scholarly journals Optimization of spectral-domain optical coherence tomography with a supercontinuum source for in vivo motion detection of low reflective outer hair cells in guinea pig cochleae

2021 ◽  
Author(s):  
Fumiaki Nin ◽  
Samuel Choi ◽  
Takeru Ota ◽  
Zhang Qi ◽  
Hiroshi Hibino
Keyword(s):  
Optical Coherence Tomography ◽  
High Resolution ◽  
Guinea Pig ◽  
Hair Cells ◽  
Sensory Epithelium ◽  
Outer Hair Cells ◽  
Acquisition Time ◽  
Total Acquisition Time ◽  
Sd Oct

AbstractSound evokes sub-nanoscale vibration within the sensory epithelium. The epithelium contains not only immotile cells but also contractile outer hair cells (OHCs) that actively shrink and elongate synchronously with the sound. However, the in vivo motion of OHCs has remained undetermined. The aim of this work is to perform high-resolution and -accuracy vibrometry in live guinea pigs with an SC-introduced spectral-domain optical coherence tomography system (SD-OCT). In this study, to reveal the effective contribution of SC source in the recording of the low reflective materials with the short total acquisition time, we compare the performances of the SC-introduced SD-OCT (SCSD-OCT) to that of the conventional SD-OCT. As inanimate comparison objects, we record a mirror, a piezo actuator, and glass windows. For the measurements in biological materials, we use in/ex vivo guinea pig cochleae. Our study achieved the optimization of a SD-OCT system for high-resolution in vivo vibrometry in the cochlear sensory epithelium, termed the organ of Corti, in mammalian cochlea. By introducing a supercontinuum (SC) light source and reducing the total acquisition time, we improve the axial resolution and overcome the difficulty in recording the low reflective material in the presence of biological noise. The high power of the SC source enables the system to achieve a spatial resolution of 1.72 ± 0.00 μm on a mirror and reducing the total acquisition time contributes to the high spatial accuracy of sub-nanoscale vibrometry. Our findings reveal the vibrations at the apical/basal region of OHCs and the extracellular matrix, basilar membrane.

Novel method using 3-dimensional segmentation in spectral domain-optical coherence tomography imaging in the chick reveals defocus-induced regional and time-sensitive asymmetries in the choroidal thickness

2016 ◽  
Vol 33 ◽  
Author(s):  
DIANE R. NAVA ◽  
BHAVNA ANTONY ◽  
LI ZHANG ◽  
MICHAEL D. ABRÀMOFF ◽  
CHRISTINE F. WILDSOET
Keyword(s):  
Optical Coherence Tomography ◽  
High Resolution ◽  
Choroidal Thickness ◽  
Optical Coherence ◽  
3 Dimensional ◽  
Choroidal Thickening ◽  
Area Centralis ◽  
Oct Imaging ◽  
Sd Oct

AbstractStudies into the mechanisms underlying the active emmetropization process by which neonatal refractive errors are corrected, have described rapid, compensatory changes in the thickness of the choroidal layer in response to imposed optical defocus. While high frequency A-scan ultrasonography, as traditionally used to characterize such changes, offers good resolution of central (on-axis) changes, evidence of local retinal control mechanisms make it imperative that more peripheral, off-axis changes also be tracked. In this study, we used in vivo high resolution spectral domain-optical coherence tomography (SD-OCT) imaging in combination with the Iowa Reference Algorithms for 3-dimensional segmentation, to more fully characterize these changes, both spatially and temporally, in young, 7-day old chicks (n = 15), which were fitted with monocular +15 D defocusing lenses to induce choroidal thickening. With these tools, we were also able to localize the retinal area centralis, which was used as a landmark along with the ocular pectin in standardizing the location of scans and aligning them for subsequent analyses of choroidal thickness (CT) changes across time and between eyes. Values were derived for each of four quadrants, centered on the area centralis, and global CT values were also derived for all eyes. Data were compared with on-axis changes measured using ultrasonography. There were significant on-axis choroidal thickening that was detected after just one day of lens wear (∼190 µm), and regional (quadrant-related) differences in choroidal responses were also found, as well as global thickness changes 1 day after treatment. The ratio of global to on-axis choroidal thicknesses, used as an index of regional variability in responses, was also found to change significantly, reflecting the significant central changes. In summary, we demonstrated in vivo high resolution SD-OCT imaging, used in combination with segmentation algorithms, to be a viable and informative approach for characterizing regional (spatial), time-sensitive changes in CT in small animals such as the chick.

scholarly journals Design and Implementation Guidelines for a Modular Spectral-Domain Optical Coherence Tomography Scanner

2018 ◽  
Vol 2018 ◽  
pp. 1-22 ◽  
Author(s):  
Farid Atry ◽  
Israel Jacob De La Rosa ◽  
Kevin R. Rarick ◽  
Ramin Pashaie
Keyword(s):  
Optical Coherence Tomography ◽  
Imaging System ◽  
Optical Design ◽  
Spectral Domain ◽  
Design Parameters ◽  
Optical Coherence ◽  
Custom Made ◽  
Essential Knowledge ◽  
Sd Oct

In the past decades, spectral-domain optical coherence tomography (SD-OCT) has transformed into a widely popular imaging technology which is used in many research and clinical applications. Despite such fast growth in the field, the technology has not been readily accessible to many research laboratories either due to the cost or inflexibility of the commercially available systems or due to the lack of essential knowledge in the field of optics to develop custom-made scanners that suit specific applications. This paper aims to provide a detailed discussion on the design and development process of a typical SD-OCT scanner. The effects of multiple design parameters, for the main optical and optomechanical components, on the overall performance of the imaging system are analyzed and discussions are provided to serve as a guideline for the development of a custom SD-OCT system. While this article can be generalized for different applications, we will demonstrate the design of a SD-OCT system and representative results for in vivo brain imaging. We explain procedures to measure the axial and transversal resolutions and field of view of the system and to understand the discrepancies between the experimental and theoretical values. The specific aim of this piece is to facilitate the process of constructing custom-made SD-OCT scanners for research groups with minimum understanding of concepts in optical design and medical imaging.

Acetylcholine response in guinea pig outer hair cells. II. Activation of a small conductance Ca2+-activated K+ channel

1996 ◽  
Vol 101 (1-2) ◽  
pp. 149-172 ◽  
Author(s):  
Anastas P. Nenov ◽  
Charles Norris ◽  
Richard P. Bobbin
Keyword(s):  
Guinea Pig ◽  
Hair Cells ◽  
Outer Hair Cells ◽  
K Channel ◽  
Small Conductance

scholarly journals Effect of an ATP-Regulated Potassium Channel Opener, Nicorandil, on Isolated Outer Hair Cells of the Guinea Pig Cochlea

1998 ◽  
Vol 1998 (Supplement96) ◽  
pp. 23-30
Author(s):  
Akimitsu Kawai ◽  
Yukihiro Sato ◽  
Takeshi Akisada ◽  
Tsuyoshi Yoshihiro ◽  
Kotaro Take ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Potassium Channel ◽  
Hair Cells ◽  
Outer Hair Cells ◽  
Potassium Channel Opener ◽  
Guinea Pig Cochlea ◽  
Channel Opener

The location and mechanism of electromotility in guinea pig outer hair cells

1993 ◽  
Vol 70 (2) ◽  
pp. 549-558 ◽  
Author(s):  
R. Hallworth ◽  
B. N. Evans ◽  
P. Dallos
Keyword(s):  
Guinea Pig ◽  
Hair Cells ◽  
Outer Hair Cell ◽  
Length Change ◽  
Opposite Polarity ◽  
Outer Hair Cells ◽  
Response Amplitude ◽  
Change Function ◽  
Length Changes ◽  
Diameter Change

1. The microchamber method was used to examine the motile responses of isolated guinea pig outer hair cells to electrical stimulation. In the microchamber method, an isolated cell is drawn partway into a suction pipette and stimulated transcellularly. The relative position of the cell in the microchamber is referred to as the exclusion fraction. 2. The length changes of the included and excluded segments were compared for constant sinusoidal stimulus amplitude as functions of the exclusion fraction. Both included and excluded segments showed maximal responses when the cell was excluded approximately halfway. Both segments showed smaller or absent responses when the cell was almost fully excluded or almost fully included. 3. When the cell was near to, but not at, the maximum exclusion, the included segment response amplitude was zero, whereas the excluded segment response amplitude was nonzero. In contrast, when the cell was nearly fully included, the excluded segment response amplitude was zero, but the included segment response amplitude was still detectable. A simple model of outer hair cell motility based on these results suggests that the cell has finite-resistance terminations and that the motors are restricted to a region above the nucleus and below its ciliated apex (cuticular plate). 4. The function describing length change as a function of command voltage was measured for each segment as the exclusion fraction was varied. The functions were similar at midrange exclusions (i.e., when the segments were about equal length), showing nonlinearity and saturability. The functions were strikingly different when the segment lengths were different. The effects of exclusion on the voltage to length-change functions suggested that the nonlinearity and saturability are local properties of the motility mechanism. 5. The diameter changes of both segments were examined. The segment diameter changes were always antiphasic to the length changes. This finding implies that the motility mechanism has an active antiphasic diameter component. The diameter change amplitude was a monotonically increasing function of exclusion for the included segment, and a decreasing function for the excluded segment. 6. The voltage to length-change and voltage to diameter-change functions were measured for the same cell and exclusion fraction. The voltage to diameter-change function was smaller in amplitude than the voltage to length-change function. The functions were of opposite polarity to each other, but were otherwise similar in character. Thus it is likely that the same motor mechanism is responsible for both axial and diameter deformations.

Guinea Pig Vestibular Type I Hair Cells Can Show Reversible Shortening

1991 ◽  
Vol 1 (3) ◽  
pp. 241-250
Author(s):  
Pascale N.M. Lapeyre ◽  
Yves Cazals
Keyword(s):  
Guinea Pig ◽  
Hair Cells ◽  
Neck Region ◽  
Outer Hair Cells ◽  
Test Solution ◽  
Induced Response ◽  
Type I ◽  
Hypotonic Solution ◽  
Bathing Medium ◽  
Water Influx

Guinea pig isolated vestibular type I hair cells (VIHCs) were recently reported by our group to respond to high [KCl] solutions by an irreversible tilt of their neck region and sometimes by a sustained shortening and swelling. A possible osmotic contribution to these shape changes was investigated by substituting gluconate (G) for chloride in the test solution, so as to minimize water influx, and also by changing the osmotic pressure of the extracellular solution. For comparison, similar experiments were also undertaken on cochlear outer hair cells (OHCs). Utricular and ampullar type I hair cells were more difficult to isolate than OHCs and, like them, responded to an isotonic high [KCl] solution by a sustained shortening and widening, which were found to be reversible for most cells when rinsed with the control solution. In a high [KG] solution, all OHCs showed a shortening reversible in the test solution; among the VIHCs tested, two-thirds presented a slight sustained shortening without widening and a third showed a spontaneously reversible shortening, particularly at the neck level. VIHCs exposed to a high [N-methyl-D-glucamine chloride] solution, this impermeant cation replacing K+ for control, presented only a slight sustained shortening. In response to osmotic changes of the bathing medium, both VIHCs and OHCs showed a sustained shortening or elongation (the latter to a lesser degree) for hypo- and hyperosmotic solutions, respectively. The VIHCs and OHCs that presented a reversible shortening in a high [KG] solution widened concomitantly with their shortening, but to a smaller extent compared with what was observed in a high [KCl] solution, and this diameter increase was reversible in the test solution, unlike the widening observed in a hypotonic solution. These results show that a reversible shortening occurred for some VIHCs; they also indicate the involvement of two components in the KCl-induced response: one osmotic and another potassium-dependent.

Ionic Currents and Electromotility in Inner Ear Hair Cells From Humans

1998 ◽  
Vol 79 (4) ◽  
pp. 2235-2239 ◽  
Author(s):  
John S. Oghalai ◽  
Jeffrey R. Holt ◽  
Takashi Nakagawa ◽  
Thomas M. Jung ◽  
Newton J. Coker ◽  
...  
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Ionic Currents ◽  
Sensory Epithelium ◽  
Outer Hair Cells ◽  
Sensory Receptor ◽  
Surgical Removal ◽  
Type I ◽  
Vestibular Hair Cells ◽  
Sensory Receptor Cells

Oghalai, John S., Jeffrey R. Holt, Takashi Nakagawa, Thomas M. Jung, Newton J. Coker, Herman A. Jenkins, Ruth Anne Eatock, and William E. Brownell. Ionic currents and electromotility in inner ear hair cells from humans. J. Neurophysiol. 79: 2235–2239, 1998. The upright posture and rich vocalizations of primates place demands on their senses of balance and hearing that differ from those of other animals. There is a wealth of behavioral, psychophysical, and CNS measures characterizing these senses in primates, but no prior recordings from their inner ear sensory receptor cells. We harvested human hair cells from patients undergoing surgical removal of life-threatening brain stem tumors and measured their ionic currents and electromotile responses. The hair cells were either isolated or left in situ in their sensory epithelium and investigated using the tight-seal, whole cell technique. We recorded from both type I and type II vestibular hair cells under voltage clamp and found four voltage-dependent currents, each of which has been reported in hair cells of other animals. Cochlear outer hair cells demonstrated electromotility in response to voltage steps like that seen in rodent animal models. Our results reveal many qualitative similarities to hair cells obtained from other animals and justify continued investigations to explore quantitative differences that may be associated with normal or pathological human sensation.

Sign in / Sign up

Export Citation Format

Share Document