Less is more: optimal recording time for measuring the steady-state accommodative response

Zhang, Hongyu and Paul D. R. Gamlin. Neurons in the posterior interposed nucleus of the cerebellum related to vergence and accommodation. I. Steady-state characteristics. J. Neurophysiol. 79: 1255–1269, 1998. The present study used single-unit recording and electrical microstimulation techniques in alert, trained rhesus monkeys to examine the involvement of the posterior interposed nucleus (IP) of the cerebellum in vergence and accommodative eye movements. Neurons related to vergence and ocular accommodation were encountered within a circumscribed region of the IP and their activity during changes in viewing distance was characterized. The activity of these neurons increased with decreases in vergence angle and accommodation (the far-response) but none showed changes in activity during changes in conjugate eye position and we therefore term them “far-response neurons.” Far-response neurons were found within a restricted region of the IP that extended ∼1 mm rostrocaudally and mediolaterally and 2 mm dorsal to the fourth ventricle. Microstimulation of this far-response region of the IP with low currents (<30 μA) often elicited divergence and accommodation for far. The behavior of 37 IP far-response neurons was examined during normal binocular viewing, during monocular viewing (blur cue alone), and during binocular viewing with accommodation open-loop (disparity cue alone). The activity of all cells was modulated under all three conditions. However, the change in activity of some of these neurons was significantly different under these three viewing conditions. The behavior of 70 IP far-response neurons was compared during normal binocular viewing and during viewing in which the accommodative response was significantly dissociated from the vergence response. The data from these two conditions was pooled and multiple regression analyses for each neuron generated two coefficients expressing the activity of the neuron relative to the vergence and to accommodative response respectively. On the basis of these coefficients, the overall activity of the neurons were classified as follows: 34 positively correlated with divergence, 11 positively correlated with far accommodation, 14 positively correlated with divergence and far accommodation, 9 positively correlated with divergence and accommodation, and 2 positively correlated with convergence and far accommodation. The results of this study demonstrate the involvement of a specific region of the posterior interposed nucleus of the cerebellum in vergence and accommodation. IP far-response neurons are active for vergence and accommodation irrespective of whether or not these eye movements are elicited by blur or disparity cues. The data in the present study strongly suggest that this cerebellar region is a far-response region that is involved in vergence as well as accommodative eye movements.

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Predicting Pure-Tone Thresholds with Dichotic Multiple Frequency Auditory Steady State Responses

Journal of the American Academy of Audiology ◽

10.3766/jaaa.16.1.2 ◽

2005 ◽

Vol 16 (01) ◽

pp. 005-017 ◽

Cited By ~ 8

Author(s):

Dunay Schmulian ◽

DeWet Swanepoel ◽

René Hugo

Keyword(s):

Steady State ◽

Pure Tone ◽

Low Frequency ◽

Tone Burst ◽

Multiple Frequency ◽

Recording Time ◽

Steady State Responses ◽

Pure Tones ◽

Auditory Steady State Responses ◽

State Responses

The accuracy of dichotic multiple frequency auditory steady state in predicting pure-tone thresholds at 0.5, 1, 2, and 4.0 kHz compared to an ABR protocol (click and tone burst at 0.5 kHz) were explored in a group of 25 hearing-impaired subjects across the degree and configuration spectrum. Mean steady state thresholds were within 14, 18, 15, and 14 dB of the pure tones at 0.5, 1, 2, and 4 kHz, compared to the tone-burst ABR at 0.5 kHz pure-tone difference of 24 dB, and a click-evoked pure-tone (2–4 kHz) difference of 9 dB. Recording time for the steady state protocol was 28 minutes (+/-11) compared to 24 minutes (+/- 9) of the ABR protocol. Degree of loss had a significant effect on steady state; configuration of hearing loss had a limited effect. Mf ASSR predicted thresholds with relative accuracy although some configurations showed discrepancies for low-frequency estimates.

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Signal-to-Noise Ratios of the Auditory Steady-State Response from Fifty-Five EEG Derivations in Adults

Journal of the American Academy of Audiology ◽

10.3766/jaaa.15.10.4 ◽

2004 ◽

Vol 15 (10) ◽

pp. 692-701 ◽

Cited By ~ 17

Author(s):

Christoph S. van der Reijden ◽

Lucas H.M. Mens ◽

Ad F.M. Snik

Keyword(s):

Steady State ◽

Single Channel ◽

Electrode Position ◽

Steady State Response ◽

Single Channel Recording ◽

Signal To Noise ◽

Recording Time ◽

State Response ◽

Test Efficiency ◽

Auditory Steady State Response

The Auditory Steady-State Response (ASSR) was recorded in 20 awake adults with normal hearing on ten EEG channels simultaneously to find derivations with the best signal-to-noise ratios (SNRs). Stimuli were 20% frequency modulated tones of 0.5 and 2 kHz at 20 dB SL, 100% amplitude modulated at 90 or 94 Hz, and presented one at a time to one ear.ASSR recordings using a set of at least three channels improved SNRs significantly by an average of between 6% (500 Hz right ear) to 118% (2 kHz right ear) above the SNRs from the conventional channels. Assuming that the recording time was proportional to 1/(SNR)2, this translates into a recording time of 89% (500 Hz right ear) to 21% (2 kHz right ear) of that for conventional single-channel recording.The three channels comprised the electrode positions inion, right mastoid, and left mastoid. All three electrode positions were referenced to Cz. Adding a fourth channel (Pz-Cz) increases the number of participants with significant responses from the 500 Hz right ear stimulus from 13 to 17. Electrode position F4 and other commonly used positions such as the forehead and right earlobe made significantly less contribution to test efficiency.

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Substantiation of informative amplitudes during registration of acoustic emission signals from the friction zone of tribosystems

PROBLEMS OF TRIBOLOGY ◽

10.31891/2079-1372-2021-99-1-6-12 ◽

2021 ◽

Vol 99 (1) ◽

pp. 6-12

Author(s):

V. Vojtov ◽

K. Fenenko ◽

A. Voitov ◽

Keyword(s):

Acoustic Emission ◽

Steady State ◽

Linear Relationship ◽

Diagnostic Technique ◽

Autocorrelation Coefficient ◽

Recording Time ◽

Friction Zone ◽

Steady State Operation ◽

Base Cluster ◽

The Impact

In this work, the dependence of the change in the probability density of the distribution of the number of pulses and amplitudes of acoustic emission (AE) signals from the friction zone at the steady-state operation of the tribosystem is obtained. Acoustic vibrations that the tribosystem generates during operation are due to the impact interaction of the roughness of the friction surfaces of their elastoplastic deformation, processes of formation and destruction of frictional links, structural and phase rearrangement of materials, the formation and development of microcracks in the surface layers of contacting bodies, separation of wear particles. The dependence allows you to determine a sufficient number of pulses in the signal frame and their amplitude values for diagnosing tribosystems during their operation. The values of the informative amplitudes of the clusters are experimentally substantiated К2, К3, К4 in relation to the base cluster К1. It is shown that an increase in the informative frequency fAE(fix) from 250 to 500 kHz, increases the value of the informative amplitude to 17,6…43,75%. Based on the results obtained, it was concluded that this fact must be taken into account when developing methods, which will increase the accuracy of diagnosing tribosystems. The autocorrelation coefficient characterizes the closeness of the linear relationship of the current and previous frames of the series for each of the analyzed clusters. By the value of the autocorrelation coefficient, one can judge the presence of a linear relationship between the values of the recorded amplitudes, their reproducibility in terms of recording time in the steady-state operation of the tribosystem. To confirm the sufficiency of the selected number of pulses in the clusters of the AE signal frame, as well as the reproducibility of the results of the analysis of frames when they shift in time of registration, an expression is obtained for calculating the autocorrelation function, which reflects the relationship between successive levels of the time series. Based on the results of the experimental data, the values of the autocorrelation coefficients were calculated, equal to 0,82…0,92, which indicates the robustness of the chosen diagnostic technique.

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Estimating Audiometric Thresholds Using Auditory Steady-State Responses

Journal of the American Academy of Audiology ◽

10.3766/jaaa.16.3.3 ◽

2005 ◽

Vol 16 (03) ◽

pp. 140-156 ◽

Cited By ~ 98

Author(s):

Terence W. Picton ◽

Andrew Dimitrijevic ◽

Maria-Cecilia Perez-Abalo ◽

Patricia Van Roon

Keyword(s):

Steady State ◽

Normal Subjects ◽

Hearing Impaired ◽

Elderly Subjects ◽

Recording Time ◽

Steady State Responses ◽

Young Subjects ◽

Auditory Steady State Responses ◽

Intensity Functions ◽

State Responses

Human auditory steady-state responses (ASSRs) were recorded using stimulus rates of 78–95 Hz in normal young subjects, in elderly subjects with relatively normal hearing, and in elderly subjects with sensorineural hearing impairment. Amplitude-intensity functions calculated relative to actual sensory thresholds (sensation level or SL) showed that amplitudes increased as stimulus intensity increased. In the hearing-impaired subjects this increase was more rapid at intensities just above threshold ("electrophysiological recruitment") than at higher intensities where the increase was similar to that seen in normal subjects. The thresholds in dB SL for recognizing an ASSR and the intersubject variability of these thresholds decreased with increasing recording time and were lower in the hearing impaired compared to the normal subjects. After 9.8 minutes of recording, the average ASSR thresholds (and standard deviations) were 12.6 ± 8.7 in the normal subjects, 12.4 ± 11.9 dB in the normal elderly, and 3.6 ± 13.5 dB SL in the hearing-impaired subjects.

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HETEROGENEOUS EXPECTATIONS AND ENDOGENOUS FLUCTUATIONS IN THE FINANCIAL ACCELERATOR FRAMEWORK

Macroeconomic Dynamics ◽

10.1017/s1365100518000251 ◽

2018 ◽

Vol 24 (2) ◽

pp. 327-359 ◽

Cited By ~ 1

Author(s):

Davide Bazzana

Keyword(s):

Monetary Policy ◽

Steady State ◽

Rational Expectations ◽

System Stability ◽

Fiscal Policies ◽

Financial Accelerator ◽

Macroeconomic Dynamics ◽

Expectations Hypothesis ◽

Macroeconomic Volatility ◽

Less Is More

This paper proposes a financial accelerator framework to study the effects of heterogeneous and bounded rational expectations on macroeconomic dynamics. The paper examines the fluctuations effects departing from the rational expectations hypothesis in order to understand if there are significant implications on macroeconomic volatility and policy prescriptions. The findings suggest that macroeconomic stability and inflation dynamics depend on the chosen set of forecasting rules, as well as on the monetary policy adopted. The model shows that no monetary policy is able to quickly stabilize the system, as some fluctuations persist. Central banks face a trade-off between macro-volatility and speed of convergence to the steady state. This result offers some ground for fiscal policies aiming to prompt system stability. In addition, the analysis reveals a counterintuitive result confirming the “less-is-more” effect: increasing the decision-making and computational abilities of the agents may not lead the system to converge to the preferable steady state.

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