The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform

R Llinas - One of the best experts on this subject based on the ideXlab platform.

  • differential modulation of rhythmic brain activity in healthy adults by a t type calcium channel blocker an meg study
    Frontiers in Human Neuroscience, 2017
    Co-Authors: Kerry D. Walton, Emeline L Maillet, John Garcia, Timothy Cardozo, Isaac R Galatzerlevy, R Llinas
    Abstract:

    1-octanol is a therapeutic candidate for disorders involving the abnormal activation of the T-type calcium current since it blocks this current specifically. Such disorders include essential tremor and a group of neurological and psychiatric disorders resulting from Thalamocortical Dysrhythmia (TCD). For example, clinically, the observable phenotype in essential tremor is the tremor itself. The differential diagnostic of TCD is not based only on clinical signs and symptoms. Rather, TCD incorporates an electromagnetic biomarker, the presence of abnormal Thalamocortical low frequency brain oscillations. The effect of 1-octanol on brain activity has not been tested. As a preliminary step to such a TCD study, we examined the short-term effects of a single dose of 1-octanol on resting brain activity in 32 healthy adults using magnetoencephalograpy (MEG). Visual inspection of baseline power spectra revealed that the subjects fell into those with strong low frequency activity (set 2, n=11) and those without such activity, but dominated by an alpha peak (set 1, n=22). Cross-validated linear discriminant analysis, using mean spectral density (MSD) in nine frequency bands as predictors, found overall that 82.5% of the subjects were classified as determined by visual inspection. The effect of 1-octanol on the MSD in narrow frequency bands differed between the two subject groups. In set 1 subjects the MSD increased in the 4.5-6.5Hz and 6.5-8.5Hz bands. This was consistent with a widening of the alpha peak toward lower frequencies. In the set 2 subjects the MSD decrease in the 2.5-4.5Hz and 4.5-6.5Hz bands. This decreased power is consistent with the blocking effect of 1-octanol on T-type calcium channels. The subjects reported no adverse effects of the 1-octanol. Since stronger low frequency activity is characteristic of patients with TCD, 1-octanol and other T-type calcium channel blockers are good candidates for treatment of this group of disorders following a placebo-controlled study.

  • Thalamocortical Dysrhythmia a theoretical update in tinnitus
    Frontiers in Neurology, 2015
    Co-Authors: Dirk De Ridder, Sven Vanneste, Berthold Langguth, R Llinas
    Abstract:

    Tinnitus is the perception of a sound in the absence of a corresponding external sound source. Pathophysiologically it has been attributed to bottom-up deafferentation and/or top-down noise-cancelling deficit. Both mechanisms are proposed to alter auditory ­Thalamocortical signal transmission, resulting in Thalamocortical Dysrhythmia (TCD). In deafferentation, TCD is characterized by a slowing down of resting state alpha to theta activity associated with an increase in surrounding gamma activity, resulting in persisting cross-frequency coupling between theta and gamma activity. Theta burst-firing increases network synchrony and recruitment, a mechanism, which might enable long-range synchrony, which in turn could represent a means for finding the missing Thalamocortical information and for gaining access to consciousness. Theta oscillations could function as a carrier wave to integrate the tinnitus-related focal auditory gamma activity in a consciousness enabling network, as envisioned by the global workspace model. This model suggests that focal activity in the brain does not reach consciousness, except if the focal activity becomes functionally coupled to a consciousness enabling network, aka the global workspace. In limited deafferentation, the missing information can be retrieved from the auditory cortical neighborhood, decreasing surround inhibition, resulting in TCD. When the deafferentation is too wide in bandwidth, it is hypothesized that the missing information is retrieved from theta-mediated parahippocampal auditory memory. This suggests that based on the amount of deafferentation TCD might change to parahippocampocortical persisting and thus pathological theta–gamma rhythm. From a Bayesian point of view, in which the brain is conceived as a prediction machine that updates its memory-based predictions through sensory updating, tinnitus is the result of a prediction error between the predicted and sensed auditory input. The decrease in sensory updating is reflected by decreased alpha activity and the prediction error results in theta–gamma and beta–gamma coupling. Thus, TCD can be considered as an adaptive mechanism to retrieve missing auditory input in tinnitus.

  • central pain a thalamic deafferentation generating Thalamocortical Dysrhythmia
    Chronic Pain and Brain Abnormalities, 2014
    Co-Authors: R Llinas, Kerry D. Walton
    Abstract:

    The mechanism responsible for the generation of central (or phantom) pain, as opposed to that resulting from the activation of nociceptive input, has been a perplexing medical puzzle. The possibility that such pain is ultimately a disconnection neurological syndrome will be the topic of this short essay. Abnormal recurrent Thalamocortical resonance of intrinsic origin will be proposed as a plausible underlying mechanism in central pain generation. Electrophysiological studies in rodents and in humans reveal the presence of continuous, low frequency (theta/delta) Thalamocortical loop recurrent oscillations that are most probably related to sensory deafferentation. For example, magnetoencephalographic (MEG) studies in humans with central pain show that low frequency activity is localized to the somatosensory cortical representation of the pain location, and to the fronto-mesial cortex. Animal studies demonstrate that low frequency oscillations originating in thalamus support an associated “edge effect” at beta or gamma band frequency at the level of the cortex. Co-localization of low and high frequency activity has also been observed in MEG studies. It is concluded that such thalamo-cortical activation at the somatosensory level provides subjective localization while the thalamic fronto-mesial loop is responsible for the emotional pain sensation.

  • central pain as a Thalamocortical Dysrhythmia a thalamic efference disconnection
    2011
    Co-Authors: Kerry D. Walton, R Llinas
    Abstract:

    The intrinsic electrical properties of neurons are presently considered as a salient parameter in brain function (Llinas 1988; Getting 1989; Connors and Gutnick 1990; Turrigiano et al. 1994; Margolis and Detwiler 2007). This is in contrast to the classical purely reflexological view, where neurons are considered to be passive agents that are activated or inhibited synaptically. This intrinsic functional view has been addressed in recent years in relation to thalamic neuron function and to its recurrent interaction with the cortex. Such a view is based upon single-cell neuronal electrophysiology (c.f. Llinas 1988; Steriade and Llinas 1988), and Thalamocortical anatomy (Jones 2007). The neurological consequences of such a perspective (Llinas et al. 1999) have been corroborated by magnetoencephalography (MEG), single-cell intraoperative recordings, and encouraging surgical outcomes (Jeanmonod et al. 1996, 2001b, 2003). Moreover, as in the case of tinnitus, where a sound stimulus can suppress the centrally generated sensation (Coles and Hallam 1987), central pain can be modulated by peripheral stimulus (Somers and Somers 1999; Inui et al. 2006). From a functional imaging perspective, electroencephalogram (EEG) (Jeanmonod et al. 1993) and MEG data have shown the presence of a distinct increase in low-frequency activation in central pain (Schulman et al. 2005). In all patients with central, but not peripheral, pain, there was a second site of low-frequency oscillations that was localized to the mesial/orbito frontal and anterior cingulated cortices, as well as the temporal (insular) cortex. Central pain patients with these MEG characteristics did not respond to spinal cord stimulation. By contrast, patients without the frontal low-frequency component responded well to such stimulation.In addition to clinical studies, direct experimental evidence for the functional organization of the thalamo-cortico-thalamo loop has been obtained in in vitro studies of rodent Thalamocortical slices (Llinas et al. 2002) that have been extended to in vivo animal studies concerning neuropathic pain (Gerke et al. 2003; Kim et al. 2003) and thalamic deafferentation (Wang and Thompson 2008). These latter results have established a direct relationship between abnormal thalamic rhythmicity and the occurrence of central pain.The relevance of an “essential thalamic structure” (i.e., a central generator) for neuropathic pain was first suggested by Head (Head and Holmes 1911). The findings summarized here extend this original proposal by addressing brain activity obtained from MEG, EEG, and preoperative unit recordings from patients with chronic neuropathic pain. We also briefly touch upon the contribution of animal studies to understanding the cellular and molecular components of neuropathic pain generation in the context of increased T-type calcium channel activty.

  • inhibition of nmdars in the nucleus reticularis of the thalamus produces delta frequency bursting
    Frontiers in Neural Circuits, 2009
    Co-Authors: Yuchun Zhang, R Llinas, John E Lisman
    Abstract:

    Injection of NMDAR antagonist into the thalamus can produce delta frequency EEG oscillations in the Thalamocortical system. It is surprising that an antagonist of an excitatory neurotransmitter should trigger such activity, and the mechanism is unknown. One hypothesis is that the antagonist blocks excitation of GABAergic cells, thus producing disinhibition. To test this hypothesis, we investigated the effect of NMDAR antagonist (APV) on cells of the nucleus reticularis (nRT) in rat brain slices, a thalamic nucleus that can serve as a pacemaker for Thalamocortical delta oscillations and that is composed entirely of GABAergic neurons. We found, unexpectedly, that nRT cells are hyperpolarized by APV. This occurs because these cells have an unusual form of NMDAR (probably NR2C) that contributes inward current at resting potential in response to ambient glutamate. The hyperpolarization produced by APV is sufficient to deinactivate T-type calcium channels, and these trigger rhythmic bursting at delta frequency. The APV-induced delta frequency bursting is abolished by dopamine D2 receptor antagonist, indicating that dopamine and NMDAR antagonist work synergistically to stimulate delta frequency bursting. Our results have significant implications concerning the electrophysiological basis of schizophrenia and bring together the NMDAR hypofunction, dopamine, and GABA theories of the disease. Our results suggest that NMDAR hypofunction and dopamine work synergistically on the GABAergic cells of the nRT to generate the delta frequency EEG oscillations, a Thalamocortical Dysrhythmia (TCD) in the awake state that is an established abnormality in schizophrenia.

Daniel Jeanmonod - One of the best experts on this subject based on the ideXlab platform.

  • Pain Ratings, Psychological Functioning and Quantitative EEG in a Controlled Study of Chronic Back Pain Patients
    2016
    Co-Authors: Stefan Schmidt, Christina Brenneisen, Thilo Hinterberger, Jose ́ Raúl Naranjo, Julian Gundlach, Claudia Schultz, Holger Kaube, Daniel Jeanmonod
    Abstract:

    Objectives: Several recent studies report the presence of a specific EEG pattern named Thalamocortical Dysrhythmia (TCD) in patients with severe chronic neurogenic pain. This is of major interest since so far no neuroscientific indicator of chronic pain could be identified. We investigated whether a TCD-like pattern could be found in patients with moderate chronic back pain, and we compared patients with neuropathic and non-neuropathic pain components. We furthermore assessed the presence of psychopathology and the degree of psychological functioning and examined whether the strength of the TCD-related EEG markers is correlated with psychological symptoms and pain ratings. Design: Controlled clinical trial with age and sex matched healthy controls. Methods: Spontaneous EEG was recorded in 37 back pain patients and 37 healthy controls. Results: We were not able to observe a statistically significant TCD effect in the EEG data of the whole patient group, but a subsample of patients with evidence for root damage showed a trend in this direction. Pain patients showed markedly increased psychopathology. In addition, patients ’ ratings of pain intensity within the last 1 to 12 months showed strong correlations with EEG power, while psychopathology was correlated to the peak frequency. Conclusion: Out of several possible interpretations the most likely conclusion is that only patients with severe pain as wel

  • Pain Ratings, Psychological Functioning and Quantitative EEG in a Controlled Study of Chronic Back Pain Patients
    2012
    Co-Authors: Stefan Schmidt, Jose Raul Naranjo, Christina Brenneisen, Thilo Hinterberger, Julian Gundlach, Claudia Schultz, Holger Kaube, Daniel Jeanmonod
    Abstract:

    ObjectivesSeveral recent studies report the presence of a specific EEG pattern named Thalamocortical Dysrhythmia (TCD) in patients with severe chronic neurogenic pain. This is of major interest since so far no neuroscientific indicator of chronic pain could be identified. We investigated whether a TCD-like pattern could be found in patients with moderate chronic back pain, and we compared patients with neuropathic and non-neuropathic pain components. We furthermore assessed the presence of psychopathology and the degree of psychological functioning and examined whether the strength of the TCD-related EEG markers is correlated with psychological symptoms and pain ratings. DesignControlled clinical trial with age and sex matched healthy controls. MethodsSpontaneous EEG was recorded in 37 back pain patients and 37 healthy controls. ResultsWe were not able to observe a statistically significant TCD effect in the EEG data of the whole patient group, but a subsample of patients with evidence for root damage showed a trend in this direction. Pain patients showed markedly increased psychopathology. In addition, patients' ratings of pain intensity within the last 1 to 12 months showed strong correlations with EEG power, while psychopathology was correlated to the peak frequency. ConclusionOut of several possible interpretations the most likely conclusion is that only patients with severe pain as well as root lesions with consecutive thalamic deafferentation develop the typical TCD pattern. Our primary method of defining ‘neuropathic pain’ could not reliably determine if such a deafferentation was present. Nevertheless the analysis of a specific subsample as well as correlations between pain ratings, psychopathology and EEG power and peak frequency give some support to the TCD concept. Trial RegistrationClinicalTrials.gov NCT00744575

  • a computational model of Thalamocortical Dysrhythmia
    European Journal of Neuroscience, 2011
    Co-Authors: Henning J Proske, Daniel Jeanmonod, Paul F M J Verschure
    Abstract:

    Functional stereotactic lesions in the central lateral nucleus of the medial thalamus have proved to be an effective treatment of neurogenic pain and other neurological disorders associated with Thalamocortical Dysrhythmia. The mechanisms underlying patient recovery after surgery are currently being explored using quantitative electroencephalography. Here we test the hypothesis that the particular role played by the non-specific medial thalamic nuclei in Thalamocortical Dysrhythmia is based on the divergent connectivity between these non-specific and reticular nuclei. We built a spiking computer model of the human Thalamocortical system consisting of specific, non-specific and reticular thalamic nuclei. In our simulations of the Thalamocortical system, deafferentation of peripheral thalamic afferents leads to hyperpolarization and subsequent bursting in the reticular nucleus. This provides strong inhibitory feedback to both the specific and the non-specific thalamic nuclei and initiates a feedback cycle of thalamic bursts in the theta frequency range. The divergent connections between the reticular and non-specific thalamic nuclei provide synchronization of the oscillating circuits. Functional silencing of the non-specific model nucleus limits reverberation and rescues the system from these oscillations. The same effect could be achieved by increasing the input to the non-specific nucleus from cortical areas. The model predicts that the invasiveness of functional neurosurgery can be reduced by targeting only deafferented areas in the medial nuclei as these are the key areas for generation and maintenance of pathological rhythms.

  • a revival of spiegel s campotomy long term results of the stereotactic pallidothalamic tractotomy against the parkinsonian Thalamocortical Dysrhythmia
    Thalamus and Related Systems, 2005
    Co-Authors: Christoph Aufenberg, A Morel, Johannes Sarnthein, Valentin Rousson, Marc N Gallay, Daniel Jeanmonod
    Abstract:

    The over-inhibition of thalamic relay cells by hyperactivity of the internal part of the globus pallidus is a cornerstone of the parkinsonian pathophysiology that leads to a distortion of the Thalamocortical dynamics called Thalamocortical Dysrhythmia (TCD). Here, we present the results of the stereotactic pallidothalamic tractotomy (PTT), which interrupts selectively the enhanced pallidal output to the thalamus in a restricted location in the fields of Forel. This operation represents a reactualization of Spiegel's campotomy. PTT was offered to 41 patients (66.1±8.5 years) suffering from chronic, therapy-resistant Parkinson's disease. It was performed bilaterally in 21 patients. Forty patients displayed mixed, i.e. tremulent and akinetic parkinsonian signs, and seven had drug-induced dyskinesias. One patient had only rest tremor. The evaluation was based on the Unified Parkinson's Disease Rating Scale (UPDRS) scores, comparing the patients' preoperative medicated state with the state at the last postoperative follow-up. We, thus, tested surgical success in terms of superiority to drug treatment. Mean follow-up was 22.4 months with 15 patients followed for >2 years. Mean improvement was 60% (P<0.001) for UPDRS III and 51% (P<0.001) for UPDRS II. Significant improvement (P<0.001) appeared in subscores for tremor (87%), limb akinesia (58%) and axial akinesia (33%). Improvement of postural stability and gait was at the limit of significance (P<0.05). Improvement of hypomimia and hypophonia did not reach statistical significance. Increase of dysarthria was significant (P<0.01). Intake of L-DOPA was reduced significantly and 21 patients were able to stop intake. Median improvement of the Quality of Life score was 67%. Improvement remained, independent of follow-up length. In conclusion, PTT provides a high, stable level of relief to parkinsonian patients whose condition cannot be controlled with pharmacotherapy. The rationale of the surgical therapy is based on a selective extrathalamic regulation of the parkinsonian TCD.

  • neuropsychiatric Thalamocortical Dysrhythmia surgical implications
    Thalamus and Related Systems, 2003
    Co-Authors: Daniel Jeanmonod, M Magnin, A Morel, M Siegemund, M Lanz, Eugene Kronberg, J Schulman, Robert Cancro, R R Ramirez, Urs Ribary
    Abstract:

    Abstract Neuropsychiatric surgery has had a long and complex history with examples of less than optimal surgical procedures implemented in wrong settings. Such past errors have raised important philosophical and ethical issues that remain with us for good reasons. However, the existence of enormous suffering due to chronic therapy-resistant disabling neuropsychiatric disorders compels a search for alternative surgical approaches based on a sound understanding of the underlying physiopathological mechanisms. We bring evidence, from single cell physiology and magnetoencephalography, for the existence of a set of neuropsychiatric disorders characterized by localized and protracted low frequency spontaneous recurrent activation of the Thalamocortical system. This condition, labeled Thalamocortical Dysrhythmia, underlies certain chronic psychotic, affective, obsessive compulsive, anxiety and impulse control disorders. Considering the central role of recurrent oscillatory Thalamocortical properties in the generation of normal hemispheric functions, we propose a surgical approach that provides a reestablishment of normal Thalamocortical oscillations without reduction of cortical tissue and its specific thalamic connectivity. It consists of small strategically placed pallidal and medial thalamic lesions that serve to make subcritical the increased low frequency Thalamocortical recurrent network activity. This result is attained via reduction of both thalamic overinhibition and low frequency oversynchronization. Thalamic disinhibition is obtained by a lesion in the anterior medial paralimbic pallidum. The medial thalamic lesion is localized in the posterior part of the central lateral nucleus, where a large majority of cells have been shown to be locked in low frequency production and to have lost their normal activation patterns. We present here our experience with 11 patients, including clinical follow ups and pre- and postsurgical magnetoencephalographic studies. The evidence speaks (1) for a benign and efficient surgical approach, and (2) for the relevance of the patient’s presurgical cognitive and social settings, making them more or less prone to postoperative psychoreactive manifestations upon rekindling of personal goals and social reentry.

Dirk De Ridder - One of the best experts on this subject based on the ideXlab platform.

  • Thalamocortical Dysrhythmia underpin the log dynamics in phantom sounds
    Progress in Brain Research, 2021
    Co-Authors: Jae-jin Song, Dirk De Ridder, Anusha Mohan, Sven Vanneste
    Abstract:

    Abstract Electrophysiological tinnitus research, such as EEG studies, typically investigates the irregularities in separate frequency bands. These frequency bands are coupled, such that the higher oscillation frequencies are nested (phase–amplitude coupled) on the lower frequencies, resulting in a 1/f power spectrum. The changes in the 1/f slope of the power spectrum in tinnitus patients are unexplored. Deviations from the 1/f pattern also reflect a change toward a more lattice (steeper slope) or random network (flatter slope) and relate to the amount of information in a network. In this study, we investigate the 1/f slope in the resting-state EEGs of tinnitus patients and relate these findings to proposed tinnitus mechanisms. Our data show that tinnitus is characterized by a slope that is flattened in comparison to the control group and that the tinnitus loudness percept correlates the steepness of the slope of the power spectrum in resting-state EEG signals for the left auditory cortex and left parahippocampus. The steepness of the slope is predominantly related to an increase in theta activity and its minor increase in gamma activity, suggesting that the slope is deviating toward white noise. These results should motivate further research into this hitherto elusive form of brain activity that resides behind the mask of the universal 1/f power spectrum observed across nature.

  • Thalamocortical Dysrhythmia detected by machine learning
    Nature Communications, 2018
    Co-Authors: Sven Vanneste, Jae-jin Song, Dirk De Ridder
    Abstract:

    Thalamocortical Dysrhythmia (TCD) is a model proposed to explain divergent neurological disorders. It is characterized by a common oscillatory pattern in which resting-state alpha activity is replaced by cross-frequency coupling of low- and high-frequency oscillations. We undertook a data-driven approach using support vector machine learning for analyzing resting-state electroencephalography oscillatory patterns in patients with Parkinson’s disease, neuropathic pain, tinnitus, and depression. We show a spectrally equivalent but spatially distinct form of TCD that depends on the specific disorder. However, we also identify brain areas that are common to the pathology of Parkinson’s disease, pain, tinnitus, and depression. This study therefore supports the validity of TCD as an oscillatory mechanism underlying diverse neurological disorders. Thalamocortical Dysrhythmia has been proposed to occur in a number of neurological and psychiatric disorders. Here, the authors use a data-driven approach to demonstrate Thalamocortical Dysrhythmia occurs in individuals with Parkinson’s disease, neuropathic pain, tinnitus, and depression.

  • Thalamocortical Dysrhythmia detected by machine learning
    Nature Publishing Group, 2018
    Co-Authors: Sven Vanneste, Jae-jin Song, Dirk De Ridder
    Abstract:

    Thalamocortical Dysrhythmia has been proposed to occur in a number of neurological and psychiatric disorders. Here, the authors use a data-driven approach to demonstrate Thalamocortical Dysrhythmia occurs in individuals with Parkinson’s disease, neuropathic pain, tinnitus, and depression

  • Thalamocortical Dysrhythmia a theoretical update in tinnitus
    Frontiers in Neurology, 2015
    Co-Authors: Dirk De Ridder, Sven Vanneste, Berthold Langguth, R Llinas
    Abstract:

    Tinnitus is the perception of a sound in the absence of a corresponding external sound source. Pathophysiologically it has been attributed to bottom-up deafferentation and/or top-down noise-cancelling deficit. Both mechanisms are proposed to alter auditory ­Thalamocortical signal transmission, resulting in Thalamocortical Dysrhythmia (TCD). In deafferentation, TCD is characterized by a slowing down of resting state alpha to theta activity associated with an increase in surrounding gamma activity, resulting in persisting cross-frequency coupling between theta and gamma activity. Theta burst-firing increases network synchrony and recruitment, a mechanism, which might enable long-range synchrony, which in turn could represent a means for finding the missing Thalamocortical information and for gaining access to consciousness. Theta oscillations could function as a carrier wave to integrate the tinnitus-related focal auditory gamma activity in a consciousness enabling network, as envisioned by the global workspace model. This model suggests that focal activity in the brain does not reach consciousness, except if the focal activity becomes functionally coupled to a consciousness enabling network, aka the global workspace. In limited deafferentation, the missing information can be retrieved from the auditory cortical neighborhood, decreasing surround inhibition, resulting in TCD. When the deafferentation is too wide in bandwidth, it is hypothesized that the missing information is retrieved from theta-mediated parahippocampal auditory memory. This suggests that based on the amount of deafferentation TCD might change to parahippocampocortical persisting and thus pathological theta–gamma rhythm. From a Bayesian point of view, in which the brain is conceived as a prediction machine that updates its memory-based predictions through sensory updating, tinnitus is the result of a prediction error between the predicted and sensed auditory input. The decrease in sensory updating is reflected by decreased alpha activity and the prediction error results in theta–gamma and beta–gamma coupling. Thus, TCD can be considered as an adaptive mechanism to retrieve missing auditory input in tinnitus.

  • tinnitus and musical hallucinosis the same but more
    NeuroImage, 2013
    Co-Authors: Sven Vanneste, Jae-jin Song, Dirk De Ridder
    Abstract:

    While tinnitus can be interpreted as a simple or elementary form of auditory phantom perception, musical hallucinosis is a more complex auditory phantom phenomenon not only limited to sound perception, but also containing semantic and musical content. It most often occurs in association with hearing loss. To elucidate the relation between simple and complex auditory phantom percepts a source localized electroencephalography (EEG) study is performed. The analyses showed in both simple and complex auditory phantoms an increase in theta-gamma activity and coupling within the auditory cortex that could be associated with the Thalamocortical Dysrhythmia model. Furthermore increased beta activity within the dorsal anterior cingulate cortex and anterior insula is demonstrated, that might be related to auditory awareness, salience and its attribution to an external sound source. The difference between simple and complex auditory phantoms relies on differential alpha band activity within the auditory cortex and on beta activity in the dorsal anterior cingulate cortex and (para)hippocampal area. This could be related to memory based load dependency, while suppression within the primary visual cortex might be due the presence of a continuous auditory cortex activation inducing an inhibitory signal to the visual system. Complex auditory phantoms further activate the right inferior frontal area (right sided Broca homolog) and right superior temporal pole that might be associated with the musical content. In summary, this study showed for the first time that simple and complex auditory phantoms might share a common neural substrate but differ as complex auditory phantoms are associated with activation in brain areas related to music and language processing.

Sven Vanneste - One of the best experts on this subject based on the ideXlab platform.

  • Thalamocortical Dysrhythmia underpin the log dynamics in phantom sounds
    Progress in Brain Research, 2021
    Co-Authors: Jae-jin Song, Dirk De Ridder, Anusha Mohan, Sven Vanneste
    Abstract:

    Abstract Electrophysiological tinnitus research, such as EEG studies, typically investigates the irregularities in separate frequency bands. These frequency bands are coupled, such that the higher oscillation frequencies are nested (phase–amplitude coupled) on the lower frequencies, resulting in a 1/f power spectrum. The changes in the 1/f slope of the power spectrum in tinnitus patients are unexplored. Deviations from the 1/f pattern also reflect a change toward a more lattice (steeper slope) or random network (flatter slope) and relate to the amount of information in a network. In this study, we investigate the 1/f slope in the resting-state EEGs of tinnitus patients and relate these findings to proposed tinnitus mechanisms. Our data show that tinnitus is characterized by a slope that is flattened in comparison to the control group and that the tinnitus loudness percept correlates the steepness of the slope of the power spectrum in resting-state EEG signals for the left auditory cortex and left parahippocampus. The steepness of the slope is predominantly related to an increase in theta activity and its minor increase in gamma activity, suggesting that the slope is deviating toward white noise. These results should motivate further research into this hitherto elusive form of brain activity that resides behind the mask of the universal 1/f power spectrum observed across nature.

  • Thalamocortical Dysrhythmia detected by machine learning
    Nature Communications, 2018
    Co-Authors: Sven Vanneste, Jae-jin Song, Dirk De Ridder
    Abstract:

    Thalamocortical Dysrhythmia (TCD) is a model proposed to explain divergent neurological disorders. It is characterized by a common oscillatory pattern in which resting-state alpha activity is replaced by cross-frequency coupling of low- and high-frequency oscillations. We undertook a data-driven approach using support vector machine learning for analyzing resting-state electroencephalography oscillatory patterns in patients with Parkinson’s disease, neuropathic pain, tinnitus, and depression. We show a spectrally equivalent but spatially distinct form of TCD that depends on the specific disorder. However, we also identify brain areas that are common to the pathology of Parkinson’s disease, pain, tinnitus, and depression. This study therefore supports the validity of TCD as an oscillatory mechanism underlying diverse neurological disorders. Thalamocortical Dysrhythmia has been proposed to occur in a number of neurological and psychiatric disorders. Here, the authors use a data-driven approach to demonstrate Thalamocortical Dysrhythmia occurs in individuals with Parkinson’s disease, neuropathic pain, tinnitus, and depression.

  • Thalamocortical Dysrhythmia detected by machine learning
    Nature Publishing Group, 2018
    Co-Authors: Sven Vanneste, Jae-jin Song, Dirk De Ridder
    Abstract:

    Thalamocortical Dysrhythmia has been proposed to occur in a number of neurological and psychiatric disorders. Here, the authors use a data-driven approach to demonstrate Thalamocortical Dysrhythmia occurs in individuals with Parkinson’s disease, neuropathic pain, tinnitus, and depression

  • Thalamocortical Dysrhythmia a theoretical update in tinnitus
    Frontiers in Neurology, 2015
    Co-Authors: Dirk De Ridder, Sven Vanneste, Berthold Langguth, R Llinas
    Abstract:

    Tinnitus is the perception of a sound in the absence of a corresponding external sound source. Pathophysiologically it has been attributed to bottom-up deafferentation and/or top-down noise-cancelling deficit. Both mechanisms are proposed to alter auditory ­Thalamocortical signal transmission, resulting in Thalamocortical Dysrhythmia (TCD). In deafferentation, TCD is characterized by a slowing down of resting state alpha to theta activity associated with an increase in surrounding gamma activity, resulting in persisting cross-frequency coupling between theta and gamma activity. Theta burst-firing increases network synchrony and recruitment, a mechanism, which might enable long-range synchrony, which in turn could represent a means for finding the missing Thalamocortical information and for gaining access to consciousness. Theta oscillations could function as a carrier wave to integrate the tinnitus-related focal auditory gamma activity in a consciousness enabling network, as envisioned by the global workspace model. This model suggests that focal activity in the brain does not reach consciousness, except if the focal activity becomes functionally coupled to a consciousness enabling network, aka the global workspace. In limited deafferentation, the missing information can be retrieved from the auditory cortical neighborhood, decreasing surround inhibition, resulting in TCD. When the deafferentation is too wide in bandwidth, it is hypothesized that the missing information is retrieved from theta-mediated parahippocampal auditory memory. This suggests that based on the amount of deafferentation TCD might change to parahippocampocortical persisting and thus pathological theta–gamma rhythm. From a Bayesian point of view, in which the brain is conceived as a prediction machine that updates its memory-based predictions through sensory updating, tinnitus is the result of a prediction error between the predicted and sensed auditory input. The decrease in sensory updating is reflected by decreased alpha activity and the prediction error results in theta–gamma and beta–gamma coupling. Thus, TCD can be considered as an adaptive mechanism to retrieve missing auditory input in tinnitus.

  • tinnitus and musical hallucinosis the same but more
    NeuroImage, 2013
    Co-Authors: Sven Vanneste, Jae-jin Song, Dirk De Ridder
    Abstract:

    While tinnitus can be interpreted as a simple or elementary form of auditory phantom perception, musical hallucinosis is a more complex auditory phantom phenomenon not only limited to sound perception, but also containing semantic and musical content. It most often occurs in association with hearing loss. To elucidate the relation between simple and complex auditory phantom percepts a source localized electroencephalography (EEG) study is performed. The analyses showed in both simple and complex auditory phantoms an increase in theta-gamma activity and coupling within the auditory cortex that could be associated with the Thalamocortical Dysrhythmia model. Furthermore increased beta activity within the dorsal anterior cingulate cortex and anterior insula is demonstrated, that might be related to auditory awareness, salience and its attribution to an external sound source. The difference between simple and complex auditory phantoms relies on differential alpha band activity within the auditory cortex and on beta activity in the dorsal anterior cingulate cortex and (para)hippocampal area. This could be related to memory based load dependency, while suppression within the primary visual cortex might be due the presence of a continuous auditory cortex activation inducing an inhibitory signal to the visual system. Complex auditory phantoms further activate the right inferior frontal area (right sided Broca homolog) and right superior temporal pole that might be associated with the musical content. In summary, this study showed for the first time that simple and complex auditory phantoms might share a common neural substrate but differ as complex auditory phantoms are associated with activation in brain areas related to music and language processing.

Urs Ribary - One of the best experts on this subject based on the ideXlab platform.

  • Thalamocortical Dysrhythmia syndrome meg imaging of neuropathic pain
    Thalamus and Related Systems, 2005
    Co-Authors: J Schulman, Urs Ribary, R R Ramirez, Martin Zonenshayn, R Llinas
    Abstract:

    Abnormal Thalamocortical dynamics have been proposed as the underlying mechanism for a subset of neurological and psychiatric disorders that include centrally generated pain. Spectral analysis and independent component-based localization of neuromagnetic signals reveal ongoing theta-range activity localized to physiologically significant cortical regions in a group of subjects with well-characterized central and peripheral lesions. In addition, recordings from subjects who failed to obtain relief from spinal cord stimulation (SCS) and from those in whom SCS was successful further delineate Thalamocortical Dysrhythmias as a mechanism that underlies chronic pain.

  • neuropsychiatric Thalamocortical Dysrhythmia surgical implications
    Thalamus and Related Systems, 2003
    Co-Authors: Daniel Jeanmonod, M Magnin, A Morel, M Siegemund, M Lanz, Eugene Kronberg, J Schulman, Robert Cancro, R R Ramirez, Urs Ribary
    Abstract:

    Abstract Neuropsychiatric surgery has had a long and complex history with examples of less than optimal surgical procedures implemented in wrong settings. Such past errors have raised important philosophical and ethical issues that remain with us for good reasons. However, the existence of enormous suffering due to chronic therapy-resistant disabling neuropsychiatric disorders compels a search for alternative surgical approaches based on a sound understanding of the underlying physiopathological mechanisms. We bring evidence, from single cell physiology and magnetoencephalography, for the existence of a set of neuropsychiatric disorders characterized by localized and protracted low frequency spontaneous recurrent activation of the Thalamocortical system. This condition, labeled Thalamocortical Dysrhythmia, underlies certain chronic psychotic, affective, obsessive compulsive, anxiety and impulse control disorders. Considering the central role of recurrent oscillatory Thalamocortical properties in the generation of normal hemispheric functions, we propose a surgical approach that provides a reestablishment of normal Thalamocortical oscillations without reduction of cortical tissue and its specific thalamic connectivity. It consists of small strategically placed pallidal and medial thalamic lesions that serve to make subcritical the increased low frequency Thalamocortical recurrent network activity. This result is attained via reduction of both thalamic overinhibition and low frequency oversynchronization. Thalamic disinhibition is obtained by a lesion in the anterior medial paralimbic pallidum. The medial thalamic lesion is localized in the posterior part of the central lateral nucleus, where a large majority of cells have been shown to be locked in low frequency production and to have lost their normal activation patterns. We present here our experience with 11 patients, including clinical follow ups and pre- and postsurgical magnetoencephalographic studies. The evidence speaks (1) for a benign and efficient surgical approach, and (2) for the relevance of the patient’s presurgical cognitive and social settings, making them more or less prone to postoperative psychoreactive manifestations upon rekindling of personal goals and social reentry.

  • neuropsychiatric Thalamocortical Dysrhythmia surgical implications
    Neurosurgery Clinics of North America, 2003
    Co-Authors: Daniel Jeanmonod, M Magnin, A Morel, M Siegemund, M Lanz, Eugene Kronberg, J Schulman, Robert Cancro, R R Ramirez, Urs Ribary
    Abstract:

    Clearly, more clinical experience must be amassed to define in detail the possibilities of this surgical approach in disabling neuropsychiatric disorders. We propose, however, that the evidence for benign and efficient surgical intervention against the neuropsychiatric TCD syndrome is already compelling. The potential appearance of strong postoperative reactive manifestations requires a close association between surgery and psychotherapy, with the latter providing support for the integration of the new situation as well as the resolution of old unresolved issues.

  • Thalamocortical Dysrhythmia ii clinical and surgical aspects
    Thalamus and Related Systems, 2001
    Co-Authors: Daniel Jeanmonod, R Llinas, M Magnin, A Morel, M Siegemund, A Cancro, M Lanz, Urs Ribary, Eugene Kronberg, J Schulman
    Abstract:

    The companion paper (Llinas et al., 2001) presents evidence, at both cellular and network levels, for the role of resonant oscillatory Thalamocortical properties in normal and pathological brain function. Here we present confirmatory single cell electrophysiology from the thalami of Thalamocortical Dysrhythmia (TCD) patients and review our surgical approach towards the relief of this chronic disabling condition, in its many forms. The goal of surgery is a rebalancing of the abnormal Thalamocortical oscillation responsible for TCD. Our approach uses small strategically placed pre-thalamic and medial thalamic lesions that serve to make subcritical the low frequency Thalamocortical reentry network attractor via desinhibition and desamplification. The lesions address classical and new stereotactic targets that provide therapeutic efficiency coupled with the sparing of the specific Thalamocortical loops.

  • Thalamocortical Dysrhythmia i functional and imaging aspects
    Thalamus and Related Systems, 2001
    Co-Authors: R Llinas, Daniel Jeanmonod, M Magnin, A Morel, Urs Ribary, Eugene Kronberg, J Schulman, Robert Cancro, Martin Zonenshayn, M Siegmund
    Abstract:

    Thalamic and cortical neurons are richly and reciprocally interconnected and support recurrent functional loops in the intact brain, but the role of this circuitry is still poorly understood. Here, we present evidence—from cellular and from functional neuroimaging in control and clinical domains—that Thalamocortical resonance is not only a prerequisite for normal cognition, but that its perturbation, in a dynamic sense (e.g. a Dysrhythmia) can underlie a variety of neurological and psychiatric disorders.