Differential Adaptation of the Linear and Nonlinear Components of the Horizontal Vestibuloocular Reflex in Squirrel Monkeys

2002 ◽  
Vol 88 (6) ◽  
pp. 3534-3540 ◽  
Author(s):  
Richard A. Clendaniel ◽  
David M. Lasker ◽  
Lloyd B. Minor
Keyword(s):  
Squirrel Monkeys ◽  
Linear Component ◽  
Vestibuloocular Reflex ◽  
Nonlinear Component ◽  
Adaptive Process ◽  
Gain Enhancement ◽  
High Acceleration ◽  
Differential Adaptation ◽  
Linear And Nonlinear ◽  
Nonlinear Components

Previous work in squirrel monkeys has demonstrated the presence of linear and nonlinear components to the horizontal vestibuloocular reflex (VOR) evoked by high-acceleration rotations. The nonlinear component is seen as a rise in gain with increasing velocity of rotation at frequencies more than 2 Hz (a velocity-dependent gain enhancement). We have shown that there are greater changes in the nonlinear than linear component of the response after spectacle-induced adaptation. The present study was conducted to determine if the two components of the response share a common adaptive process. The gain of the VOR, in the dark, to sinusoidal stimuli at 4 Hz (peak velocities: 20–150°/s) and 10 Hz (peak velocities: 20 and 100°/s) was measured pre- and postadaptation. Adaptation was induced over 4 h with ×0.45 minimizing spectacles. Sum-of-sines stimuli were used to induce adaptation, and the parameters of the stimuli were adjusted to invoke only the linear or both linear and nonlinear components of the response. Preadaptation, there was a velocity-dependent gain enhancement at 4 and 10 Hz. In postadaptation with the paradigms that only recruited the linear component, there was a decrease in gain and a persistent velocity-dependent gain enhancement (indicating adaptation of only the linear component). After adaptation with the paradigm designed to recruit both the linear and nonlinear components, there was a decrease in gain and no velocity-dependent gain enhancement (indicating adaptation of both components). There were comparable changes in the response to steps of acceleration. We interpret these results to indicate that separate processes drive the adaptation of the linear and nonlinear components of the response.

Linear and nonlinear components of human electroretinogram

1984 ◽  
Vol 51 (5) ◽  
pp. 952-967 ◽  
Author(s):  
C. L. Baker ◽  
R. F. Hess
Keyword(s):  
Steady State ◽  
Spatial Frequency ◽  
Step Response ◽  
Linear Component ◽  
Fast Wave ◽  
Uniform Field ◽  
Nonlinear Component ◽  
Symmetric Component ◽  
Linear And Nonlinear ◽  
Nonlinear Components

We compared electroretinographic (ERG) responses to uniform-field and a variety of pattern stimuli using both transient and steady-state analyses. Evidence is provided that for all of these stimuli, the peak at high temporal frequencies in the steady-state response corresponds to the fast wave of the transient response and that the peak at low temporal frequencies corresponds to the slow wave of the step response. A variety of contrast-modulated grating stimuli were used to demonstrate that the fast, high-frequency response can be regarded as the sum of two components, an "odd-symmetric" component, which behaves linearly and is independent of spatial frequency, and an "even-symmetric" component, which behaves nonlinearly and has a band-pass spatial-frequency dependence. The prevailing distinction that is made between pattern and uniform-field ERGs is a consequence of the fact that the uniform-field ERG is dominated by the odd-symmetric (linear) component, whereas the so-called pattern (contrast reversal) ERG reveals the even-symmetric (nonlinear) component in isolation. Since a uniform field can also drive the nonlinear component, the present dichotomy ("luminance" versus "pattern") can be better understood in terms of the linear and nonlinear components of the response rather than in terms of the stimuli that produce them.

Horizontal Vestibuloocular Reflex Evoked by High-Acceleration Rotations in the Squirrel Monkey. IV. Responses After Spectacle-Induced Adaptation

2001 ◽  
Vol 86 (4) ◽  
pp. 1594-1611 ◽  
Author(s):  
Richard A. Clendaniel ◽  
David M. Lasker ◽  
Lloyd B. Minor
Keyword(s):  
Linear Term ◽  
Linear Component ◽  
Vestibuloocular Reflex ◽  
Gain Enhancement ◽  
High Acceleration ◽  
Normal Behavior ◽  
Adaptive Processes ◽  
Vor Adaptation ◽  
Differential Increase ◽  
Sinusoidal Rotations

The horizontal angular vestibuloocular reflex (VOR) evoked by sinusoidal rotations from 0.5 to 15 Hz and acceleration steps up to 3,000°/s2 to 150°/s was studied in six squirrel monkeys following adaptation with ×2.2 magnifying and ×0.45 minimizing spectacles. For sinusoidal rotations with peak velocities of 20°/s, there were significant changes in gain at all frequencies; however, the greatest gain changes occurred at the lower frequencies. The frequency- and velocity-dependent gain enhancement seen in normal monkeys was accentuated following adaptation to magnifying spectacles and diminished with adaptation to minimizing spectacles. A differential increase in gain for the steps of acceleration was noted after adaptation to the magnifying spectacles. The gain during the acceleration portion, G A, of a step of acceleration (3,000°/s2 to 150°/s) increased from preadaptation values of 1.05 ± 0.08 to 1.96 ± 0.16, while the gain during the velocity plateau, G V, only increased from 0.93 ± 0.04 to 1.36 ± 0.08. Polynomial fits to the trajectory of the response during the acceleration step revealed a greater increase in the cubic than the linear term following adaptation with the magnifying lenses. Following adaptation to the minimizing lenses, the value of G A decreased to 0.61 ± 0.08, and the value of G V decreased to 0.59 ± 0.09 for the 3,000°/s2 steps of acceleration. Polynomial fits to the trajectory of the response during the acceleration step revealed that there was a significantly greater reduction in the cubic term than in the linear term following adaptation with the minimizing lenses. These findings indicate that there is greater modification of the nonlinear as compared with the linear component of the VOR with spectacle-induced adaptation. In addition, the latency to the onset of the adapted response varied with the dynamics of the stimulus. The findings were modeled with a bilateral model of the VOR containing linear and nonlinear pathways that describe the normal behavior and adaptive processes. Adaptation for the linear pathway is described by a transfer function that shows the dependence of adaptation on the frequency of the head movement. The adaptive process for the nonlinear pathway is a gain enhancement element that provides for the accentuated gain with rising head velocity and the increased cubic component of the responses to steps of acceleration. While this model is substantially different from earlier models of VOR adaptation, it accounts for the data in the present experiments and also predicts the findings observed in the earlier studies.

Horizontal Vestibuloocular Reflex Evoked by High-Acceleration Rotations in the Squirrel Monkey. III. Responses After Labyrinthectomy

2000 ◽  
Vol 83 (5) ◽  
pp. 2482-2496 ◽  
Author(s):  
David M. Lasker ◽  
Timothy E. Hullar ◽  
Lloyd B. Minor
Keyword(s):  
Squirrel Monkey ◽  
High Frequency ◽  
Squirrel Monkeys ◽  
Spontaneous Nystagmus ◽  
Vestibuloocular Reflex ◽  
Testing Session ◽  
High Acceleration ◽  
Unilateral Labyrinthectomy ◽  
Linear And Nonlinear ◽  
Sinusoidal Rotations

The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in four squirrel monkeys after unilateral labyrinthectomy. Spontaneous nystagmus was measured at the beginning and end of each testing session. During the period that animals were kept in darkness (4 days), the nystagmus at each of these times measured ∼20°/s. Within 18–24 h after return to the light, the nystagmus (measured in darkness) decreased to 2.8 ± 1.5°/s (mean ± SD) when recorded at the beginning but was 20.3 ± 3.9°/s at the end of the testing session. The latency of the VOR measured from responses to steps of acceleration (3,000°/s2 reaching a velocity of 150°/s) was 8.4 ± 0.3 ms for responses to ipsilesional rotations and 7.7 ± 0.4 ms for contralesional rotations. During the period that animals were kept in darkness after the labyrinthectomy, the gain of the VOR measured during the steps of acceleration was 0.67 ± 0.12 for contralesional rotations and 0.39 ± 0.04 for ipsilesional rotations. Within 18–24 h after return to light, the VOR gain for contralesional rotations increased to 0.87 ± 0.08, whereas there was only a slight increase for ipsilesional rotations to 0.41 ± 0.06. A symmetrical increase in the gain measured at the plateau of head velocity was noted after the animals were returned to light. The VOR evoked by sinusoidal rotations of 2–15 Hz, ±20°/s, showed a better recovery of gain at lower (2–4 Hz) than at higher (6–15 Hz) frequencies. At 0.5 Hz, gain decreased symmetrically when the peak amplitude was increased from 20 to 100°/s. At 10 Hz, gain was decreased for ipsilesional half-cycles and increased for contralesional half-cycles when velocity was raised from 20 to 50°/s. A model incorporating linear and nonlinear pathways was used to simulate the data. Selective increases in the gain for the linear pathway accounted for the recovery in VOR gain for responses at the velocity plateau of the steps of acceleration and for the sinusoidal rotations at lower peak velocities. The increase in gain for contralesional responses to steps of acceleration and sinusoidal rotations at higher frequencies and velocities was due to an increase in the contribution of the nonlinear pathway. This pathway was driven into cutoff and therefore did not affect responses for rotations toward the lesioned side.

Simulation-based site amplification model for shallow bedrock sites in Korea

2021 ◽  
pp. 875529302098198
Author(s):  
Muhammad Aaqib ◽  
Duhee Park ◽  
Muhammad Bilal Adeel ◽  
Youssef M A Hashash ◽  
Okan Ilhan
Keyword(s):  
Linear Models ◽  
Site Response ◽  
Site Amplification ◽  
One Dimensional ◽  
Nonlinear Component ◽  
Nonlinear Site Response ◽  
Simulation Based ◽  
Linear And Nonlinear ◽  
Input Motion ◽  
Nonlinear Components

A new simulation-based site amplification model for shallow sites with thickness less than 30 m in Korea is developed. The site amplification model consists of linear and nonlinear components that are developed from one-dimensional linear and nonlinear site response analyses. A suite of measured shear wave velocity profiles is used to develop corresponding randomized profiles. A VS30 scaled linear amplification model and a model dependent on both VS30 and site period are developed. The proposed linear models compare well with the amplification equations developed for the western United States (WUS) at short periods but show a distinct curved bump between 0.1 and 0.5 s that corresponds to the range of site natural periods of shallow sites. The response at periods longer than 0.5 s is demonstrated to be lower than those of the WUS models. The functional form widely used in both WUS and central and eastern North America (CENA), for the nonlinear component of the site amplification model, is employed in this study. The slope of the proposed nonlinear component with respect to the input motion intensity is demonstrated to be higher than those of both the WUS and CENA models, particularly for soft sites with VS30 < 300 m/s and at periods shorter than 0.2 s. The nonlinear component deviates from the models for generic sites even at low ground motion intensities. The comparisons highlight the uniqueness of the amplification characteristics of shallow sites that a generic site amplification model is unable to capture.

Horizontal Vestibuloocular Reflex Evoked by High-Acceleration Rotations in the Squirrel Monkey. II. Responses After Canal Plugging

1999 ◽  
Vol 82 (3) ◽  
pp. 1271-1285 ◽  
Author(s):  
David M. Lasker ◽  
Douglas D. Backous ◽  
Anna Lysakowski ◽  
Griffin L. Davis ◽  
Lloyd B. Minor
Keyword(s):  
High Frequency ◽  
Peak Velocity ◽  
Vestibular Function ◽  
Semicircular Canals ◽  
Vestibuloocular Reflex ◽  
Half Cycle ◽  
High Acceleration ◽  
Linear And Nonlinear ◽  
Residual Response ◽  
Sinusoidal Rotations

The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in four squirrel monkeys after unilateral plugging of the three semicircular canals. During the period (1–4 days) that animals were kept in darkness after plugging, the gain during steps of acceleration (3,000°/s2, peak velocity = 150°/s) was 0.61 ± 0.14 (mean ± SD) for contralesional rotations and 0.33 ± 0.03 for ipsilesional rotations. Within 18–24 h after animals were returned to light, the VOR gain for contralesional rotations increased to 0.88 ± 0.05, whereas there was only a slight increase in the gain for ipsilesional rotations to 0.37 ± 0.07. A symmetrical increase in the gain measured at the plateau of head velocity was noted after animals were returned to light. The latency of the VOR was 8.2 ± 0.4 ms for ipsilesional and 7.1 ± 0.3 ms for contralesional rotations. The VOR evoked by sinusoidal rotations of 0.5–15 Hz, ±20°/s had no significant half-cycle asymmetries. The recovery of gain for these responses after plugging was greater at lower than at higher frequencies. Responses to rotations at higher velocities for frequencies ≥4 Hz showed an increase in contralesional half-cycle gain, whereas ipsilesional half-cycle gain was unchanged. A residual response that appeared to be canal and not otolith mediated was noted after plugging of all six semicircular canals. This response increased with frequency to reach a gain of 0.23 ± 0.03 at 15 Hz, resembling that predicted based on a reduction of the dominant time constant of the canal to 32 ms after plugging. A model incorporating linear and nonlinear pathways was used to simulate the data. The coefficients of this model were determined from data in animals with intact vestibular function. Selective increases in the gain for the linear and nonlinear pathways predicted the changes in recovery observed after canal plugging. An increase in gain of the linear pathway accounted for the recovery in VOR gain for both responses at the velocity plateau of the steps of acceleration and for the sinusoidal rotations at lower peak velocities. The increase in gain for contralesional responses to steps of acceleration and sinusoidal rotations at higher frequencies and velocities was due to an increase in the gain of the nonlinear pathway. This pathway was driven into inhibitory cutoff at low velocities and therefore made no contribution for rotations toward the ipsilesional side.

scholarly journals Probing the linearity and nonlinearity in the transitions of the atmospheric circulation

2001 ◽  
Vol 8 (6) ◽  
pp. 341-345 ◽  
Author(s):  
A. A. Tsonis
Keyword(s):  
Dynamical System ◽  
Information Theory ◽  
Time Series ◽  
Atmospheric Circulation ◽  
Nonlinear Model ◽  
Linear Component ◽  
Linear And Nonlinear ◽  
Definition Of ◽  
Nonlinear Components ◽  
Nonlinear Predictability

Abstract. In this paper, we apply the principles of information theory that relate to the definition of nonlinear predictability, which is a measure that describes both the linear and nonlinear components of a system. By comparing this measure to a measure of linear predictability, one can assess whether a given system has a strong nonlinear or a strong linear component. This provides insights as to whether the system should be modelled by a nonlinear model or by a linear model. We apply these ideas to a known dynamical system and to a time series that describe the transitions in atmospheric circulation.

Capacity of Vertical VOR Adaptation in Squirrel Monkey

2002 ◽  
Vol 88 (6) ◽  
pp. 3194-3207 ◽  
Author(s):  
Y. Hirata ◽  
J. M. Lockard ◽  
S. M. Highstein
Keyword(s):  
Motor Learning ◽  
Head Movement ◽  
High Frequency ◽  
Low Frequency ◽  
Squirrel Monkeys ◽  
Head Motion ◽  
Vestibuloocular Reflex ◽  
Differential Adaptation ◽  
Vor Adaptation ◽  
Eye Velocity

Squirrel monkeys were trained using newly developed visual-vestibular mismatch paradigms to test the asymmetrical simultaneous induction of vertical vestibuloocular reflex (VOR) gain changes in opposite directions (high and low) either in the upward and downward directions or in response to high- and low-frequency stimuli. The first paradigm consists of sinusoidal head movement [ Asin(ω t)] and a full rectified sinusoidal optokinetic stimulus [±‖ A sin(ω t)‖], whereas the second paradigm consists of the sum of two sinusoids with different frequencies { A sin(ω1 t) + A sin(ω2 t) for head motion and ±[ Asin(ω1 t) − Asin(ω2 t)] for the optokinetic stimulus, ω1 = 0.1π, ω2 = 5π}. The first paradigm induced a half rectified sinusoidal eye-velocity trace, i.e., suppression of the VOR during upward head motion and enhancement during downward head motion or vise versa, whereas the second paradigm induced suppression of the VOR at the low-frequency ω1 and enhancement at the high-frequency ω2 or vise versa. After 4 h of exposure to these paradigms, VOR gains of up and down or high and low frequency were modified in opposite directions. We conclude that the monkey vertical VOR system is capable of up-down directionally differential adaptation as well as high-low frequency differential adaptation. However, experiments also suggest that these gain controls are not completely independent because the magnitudes of the gain changes during simultaneous asymmetrical training were less than those achieved by symmetrical training or training in only one of the two components, indicating an influence of the gain controls on each other. These results confine the adaptive site(s) responsible for vertical VOR motor learning to those that can process up and downward or low- and high-frequency head signal separately but not completely independently.

scholarly journals Electricity consumption forecasting using DFT decomposition based hybrid ARIMA-DLSTM model

2021 ◽  
Vol 24 (2) ◽  
pp. 1107
Author(s):  
Osman Yakubu ◽  
Narendra Babu C.
Keyword(s):  
Time Series Data ◽  
Short Term Memory ◽  
Moving Average ◽  
Electricity Consumption ◽  
Series Data ◽  
Linear Component ◽  
Proposed Model ◽  
Consumption Data ◽  
Linear And Nonlinear ◽  
Nonlinear Components

Forecasting electricity consumption is vital, it guides policy makers and electricity distribution companies in formulating policies to manage production and curb pilfering. Accurately forecasting electricity consumption is a challenging task. Relying on a single model to forecast electricity consumption data which comprises both linear and nonlinear components produces inaccurate results. In this paper, a hybrid model using autoregressive integrated moving average (ARIMA) and deep long short-term memory (DLSTM) model based on discrete fourier transform (DFT) decomposition is presented. Aided by its superior decomposition capability, filtering using DFT can efficiently decompose the data into linear and nonlinear components. ARIMA is employed to model the linear component, while DLSTM is applied on the nonlinear component; the two predictions are then combined to obtain the final predicted consumption. The proposed techniques are applied on the household electricity consumption data of France to obtain forecasts for one day, one week and ten days ahead consumption. The results reveal that the proposed model outperforms other benchmark models considered in this investigation as it attained lower error values. The proposed model could accurately decompose time series data without exhibiting a performance degradation, thereby enhancing prediction accuracy.

Nonlinearity of Dependence of Integral Friction Index of Tribosystem from Hydrophilic Properties of Surface-Modified Metal Fillers

2014 ◽  
Vol 1040 ◽  
pp. 103-106 ◽  
Author(s):  
E.A. Nazarova ◽  
A.G. Syrkov ◽  
V.N. Brichkin
Keyword(s):  
Linear Component ◽  
Integral Index ◽  
Metal Filler ◽  
Antifriction Properties ◽  
Adsorption Of Water ◽  
Linear And Nonlinear ◽  
Surface Modified ◽  
Nonlinear Components ◽  
Ammonium Compounds ◽  
Stable Linear

Linear and nonlinear components relation in integral index of friction (D) for tribosystem dependence on hydrophilic properties of metal fillers (M=Cu, Al, Ni) has been considered. Metal fillers (M=Cu, Al, Ni) have been modified in surface layer with quaternary ammonium compounds. It was found that systems with Cu-based fillers had sufficiently high and stable linear component. The best antifriction properties of tribosystem correspond to metal filler with maximum nonlinear component in D = f(a) dependence, where a is adsorption of water.

Neural computation of motion in the fly visual system: quadratic nonlinearity of responses induced by picrotoxin in the HS and CH cells

1995 ◽  
Vol 74 (6) ◽  
pp. 2665-2684 ◽  
Author(s):  
Y. Kondoh ◽  
Y. Hasegawa ◽  
J. Okuma ◽  
F. Takahashi
Keyword(s):  
Mean Square Error ◽  
Order Term ◽  
Mirror Image ◽  
Second Order ◽  
The Other ◽  
Linear Component ◽  
Mean Square ◽  
Nonlinear Component ◽  
First Order ◽  
Order Kernel

1. A computational model accounting for motion detection in the fly was examined by comparing responses in motion-sensitive horizontal system (HS) and centrifugal horizontal (CH) cells in the fly's lobula plate with a computer simulation implemented on a motion detector of the correlation type, the Reichardt detector. First-order (linear) and second-order (quadratic nonlinear) Wiener kernels from intracellularly recorded responses to moving patterns were computed by cross correlating with the time-dependent position of the stimulus, and were used to characterize response to motion in those cells. 2. When the fly was stimulated with moving vertical stripes with a spatial wavelength of 5-40 degrees, the HS and CH cells showed basically a biphasic first-order kernel, having an initial depolarization that was followed by hyperpolarization. The linear model matched well with the actual response, with a mean square error of 27% at best, indicating that the linear component comprises a major part of responses in these cells. The second-order nonlinearity was insignificant. When stimulated at a spatial wavelength of 2.5 degrees, the first-order kernel showed a significant decrease in amplitude, and was initially hyperpolarized; the second-order kernel was, on the other hand, well defined, having two hyperpolarizing valleys on the diagonal with two off-diagonal peaks. 3. The blockage of inhibitory interactions in the visual system by application of 10-4 M picrotoxin, however, evoked a nonlinear response that could be decomposed into the sum of the first-order (linear) and second-order (quadratic nonlinear) terms with a mean square error of 30-50%. The first-order term, comprising 10-20% of the picrotoxin-evoked response, is characterized by a differentiating first-order kernel. It thus codes the velocity of motion. The second-order term, comprising 30-40% of the response, is defined by a second-order kernel with two depolarizing peaks on the diagonal and two off-diagonal hyperpolarizing valleys, suggesting that the nonlinear component represents the power of motion. 4. Responses in the Reichardt detector, consisting of two mirror-image subunits with spatiotemporal low-pass filters followed by a multiplication stage, were computer simulated and then analyzed by the Wiener kernel method. The simulated responses were linearly related to the pattern velocity (with a mean square error of 13% for the linear model) and matched well with the observed responses in the HS and CH cells. After the multiplication stage, the linear component comprised 15-25% and the quadratic nonlinear component comprised 60-70% of the simulated response, which was similar to the picrotoxin-induced response in the HS cells. The quadratic nonlinear components were balanced between the right and left sides, and could be eliminated completely by their contralateral counterpart via a subtraction process. On the other hand, the linear component on one side was the mirror image of that on the other side, as expected from the kernel configurations. 5. These results suggest that responses to motion in the HS and CH cells depend on the multiplication process in which both the velocity and power components of motion are computed, and that a putative subtraction process selectively eliminates the nonlinear components but amplifies the linear component. The nonlinear component is directionally insensitive because of its quadratic non-linearity. Therefore the subtraction process allows the subsequent cells integrating motion (such as the HS cells) to tune the direction of motion more sharply.

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