J J Eggermont

The University of Calgary, Calgary, Alberta, Canada

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Publications (222)605.24 Total impact

  • Jos J. Eggermont
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    ABSTRACT: Spontaneous neural activity in the auditory nerve fibers and in auditory cortex in healthy animals is discussed with respect to the question: Is spontaneous activity noise or information carrier? The studies reviewed suggest strongly that spontaneous activity is a carrier of information. Subsequently, I review the numerous findings in the impaired auditory system, particularly with reference to noise trauma and tinnitus. Here the common assumption is that tinnitus reflects increased noise in the auditory system that among others affects temporal processing and interferes with the gap-startle reflex, which is frequently used as a behavioral assay for tinnitus. It is, however, more likely that the increased spontaneous activity in tinnitus, firing rate as well as neural synchrony, carries information that shapes the activity of downstream structures, including non-auditory ones, and leading to the tinnitus percept. The main drivers of that process are bursting and synchronous firing, which facilitates transfer of activity across synapses, and allows formation of auditory objects, such as tinnitus
    Frontiers in Neural Circuits 04/2015; 9. DOI:10.3389/fncir.2015.00019 · 2.95 Impact Factor
  • J J Eggermont
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    ABSTRACT: Animal models of tinnitus complement human findings and potentially deepen our insight into the neural substrates of tinnitus. The fact that animal data are largely based on recordings from the auditory system, in particular from subcortical structures, makes comparison with human electrophysiological data from predominantly cortical areas difficult. Electro/magnetoencephalography and imaging data extend beyond the auditory cortex. The most challenging link to be made is the one between the macroscopic data in humans and the microscopic (single neuron action potentials) and mesoscopic (local field potentials) results obtained in animal models. Since invasive recordings in humans are rare, a bridge needs to be built on the basis of changes in brain rhythms in animals with putative tinnitus.
    HNO 04/2015; 63(4):298-301. DOI:10.1007/s00106-014-2980-8 · 0.54 Impact Factor
  • Jos J Eggermont
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    ABSTRACT: Tinnitus is the sound heard in the absence of physical sound sources external or internal to the body. Tinnitus never occurs in isolation; it typically develops after hearing loss, and not infrequently for losses at the higher frequencies not tested in clinical audiology. Furthermore, tinnitus is often accompanied by hyperacusis, i.e. increased loudness sensitivity, which may reflect the central gain change in the auditory system that occurs after hearing loss. I will first review the electrophysiological findings in the thalamus and cortex pertaining to animal research into tinnitus. This will comprise the changes in tonotopic maps, spontaneous firing rates and changes in pairwise neural cross-correlation induced by tinnitus-inducing agents that are commonly used in animal experiments. These are systemic application of sodium salicylate, and noise exposure at levels ranging from those that do not cause a hearing loss, to those that only cause a temporary threshold shift, to those that cause a permanent hearing loss. Following this, I will review neuroimaging and electrophysiological findings in the auditory cortex in humans with tinnitus. The neural substrates of tinnitus derived from animal data do not apply universally, as neither hearing loss nor hyperacusis appear to be necessary conditions for tinnitus to occur in humans. Finally, I will relate the findings in humans to the predictions from animal models of tinnitus. These comparisons indicate that neural correlates of tinnitus can be studied successfully both at the level of animal models and in humans. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
    European Journal of Neuroscience 03/2015; 41(5):665-76. DOI:10.1111/ejn.12759 · 3.67 Impact Factor
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    Jos J Eggermont · Peter A Tass
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    ABSTRACT: Tinnitus is the conscious perception of sound heard in the absence of physical sound sources external or internal to the body, reflected in aberrant neural synchrony of spontaneous or resting-state brain activity. Neural synchrony is generated by the nearly simultaneous firing of individual neurons, of the synchronization of membrane-potential changes in local neural groups as reflected in the local field potentials, resulting in the presence of oscil-latory brain waves in the EEG. Noise-induced hearing loss, often resulting in tinnitus, causes a reorganization of the tonotopic map in auditory cortex and increased spontaneous firing rates and neural synchrony. Spontaneous brain rhythms rely on neural synchrony. Abnormal neural synchrony in tinnitus appears to be confined to specific frequency bands of brain rhythms. Increases in delta-band activity are generated by deafferented/deprived neuronal networks resulting from hearing loss. Coordinated reset (CR) stimulation was developed in order to specifically counteract such abnormal neuronal synchrony by desynchronization. The goal of acoustic CR neuromodulation is to desynchronize tinnitus-related abnormal delta-band oscillations. CR neuromodulation does not require permanent stimulus delivery in order to achieve long-lasting desynchronization or even a full-blown anti-kindling but may have cumulative effects, i.e., the effect of different CR epochs separated by pauses may accumulate. Unlike other approaches, acoustic CR neuromodulation does not intend to reduce tinnitus-related neuronal activity by employing lateral inhibition. The potential efficacy of acoustic CR modulation was shown in a clinical proof of concept trial, where effects achieved in 12 weeks of treatment delivered 4–6 h/day persisted through a preplanned 4-week therapy pause and showed sustained long-term effects after 10 months of therapy, leading to 75% responders.
    Frontiers in Neurology 02/2015; 6. DOI:10.3389/fneur.2015.00029
  • Jos J Eggermont
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    ABSTRACT: Ten years ago, animal models of noise-induced hearing loss predicted three cortical neural correlates of tinnitus resulting from noise-induced hearing loss: increased spontaneous firing rates, increased neural synchrony, and reorganization of tonotopic maps. Salicylate also induces tinnitus, however, the cortical correlates were reduced spontaneous firing rates, unchanged neural synchrony but some change to the tonotopic map. In both conditions increased central gain, potentially a correlate of hyperacusis, was found. Behavioral animal models suggested that tinnitus occurred, albeit not in all cases. The study of the neural substrates of tinnitus in humans is currently strongly based on network connectivity using either spontaneous EEG or MEG. Brain imaging combined with powerful analyses is now able to provide in excellent detail the lay out of tonotopic maps, and has shown that in people with tinnitus (and clinical normal hearing up to 8 kHz) no changes in tonotopic maps need to occur, dispensing therefore of one of the postulated neural correlates. Patients with hyperacusis and tinnitus showed increased gain, as measured using fMRI, from brainstem to cortex, whereas patients with tinnitus without hyperacusis only showed this in auditory cortex. This suggested that top down mechanisms are also needed. The open problems can be formulated by the following questions. 1) Are the neural substrates of tinnitus etiology dependent? 2) Can animal results based on single unit and local field potentials be validated in humans? 3) Can sufficient vs. necessary neural substrates for tinnitus be established. 4) What is the role of attention and stress in engraining tinnitus in memory?
    Hearing Research 10/2014; 319. DOI:10.1016/j.heares.2014.10.002 · 2.85 Impact Factor
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    Jos J Eggermont · Larry E Roberts
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    ABSTRACT: Chronic tinnitus (ringing of the ears) is a medically untreatable condition that reduces quality of life for millions of individuals worldwide. Most cases are associated with hearing loss that may be detected by the audiogram or by more sensitive measures. Converging evidence from animal models and studies of human tinnitus sufferers indicates that, while cochlear damage is a trigger, most cases of tinnitus are not generated by irritative processes persisting in the cochlea but by changes that take place in central auditory pathways when auditory neurons lose their input from the ear. Forms of neural plasticity underlie these neural changes, which include increased spontaneous activity and neural gain in deafferented central auditory structures, increased synchronous activity in these structures, alterations in the tonotopic organization of auditory cortex, and changes in network behavior in nonauditory brain regions detected by functional imaging of individuals with tinnitus and corroborated by animal investigations. Research on the molecular mechanisms that underlie neural changes in tinnitus is in its infancy and represents a frontier for investigation.
    Cell and Tissue Research 09/2014; 361(1). DOI:10.1007/s00441-014-1992-8 · 3.33 Impact Factor
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    ABSTRACT: People are increasingly being exposed to environmental noise from traffic, media and other sources that falls within and outside legal limits. Although such environmental noise is known to cause stress in the auditory system, it is still generally considered to be harmless. This complacency may be misplaced: even in the absence of cochlear damage, new findings suggest that environmental noise may progressively degrade hearing through alterations in the way sound is represented in the adult auditory cortex.
    Nature reviews Neuroscience 06/2014; 15(7):483-91. DOI:10.1038/nrn3744 · 31.38 Impact Factor
  • Jos J Eggermont
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    ABSTRACT: Human temporal processing relies on bottom-up as well as top-down mechanisms. Animal models thereof, in the vast majority, are only probing the bottom-up mechanisms. I will review the vast literature underlying auditory temporal processing to elucidate some basic mechanisms that underlie the majority of temporal processing findings. Some basic findings in auditory temporal processing can all be based on mechanisms determining perstimulatory adaptation of firing rate. This is based on transmitter release mechanisms in peripheral as well as central synapses. It is surprising that the adaptation and recovery time constants that define perstimulatory firing rate adaptation are not very different between auditory periphery and auditory cortex when probed with similar stimuli. It is shown that forward masking, gap and VOT detection, and temporal modulation transfer functions are all directly related to perstimulatory adaptation, whereas stimulus-specific adaptation is at least partly dependent on it. Species differences and the fact that most of the studies reviewed were done in anesthetized animals need to be taken into account when extrapolating animal findings to human perceptual studies. In addition, the accuracy of first-spike latency plays a major role in sound localization and in the brainstem mechanisms for periodicity pitch and forms the basis for understanding evoked potential studies in humans. These mechanisms are also crucial for determining neural synchrony underlying perceptual binding and some important aspects of stream segregation.
    International journal of psychophysiology: official journal of the International Organization of Psychophysiology 04/2014; 95(2). DOI:10.1016/j.ijpsycho.2014.03.011 · 2.65 Impact Factor
  • Jos J. Eggermont
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    ABSTRACT: Human temporal processing relies on bottom-up as well as top-down mechanisms. Animal models thereof, in the vast majority, are only probing the bottom-up mechanisms. I will review the vast literature underlying auditory temporal processing to elucidate some basic mechanisms that underlie the majority of temporal processing findings. Some basic findings in auditory temporal processing can all be based on mechanisms determining perstimulatory adaptation of firing rate. This is based on transmitter release mechanisms in peripheral as well as central synapses. It is surprising that the adaptation and recovery time constants that define perstimulatory firing rate adaptation are not very different between auditory periphery and auditory cortex when probed with similar stimuli. It is shown that forward masking, gap and VOT detection, and temporal modulation transfer functions are all directly related to perstimulatory adaptation, whereas stimulus-specific adaptation is at least partly dependent on it. Species differences and the fact that most of the studies reviewed were done in anesthetized animals need to be taken into account when extrapolating animal findings to human perceptual studies. In addition, the accuracy of first-spike latency plays a major role in sound localization and in the brainstem mechanisms for periodicity pitch and forms the basis for understanding evoked potential studies in humans. These mechanisms are also crucial for determining neural synchrony underlying perceptual binding and some important aspects of stream segregation.
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    Jos J Eggermont · Raymundo Munguia · Gregory Shaw
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    ABSTRACT: Here we use a modification of the Joint-Peri-Stimulus-Time histogram (JPSTH) to investigate triple correlations between cat auditory cortex neurons. The modified procedure allowed the decomposition of the xy-pair correlation into a part that is due to the correlation of the x and y units with the trigger unit, and a remaining 'pair correlation'. We analyzed 16 sets of 15-minute duration stationary spontaneous recordings in primary auditory cortex (AI) with between 11 and 14 electrodes from 2 arrays of 8 electrodes each that provided spontaneous firing rates above 0.22 sp/s and for which reliable frequency-tuning curves could be obtained and the characteristic frequency (CF) was estimated. Thus we evaluated 11,282 conditional cross-correlation functions. The predictor for the conditional cross-correlation, calculated on the assumption that the trigger unit had no effect on the xy-pair correlation but using the same fraction of xy spikes, was equal to the conventional pair-wise correlation function between units xy. The conditional correlation of the xy-pair due to correlation of the x and/or y unit with the trigger unit decreased with the geometric mean distance of the xy pair to the trigger unit, but was independent of the pair cross-correlation coefficient. The conditional pair correlation coefficient was estimated at 78% of the measured pair correlation coefficient. Assuming a geometric decreasing effect of activities of units on other electrodes on the conditional correlation, we estimated the potential contribution of a large number of contributing units on the measured pair correlation at 35-50 of that correlation. This suggests that conventionally measured pair correlations in auditory cortex under ketamine anesthesia overestimate the 'true pair correlation', likely resulting from massive common input, by potentially up to a factor 2.
    Hearing research 08/2013; 304. DOI:10.1016/j.heares.2013.07.019 · 2.85 Impact Factor
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    Larry E Roberts · Fatima T Husain · Jos J Eggermont
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    ABSTRACT: Neural mechanisms that detect changes in the auditory environment appear to rely on processes that predict sensory state. Here we propose that in tinnitus there is a disparity between what the brain predicts it should be hearing (this prediction based on aberrant neural activity occurring in cortical frequency regions affected by hearing loss and underlying the tinnitus percept) and the acoustic information that is delivered to the brain by the damaged cochlea. The disparity between the predicted and delivered inputs activates a system for auditory attention that facilitates through subcortical neuromodulatory systems neuroplastic changes that contribute to the generation of tinnitus. We review behavioral and functional brain imaging evidence for persisting auditory attention in tinnitus and present a qualitative model for how attention operates in normal hearing and may be triggered in tinnitus accompanied by hearing loss. The viewpoint has implications for the role of cochlear pathology in tinnitus, for neural plasticity and the contribution of forebrain neuromodulatory systems in tinnitus, and for tinnitus management and treatment.
    Neuroscience & Biobehavioral Reviews 07/2013; 37(8). DOI:10.1016/j.neubiorev.2013.07.007 · 10.28 Impact Factor
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    Jos J Eggermont
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    ABSTRACT: There is an almost dogmatic view of the different effects of moderate-level sound stimulation in neonatal vs. adult animals. It is often stated that exposure in neonates results in an expansion of the cortical area that responds to the frequencies present in the sound, being either pure tones or frequency modulated sounds. In contrast, recent findings on stimulating adult animals for a sufficiently long time with similar sounds show a contraction of the cortical region responding to those sounds. In this review I will suggest that most neonatal animal results have been wrongly interpreted (albeit generally not by the original authors) and that the changes caused in the critical period (CP) and in adulthood are very similar. Thus, the mechanisms leading to the cortical map changes appear to be similar in the CP and in adulthood. Despite this similarity, the changes induced in the CP are occurring faster and are generally permanent (unless extensive training paradigms to revert the changes are involved), whereas in adults the induction is slower and a slow recovery (months) to pre-exposure conditions takes place.
    Frontiers in Systems Neuroscience 05/2013; 7:12. DOI:10.3389/fnsys.2013.00012
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    R Munguia · M Pienkowski · J J Eggermont
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    ABSTRACT: Changes of neural activity in animal models have been correlated with tinnitus in humans. For instance, increased spontaneous firing rates (SFR), increased spontaneous neural synchrony, and cortical tonotopic map reorganization may underlie this phantom auditory percept. The aim of this study is to quantify the changes in SFR activity in the cat primary auditory cortex, after long-term exposure to different types of non-traumatic acoustic environments. For that purpose, four different groups of adult cats were exposed to moderate-level (∼70dB SPL), behaviorally-irrelevant sounds for several weeks to months, and their SFRs were compared with those in control cats. The sounds consisted of random multi-frequency tone pip ensembles with various bandwidths (2-4kHz, 4-20kHz, and a pair of third-octave bands centered at 4 and 16kHz), as well as a "factory noise". Auditory brainstem response (ABR) thresholds, ABR wave 3 amplitudes at ∼55 and 75dB SPL, and distortion product otoacoustic emission (DPOAE) amplitudes were unaffected by the exposure. However, we found that the SFR decreased within the exposure frequency range and increased outside the exposure range. This increased SFR for units with characteristic frequencies outside the exposure frequency range, which was slow to reverse after the exposure offset, suggests a mechanism for tinnitus in the absence of hearing loss.
    Neuroscience Letters 05/2013; 546. DOI:10.1016/j.neulet.2013.04.048 · 2.06 Impact Factor
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    Martin Pienkowski · Raymundo Munguia · Jos J Eggermont
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    ABSTRACT: Persistent, passive exposure of adult cats to bandlimited tone pip ensembles or sharply-filtered white noise at moderate levels (∼70 dB SPL) leads to a long-term suppression of spontaneous and sound-evoked activity in the region(s) of primary auditory cortex (AI) normally tuned to the exposure spectrum, and to an enhancement of activity in one or more neighboring regions of AI, all in the apparent absence of hearing loss. Here, we first examined the effects of passive exposure to a more structured, real-world noise, consisting of a mix of power tool and construction sounds. This "factory noise" had less pronounced effects on adult cat AI than our previous random tone pip ensembles and white noise, and these effects appeared limited to the region of AI tuned to frequencies near the sharp factory noise cutoff at 16 kHz. To further investigate the role of sharp spectral edges in passive exposure-induced cortical plasticity, a second group of adult cats was exposed to a tone pip ensemble with a flat spectrum between 2 and 4 kHz and shallow cutoff slopes (12 dB/oct) on either side. Compared to our previous ensemble with the same power in the 2-4 kHz band but very steep slopes, exposure to the overall more intense, sloped stimulus had much weaker effects on AI. Finally, we explored the issue of exposure stimulus spectrotemporal density and found that low aggregate tone pip presentation rates of about one per second sufficed to induce changes in the adult AI similar to those characteristic of our previous, much denser exposures. These results are discussed in light of the putative mechanisms underlying exposure-induced auditory cortical plasticity, and the potential adverse consequences of working or living in moderately noisy environments.
    Hearing research 11/2012; 296. DOI:10.1016/j.heares.2012.11.006 · 2.85 Impact Factor
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    Jos J Eggermont · Larry E Roberts
    Frontiers in Systems Neuroscience 07/2012; 6:53. DOI:10.3389/fnsys.2012.00053
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    Martin Pienkowski · Jos J Eggermont
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    ABSTRACT: It has become increasingly clear that even occasional exposure to loud sounds in occupational or recreational settings can cause irreversible damage to the hair cells of the cochlea and the auditory nerve fibers, even if the resulting partial loss of hearing sensitivity, usually accompanied by tinnitus, disappears within hours or days of the exposure. Such exposure may explain at least some cases of poor speech intelligibility in noise in the face of a normal or near-normal audiogram. Recent findings from our laboratory suggest that long-term changes to auditory brain function-potentially leading to problems with speech intelligibility-can be effected by persistent, passive exposure to more moderate levels of noise (in the 70 dB SPL range) in the apparent absence of damage to the auditory periphery (as reflected in normal distortion product otoacoustic emissions and auditory brainstem responses). Specifically, passive exposure of adult cats to moderate levels of band-pass-filtered noise, or to band-limited ensembles of dense, random tone pips, can lead to a profound decrease of neural activity in the auditory cortex roughly in the exposure frequency range, and to an increase of activity outside that range. This can progress to an apparent reorganization of the cortical tonotopic map, which is reminiscent of the reorganization resulting from hearing loss restricted to a part of the hearing frequency range, although again, no hearing loss was apparent after our moderate-level sound exposure. Here, we review this work focusing specifically on the potential hearing problems that may arise despite a normally functioning auditory periphery.
    Ear and hearing 02/2012; 33(3):305-14. DOI:10.1097/AUD.0b013e318241e880 · 2.83 Impact Factor
  • Jos J Eggermont
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    ABSTRACT: Animal models of tinnitus require a behavioral correlate thereof. Various conditioned response methods and gap-startle reflex methods are in use and the outcomes generally correspond with putative electrophysiological substrates of tinnitus. However, for salicylate-induced tinnitus there is discordance between the behavioral and electrophysiological test results. As a result, it is not clear what the various tests are reflecting. A review of the, mostly sub-cortical, neural circuits that underlie the behavioral responses suggests that cortical electrophysiological correlates do not necessarily have to correspond with behavioral ones. Human objective correlates of tinnitus point heavily into cortical network, but not just auditory cortex, correlates of tinnitus. Furthermore, the synaptic mechanisms underlying spontaneous firing rate changes may be different from those involved in driven neural activity.
    Hearing research 02/2012; 295. DOI:10.1016/j.heares.2012.01.005 · 2.85 Impact Factor
  • Jos J. Eggermont · Jean K. Moore
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    ABSTRACT: There are three essential aspects to consider in the description of human auditory maturation, namely, the structural, the functional and the behavioral. Structural aspects were studied by histological methods, and in living persons by neuroimaging methods and auditory evoked potentials or magnetic fields. Discrimination, as a behavioral process, is the ability to recognize the differences between auditory stimuli, and involves two subsystems: Analysis of the physical parameters of the stimulus is performed by the brainstem. Attention to and awareness of the stimulus is mediated by the RAS (and later thalamic) input into the layer I system. Discriminative ability and both subsystems are operational in the months before and after term birth. Perception and cortical connections begin to develop slowly in the second half of the first year of life, and continue into late childhood/teen/adult years. This phase is characterized by maturation of thalmocortical input. Maturational time constants increase stepwise from the periphery (4 weeks), via brainstem (6 month) to the thalamo-cortical system (6 years), and correspond well with behavioral indices of sensory discrimination and perception. Three pathways to the auditory cortex can be distinguished and appear to mature along very different timelines. The ones that mature early, i.e., the reticular activating system pathway and the extralemniscal, non-tonotopically organized, pathway, are generally adult-like at the end of the maturation of the neural discrimination system, i.e., by 1.5–2 years of age. The lemniscal, tonotopically-organized, pathway appears the slowest to mature, well into the late teens or early twenties, and correlates with the maturation of the perceptual system.
    Human Auditory Development, 01/2012: pages 61-105;
  • Martin Pienkowski · Jos J Eggermont
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    ABSTRACT: The distribution of neuronal characteristic frequencies over the area of primary auditory cortex (AI) roughly reflects the tonotopic organization of the cochlea. However, because the area of AI activated by any given sound frequency increases erratically with sound level, it has generally been proposed that frequency is represented in AI not with a rate-place code but with some more complex, distributed code. Here, on the basis of both spike and local field potential (LFP) recordings in the anesthetized cat, we show that the tonotopic representation in AI is much more level tolerant when mapped with spectrotemporally dense tone pip ensembles rather than with individually presented tone pips. That is, we show that the tuning properties of individual unit and LFP responses are less variable with sound level under dense compared with sparse stimulation, and that the spatial frequency resolution achieved by the AI neural population at moderate stimulus levels (65 dB SPL) is better with densely than with sparsely presented sounds. This implies that nonlinear processing in the central auditory system can compensate (in part) for the level-dependent coding of sound frequency in the cochlea, and suggests that there may be a functional role for the cortical tonotopic map in the representation of complex sounds.
    Journal of Neurophysiology 06/2011; 106(2):1016-27. DOI:10.1152/jn.00291.2011 · 3.04 Impact Factor
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    Jos J Eggermont · Raymundo Munguia · Martin Pienkowski · Greg Shaw
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    ABSTRACT: Multi-electrode array recordings of spike and local field potential (LFP) activity were made from primary auditory cortex of 12 normal hearing, ketamine-anesthetized cats. We evaluated 259 spectro-temporal receptive fields (STRFs) and 492 frequency-tuning curves (FTCs) based on LFPs and spikes simultaneously recorded on the same electrode. We compared their characteristic frequency (CF) gradients and their cross-correlation distances. The CF gradient for spike-based FTCs was about twice that for 2-40 Hz-filtered LFP-based FTCs, indicating greatly reduced frequency selectivity for LFPs. We also present comparisons for LFPs band-pass filtered between 4-8 Hz, 8-16 Hz and 16-40 Hz, with spike-based STRFs, on the basis of their marginal frequency distributions. We find on average a significantly larger correlation between the spike based marginal frequency distributions and those based on the 16-40 Hz filtered LFP, compared to those based on the 4-8 Hz, 8-16 Hz and 2-40 Hz filtered LFP. This suggests greater frequency specificity for the 16-40 Hz LFPs compared to those of lower frequency content. For spontaneous LFP and spike activity we evaluated 1373 pair correlations for pairs with >200 spikes in 900 s per electrode. Peak correlation-coefficient space constants were similar for the 2-40 Hz filtered LFP (5.5 mm) and the 16-40 Hz LFP (7.4 mm), whereas for spike-pair correlations it was about half that, at 3.2 mm. Comparing spike-pairs with 2-40 Hz (and 16-40 Hz) LFP-pair correlations showed that about 16% (9%) of the variance in the spike-pair correlations could be explained from LFP-pair correlations recorded on the same electrodes within the same electrode array. This larger correlation distance combined with the reduced CF gradient and much broader frequency selectivity suggests that LFPs are not a substitute for spike activity in primary auditory cortex.
    PLoS ONE 05/2011; 6(5):e20046. DOI:10.1371/journal.pone.0020046 · 3.23 Impact Factor

Publication Stats

10k Citations
605.24 Total Impact Points

Institutions

  • 1987–2015
    • The University of Calgary
      • • Department of Physiology and Pharmacology
      • • Department of Psychology
      Calgary, Alberta, Canada
  • 1973–2009
    • Leiden University
      Leyden, South Holland, Netherlands
  • 2006
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 1997
    • St. Marianna University School of Medicine
      • Department of Otolaryngology
      Kawasaki Si, Kanagawa, Japan
  • 1996
    • House Research Institute
      Los Ángeles, California, United States
  • 1981–1987
    • Radboud University Nijmegen
      • Department of Biophysics
      Nymegen, Gelderland, Netherlands
  • 1978–1981
    • University of California, Los Angeles
      • Brain Research Institute
      Los Ángeles, California, United States
  • 1975–1979
    • Leiden University Medical Centre
      Leyden, South Holland, Netherlands