An electrophysiological measure of tonotopic selectivity in normal-hearing humans and cats

We describe a non-invasive electrophysiological (EEG) measure of tonotopic selectivity and compare the results between humans and cats. Sequences of 50-ms tone-burst probes were presented at 1-second intervals against a continuous noise masker, and the averaged cortical onset response (COR) to the probe was measured using EEG electrodes placed on the scalp. The noise masker had a bandwidth of 1 or 1/8th octave, geometrically centred on 4000 Hz for humans and 8000 Hz for cats. Probe frequency was either -0.5, -0.25, 0, 0.25 or 0.5 octaves re 4000/8000 Hz. The COR was larger for probe frequencies more distant from the noise geometrical centre, and this effect was greater for the 1/8th-octave than for the 1-octave masker. This pattern broadly reflected the masked excitation patterns obtained psychophysically with similar stimuli in a companion paper. However, the positive signal-to-noise ratio used to obtain reliable COR measures meant that some aspects of the data differed from those obtained psychophysically, in a way that could be partly explained by the upward spread of the probe’s excitation pattern. We argue that although COR measures are affected by some factors that differ from those that influence psychophysical masked detection thresholds, they can reveal differences in the width of excitation patterns produced by different stimuli. We also argue that the paradigm may be effectively applied to cochlear-implant experiments in humans and animals.

Diagnosis of Subungual Glomus Tumors with 18 MHz Ultrasound and CDFI

To evaluate the imaging features of subungual glomus tumors using 18 MHz high-frequency ultrasound with CDFI (Color Doppler Flow Imaging). 20 patients treated by surgical resection and examined by ultrasound between January 2008 and December 2019. All eligible cases are divided into two groups: Group A used the probe frequency of 9–14 MHz from January 2008 to December 2014, and Group B used the probe frequency of 18 MHz from January 2015 to December 2019. Patient demographics, clinical records, pathologic specimens and sonography features were reviewed. 50% of tumors in Group A and 100% of tumors in Group B showed clear boundary and regular shape. Blood flow signals were identified inside 50% tumors in Group A (3 in 6), all 14 cases with blood flow signals detected in Group B (14 in 14,100%). 2 cases were misdiagnosed and 1 case escaped diagnosis in Group A, no case was misdiagnosed in Group B. The accuracy of diagnosis rate of Group B is significantly higher than that of Group A. 18-MHz ultrasound combined with CDFI may be a practical useful tool for detecting subungual glomus tumors. More importantly 18-MHz ultrasound can obviously improve the diagnostic accuracy.

Rate and synchrony at the level of the auditory nerve are not sufficient to account for behaviorally estimated cochlear compression - a modeling study

Methods based on psychoacoustical forward masking have been proposed to estimate the local compressive growth of the basilar membrane (BM). This results from normal outer hair cells function, which leads to level-dependent amplification of BM vibration. Psychoacoustical methods assume that cochlear processing can be isolated from the response of the overall system, that sensitivity is dominated by the tonotopic location of the probe and that the effect of forward masking is different for on- and off-characteristic frequency (CF) maskers. In the present study, a computational model of the auditory nerve (AN) in combination with signal detection theory was used to test these assumptions. The underlying idea was that, for the BM compression to be estimated using psychoacoustics, enough information should be preserved at the level of the AN, because this forms an information bottleneck in the ascending auditory pathway. The simulated AN responses were quantified in terms of rate and synchrony for different types of AN fibers and CFs. The results show that, when using a low-intensity probe, local activity at the tonotopic location of the probe frequency is the dominant contributor to sensitivity in the healthy auditory system. However, on- and off-CF maskers produced similar forward masking onto the probe, which was mainly encoded by high- and to little extent by medium-spontaneous rate fibers. The simulation results suggested that the estimate of compression based on the behavioral experiments cannot be derived from sensitivity at the level of the AN but may require additional contributions, supporting previous physiological studies.

Echocardiographic evaluation of normal adult left Ventricular geometry in a Nigerian population

BackgroundDifferences have shown to exist in some echocardiographic measurements that were attributed to racial, ethnic and gender. This study determined echocardiographic baseline data of normal adult left ventricular (LV) geometry in our locality.MethodsThe study was performed on 1,192 apparently healthy adults. Participants below the age of 18 years or those with congenital or acquired cardiac abnormalities and history of long-term regular physical training were excluded. Trans-thoracic echocardiography was performed with Vivid T8 GE dedicated echocardiography machine with probe frequency of 1.7 to 3.2 MHz with integrated electrocardiography (ECG) recording electrodes. The study determined normal dimensions of interventricular diamensions. All measurements were indexed to body surface area (BSA) to obtain echocardiographic baseline normal reference values.ResultsThe mean + SD values of LV parameters for male and female participants were: LVIDd (44.80 ± 5.71 mm vs 42.75 ± 5.21 mm), LVIDs (33.54 ± 5.37 mm vs 30.38 ± 4.81 mm), and LVPWd (8.32 ± 1.26 mm vs 7.51 ± 1.22 mm). Females had more statistically significant interventricular septum in diastole (IVSd) (8.20 ± 1.38 mm vs 7.05 ± 1.27 mm) and interventricular septum in systole (IVSs) (9.08 ± 1.42 mm vs 8.99 ± 1.33 mm) (P < 0.05).ConclusionThis research established echocardiographic baseline normal adult left ventricular geometry in the study population because in order to detect abnormalities, accurate definition of normal values of echocardiographic measurements is of utmost importance for a reliable clinical decision making.

Artificial Neural Network Modelling for Prediction of SNR Effected by Probe Properties on Ultrasonic Inspection of Austenitic Stainless Steel Weldments

Many austenitic stainless steel components are used in the construction of nuclear power plants. These components are joined by different welding processes, and radiation damages occur in the welds during the service life of the plant. The plants are inspected periodically with ultrasonic test methods. Many ultrasonic inspection problems arise due to the weld metal microstructure of austenitic stainless steel weldments. The present research was conducted in order to describe the affects of probe angle and probe frequency of both transversal and longitudinal wave probes on detecting the defects of austenitic stainless steel weldments. Feed forward back propagation artificial neural network (ANN) models have been developed for predicting signal to noise ratio (SNR) of transversal and longitudinal wave probes. Input variables that affect SNR output in these models are welding angle, probe angle, probe frequency and sound path. Of the experimental data, 80% is used for a training dataset and 20% is used for a testing dataset with 10 neurons in hidden layers in developed ANN models. Mean absolute error (MAE) and mean absolute percentage error (MAPE) types are calculated as 0.0656 and 16.28%, respectively, to predict performance of ANN models in a transversal wave probe. In addition, MAE and MAPE are calculated as 0.0478 and 18.01%, respectively, for performance in a longitudinal wave probe.

Examining the effects of probe frequency, response options, and framing within the thought-probe method

A recent surge of interest into the empirical measurement of mind-wandering has led to an increase in the use of thought-probing to measure attentional states, which has led to a large degree of variability in methodologies across studies (Weinstein, in press). Three sources of variation in methodology include the frequency of thought probes during a task, the number of response options provided for each probe, and the way in which various attentional states are framed during task instructions. Method variation can potentially affect behavioral performance on the tasks into which thought probes are embedded, the experience of various attentional states within those tasks, and/or response biases to thought probes. Therefore, such variation can be problematic both pragmatically and theoretically. Across three experiments we examined how manipulating probe frequency, response options, and framing affected behavioral performance and responses to thought probes. Probe frequency and framing did not affect behavioral performance or probe responses. But based on the present results we argue that thought probes need at least three response corresponding to on-task, off-task, and task-related interference. When specifically investigating mind-wandering, probe responses should also distinguish between mind-wandering, external distraction, and mind-blanking.