scholarly journals Combining time-frequency and spatial information for the detection of sleep spindles

2015 ◽  
Vol 9 ◽  
Author(s):  
Christian O'Reilly ◽  
Jonathan Godbout ◽  
Julie Carrier ◽  
Jean-Marc Lina
Keyword(s):  
Spatial Information ◽  
Sleep Spindles ◽  
Time Frequency

scholarly journals Particle-filter tracking of sounds for frequency-independent 3D audio rendering from distributed B-format recordings

Acta Acustica ◽  
2021 ◽  
Vol 5 ◽  
pp. 20
Author(s):  
Matthias Blochberger ◽  
Franz Zotter
Keyword(s):  
Particle Filter ◽  
Spatial Information ◽  
Multiple Perspectives ◽  
Directional Information ◽  
Time Frequency ◽  
Perceptual Evaluation ◽  
3D Audio ◽  
Audio Rendering ◽  
Sound Objects ◽  
Definition Of

Six-Degree-of-Freedom (6DoF) audio rendering interactively synthesizes spatial audio signals for a variable listener perspective based on surround recordings taken at multiple perspectives distributed across the listening area in the acoustic scene. Methods that rely on recording-implicit directional information and interpolate the listener perspective without the attempt of localizing and extracting sounds often yield high audio quality, but are limited in spatial definition. Methods that perform sound localization, extraction, and rendering typically operate in the time-frequency domain and risk introducing artifacts such as musical noise. We propose to take advantage of the rich spatial information recorded in the broadband time-domain signals of the multitude of distributed first-order (B-format) recording perspectives. Broadband time-variant signal extraction retrieving direct signals and leaving residuals to approximate diffuse and spacious sounds is less of a quality risk, and likewise is the broadband re-encoding to enhance spatial definition of both signal types. To detect and track direct sound objects in this process, we combine the directional data recorded at the single perspectives into a volumetric multi-perspective activity map for particle-filter tracking. Our technical and perceptual evaluation confirms that this kind of processing enhances the otherwise limited spatial definition of direct-sound objects of other broadband but signal-independent virtual loudspeaker object (VLO) or Vector-Based Intensity Panning (VBIP) interpolation approaches.

scholarly journals Sleep spindles, ripples, and interictal epileptiform discharges in the human anterior and mediodorsal thalamus

2021 ◽  
Author(s):  
Orsolya Szalardy ◽  
Peter Simor ◽  
Peter Przemyslaw Ujma ◽  
Zsofia Jordan ◽  
Laszlo Halasz ◽  
...  
Keyword(s):  
Neural Plasticity ◽  
Nrem Sleep ◽  
Cortical Activity ◽  
Sleep Spindles ◽  
Time Frequency ◽  
Scalp Eeg ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges ◽  
Human Thalamus ◽  
Result Show

Sleep spindles are major oscillatory components of Non-Rapid Eye Movement (NREM) sleep, reflecting hyperpolarization-rebound sequences of thalamocortical neurons, the inhibition of which is caused by the NREM-dependent activation of GABAergic neurons in the reticular thalamic nucleus. Reports suggest a link between sleep spindles and several forms of interictal epileptic discharges (IEDs) which are considered as expressions of pathological off-line neural plasticity in the central nervous system. Here we investigated the relationship between thalamic sleep spindles, IEDs and ripples in the anterior and mediodorsal nuclei (ANT and MD) of epilepsy patients. Whole-night LFP from the ANT and MD were co-registered with scalp EEG/polysomnography by using externalized leads in 15 epilepsy patients undergoing Deep Brain Stimulation protocol. Slow (~12 Hz) and fast (~14 Hz) sleep spindles were present in the human ANT and MD. Roughly, one third of thalamic sleep spindles were associated with IEDs or ripples. Both IED- and ripple-associated spindles were longer than pure spindles. IED-associated thalamic sleep spindles were characterized by broadband increase in thalamic and cortical activity, both below and above the spindle frequency range, whereas ripple-associated thalamic spindles exceeded pure spindles in terms of 80-200 Hz thalamic, but not cortical activity as indicated by time-frequency analysis. These result show that thalamic spindles coupled with IEDs are reflected at the scalp slow and beta-gamma oscillation as well. IED density during sleep spindles in the MD, but not in the ANT was identified as correlates of years spent with epilepsy, whereas no signs of pathological processes were correlated with measures of ripple and spindle association. Furthermore, the density of ripple-associated sleep spindles in the ANT showed a positive correlation with general intelligence. Our findings indicate the complex and multifaceted role of the human thalamus in sleep spindle-related physiological and pathological neural plasticity.

scholarly journals A time-frequency analysis of the dynamics of cortical networks of sleep spindles from MEG-EEG recordings

2014 ◽  
Vol 8 ◽  
Author(s):  
Younes Zerouali ◽  
Jean-Marc Lina ◽  
Zoran Sekerovic ◽  
Jonathan Godbout ◽  
Jonathan Dube ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Sleep Spindles ◽  
Cortical Networks ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Eeg Recordings

Time-frequency dynamics during sleep spindles on the EEG in rodents with a genetic predisposition to absence epilepsy (WAG/Rij rats)

2015 ◽  
Author(s):  
Alexander E. Hramov ◽  
Evgenija Y. Sitnikova ◽  
Alexey N. Pavlov ◽  
Vadim V. Grubov ◽  
Alexey A. Koronovskii ◽  
...  
Keyword(s):  
Genetic Predisposition ◽  
Absence Epilepsy ◽  
Sleep Spindles ◽  
Time Frequency

scholarly journals Sleep spindles mediate hippocampal-neocortical coupling during sharp-wave ripples

2019 ◽  
Author(s):  
Hong-Viet. V. Ngo ◽  
Juergen Fell ◽  
Bernhard P. Staresina
Keyword(s):  
Eye Movement ◽  
Information Transfer ◽  
Communication Channels ◽  
Nrem Sleep ◽  
Sleep Spindles ◽  
Coherence Analysis ◽  
Time Frequency ◽  
Target Sites ◽  
Spindle Power

AbstractSleep is pivotal for the consolidation of memories [1]. According to two-stage accounts, experiences are temporarily stored in the hippocampus and gradually translocated to neocortical sites during non-rapid-eye-movement (NREM) sleep [2,3]. Mechanistically, information transfer is thought to rely on interactions between thalamocortical spindles and hippocampal ripples. In particular, spindles may open precisely-timed communication channels, across which reactivation patterns may travel between the hippocampus and cortical target sites when ripples occur. To test this hypothesis, we first derived time-frequency representations (TFRs) in hippocampus (HIPP) and at scalp electrode Cz (neocortex, NC) time-locked to individual hippocampal ripple events. Compared to matched ripple-free intervals, results revealed a concurrent increase in spindle power both in HIPP and NC. As revealed by coherence analysis, hippocampal-neocortical coupling was indeed enhanced in the spindle band around ripples. Finally, we examined the directionality of spindle coupling and observed a strong driving effect from NC to HIPP. Specifically, ∼250 ms prior to the HIPP ripple, NC spindles emerge and entrain HIPP spindles. Both regions then remain synchronised until ∼500 ms after the ripple. Consistent with recent rodent work, these findings suggest that active consolidation is initiated by neocortex and draws on neocortical-hippocampal-neocortical reactivation loops [4], with a role of sleep spindles in mediating this process.

scholarly journals Age-Dependent Increase of Absence Seizures and Intrinsic Frequency Dynamics of Sleep Spindles in Rats

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Evgenia Sitnikova ◽  
Alexander E. Hramov ◽  
Vadim Grubov ◽  
Alexey A. Koronovsky
Keyword(s):  
Neurological Diseases ◽  
Epileptic Activity ◽  
Absence Epilepsy ◽  
Sleep Spindles ◽  
Intrinsic Frequency ◽  
Time Frequency ◽  
Age Dependent ◽  
Spike Wave Discharges ◽  
Epileptic Spike ◽  
Spike Wave

The risk of neurological diseases increases with age. In WAG/Rij rat model of absence epilepsy, the incidence of epileptic spike-wave discharges is known to be elevated with age. Considering close relationship between epileptic spike-wave discharges and physiologic sleep spindles, it was assumed that age-dependent increase of epileptic activity may affect time-frequency characteristics of sleep spindles. In order to examine this hypothesis, electroencephalograms (EEG) were recorded in WAG/Rij rats successively at the ages 5, 7, and 9 months. Spike-wave discharges and sleep spindles were detected in frontal EEG channel. Sleep spindles were identified automatically using wavelet-based algorithm. Instantaneous (localized in time) frequency of sleep spindles was determined using continuous wavelet transform of EEG signal, and intraspindle frequency dynamics were further examined. It was found that in 5-months-old rats epileptic activity has not fully developed (preclinical stage) and sleep spindles demonstrated an increase of instantaneous frequency from beginning to the end. At the age of 7 and 9 months, when animals developed matured and longer epileptic discharges (symptomatic stage), their sleep spindles did not display changes of intrinsic frequency. The present data suggest that age-dependent increase of epileptic activity in WAG/Rij rats affects intrinsic dynamics of sleep spindle frequency.

Time-frequency characteristics and dynamics of sleep spindles in WAG/Rij rats with absence epilepsy

2014 ◽  
Vol 1543 ◽  
pp. 290-299 ◽  
Author(s):  
Evgenia Sitnikova ◽  
Alexander E. Hramov ◽  
Vadim Grubov ◽  
Alexey A. Koronovsky
Keyword(s):  
Absence Epilepsy ◽  
Frequency Characteristics ◽  
Sleep Spindles ◽  
Time Frequency

scholarly journals Speech recognition with a hearing-aid processing scheme combining beamforming with mask-informed speech enhancement

2022 ◽  
Vol 26 ◽  
pp. 233121652110686
Author(s):  
Tim Green ◽  
Gaston Hilkhuysen ◽  
Mark Huckvale ◽  
Stuart Rosen ◽  
Mike Brookes ◽  
...  
Keyword(s):  
Speech Enhancement ◽  
Hearing Aids ◽  
Spatial Information ◽  
Signal To Noise Ratio ◽  
Target Position ◽  
Spatial Diversity ◽  
Processing Scheme ◽  
Time Frequency ◽  
Sentence Recognition ◽  
Enhancement Method

A signal processing approach combining beamforming with mask-informed speech enhancement was assessed by measuring sentence recognition in listeners with mild-to-moderate hearing impairment in adverse listening conditions that simulated the output of behind-the-ear hearing aids in a noisy classroom. Two types of beamforming were compared: binaural, with the two microphones of each aid treated as a single array, and bilateral, where independent left and right beamformers were derived. Binaural beamforming produces a narrower beam, maximising improvement in signal-to-noise ratio (SNR), but eliminates the spatial diversity that is preserved in bilateral beamforming. Each beamformer type was optimised for the true target position and implemented with and without additional speech enhancement in which spectral features extracted from the beamformer output were passed to a deep neural network trained to identify time-frequency regions dominated by target speech. Additional conditions comprising binaural beamforming combined with speech enhancement implemented using Wiener filtering or modulation-domain Kalman filtering were tested in normally-hearing (NH) listeners. Both beamformer types gave substantial improvements relative to no processing, with significantly greater benefit for binaural beamforming. Performance with additional mask-informed enhancement was poorer than with beamforming alone, for both beamformer types and both listener groups. In NH listeners the addition of mask-informed enhancement produced significantly poorer performance than both other forms of enhancement, neither of which differed from the beamformer alone. In summary, the additional improvement in SNR provided by binaural beamforming appeared to outweigh loss of spatial information, while speech understanding was not further improved by the mask-informed enhancement method implemented here.

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