Unmasking the obligatory components of nociceptive event-related brain potentials

2013 ◽  
Vol 110 (10) ◽  
pp. 2312-2324 ◽  
Author(s):  
A. Mouraux ◽  
A. L. De Paepe ◽  
E. Marot ◽  
L. Plaghki ◽  
G. D. Iannetti ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Cognitive Processes ◽  
Interstimulus Interval ◽  
Significant Contribution ◽  
Signal To Noise Ratio ◽  
Rapid Rate ◽  
Signal To Noise ◽  
Brain Potentials ◽  
Cortical Responses ◽  
Area 3B

It has been hypothesized that the human cortical responses to nociceptive and nonnociceptive somatosensory inputs differ. Supporting this view, somatosensory-evoked potentials (SEPs) elicited by thermal nociceptive stimuli have been suggested to originate from areas 1 and 2 of the contralateral primary somatosensory (S1), operculo-insular, and cingulate cortices, whereas the early components of nonnociceptive SEPs mainly originate from area 3b of S1. However, to avoid producing a burn lesion, and sensitize or fatigue nociceptors, thermonociceptive SEPs are typically obtained by delivering a small number of stimuli with a large and variable interstimulus interval (ISI). In contrast, the early components of nonnociceptive SEPs are usually obtained by applying many stimuli at a rapid rate. Hence, previously reported differences between nociceptive and nonnociceptive SEPs could be due to differences in signal-to-noise ratio and/or differences in the contribution of cognitive processes related, for example, to arousal and attention. Here, using intraepidermal electrical stimulation to selectively activate Aδ-nociceptors at a fast and constant 1-s ISI, we found that the nociceptive SEPs obtained with a long ISI are no longer identified, indicating that these responses are not obligatory for nociception. Furthermore, using a blind source separation, we found that, unlike the obligatory components of nonnociceptive SEPs, the obligatory components of nociceptive SEPs do not receive a significant contribution from a contralateral source possibly originating from S1. Instead, they were best explained by sources compatible with bilateral operculo-insular and/or cingulate locations. Taken together, our results indicate that the obligatory components of nociceptive and nonnociceptive SEPs are fundamentally different.

scholarly journals The categorical neural organization of speech aids its perception in noise

2019 ◽  
Author(s):  
Gavin M. Bidelman ◽  
Lauren C. Bush ◽  
Alex M. Boudreaux
Keyword(s):  
Categorical Perception ◽  
Signal To Noise Ratio ◽  
Speech Code ◽  
Phonetic Category ◽  
Neural Responses ◽  
Cocktail Party ◽  
Signal To Noise ◽  
Brain Potentials ◽  
Neural Organization ◽  
Abstract Categories

ABSTRACTWe investigated whether the categorical perception (CP) of speech might also provide a mechanism that aids its perception in noise. We varied signal-to-noise ratio (SNR) [clear, 0 dB, -5 dB] while listeners classified an acoustic-phonetic continuum (/u/ to /a/). Noise-related changes in behavioral categorization were only observed at the lowest SNR. Event-related brain potentials (ERPs) differentiated phonetic vs. non-phonetic (category ambiguous) speech by the P2 wave (∼180-320 ms). Paralleling behavior, neural responses to speech with clear phonetic status (i.e., continuum endpoints) were largely invariant to noise, whereas responses to ambiguous tokens declined with decreasing SNR. Results demonstrate that phonetic speech representations are more resistant to degradation than corresponding acoustic representations. Findings suggest the mere process of binning speech sounds into categories provides a robust mechanism to aid perception at the “cocktail party” by fortifying abstract categories from the acoustic signal and making the speech code more resistant to external interferences.

Effect of Synchronized Linked Band Selection on Speech Intelligibility of Bilateral Cochlear Implant Users

2020 ◽  
Author(s):  
Tom Gajęcki ◽  
Waldo Nogueira
Keyword(s):  
Electrical Stimulation ◽  
Cochlear Implant ◽  
Background Noise ◽  
Speech Intelligibility ◽  
Signal To Noise Ratio ◽  
Normal Hearing ◽  
Band Selection ◽  
Signal To Noise ◽  
Intelligibility Test ◽  
Bilateral Cochlear Implant

Normal hearing listeners have the ability to exploit the audio input perceived by each ear to extract target information in challenging listening scenarios. Bilateral cochlear implant (BiCI) users, however, do not benefit as much as normal hearing listeners do from a bilateral input. In this study, we investigate the effect that bilaterally linked band selection, bilaterally synchronized electrical stimulation and ideal binary masks (IdBMs) have on the ability of 10 BiCIs to understand speech in background noise. The performance was assessed through a sentence-based speech intelligibility test, in a scenario where the speech signal was presented from the front and the interfering noise from one side. The linked band selection relies on the most favorable signal-to-noise-ratio (SNR) ear, which will select the bands to be stimulated for both CIs. Results show that no benefit from adding a second CI to the most favorable SNR side was achieved for any of the tested bilateral conditions. However, when using both devices, speech perception results show that performing linked band selection, besides delivering bilaterally synchronized electrical stimulation, leads to an improvement compared to standard clinical setups. Moreover, the outcomes of this work show that by applying IdBMs, subjects achieve speech intelligibility scores similar to the ones without background noise.

Measurement of endogenous norepinephrine overflow from canine saphenous veins

1979 ◽  
Vol 236 (2) ◽  
pp. H263-H267 ◽  
Author(s):  
S. M. Muldoon ◽  
G. M. Tyce ◽  
T. P. Moyer ◽  
D. K. Rorie
Keyword(s):  
High Performance Liquid Chromatography ◽  
Electrical Stimulation ◽  
Liquid Chromatography ◽  
Electrochemical Detection ◽  
High Performance ◽  
Signal To Noise Ratio ◽  
Isometric Tension ◽  
Signal To Noise ◽  
Saphenous Veins ◽  
Noise Ratio

A method for the measurement of norepinephrine (NE) overflow from isolated superfused canine saphenous veins is described. This method involves concentrating NE present in the superfusate, followed by measurement of its concentration by high-performance liquid chromatography with electrochemical detection. The limit of sensitivity of the method (defined as a signal-to-noise ratio of 5) was 25 pg. NE concentration measured by this method correlated well (r = 0.95) with that measured by standard fluorometric methods. Electrical stimulation caused an initial overflow of a mean of 115 X 10(-18) mol NE/mg of vein per pulse; this was associated with an increase in isometric tension. With continued stimulation, less NE overflowed into the superfusate, although tension was not reduced appreciably.

Modulation of PFC Pyramidal Cell Excitability by Clonidine: A Computational Modeling Study

2006 ◽  
Author(s):  
T. S. Jang ◽  
J. Nair ◽  
S. Nair ◽  
A. Lavin
Keyword(s):  
Cognitive Processes ◽  
Background Noise ◽  
Signal To Noise Ratio ◽  
Therapeutic Effects ◽  
Negative Effects ◽  
Signal To Noise ◽  
Improve Performance ◽  
Cell Excitability ◽  
External Stimuli ◽  
Stimulation Of

The prefrontal cortex (PFC) is critically involved in cognitive processes underlying working memory (WM), attention, and inhibition of responses to non-relevant stimuli (Fuster, 2000; Goldman-Rakic, 1996). In this context, catecholaminergic inputs have proven to be critical for the regulation of these cognitive processes (Levitt et al., 1984; Lewis et al., 1987; Lewis and Morrison, 1989; Porrino and Goldman-Rakic, 1982). Aston-Jones and Bloom (1981a, b) showed that, in addition to dopamine (DA) the norepinephrine (NE) neurons located in the locus coeruleus (LC) and terminating in the PFC are important in mediating selective and sustained attention and vigilance. Moreover, stimulation of the LC increases the discrimination of incoming external stimuli to the PFC by reducing the background noise, therefore enhancing the cortical signal-to-noise ratio (Aston-Jones et al., 1985; Berridge and Waterhouse, 2003; Foote et al., 1980, 1983; Waterhouse et al., 1980; Robbins, 2000). More recently, several studies have shown that adrenergic agonists, especially specific alpha-2 agonists, are very effective in enhancing WM and attention. Indeed, administration of alpha-2 agonists can ameliorate some of the negative effects on cognition produced by NE depletion due to aging in monkeys (Arnsten and Goldman-Rakic, 1985; Arnsten et al., 1988; Arnsten and Leslie, 1991) and improve performance in WM-related tasks in young monkeys with NE depletion (Arnsten and Goldman-Rakic, 1985; Cai et al., 1993). Moreover, the therapeutic effects of the specific alpha-2 agonists, clonidine and guanfacine in treating disorders related to dysfunction of WM in patients have been proved (Fields et al., 1988; Mair and McEntree 1986, 1988; Hunt et al., 1985, 1990, 1995).

Determination of the Best Emulsion for the Microscopy of Crystals

1981 ◽  
Vol 39 ◽  
pp. 32-33
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Spatial Frequency ◽  
Information Transfer ◽  
Signal To Noise Ratio ◽  
Experimental Situation ◽  
Photographic Emulsion ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Frequency Space ◽  
Noise Ratio

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.

Experiments in Bright-Field Imaging with Hollow-Cone Illumination

1981 ◽  
Vol 39 ◽  
pp. 226-227
Author(s):  
W. Kunath ◽  
K. Weiss ◽  
E. Zeitler
Keyword(s):  
Signal To Noise Ratio ◽  
Carbon Support ◽  
Electronic System ◽  
Optic Axis ◽  
Hollow Cone ◽  
Signal To Noise ◽  
Bright Field ◽  
Noise Ratio ◽  
Single Field ◽  
Field Imaging

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.

Correlation averaging of two-dimensional crystals: basic strategy and refinements

1986 ◽  
Vol 44 ◽  
pp. 136-139
Author(s):  
W. Baumeister ◽  
R. Rachel ◽  
R. Guckenberger ◽  
R. Hegerl
Keyword(s):  
Low Dose ◽  
Signal To Noise Ratio ◽  
Real Space ◽  
Fourier Domain ◽  
Two Dimensional ◽  
Signal To Noise ◽  
Unit Cells ◽  
Lateral Displacements ◽  
Established Technique ◽  
Crystalline Array

IntroductionCorrelation averaging (CAV) is meanwhile an established technique in image processing of two-dimensional crystals /1,2/. The basic idea is to detect the real positions of unit cells in a crystalline array by means of correlation functions and to average them by real space superposition of the aligned motifs. The signal-to-noise ratio improves in proportion to the number of motifs included in the average. Unlike filtering in the Fourier domain, CAV corrects for lateral displacements of the unit cells; thus it avoids the loss of resolution entailed by these distortions in the conventional approach. Here we report on some variants of the method, aimed at retrieving a maximum of information from images with very low signal-to-noise ratios (low dose microscopy of unstained or lightly stained specimens) while keeping the procedure economical.

Information capacity and bandwidth limitations in the SEM

1989 ◽  
Vol 47 ◽  
pp. 84-85
Author(s):  
D. C. Joy ◽  
R. D. Bunn
Keyword(s):  
Signal To Noise Ratio ◽  
Critical Dimension ◽  
Information Capacity ◽  
Acquisition Time ◽  
Signal To Noise ◽  
Sem Image ◽  
Probe Size ◽  
Minimum Number ◽  
Noise Ratio ◽  
Signal Channel

The information available from an SEM image is limited both by the inherent signal to noise ratio that characterizes the image and as a result of the transformations that it may undergo as it is passed through the amplifying circuits of the instrument. In applications such as Critical Dimension Metrology it is necessary to be able to quantify these limitations in order to be able to assess the likely precision of any measurement made with the microscope.The information capacity of an SEM signal, defined as the minimum number of bits needed to encode the output signal, depends on the signal to noise ratio of the image - which in turn depends on the probe size and source brightness and acquisition time per pixel - and on the efficiency of the specimen in producing the signal that is being observed. A detailed analysis of the secondary electron case shows that the information capacity C (bits/pixel) of the SEM signal channel could be written as :

Speech Reception in the Presence of Classroom Noise

1979 ◽  
Vol 10 (4) ◽  
pp. 221-230 ◽  
Author(s):  
Veronica Smyth
Keyword(s):  
Signal To Noise Ratio ◽  
Learning Processes ◽  
Speech Discrimination ◽  
Signal To Noise ◽  
Speech Reception ◽  
Monosyllabic Words ◽  
Noise Ratio

Three hundred children from five to 12 years of age were required to discriminate simple, familiar, monosyllabic words under two conditions: 1) quiet, and 2) in the presence of background classroom noise. Of the sample, 45.3% made errors in speech discrimination in the presence of background classroom noise. The effect was most marked in children younger than seven years six months. The results are discussed considering the signal-to-noise ratio and the possible effects of unwanted classroom noise on learning processes.

Effects of Fundamental Frequency Contours on Sentence Recognition in Mandarin-Speaking Children With Cochlear Implants

2020 ◽  
Vol 63 (11) ◽  
pp. 3855-3864
Author(s):  
Wanting Huang ◽  
Lena L. N. Wong ◽  
Fei Chen ◽  
Haihong Liu ◽  
Wei Liang
Keyword(s):  
Cochlear Implants ◽  
Fundamental Frequency ◽  
Signal To Noise Ratio ◽  
Lexical Tone ◽  
Signal To Noise ◽  
Sentence Recognition ◽  
Test Conditions ◽  
Age Appropriate ◽  
F0 Contour ◽  
Appropriate Sentences

Purpose Fundamental frequency (F0) is the primary acoustic cue for lexical tone perception in tonal languages but is processed in a limited way in cochlear implant (CI) systems. The aim of this study was to evaluate the importance of F0 contours in sentence recognition in Mandarin-speaking children with CIs and find out whether it is similar to/different from that in age-matched normal-hearing (NH) peers. Method Age-appropriate sentences, with F0 contours manipulated to be either natural or flattened, were randomly presented to preschool children with CIs and their age-matched peers with NH under three test conditions: in quiet, in white noise, and with competing sentences at 0 dB signal-to-noise ratio. Results The neutralization of F0 contours resulted in a significant reduction in sentence recognition. While this was seen only in noise conditions among NH children, it was observed throughout all test conditions among children with CIs. Moreover, the F0 contour-induced accuracy reduction ratios (i.e., the reduction in sentence recognition resulting from the neutralization of F0 contours compared to the normal F0 condition) were significantly greater in children with CIs than in NH children in all test conditions. Conclusions F0 contours play a major role in sentence recognition in both quiet and noise among pediatric implantees, and the contribution of the F0 contour is even more salient than that in age-matched NH children. These results also suggest that there may be differences between children with CIs and NH children in how F0 contours are processed.

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