Publikace

Publikovali jsme původní příspěvky v několika světových špičkových mezinárodních vědeckých časopisech a prezentovali své výsledky na řadě mezinárodních kongresů a konferencí, zde uvádíme jen impaktované publikace za posledních pět let:

Publikace našeho týmu

Detection of Interictal Epileptiform Discharges Using Signal Envelope Distribution Modelling: Application to Epileptic and Non-Epileptic Intracranial Recordings

  • DOI: 10.1007/s10548-014-0379-1
  • Odkaz: https://doi.org/10.1007/s10548-014-0379-1
  • Pracoviště: Katedra teorie obvodů
  • Anotace:
    Interictal epileptiform discharges (spikes, IEDs) are electrographic markers of epileptic tissue and their quantification is utilized in planning of surgical resection. Visual analysis of long-term multi-channel intracranial recordings is extremely laborious and prone to bias. Development of new and reliable techniques of automatic spike detection represents a crucial step towards increasing the information yield of intracranial recordings and to improve surgical outcome. In this study, we designed a novel and robust detection algorithm that adaptively models statistical distributions of signal envelopes and enables discrimination of signals containing IEDs from signals with background activity. This detector demonstrates performance superior both to human readers and to an established detector. It is even capable of identifying low-amplitude IEDs which are often missed by experts and which may represent an important source of clinical information. Application of the detector to non-epileptic intracranial data from patients with intractable facial pain revealed the existence of sharp transients with waveforms reminiscent of interictal discharges that can represent biological sources of false positive detections. Identification of these transients enabled us to develop and propose secondary processing steps, which may exclude these transients, improving the detector’s specificity and having important implications for future development of spike detectors in general.

Characteristics and occurrence of speech impairment in Huntington's disease: possible influence of antipsychotic medication

  • DOI: 10.1007/s00702-014-1229-8
  • Odkaz: https://doi.org/10.1007/s00702-014-1229-8
  • Pracoviště: Katedra teorie obvodů
  • Anotace:
    Although motor speech impairment is a common manifestation of Huntington’s disease (HD), its description remains limited. The aim of the current study was therefore to estimate the occurrence and characteristics of speech disorder in HD and to explore the influence of antipsychotic medication on speech performance. Speech samples, including reading passage and monologue, were acquired from 40 individuals diagnosed with HD and 40 age- and sex-matched healthy controls. Objective acoustic analyses were used to evaluate key aspects of speech including vowel articulation, intensity, pitch and timing. A predictive model was constructed to detect the occurrence and most prominent patterns of speech dysfunction in HD. We revealed that 93 % of HD patients manifest some degree of speech impairment. Decreased number of pauses, slower articulation rate, imprecise vowel articulation and excess intensity variations were found to be the most salient patterns of speech dysfunction in HD. We further demonstrated that antipsychotic medication may induce excessive loudness and pitch variations perceptually resembling excess patterns of word stress, and may also accentuate general problems with speech timing. Additionally, antipsychotics induced a slight improvement of vowel articulation. Specific speech alterations observed in HD patients indicate that speech production may reflect the pathophysiology of the disease as well as treatment effects, and may therefore be considered a valuable marker of functional disability in HD.

Phonatory Dysfunction as a Preclinical Symptom of Huntington Disease

  • Autoři: doc. Ing. Jan Rusz, Ph.D., Saft, C., Schlegel, U., Hoffman, R., Skodda, S.
  • Publikace: PLoS ONE. 2014, 9(11), 1-7. ISSN 1932-6203.
  • Rok: 2014
  • DOI: 10.1371/journal.pone.0113412
  • Odkaz: https://doi.org/10.1371/journal.pone.0113412
  • Pracoviště: Katedra teorie obvodů
  • Anotace:
    Purpose: Although dysphonia has been shown to be a common sign of Huntington disease (HD), the extent of phonatory dysfunction in gene positive premanifest HD individuals remains unknown. The aim of the current study was to explore the possible occurrence of phonatory abnormalities in prodromal HD. Method: Sustained vowel phonations were acquired from 28 premanifest HD individuals and 28 healthy controls of comparable age. Data were analysed acoustically for measures of several phonatory dimensions including airflow insufficiency, aperiodicity, irregular vibration of vocal folds, signal perturbations, increased noise, vocal tremor and articulation deficiency. A predictive model was built to find the best combination of acoustic features and estimate sensitivity/specificity for differentiation between premanifest HD subjects and controls. The extent of voice deficits according to a specific phonatory dimension was determined using statistical decision making theory. The results were correlated to global motor function, cognitive score, disease burden score and estimated years to disease onset. Results: Measures of aperiodicity and increased noise were able to significantly differentiate between premanifest HD individuals and controls (p,0.01). The combination of these aspects of dysphonia led to a sensitivity of 91.5% and specificity of 79.2% to correctly distinguish speakers with premanifest HD from healthy individuals. Some form of disrupted phonatory function was revealed in 68% of our premanifest HD subjects, where 18% had one affected phonatory dimension and 50% showed impairment of two or more dimensions. A relationship between pitch control and cognitive score was also observed (r =20.50, p = 0.007). Conclusions: Phonatory abnormalities are detectable even the in premotor stages of HD. Speech investigation may have the potential to provide functional biomarkers of HD and could be included in future clinical trials and therapeutic interventions.

Automatic Evaluation of Articulatory Disorders in Parkinson's Disease

  • DOI: 10.1109/TASLP.2014.2329734
  • Odkaz: https://doi.org/10.1109/TASLP.2014.2329734
  • Pracoviště: Katedra teorie obvodů
  • Anotace:
    Although articulatory deficits represent an important manifestation of dysarthria in Parkinson’s disease (PD), the most widely used methods currently available for the automatic evaluation of speech performance are focused on the assessment of dysphonia. The aim of the present study was to design a reliable automatic approach for the precise estimation of articulatory deficits in PD. Twenty-four individuals diagnosed with de novo PD and twenty-two age-matched healthy controls were recruited. Each participant performed diadochokinetic tasks based upon the fast repetition of /pa/-/ta/-/ka/ syllables. All phonemes were manually labeled and an algorithm for their automatic detection was designed. Subsequently, 13 features describing six different articulatory aspects of speech including vowel quality, coordination of laryngeal and supralaryngeal activity, precision of consonant articulation, tongue movement, occlusion weakening, and speech timing were analyzed. In addition, a classification experiment using a support vector machine based on articulatory features was proposed to differentiate between PD patients and healthy controls. The proposed detection algorithm reached approximately 80% accuracy for a 5 ms threshold of absolute difference between manually labeled references and automatically detected positions. When compared to controls, PD patients showed impaired articulatory performance in all investigated speech dimensions (p < 0.05). Moreover, using the six features representing different aspects of articulation, the best overall classification result attained a success rate of 88% in separating PD from controls. Imprecise consonant articulation was found to be the most powerful indicator of PD-related dysarthria. We envisage our approach as the first step towards development of acoustic methods allowing the automated assessment of articulatory features in dysarthrias.

Acoustic Parameters for Classification of Breathiness in Continuous Speech According to the GRBAS Scale

  • Autoři: Stráník, A., prof. Ing. Roman Čmejla, CSc., Vokřál, J.
  • Publikace: Journal of Voice. 2014, 28(5), 653.e9-653.e17. ISSN 0892-1997.
  • Rok: 2014
  • DOI: 10.1016/j.jvoice.2013.07.016
  • Odkaz: https://doi.org/10.1016/j.jvoice.2013.07.016
  • Pracoviště: Katedra teorie obvodů
  • Anotace:
    The purpose of this study was to classify objectively breathiness in continuous speech according to a subjective evaluation of voice based on the GRBAS scale. The level of breathiness in continuous speech can be effectively described by automatic system–based analysis of acoustic measures. The proposed automatic system is able to determine the level of breathiness in continuous speech with sufficient precision.

Eye Movements in Ephedrone-Induced Parkinsonism

  • Autoři: Bonnet, C., doc. Ing. Jan Rusz, Ph.D., Megrelishvili, M., Mgr. Tomáš Sieger, Ph.D., Matoušková, O., Okujava, M., Brožová, H., Nikolai, T., Hanuška, J., Kapianidze, M., Mikeladze, N., Botchorishvili, N., Khatiashvili, I., Janelidze, M., Serranová, T., Fiala, O., Roth, J., Bergquist, J., Jech, R., Rivaud-Péchoux, S., Gaymard, B., Růžička, E.
  • Publikace: PLoS ONE. 2014, 9(8), 1-8. ISSN 1932-6203.
  • Rok: 2014
  • DOI: 10.1371/journal.pone.0104784
  • Odkaz: https://doi.org/10.1371/journal.pone.0104784
  • Pracoviště: Katedra teorie obvodů, Katedra kybernetiky
  • Anotace:
    Patients with ephedrone parkinsonism (EP) show a complex, rapidly progressive, irreversible, and levodopa non-responsive parkinsonian and dystonic syndrome due to manganese intoxication. Eye movements may help to differentiate parkinsonian syndromes providing insights into which brain networks are affected in the underlying disease, but they have never been systematically studied in EP. Horizontal and vertical eye movements were recorded in 28 EP and compared to 21 Parkinson's disease (PD) patients, and 27 age- and gender-matched healthy subjects using standardized oculomotor tasks with infrared videooculography. EP patients showed slow and hypometric horizontal saccades, an increased occurrence of square wave jerks, long latencies of vertical antisaccades, a high error rate in the horizontal antisaccade task, and made more errors than controls when pro- and antisaccades were mixed. Based on oculomotor performance, a direct differentiation between EP and PD was possible only by the velocity of horizontal saccades. All remaining metrics were similar between both patient groups. EP patients present extensive oculomotor disturbances probably due to manganese-induced damage to the basal ganglia, reflecting their role in oculomotor system.

A distinct variant of mixed dysarthria reflects parkinsonism and dystonia due to ephedrone abuse

  • Autoři: doc. Ing. Jan Rusz, Ph.D., Megrelishvili, M., Bonnet, C., Okujava, M., Brožová, H., Khatiashvili, I., Sekhniashvili, M., Janelidze, M., Tolosa, E., Růžička, E.
  • Publikace: Journal of Neural Transmission. 2014, 121(6), 655-664. ISSN 0300-9564.
  • Rok: 2014
  • DOI: 10.1007/s00702-014-1158-6
  • Odkaz: https://doi.org/10.1007/s00702-014-1158-6
  • Pracoviště: Katedra teorie obvodů
  • Anotace:
    A distinctive alteration of speech has been reported in patients suffering from ephedrone-induced parkinsonism. However, an objective assessment of dysarthria has not been performed in ephedrone users. We studied 28 young Caucasian men from Georgia with a previous history of ephedrone abuse and compared them to 25 age-matched healthy controls. Speech examination, brain MRI, and NNIPPS-Parkinson plus scale were performed in all patients. The accurate differential diagnosis of dysarthria subtypes was based on the quantitative acoustic analyses of 15 speech dimensions. We revealed a distinct variant of mixed dysarthria with a combination of hyperkinetic and hypokinetic components representing the altered motor programming of dystonia and bradykinesia in ephedrone-induced parkinsonism. According to acoustic analyses, all patients presented at least one affected speech dimension, whereas dysarthria was moderate in 43 % and severe in 36 % of patients. Further findings indicated relationships between motor subscores of dystonia and bradykinesia and speech components of loudness (r = -0.54, p<0.01), articulation (r = 0.40, p<0.05), and timing (r = -0.53, p<0.01). In ephedrone-induced parkinsonism a prominent mixed hyperkinetic–hypokinetic dysarthria occurs that appears related to marked dystonia and bradykinesia and probably reflects manganese induced toxic and neurodegenerative damage to the globus pallidus internus and substantia nigra.

Evaluation of disfluent speech by means of automatic acoustic measurements

  • Autoři: Lustyk, T., Bergl, P., prof. Ing. Roman Čmejla, CSc.,
  • Publikace: JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA. 2014, 135(3), 1457-1468. ISSN 0001-4966.
  • Rok: 2014
  • DOI: 10.1121/1.4863646
  • Odkaz: https://doi.org/10.1121/1.4863646
  • Pracoviště: Katedra teorie obvodů
  • Anotace:
    An experiment was carried out to determine whether the level of the speech fluency disorder can be estimated by means of automatic acoustic measurements. These measures analyze, for example, the amount of silence in a recording or the number of abrupt spectral changes in a speech signal. All the measures were designed to take into account symptoms of stuttering. In the experiment, 118 audio recordings of read speech by Czech native speakers were employed. The results indicate that the human-made rating of the speech fluency disorder in read speech can be predicted on the basis of automatic measurements. The number of abrupt spectral changes in the speech segments turns out to be the most appropriate measure to describe the overall speech performance. The results also imply that there are measures with good results describing partial symptoms (especially fixed postures without audible airflow).

Acoustic Investigation of Stress Patterns in Parkinson's Disease

  • DOI: 10.1016/j.jvoice.2013.07.001
  • Odkaz: https://doi.org/10.1016/j.jvoice.2013.07.001
  • Pracoviště: Katedra teorie obvodů
  • Anotace:
    Objectives. Although reduced stress is thought to be one of the most deviant speech dimensions in hypokinetic dysarthria associated with Parkinson’s disease (PD), the mechanisms of stress production in PD have not been thoroughly explored by objective methods. The aim of the present study was to quantify the effect of PD on prosodic characteristics and to describe contrastive stress patterns in parkinsonian speech. Methods. The ability of 20 male speakers with early PD and 16 age- and gender-matched healthy controls (HCs) to signal contrastive stress was investigated. Each participant was instructed to unnaturally emphasize five key words while reading a short block of text. Acoustic analyses were based on the measurement of pitch, intensity, and duration. In addition, an innovative measurement termed the stress pattern index (SPI) was designed to mirror the effect of all distinct acoustic cues exploited during stress production. Results. Although PD patients demonstrated a reduced ability to convey contrastive stress, they could still notably increase pitch, intensity, and duration to emphasize a word within a sentence. No differences were revealed between PD and HC stress productions using the measurements of pitch, intensity, duration, and intensity range. However, restricted SPI and pitch range were evident in the PD group. Conclusions. A reduced ability to express stress seems to be the distinctive pattern of hypokinetic dysarthria, even in the early stages of PD. Because PD patients were able to consciously improve their speech performance using multiple acoustic cues, the introduction of speech therapy may be rewarding.

Objective Acoustic Quantification of Phonatory Dysfunction in Huntington's Disease

  • DOI: 10.1371/journal.pone.0065881
  • Odkaz: https://doi.org/10.1371/journal.pone.0065881
  • Pracoviště: Katedra teorie obvodů
  • Anotace:
    Purpose: Although speech motor changes are reported as a common sign of Huntington’s disease (HD), the most prominent signs of voice dysfunction remain unknown. The aim of the current study was to explore specific changes in phonatory function in subjects with HD. Method: 34 subjects with HD and 34 age- and sex-matched healthy controls were examined. Participants performed sustained vowel phonation for subsequent analyses of airflow insufficiency, aperiodicity, irregular vibrations of vocal folds, signal perturbations, increased noise, and articulation deficiency. In total, 272 phonations were collected and 12 voice parameters were extracted. Subsequently, a predictive model was built to find the most salient patterns of voice disorders in HD. The results were also correlated with disease severity according to the Unified HD Rating Scale (UHDRS) motor score. Results: Subjects with HD showed deterioration in all investigated phonatory functions. Irregular pitch fluctuations, sudden phonation interruption, increased noise, and misplacement of articulators were found to be most significant patterns of phonatory dysfunction in HD (p < 0.001). The combination of these four dysphonia aspects contributed to the best classification performance of 94.1 % (sensitivity: 95.1 %; specificity: 93.2 %) in the separation of HD patients from healthy participants. Our results further indicated stronger associations between sudden phonation interruption and voluntary components of the UHDRS (r = - 0.48, p < 0.01) and between misplacement of articulators and involuntary components of the UHDRS (r = 0.52, p < 0.01). Conclusions: Our configuration of phonatory features can detect subtle voice abnormalities in subjects with HD. As impairment of phonatory function in HD was found to parallel increasing motor involvement, a qualitative description of voice dysfunction may be helpful to gain better insight into the pathophysiology of the vocal mechanism.

Za stránku zodpovídá: RNDr. Patrik Mottl, Ph.D.