scholarly journals Behavior and modeling of two-dimensional precedence effect in head-unrestrained cats

2015 ◽  
Vol 114 (2) ◽  
pp. 1272-1285
Author(s):  
Yan Gai ◽  
Janet L. Ruhland ◽  
Tom C. T. Yin
Keyword(s):  
Potassium Current ◽  
Horizontal Plane ◽  
Sagittal Plane ◽  
Precedence Effect ◽  
The Novel ◽  
Medial Superior Olive ◽  
Localization Dominance ◽  
Low Threshold ◽  
Spatial Locations ◽  
Auditory Illusion

The precedence effect (PE) is an auditory illusion that occurs when listeners localize nearly coincident and similar sounds from different spatial locations, such as a direct sound and its echo. It has mostly been studied in humans and animals with immobile heads in the horizontal plane; speaker pairs were often symmetrically located in the frontal hemifield. The present study examined the PE in head-unrestrained cats for a variety of paired-sound conditions along the horizontal, vertical, and diagonal axes. Cats were trained with operant conditioning to direct their gaze to the perceived sound location. Stereotypical PE-like behaviors were observed for speaker pairs placed in azimuth or diagonally in the frontal hemifield as the interstimulus delay was varied. For speaker pairs in the median sagittal plane, no clear PE-like behavior occurred. Interestingly, when speakers were placed diagonally in front of the cat, certain PE-like behavior emerged along the vertical dimension. However, PE-like behavior was not observed when both speakers were located in the left hemifield. A Hodgkin-Huxley model was used to simulate responses of neurons in the medial superior olive (MSO) to sound pairs in azimuth. The novel simulation incorporated a low-threshold potassium current and frequency mismatches to generate internal delays. The model exhibited distinct PE-like behavior, such as summing localization and localization dominance. The simulation indicated that certain encoding of the PE could have occurred before information reaches the inferior colliculus, and MSO neurons with binaural inputs having mismatched characteristic frequencies may play an important role.

Psychophysical Investigation of an Auditory Spatial Illusion in Cats: The Precedence Effect

2003 ◽  
Vol 90 (4) ◽  
pp. 2149-2162 ◽  
Author(s):  
Daniel J. Tollin ◽  
Tom C.T. Yin
Keyword(s):  
Horizontal Plane ◽  
Sagittal Plane ◽  
Source Location ◽  
Precedence Effect ◽  
Search Coil ◽  
Localization Dominance ◽  
Reverberant Environments ◽  
Echo Threshold ◽  
Search Coil Technique

The precedence effect (PE) describes several spatial perceptual phenomena that occur when similar sounds are presented from two different locations and separated by a delay. The mechanisms that produce the effect are thought to be responsible for the ability to localize sounds in reverberant environments. Although the physiological bases for the PE have been studied, little is known about how these sounds are localized by species other than humans. Here we used the search coil technique to measure the eye positions of cats trained to saccade to the apparent locations of sounds. To study the PE, brief broadband stimuli were presented from two locations, with a delay between their onsets; the delayed sound meant to simulate a single reflection. Although the cats accurately localized single sources, the apparent locations of the paired sources depended on the delay. First, the cats exhibited summing localization, the perception of a “phantom” sound located between the sources, for delays < ±400 μs for sources positioned in azimuth along the horizontal plane, but not for sources positioned in elevation along the sagittal plane. Second, consistent with localization dominance, for delays from 400 μs to about 10 ms, the cats oriented toward the leading source location only, with little influence of the lagging source, both for horizontally and vertically placed sources. Finally, the echo threshold was reached for delays >10 ms, where the cats first began to orient to the lagging source on some trials. These data reveal that cats experience the PE phenomena similarly to humans.

Neural Correlates of the Precedence Effect in the Inferior Colliculus of Behaving Cats

2004 ◽  
Vol 92 (6) ◽  
pp. 3286-3297 ◽  
Author(s):  
Daniel J. Tollin ◽  
Luis C. Populin ◽  
Tom C. T. Yin
Keyword(s):  
Inferior Colliculus ◽  
Sound Localization ◽  
Species Differences ◽  
Behavioral Responses ◽  
Neural Correlates ◽  
Precedence Effect ◽  
Single Neurons ◽  
Localization Dominance ◽  
Echo Threshold ◽  
Spatial Locations

Several auditory spatial illusions, collectively called the precedence effect (PE), occur when transient sounds are presented from two different spatial locations but separated in time by an interstimulus delay (ISD). For ISDs in the range of localization dominance (<10 ms), a single fused sound is typically located near the leading source location only, as if the location of the lagging source were suppressed. For longer ISDs, both the leading and lagging sources can be heard and localized, and the shortest ISD where this occurs is called the echo threshold. Previous physiological studies of the extracellular responses of single neurons in the inferior colliculus (IC) of anesthetized cats and unanesthetized rabbits with sounds known to elicit the PE have shown correlates of these phenomena though there were differences in the physiologically measured echo thresholds. Here we recorded in the IC of awake, behaving cats using stimuli that we have shown to evoke behavioral responses that are consistent with the precedence effect. For small ISDs, responses to the lag were reduced or eliminated consistent with psychophysical data showing that sound localization is based on the leading source. At longer ISDs, the responses to the lagging source recovered at ISDs comparable to psychophysically measured echo thresholds. Thus it appears that anesthesia, and not species differences, accounts for the discrepancies in the earlier studies.

scholarly journals Soma-axon coupling configurations that enhance neuronal coincidence detection

2018 ◽  
Author(s):  
Joshua H Goldwyn ◽  
Michiel WH Remme ◽  
John Rinzel
Keyword(s):  
Parameter Space ◽  
Negative Feedback ◽  
Potassium Current ◽  
Auditory Brainstem ◽  
Coincidence Detection ◽  
Detection Sensitivity ◽  
Medial Superior Olive ◽  
Coupled Models ◽  
Input Region ◽  
Low Threshold

AbstractCoincidence detector neurons transmit timing information by responding preferentially to concurrent synaptic inputs. Principal cells of the medial superior olive (MSO) in the mammalian auditory brainstem are superb coincidence detectors. They encode sound source location with high temporal precision, distinguishing submillisecond timing differences among inputs. We investigate computationally how dynamic coupling between the “input” region (soma and dendrite) and the spike-generating “output” region (axon and axon initial segment) can enhance coincidence detection in MSO neurons. To do this, we formulate a two-compartment neuron model and characterize extensively coincidence detection sensitivity throughout a parameter space of coupling configurations. We focus on the interaction between coupling configuration and two currents that provide dynamic, voltage-gated, negative feedback in subthreshold voltage range: sodium current with rapid inactivation and low-threshold potassium current, IKLT. These currents reduce synaptic summation and can prevent spike generation unless inputs arrive with near simultaneity. We show that strong soma-to-axon coupling promotes the negative feedback effects of sodium inactivation and is, therefore, advantageous for coincidence detection. Furthermore, the “feedforward” combination of strong soma-to-axon coupling and weak axon-to-soma coupling enables spikes to be generated efficiently (few sodium channels needed) and with rapid recovery that enhances high-frequency coincidence detection. These observations detail the functional benefit of the strongly feedforward configuration that has been observed in physiological studies of MSO neurons. We find that IKLT further enhances coincidence detection sensitivity, but with effects that depend on coupling configuration. For instance, in weakly-coupled models, IKLT in the spike-generator compartment enhances coincidence detection more effectively than IKLT in the input compartment. By using a minimal model of soma-to-axon coupling, we connect structure, dynamics, and computation. Here, we consider the particular case of MSO coincidence detectors. In principle, our method for creating and exploring a parameter space of two-compartment models can be applied to other neurons.Author summaryBrain cells (neurons) are spatially extended structures. The locations at which neurons receive inputs and generate outputs are often distinct. We formulate and study a minimal mathematical model that describes the dynamical coupling between the input and output regions of a neuron. We construct our model to reflect known properties of neurons in the auditory brainstem that play an important role in our ability to locate sound sources. These neurons are known as “coincidence detectors” because they are most likely to respond when they receive simultaneous inputs. We use simulations to explore coincidence detection sensitivity throughout the parameter space of input-output coupling and to identify the coupling configurations that are best for neural coincidence detection. We find that strong forward coupling (from input region to output region), enhances coincidence detection sensitivity in our model and that low-threshold potassium current further improves coincidence detection. Our study is significant in that we detail how cell structure affects neuronal dynamics and, consequently, the ability of neurons to perform as temporally-precise coincidence detectors.

scholarly journals Validation of Freehand Cervical Pedicle Screw Placement in Subaxial Spine Using the “Burcev Technique”: A Cadaveric Study

2021 ◽  
Author(s):  
Mantu Jain ◽  
Rabi N. Sahu ◽  
Manisha R. Gaikwad ◽  
Sashikanta Panda ◽  
Amit Tirpude ◽  
...  
Keyword(s):  
Horizontal Plane ◽  
Sagittal Plane ◽  
Pedicle Screws ◽  
Continuous Variables ◽  
Pedicle Screw Placement ◽  
Cervical Pedicle Screw ◽  
Freehand Technique ◽  
Computed Tomography Scans ◽  
Cervical Pedicle ◽  
Cervical Pedicle Screws

AbstractThe present study attempted to validate the “Burcev freehand method” based on anatomical observations in Indian cadavers. The study was conducted on 32 cervical pedicle screws (CPSs) that were placed in four cadavers by the authors according to the “freehand technique,” described by Burcev et al, without the aid of fluoroscopy and the trajectory verified by computed tomography scans. The screws were designated as satisfactory, permissible, or unacceptable. Descriptive variables were represented in number and percentages, continuous variables were represented as mean ± standard deviation (SD). Of the 32 CPSs placed, 24 (75%) exhibited a satisfactory position, 1 (3%) exhibited a permissible position, and 7 (22%) exhibited an unacceptable position. Of the seven CPSs in the unacceptable group, four exhibited a lateral breach and three exhibited a medial breach, whereas the CPS in the permissible group exhibited a medial breach. The overall angle with contralateral lamina in the horizontal plane in terms of mean ± SD was 175.43 ± 2.82, 169.49, and 169.65 ± 6.46 degrees in the satisfactory, permissible, and unacceptable groups, respectively. In the sagittal plane, the screws exhibited an angle of 88.15 ± 3.56 degrees. No breach was observed superiorly or inferiorly. The “Burcev technique” is replicable with similar results in cadavers. Further studies must be conducted in a clinical setting to ensure its safety.

scholarly journals (Non)Places of Bangalore: Where the East Meets the West in Bharati Mukherjee’s Miss New India

2019 ◽  
pp. 83-90
Author(s):  
Izabella Kimak
Keyword(s):  
South Asia ◽  
South Asian ◽  
Asian American ◽  
The Novel ◽  
The West ◽  
South Asian American ◽  
Primary Location ◽  
Spatial Locations ◽  
The Impact

This essay constitutes an attempt at reading Bharati Mukherjee’s 2011 novel, Miss New India, through the prism of spatial locations depicted in it. Unlike many of the texts in the late South Asian American author’s oeuvre, which depict migration from the East to the West, Miss New India is located exclusively within South Asia. This notwithstanding, the novel focuses on the impact the West used to and continues to exert on the East. I would like to argue that through her depictions of places and non-places of Bangalore-the novel’s primary location-Mukherjee points to the spatial interconnectedness of the East and the West as well as to the temporal interconnectedness of the colonial past and postcolonial, late-capitalist present.

scholarly journals A Novel H+ Conductance in Eosinophils

1999 ◽  
Vol 190 (2) ◽  
pp. 183-194 ◽  
Author(s):  
Botond Bánfi ◽  
Jacques Schrenzel ◽  
Oliver Nüsse ◽  
Daniel P. Lew ◽  
Erzsébet Ligeti ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
The Novel ◽  
Experimental Conditions ◽  
Intact Cells ◽  
Electrophysiological Studies ◽  
Dependent Signal ◽  
Low Threshold ◽  
Nadph Oxidase Activation ◽  
In Cells

Efficient mechanisms of H+ ion extrusion are crucial for normal NADPH oxidase function. However, whether the NADPH oxidase—in analogy with mitochondrial cytochromes—has an inherent H+ channel activity remains uncertain: electrophysiological studies did not find altered H+ currents in cells from patients with chronic granulomatous disease (CGD), challenging earlier reports in intact cells. In this study, we describe the presence of two different types of H+ currents in human eosinophils. The “classical” H+ current had properties similar to previously described H+ conductances and was present in CGD cells. In contrast, the “novel” type of H+ current had not been described previously and displayed unique properties: (a) it was absent in cells from gp91- or p47-deficient CGD patients; (b) it was only observed under experimental conditions that allowed NADPH oxidase activation; (c) because of its low threshold of voltage activation, it allowed proton influx and cytosolic acidification; (d) it activated faster and deactivated with slower and distinct kinetics than the classical H+ currents; and (e) it was ∼20-fold more sensitive to Zn2+ and was blocked by the histidine-reactive agent, diethylpyrocarbonate (DEPC). In summary, our results demonstrate that the NADPH oxidase or a closely associated protein provides a novel type of H+ conductance during phagocyte activation. The unique properties of this conductance suggest that its physiological function is not restricted to H+ extrusion and repolarization, but might include depolarization, pH-dependent signal termination, and determination of the phagosomal pH set point.

scholarly journals Inhibition of Human Ether-A-Go-Go-Related Gene (hERG) Potassium Current by the Novel Sotalol Analogue, Soestalol

2020 ◽  
Vol 6 (7) ◽  
pp. 756-759
Author(s):  
Tyler Shugg ◽  
John C. Somberg ◽  
Janos Molnar ◽  
Brian R. Overholser
Keyword(s):  
Potassium Current ◽  
The Novel ◽  
Related Gene

The Function of the Acromioclavicular and Coracoclavicular Ligaments in Shoulder Motion

2012 ◽  
Vol 40 (11) ◽  
pp. 2617-2626 ◽  
Author(s):  
Satoshi Oki ◽  
Noboru Matsumura ◽  
Wataru Iwamoto ◽  
Hiroyasu Ikegami ◽  
Yoshimori Kiriyama ◽  
...  
Keyword(s):  
Horizontal Plane ◽  
Acromioclavicular Joint ◽  
Sagittal Plane ◽  
Shoulder Girdle ◽  
Surgical Reconstruction ◽  
Acromioclavicular Joint Dislocation ◽  
Joint Dislocation ◽  
3 Dimensional ◽  
Joint Dislocations ◽  
Ligament Disruption

Background: Scapulothoracic dyskinesis is an important consequence of acromioclavicular joint dislocations. However, no reports have described changes in 3-dimensional motions of the scapula and clavicle with respect to the thorax caused by acromioclavicular joint dislocation. Hypothesis: Sectioning of the acromioclavicular (AC) and coracoclavicular (CC) ligaments affects scapular and clavicular motion in a whole-cadaver model. Study Design: Controlled laboratory study. Methods: We evaluated shoulder girdle motion (scapula, clavicle, and humerus) relative to the thorax of 14 shoulders from 8 whole cadavers after sequential sectioning of the AC and CC ligaments (trapezoid and conoid ligaments). An electromagnetic tracking device measured 3-dimensional kinematics of the scapula and clavicle during humerothoracic elevation in the coronal and sagittal planes and adduction in the horizontal plane. Results: Sectioning of the AC ligament increased clavicular retraction during sagittal plane elevation and horizontal plane adduction. Sectioning of the trapezoid ligament decreased scapular external rotation during sagittal plane elevation and horizontal plane adduction. Sectioning of the conoid ligament decreased scapular posterior tilting during sagittal plane elevation and horizontal plane adduction. Acromioclavicular and CC ligament sectioning also delayed clavicular posterior rotation and increased clavicular upward rotation during coronal plane elevation. Conclusion: Our study revealed that AC and CC ligament disruption affected in vitro shoulder girdle kinematics in the whole-cadaver model. Clinical Relevance: The results of this cadaveric study revealed that AC and CC ligament disruption could cause dyskinesis of the scapula and clavicle. The kinematic changes could be a potential source of pain and dysfunction in the shoulder with AC joint dislocation, and therefore surgical reconstruction may be indicated in certain patients.

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