ECoG high gamma activity reveals distinct cortical representations of lyrics passages, harmonic and timbre-related changes in a rock song

Listening to music moves our minds and moods, stirring interest in its neural underpinnings. A multitude of compositional features drives the appeal of natural music. How such original music, where a composer's opus is not manipulated for experimental purposes, engages a listener's brain has not been studied until recently. Here, we report an in-depth analysis of two electrocorticographic (ECoG) data sets obtained over the left hemisphere in ten patients during presentation of either a rock song or a read-out narrative. First, the time courses of five acoustic features (intensity, presence/absence of vocals with lyrics, spectral centroid, harmonic change, and pulse clarity) were extracted from the audio tracks and found to be correlated with each other to varying degrees. In a second step, we uncovered the specific impact of each musical feature on ECoG high-gamma power (70–170 Hz) by calculating partial correlations to remove the influence of the other four features. In the music condition, the onset and offset of vocal lyrics in ongoing instrumental music was consistently identified within the group as the dominant driver for ECoG high-gamma power changes over temporal auditory areas, while concurrently subject-individual activation spots were identified for sound intensity, timbral, and harmonic features. The distinct cortical activations to vocal speech-related content embedded in instrumental music directly demonstrate that song integrated in instrumental music represents a distinct dimension in complex music. In contrast, in the speech condition, the full sound envelope was reflected in the high gamma response rather than the onset or offset of the vocal lyrics. This demonstrates how the contributions of stimulus features that modulate the brain response differ across the two examples of a full-length natural stimulus, which suggests a context-dependent feature selection in the processing of complex auditory stimuli

Propuesta de una batería de ejercicios físicos para mejorar la resistencia en futbolistas en rango de edad 12 a 14 años en la Escuela Club Deportivo Nuevos Amigos Siglo XXI

Para todo deporte o disciplina deportiva se necesita un poco de resistencia, esto hace que el cuerpo genere la fatiga en un tiempo más prolongado del ejercicio y haya un mejor rendimiento técnico a la hora de efectuarlo, es por eso la idea de aplicar una batería de ejercicios físicos para mejorar la resistencia en futbolistas en rango de edad de 12 a 14 años, donde se sabe que la resistencia que maneja este deporte es mixta por la larga duración de sus partidos, y la gran cantidad de sprint y saltos que se pueden ejecutar. Este estudio se realizara en el Club Deportivo Nuevos Amigos Siglo XXI del municipio de Palmira, Valle del Cauca.PregradoLICENCIADO(A) EN EDUCACIÓN FÍSICA Y DEPORTE

Assessment of Human Muscle Fatigue from Surface EMG Signals Recorded during Isometric Voluntary Contractions by using a Cosine Modulated Filter Bank

Human muscle fatigue involves both a decrease in the frequency and increase in the amplitude of a surface electromyographic (EMG) signal. Muscle fatigue is also related to a decrease of the force impeding to reach the same initial level of the maximum voluntary contraction (MVC). To determine muscle fatigue indices, a method is proposed by decomposing a surface EMG signal into 32-subbands. This decomposition was attained by using a cosine modulated filter bank. The surface EMG signals analyzed during this research were recorded during isometric voluntary contractions. Both the instantaneous mean frequency (IMF) and the instantaneous amplitude (IA) are estimated from the 32-subbands of the filter bank and are used as indicators of muscle fatigue. For evaluating the IMF and the IA estimated from the filter bank, two other standard techniques, the spectrogram and the smoothed pseudoWigner-Ville (SPWV) distribution, were also implemented. A regression-free area ratio, introduced first by Merletti, was adopted to compute an EMG index from both estimates the IMF and IA. These indices were then classified - by using a joint analysis of frequency and amplitude (JASA) - into one of the four muscle activity regions: muscle increase force, muscle recovery, muscle decrease force, and muscle fatigue. Surface EMG signals were recorded from 26 normal human subjects who exerted first 70% and then 100% of their MVC at intervals session of eight hours. It was found that EMG indices derived from the proposed filter bank are equivalent to those EMG indices derived from the spectrogram and the SPWV distribution. Furthermore, muscle fatigue indices derived from the filter bank indicated that they could be used as indices to determine human muscle fatigue. These results were confirmed by correlating the resulting muscle fatigue indices with perceived levels of discomfort reported by the subjects after performing an exertion of 70% MVC in hours two, four, and six

Development and Validation of a Novel Framework to Map Brain Function

Neuroimaging approaches have identified multiple brain sites that are activated in music perception, including the posterior part of the superior temporal gyrus and adjacent perisylvian areas. Yet, to what extent brain signals represent the time course of specific acoustic features in natural auditory stimuli and the detailed spatial and temporal relationship of neural signals that support auditory function are largely unknown. In the two studies documented in this dissertation, a novel neuroimaging framework is applied to electrophysiological signals recorded from the surface of the brains (electrocorticography (ECoG)) of 8-10 human epileptic subjects while they were listening to a continuous piece of music. This framework allows clinicians and researchers to identify those ECoG features related to the processing of a continuous piece of music and to investigate their spatial, temporal, and causal relationships. The results presented here demonstrate robust stimulus-related modulations in the alpha (8-12 Hz) and high gamma (70-110 Hz) bands at neuroanatomical locations implicated in auditory processing. Specifically, stimulus-related ECoG modulations in the alpha band were identified in areas adjacent to primary auditory cortex, which are known to receive afferent auditory projections from the thalamus. In contrast, stimulus-related ECoG modulations in the high gamma band were identified not only in areas close to primary auditory cortex, but also in other perisylvian areas known to be involved in higher-order auditory processing, and in an unexpected and distinct area in superior premotor cortex. Moreover, ECoG activity in the high gamma band recorded from these cortical areas were observed to be highly correlated with the sound intensity of music. Across all implicated areas, modulations in the high gamma band preceded those in the alpha band by 280 ms, and activity in the high gamma band causally predicted alpha activity, but not vice versa (Granger causality, p \u3c 1e-8). Additionally, detailed analyses using Granger causality identified causal relationships of high gamma activity between distinct locations in early auditory pathways within STG and posterior STG, between posterior STG and inferior frontal cortex, and between STG and the newly identified location in premotor cortex. Evidence suggests that these relationships reflect direct cortico-cortical connections rather than common driving input from subcortical structures such as the thalamus. In summary, analyses showed that ECoG signals encode information about the sound intensity of music, and define the spatial and temporal relationships between music-related brain activity in the alpha and high gamma bands. They provide experimental evidence supporting current theories about the putative mechanisms of alpha and gamma activity, i.e., reflections of thalamo-cortical interactions and local cortical neural activity, respectively. These results are also in agreement with existing functional models of auditory processing and highlight a previously largely unrecognized role of superior premotor cortex in music processing. Results documented in this study make a strong case for the use of ECoG to map brain activity and brain networks related to cognitive, sensory, and motor functions.^ Keywords: electrocorticography (ECoG), alpha and high gamma activity, thalamo-cortical interactions, epilepsy, neurosurgery, brain activity and networks

Prevalence and Temporal Distribution of Extrasystoles in Septic ICU Patients: The Feasibility of Predicting Fluid Responsiveness Using Extrasystoles

Background. Extrasystoles may be useful for predicting the response to fluid therapy in hemodynamically unstable patients but their prevalence is unknown. The aim of this study was to estimate the availability of extrasystoles in intensive care unit patients diagnosed with sepsis. The study aim was not to validate the fluid responsiveness prediction ability of extrasystoles. Methods. Twenty-four-hour ECG recordings from a convenience sample of 50 patients diagnosed with sepsis were extracted from the MIMIC-II waveform database, and ECGs were visually examined for correct QRS complex detection. Custom-made algorithms identified potential extrasystoles based on RR intervals. Two raters visually confirmed or rejected the potential extrasystoles and then classified them as ventricular, supraventricular, or unknown origin. Extrasystole availability was calculated as extrasystolic coverage for each 24 h ECG recording, that is, the percentage of the 24 h recording where an extrasystole had occurred in the preceding 30 minutes. Results. Mean extrasystolic coverage was 53.3% (confidence interval: [42.8; 63.6]%) and ventricular extrasystolic coverage was 21.4 [13.5; 29.8]%. Interrater reliability was strong for confirming/rejecting extrasystoles. Conclusions. Extrasystoles are available for fluid responsiveness prediction in septic patients in about half of the time. With this extrasystolic availability, we believe the method to be considered for clinical use, provided that future studies validate the method’s fluid responsiveness prediction ability

Spatial and temporal relationships of electrocorticographic alpha and gamma activity during auditory processing

Neuroimaging approaches have implicated multiple brain sites in musical perception, including the posterior part of the superior temporal gyrus and adjacent perisylvian areas. However, the detailed spatial and temporal relationship of neural signals that support auditory processing is largely unknown. In this study, we applied a novel inter-subject analysis approach to electrophysiological signals recorded from the surface of the brain (electrocorticography (ECoG)) in ten human subjects. This approach allowed us to reliably identify those ECoG features that were related to the processing of a complex auditory stimulus (i.e., continuous piece of music) and to investigate their spatial, temporal, and causal relationships. Our results identified stimulus-related modulations in the alpha (8-12 Hz) and high gamma (70-110 Hz) bands at neuroanatomical locations implicated in auditory processing. Specifically, we identified stimulus-related ECoG modulations in the alpha band in areas adjacent to primary auditory cortex, which are known to receive afferent auditory projections from the thalamus (80 of a total of 15,107 tested sites). In contrast, we identified stimulus-related ECoG modulations in the high gamma band not only in areas close to primary auditory cortex but also in other perisylvian areas known to be involved in higher-order auditory processing, and in superior premotor cortex (412/15,107 sites). Across all implicated areas, modulations in the high gamma band preceded those in the alpha band by 280 ms, and activity in the high gamma band causally predicted alpha activity, but not vice versa (Granger causality, p<1e(-8)). Additionally, detailed analyses using Granger causality identified causal relationships of high gamma activity between distinct locations in early auditory pathways within superior temporal gyrus (STG) and posterior STG, between posterior STG and inferior frontal cortex, and between STG and premotor cortex. Evidence suggests that these relationships reflect direct cortico-cortical connections rather than common driving input from subcortical structures such as the thalamus. In summary, our inter-subject analyses defined the spatial and temporal relationships between music-related brain activity in the alpha and high gamma bands. They provide experimental evidence supporting current theories about the putative mechanisms of alpha and gamma activity, i.e., reflections of thalamo-cortical interactions and local cortical neural activity, respectively, and the results are also in agreement with existing functional models of auditory processing

Longitudinal Validation of Right Ventricular Pressure Monitoring for the Assessment of Right Ventricular Systolic Dysfunction in a Large Animal Ischemic Model

CONTEXT:. Right ventricular (RV) dysfunction is a major cause of morbidity and mortality in intensive care and cardiac surgery. Early detection of RV dysfunction may be facilitated by continuous monitoring of RV waveform obtained from a pulmonary artery catheter. The objective is to evaluate the extent to which RV pressure monitoring can detect changes in RV systolic performance assess by RV end-systolic elastance (Ees) following the development of an acute RV ischemic in a porcine model. HYPOTHESIS:. RV pressure monitoring can detect changes in RV systolic performance assess by RV Ees following the development of an acute RV ischemic model. METHODS AND MODELS:. Acute ischemic RV dysfunction was induced by progressive embolization of microsphere in the right coronary artery to mimic RV dysfunction clinically experienced during cardiopulmonary bypass separation caused by air microemboli. RV hemodynamic performance was assessed using RV pressure waveform-derived parameters and RV Ees obtained using a conductance catheter during inferior vena cava occlusions. RESULTS:. Acute ischemia resulted in a significant reduction in RV Ees from 0.26 mm Hg/mL (interquartile range, 0.16–0.32 mm Hg/mL) to 0.14 mm Hg/mL (0.11–0.19 mm Hg/mL; p < 0.010), cardiac output from 6.3 L/min (5.7–7 L/min) to 4.5 (3.9–5.2 L/min; p = 0.007), mean systemic arterial pressure from 72 mm Hg (66–74 mm Hg) to 51 mm Hg (46–56 mm Hg; p < 0.001), and mixed venous oxygen saturation from 65% (57–72%) to 41% (35–45%; p < 0.001). Linear mixed-effect model analysis was used to assess the relationship between Ees and RV pressure-derived parameters. The reduction in RV Ees best correlated with a reduction in RV maximum first derivative of pressure during isovolumetric contraction (dP/dtmax) and single-beat RV Ees. Adjusting RV dP/dtmax for heart rate resulted in an improved surrogate of RV Ees. INTERPRETATION AND CONCLUSIONS:. Stepwise decreases in RV Ees during acute ischemic RV dysfunction were accurately tracked by RV dP/dtmax derived from the RV pressure waveform