Purpose Fundamental frequency (F0) is the primary acoustic cue for lexical tone perception in tonal languages but is processed in a limited way in cochlear implant (CI) systems. The aim of this study was to evaluate the importance of F0 contours in sentence recognition in Mandarin-speaking children with CIs and find out whether it is similar to/different from that in age-matched normal-hearing (NH) peers. Method Age-appropriate sentences, with F0 contours manipulated to be either natural or flattened, were randomly presented to preschool children with CIs and their age-matched peers with NH under three test conditions: in quiet, in white noise, and with competing sentences at 0 dB signal-to-noise ratio. Results The neutralization of F0 contours resulted in a significant reduction in sentence recognition. While this was seen only in noise conditions among NH children, it was observed throughout all test conditions among children with CIs. Moreover, the F0 contour-induced accuracy reduction ratios (i.e., the reduction in sentence recognition resulting from the neutralization of F0 contours compared to the normal F0 condition) were significantly greater in children with CIs than in NH children in all test conditions. Conclusions F0 contours play a major role in sentence recognition in both quiet and noise among pediatric implantees, and the contribution of the F0 contour is even more salient than that in age-matched NH children. These results also suggest that there may be differences between children with CIs and NH children in how F0 contours are processed.

Age at Full-Time Use Predicts Language Outcomes Better Than Age of Surgery in Children Who Use Cochlear Implants

2019 ◽  
Vol 28 (4) ◽  
pp. 986-992 ◽  
Author(s):  
Lisa R. Park ◽  
Erika B. Gagnon ◽  
Erin Thompson ◽  
Kevin D. Brown
Keyword(s):  
Cochlear Implants ◽  
Time Use ◽  
Expressive Language ◽  
Normal Hearing ◽  
Full Time ◽  
Language Outcomes ◽  
Age At Surgery ◽  
Device Placement ◽  
Device Use ◽  
Better Than

Purpose The aims of this study were to (a) determine a metric for describing full-time use (FTU), (b) establish whether age at FTU in children with cochlear implants (CIs) predicts language at 3 years of age better than age at surgery, and (c) describe the extent of FTU and length of time it took to establish FTU in this population. Method This retrospective analysis examined receptive and expressive language outcomes at 3 years of age for 40 children with CIs. Multiple linear regression analyses were run with age at surgery and age at FTU as predictor variables. FTU definitions included 8 hr of device use and 80% of average waking hours for a typically developing child. Descriptive statistics were used to describe the establishment and degree of FTU. Results Although 8 hr of daily wear is typically considered FTU in the literature, the 80% hearing hours percentage metric accounts for more variability in outcomes. For both receptive and expressive language, age at FTU was found to be a better predictor of outcomes than age at surgery. It took an average of 17 months for children in this cohort to establish FTU, and only 52.5% reached this milestone by the time they were 3 years old. Conclusions Children with normal hearing can access spoken language whenever they are awake, and the amount of time young children are awake increases with age. A metric that incorporates the percentage of time that children with CIs have access to sound as compared to their same-aged peers with normal hearing accounts for more variability in outcomes than using an arbitrary number of hours. Although early FTU is not possible without surgery occurring at a young age, device placement does not guarantee use and does not predict language outcomes as well as age at FTU.

Overview of Current Approaches to Aural Rehabilitation for Adults With Cochlear Implants

2020 ◽  
Vol 5 (5) ◽  
pp. 1175-1187
Author(s):  
Rachel Glade ◽  
Erin Taylor ◽  
Deborah S. Culbertson ◽  
Christin Ray
Keyword(s):  
Health Care ◽  
Clinical Practice ◽  
Cochlear Implants ◽  
Practice Patterns ◽  
The United States ◽  
Care Providers ◽  
Aural Rehabilitation ◽  
Starting Point ◽  
Clinical Models ◽  
Hearing Health

Purpose This clinical focus article provides an overview of clinical models currently being used for the provision of comprehensive aural rehabilitation (AR) for adults with cochlear implants (CIs) in the Unites States. Method Clinical AR models utilized by hearing health care providers from nine clinics across the United States were discussed with regard to interprofessional AR practice patterns in the adult CI population. The clinical models were presented in the context of existing knowledge and gaps in the literature. Future directions were proposed for optimizing the provision of AR for the adult CI patient population. Findings/Conclusions There is a general agreement that AR is an integral part of hearing health care for adults with CIs. While the provision of AR is feasible in different clinical practice settings, service delivery models are variable across hearing health care professionals and settings. AR may include interprofessional collaboration among surgeons, audiologists, and speech-language pathologists with varying roles based on the characteristics of a particular setting. Despite various existing barriers, the clinical practice patterns identified here provide a starting point toward a more standard approach to comprehensive AR for adults with CIs.

Selecting the Optimal FM System for Children With Cochlear Implants

2008 ◽  
Vol 18 (1) ◽  
pp. 19-24
Author(s):  
Erin C. Schafer
Keyword(s):  
Speech Recognition ◽  
Cochlear Implants ◽  
Empirical Research ◽  
Background Noise ◽  
Signal To Noise Ratio ◽  
Evidence Based ◽  
Signal To Noise ◽  
Speech Processor ◽  
System Input ◽  
Optimal Type

Children who use cochlear implants experience significant difficulty hearing speech in the presence of background noise, such as in the classroom. To address these difficulties, audiologists often recommend frequency-modulated (FM) systems for children with cochlear implants. The purpose of this article is to examine current empirical research in the area of FM systems and cochlear implants. Discussion topics will include selecting the optimal type of FM receiver, benefits of binaural FM-system input, importance of DAI receiver-gain settings, and effects of speech-processor programming on speech recognition. FM systems significantly improve the signal-to-noise ratio at the child's ear through the use of three types of FM receivers: mounted speakers, desktop speakers, or direct-audio input (DAI). This discussion will aid audiologists in making evidence-based recommendations for children using cochlear implants and FM systems.

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