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  • 1
    Online Resource
    Online Resource
    Wiley ; 2019
    In:  International Journal of Imaging Systems and Technology Vol. 29, No. 4 ( 2019-12), p. 686-700
    In: International Journal of Imaging Systems and Technology, Wiley, Vol. 29, No. 4 ( 2019-12), p. 686-700
    Abstract: Brain source imaging based on EEG aims to reconstruct the neural activities producing the scalp potentials. This includes solving the forward and inverse problems. The aim of the inverse problem is to estimate the activity of the brain sources based on the measured data and leadfield matrix computed in the forward step. Spatial filtering, also known as beamforming, is an inverse method that reconstructs the time course of the source at a particular location by weighting and linearly combining the sensor data. In this paper, we considered a temporal assumption related to the time course of the source, namely sparsity, in the Linearly Constrained Minimum Variance (LCMV) beamformer. This assumption sounds reasonable since not all brain sources are active all the time such as epileptic spikes and also some experimental protocols such as electrical stimulations of a peripheral nerve can be sparse in time. Developing the sparse beamformer is done by incorporating L1‐norm regularization of the beamformer output in the relevant cost function while obtaining the filter weights. We called this new beamformer SParse LCMV (SP‐LCMV). We compared the performance of the SP‐LCMV with that of LCMV for both superficial and deep sources with different amplitudes using synthetic EEG signals. Also, we compared them in localization and reconstruction of sources underlying electric median nerve stimulation. Results show that the proposed sparse beamformer can enhance reconstruction of sparse sources especially in the case of sources with high amplitude spikes.
    Type of Medium: Online Resource
    ISSN: 0899-9457 , 1098-1098
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2009087-0
    SSG: 11
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  • 2
    In: International Journal of Neuropsychopharmacology, Oxford University Press (OUP), Vol. 25, No. 8 ( 2022-08-16), p. 631-644
    Abstract: Although transcranial direct current stimulation (tDCS) has shown to potentially mitigate drug craving and attentional bias to drug-related stimuli, individual differences in such modulatory effects of tDCS are less understood. In this study, we aimed to investigate a source of the inter-subject variability in the tDCS effects that can be useful for tDCS-based treatments of individuals with methamphetamine (MA) use disorder (IMUD). Methods Forty-two IMUD (all male) were randomly assigned to receive a single-session of either sham or real bilateral tDCS (anodal right/cathodal left) over the dorsolateral prefrontal cortex. The tDCS effect on MA craving and biased attention to drug stimuli were investigated by quantifying EEG-derived P3 (a measure of initial attentional bias) and late positive potential (LPP; a measure of sustained motivated attention) elicited by these stimuli. To assess the association of changes in P3 and LPP with brain connectivity network (BCN) topology, the correlation between topology metrics, specifically those related to the efficiency of information processing, and the tDCS effect was investigated. Results The P3 amplitude significantly decreased following the tDCS session, whereas the amplitudes increased in the sham group. The changes in P3 amplitudes were significantly correlated with communication efficiency measured by BCN topology metrics (r = −0.47, P = .03; r = −0.49, P = .02). There was no significant change in LPP amplitude due to the tDCS application. Conclusions These findings validate that tDCS mitigates initial attentional bias, but not the sustained motivated attention, to MA stimuli. Importantly, however, results also show that the individual differences in the effects of tDCS may be underpinned by communication efficiency of the BCN topology, and therefore, these BCN topology metrics may have the potential to robustly predict the effectiveness of tDCS-based interventions on MA craving and attentional bias to MA stimuli among IMUD.
    Type of Medium: Online Resource
    ISSN: 1461-1457 , 1469-5111
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 1501053-3
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  • 3
    Online Resource
    Online Resource
    Iris Publishers LLC ; 2018
    In:  Archives in Biomedical Engineering & Biotechnology Vol. 1, No. 1 ( 2018)
    In: Archives in Biomedical Engineering & Biotechnology, Iris Publishers LLC, Vol. 1, No. 1 ( 2018)
    Type of Medium: Online Resource
    ISSN: 2687-8100
    URL: Issue
    Language: Unknown
    Publisher: Iris Publishers LLC
    Publication Date: 2018
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  • 4
    In: Frontiers in Biomedical Technologies, Knowledge E DMCC, ( 2019-06-17)
    Abstract: Event-Related Potentials (ERPs) have been used in addiction studies to evaluate cognitive performance and craving in individuals with Substance Use Dependence (SUD). This paper reviews studies that used ERPs to investigate cue reactivity, inhibitory control and error processing in SUDs. Five abused substances are included in the investigation, i.e. alcohol, nicotine, cannabis, cocaine, and methamphetamine. For each substance, the main recent findings related to the ERPs are specifically discussed, according to the latency of ERPs. The results show that individuals with SUDs allocate more attention resources to the cognitive processing of substance-related cues, indexed by increased amplitude of middle and late latency ERPs. Laboratory observations also show amplitude enlargement for early latency ERPs. SUDs reveal a deficiency in the inhibitory control and conscious error processing, indexed by attenuated N2 and Pe amplitude. The cognitive and motor inhibitory component (P3) changes show a controversial result. This study expands the findings of previous related reviews implying that substance abusers allocate more attentional resources to drug cues indexed by enlarged P3 and LPP amplitude. Regarding P3 elicited in inhibitory control tasks, there is not still convergent results, while N2 and Pe become attenuated as reported in previous reviews. The outcomes also show that the chance of relapse to substance abuse could be predicted by recording ERPs reflecting inhibitory control and error processing.  
    Type of Medium: Online Resource
    ISSN: 2345-5837
    Language: Unknown
    Publisher: Knowledge E DMCC
    Publication Date: 2019
    detail.hit.zdb_id: 2806579-7
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  • 5
    Online Resource
    Online Resource
    Knowledge E DMCC ; 2023
    In:  Frontiers in Biomedical Technologies ( 2023-07-11)
    In: Frontiers in Biomedical Technologies, Knowledge E DMCC, ( 2023-07-11)
    Abstract: Purpose: Utilizing Electroencephalogram (EEG) is more than at any time in history, therefore we have introduced an open-source MATLAB function to provide simulated EEG which is as equivalent as viable to empirical EEG in a user-friendly way with ground truth that is not accessible in real EEG records. This function should be versatile due to the requirements such as the number and orientation of sources, various noises, mode of activation function, and different anatomical structures. Materials and Methods: We indicate all phases, modes, and formulas which constitute EEGg, EEG generator. This function supports selecting main sources locations and orientation, choosing SNR with white Gaussian noise, electrode numbers, and mode of activation functions. Also, users have the option to use automatic or partly automatic, or fully automatic EEG construction in EEGg. This function is ready to use at https://github.com/Avayekta/EEG. Results: EEGg is designed with several parameters that users have chosen. Hence, users can choose different variables to inspect the time and frequency aspects of synthetic EEG. Conclusion: EEGg is a multi-purpose and comprehensive function to mimic EEG but with ground-truth EEG data and adjustable parameters.
    Type of Medium: Online Resource
    ISSN: 2345-5837
    Language: Unknown
    Publisher: Knowledge E DMCC
    Publication Date: 2023
    detail.hit.zdb_id: 2806579-7
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  • 6
    Online Resource
    Online Resource
    Knowledge E DMCC ; 2019
    In:  Frontiers in Biomedical Technologies ( 2019-10-30)
    In: Frontiers in Biomedical Technologies, Knowledge E DMCC, ( 2019-10-30)
    Abstract: Purpose: Passive Acoustic Thermometer (PAT) is a safe method for internal temperature estimation that works based on acoustic radiation of materials with a specific temperature. Several experimental studies have been carried out so far in the field of PAT. While, to the best of our knowledge, there is no simulation-based research reported yet. Materials and Methods: In this article (for the first time) we proposed a simulation framework for evaluating the PAT methodologies. This framework supports the generation of acoustic radiation, signal processing, parameter estimation, and temperature reconstruction processes. At the moment, the proposed framework estimates the temperature in the frequency domain and uses the frequency spectrum of the acquired ultrasound signals captured by a single transducer. Results: Using the proposed framework, we tried to implement previously practical experiments and the results of the simulation are consistent with those of the practical experiment. The mean error of temperature estimation was below 0.45 °C. The results show that it is possible to use this framework to evaluate the PAT in different scenarios. Conclusion: Therefore, this method enhances the possibility of examination of different conditions and algorithms. It also reduces the cost of practical experiment.
    Type of Medium: Online Resource
    ISSN: 2345-5837
    Language: Unknown
    Publisher: Knowledge E DMCC
    Publication Date: 2019
    detail.hit.zdb_id: 2806579-7
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  • 7
    Online Resource
    Online Resource
    Knowledge E DMCC ; 2023
    In:  Frontiers in Biomedical Technologies ( 2023-09-29)
    In: Frontiers in Biomedical Technologies, Knowledge E DMCC, ( 2023-09-29)
    Abstract: Purpose: A new code based on Helmholtz decomposition is presented to separate longitudinal (pressure) and transverse (shear) components of a mixed wave field. This algorithm will help isolate shear or pressure components of an elastic wave to further concentrate on each specific wave and its physical characteristics, particularly in medical imaging instrument development and image processing techniques. Materials and Methods: Using the combination of Fourier transform and Helmholtz decomposition, first, the mathematical basis of the work is prepared. After reaching a usable formula, this basis is embedded in the Code written in MATLAB program. Then, various test data containing shear and pressure waves were created and fed to the Code to evaluate its ability to decompose the displacements into the shear and pressure waves. Results: This new algorithm successfully isolated the transverse and longitudinal wavefront of the mixed wavefield. The Code demonstrated 100% accuracy for separating the shear wave and more than 99% for the pressure wave. Moreover, the background noise was kept under 0.03% in every step. Conclusion: The results show that using Helmholtz decomposition in Fourier space on 3D data can help decompose a displacement field into its irrotational and solenoidal components with high accuracy. A weak dependency on wave thickness and contrast was observed, but the algorithm's accuracy never fell below 99%.
    Type of Medium: Online Resource
    ISSN: 2345-5837
    Language: Unknown
    Publisher: Knowledge E DMCC
    Publication Date: 2023
    detail.hit.zdb_id: 2806579-7
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  • 8
    Online Resource
    Online Resource
    Elsevier BV ; 2021
    In:  Computer Methods and Programs in Biomedicine Update Vol. 1 ( 2021), p. 100027-
    In: Computer Methods and Programs in Biomedicine Update, Elsevier BV, Vol. 1 ( 2021), p. 100027-
    Type of Medium: Online Resource
    ISSN: 2666-9900
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 3075072-6
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  • 9
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2019
    In:  Circuits, Systems, and Signal Processing Vol. 38, No. 3 ( 2019-3), p. 1264-1286
    In: Circuits, Systems, and Signal Processing, Springer Science and Business Media LLC, Vol. 38, No. 3 ( 2019-3), p. 1264-1286
    Type of Medium: Online Resource
    ISSN: 0278-081X , 1531-5878
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 2085136-4
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  • 10
    In: Information Sciences, Elsevier BV, Vol. 622 ( 2023-04), p. 1-15
    Type of Medium: Online Resource
    ISSN: 0020-0255
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 218760-7
    detail.hit.zdb_id: 1478990-5
    SSG: 24,1
    SSG: 7,11
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