Postsynaptic Dorsal Column and Cuneate Correlations in the Raccoon: A Re-evaluation by Parallel-Cascade Analysis

2002 ◽  
Vol 88 (6) ◽  
pp. 3372-3376
Author(s):  
Andrew S. French ◽  
Susan H. Dick ◽  
Douglas D. Rasmusson
Keyword(s):  
Cross Correlation ◽  
Volterra Series ◽  
Receptive Fields ◽  
Dorsal Column ◽  
Second Order ◽  
Input Signals ◽  
Cascade Analysis ◽  
Postsynaptic Dorsal Column ◽  
Positive Correlations ◽  
Cascade Method

In a previous study, we reported evidence for correlations between the firing of postsynaptic dorsal column (PSDC) neurons and cuneate neurons with overlapping receptive fields on the glabrous skin of the raccoon forepaw. The evidence was based on cross-correlation and frequency response analyses of spontaneously firing neurons. However, cross-correlation without white noise Gaussian analog inputs or Poisson distributed pulse train inputs is difficult to interpret because of the inherent convolution with the autocorrelation of the unknown input signals. While the data suggested positive correlations in the spinocuneate direction for most neuron pairs, we could not estimate the temporal characteristics of these putative connections. We have now re-analyzed these data using a parallel-cascade method to estimate the first- and second-order kernels of a Volterra series approximation to the spinocuneate system. This unbiased analysis suggests that a positive correlation occurs after about 5 ms, probably followed by a negative correlation at about 12 ms. Second-order kernels also had repeatable structure, indicating dual pathways with time separations of at least 10 ms.

A Modified Volterra Series Representation for a Class of Single-Valued, Continuous Nonlinear Systems

1980 ◽  
Vol 102 (3) ◽  
pp. 163-167 ◽  
Author(s):  
G. A. Parker ◽  
E. L. Moore
Keyword(s):  
Cross Correlation ◽  
Volterra Series ◽  
Series Representation ◽  
Weighting Coefficient ◽  
Functional Series ◽  
Level Sequence ◽  
Input Signals ◽  
Volterra Functional Series ◽  
Special Case ◽  
Modified Functional

A modification is presented to the Volterra functional series representation of the response from a cascaded linear-nonlinear-linear system in which the nonlinear element is single-valued, separable, and continuous. The particular advantage of this approach is that the dynamic effects represented in the convolution terms are independent of the bias or mean level of the input signal to the system. The effects of bias and element gain are included in a weighting coefficient βi (m) to each term in the series, with the first term representing the small signal gain of the system. The special case of pseudo-random input signals to the nonlinear system model is also examined using the modified functional series. It is concluded that the three-level sequence is particularly useful in producing a truncation in the modified cross-correlation series representation of the system.

Comparative Study of Viscerosomatic Input Onto Postsynaptic Dorsal Column and Spinothalamic Tract Neurons in the Primate

1999 ◽  
Vol 82 (4) ◽  
pp. 1876-1882 ◽  
Author(s):  
Elie D. Al-Chaer ◽  
Yi Feng ◽  
William D. Willis
Keyword(s):  
Macaca Fascicularis ◽  
Receptive Fields ◽  
Central Canal ◽  
Dorsal Column ◽  
Spinothalamic Tract ◽  
Colorectal Distension ◽  
Hind Limbs ◽  
Upper Cervical ◽  
Postsynaptic Dorsal Column

The purpose of the present investigation was to examine, in the primate, the role of the postsynaptic dorsal column (PSDC) system and that of the spinothalamic tract (STT) in viscerosensory processing by comparing the responses of neurons in these pathways to colorectal distension (CRD). Experiments were done on four anesthetized male monkeys ( Macaca fascicularis). Extracellular recordings were made from a total of 100 neurons randomly located in the L6–S1 segments of the spinal cord. Most of these neurons had cutaneous receptive fields in the perineal area, on the hind limbs or on the rump. Forty-eight percent were PSDC neurons activated antidromically from the upper cervical dorsal column or the nucleus gracilis, 17% were STT neurons activated antidromically from the thalamus, and 35% were unidentified. Twenty-one PSDC neurons, located mostly near the central canal, were excited by CRD and three were inhibited. Twenty-four PSDC neurons, mostly located in the nucleus proprius, did not respond to CRD. Of the 17 STT neurons, 7 neurons were excited by CRD, 4 neurons were inhibited, and 6 neurons did not respond to CRD. Of the unidentified neurons, 23 were excited by CRD, 7 were inhibited, and 5 did not respond. The average responses of STT and PSDC neurons excited by CRD were comparable in magnitude and duration. These results suggest that the major role of the PSDC pathway in viscerosensory processing may be due to a quantitative rather than a qualitative neuronal dominance over the STT.

Nociceptive pathways: anatomy and physiology of nociceptive ascending pathways

1985 ◽  
Vol 308 (1136) ◽  
pp. 253-268 ◽  
Keyword(s):  
Spinal Cord ◽  
Thalamic Nucleus ◽  
Receptive Fields ◽  
Dorsal Column ◽  
Spinothalamic Tract ◽  
Anatomy And Physiology ◽  
Nociceptive Pathways ◽  
Ascending Pathways ◽  
Postsynaptic Dorsal Column ◽  
Affective Components

In primates, the principal nociceptive pathways ascend in the anterolateral quadrant of the spinal cord. Among these, the spinothalamic tract (s.t.t.) is the best studied. Cells in Rexed’s laminae I and V project to the ventro-posterolateral (v.p.l.) thalamic nucleus. Other cells in the same and deeper laminae terminate in the intralaminar complex. Spinothalamic tract cells may be nociceptive-specific or multireceptive. Those ending in v.p.l. have restricted, contralateral receptive fields, whereas those projecting to the intralaminar region often have large, bilateral receptive fields. Spinoreticular tract (s.r.t.) cells are concentrated in laminae VII and VIII and may be nociceptive. It is proposed that the s.t.t. contributes to sensory-discriminative processing of pain and that the s.t.t. and s.r.t. play a role in the motivational-affective components of pain. Alternative nociceptive pathways are the spinocervical and postsynaptic dorsal column tracts.

scholarly journals Parsimonious truncated Newton method for time-domain full waveform inversion based on Fourier-domain full-scattered-field approximation

Geophysics ◽  
2021 ◽  
pp. 1-147
Author(s):  
Peng Yong ◽  
Romain Brossier ◽  
Ludovic Métivier
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Cross Correlation ◽  
Waveform Inversion ◽  
Field Approximation ◽  
Second Order ◽  
Vector Product ◽  
First Order ◽  
Full Waveform ◽  
Truncated Newton

In order to exploit Hessian information in Full Waveform Inversion (FWI), the matrix-free truncated Newton method can be used. In such a method, Hessian-vector product computation is one of the major concerns due to the huge memory requirements and demanding computational cost. Using the adjoint-state method, the Hessian-vector product can be estimated by zero-lag cross-correlation of the first-order/second-order incident wavefields and the second-order/first-order adjoint wavefields. Different from the implementation in frequency-domain FWI, Hessian-vector product construction in the time domain becomes much more challenging as it is not affordable to store the entire time-dependent wavefields. The widely used wavefield recomputation strategy leads to computationally intensive tasks. We present an efficient alternative approach to computing the Hessian-vector product for time-domain FWI. In our method, discrete Fourier transform is applied to extract frequency-domain components of involved wavefields, which are used to compute wavefield cross-correlation in the frequency domain. This makes it possible to avoid reconstructing the first-order and second-order incident wavefields. In addition, a full-scattered-field approximation is proposed to efficiently simplify the second-order incident and adjoint wavefields computation, which enables us to refrain from repeatedly solving the first-order incident and adjoint equations for the second-order incident and adjoint wavefields (re)computation. With the proposed method, the computational time can be reduced by 70% and 80% in viscous media for Gauss-Newton and full-Newton Hessian-vector product construction, respectively. The effectiveness of our method is also verified in the frame of a 2D multi-parameter inversion, in which the proposed method almost reaches the same iterative convergence of the conventional time-domain implementation.

Statistical Analysis of Second-Order Response of Marine Structures

1985 ◽  
Vol 29 (04) ◽  
pp. 270-284 ◽  
Author(s):  
Arvid Naess
Keyword(s):  
Volterra Series ◽  
Theoretical Method ◽  
Problem Formulation ◽  
Second Order ◽  
Quadratic Term ◽  
Closed Form Solutions ◽  
Marine Structure ◽  
Asymptotic Expressions ◽  
The Mean ◽  
Extreme Responses

A theoretical method is presented for estimating the response statistics of a marine structure that can be modeled as a second-order dynamic system subjected to a stationary, Gaussian sea. The method is particularly suitable for predicting extreme responses. The problem formulation expresses the response in terms of a second-order Volterra series, that is, including a linear and a quadratic term. For this response process the mean upcrossing frequency is found and asymptotic expressions are established that can be used to obtain closed-form solutions to the extreme-value problem.

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