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Questions tagged [eeg]

The recording of voltages along the scalp for the purpose of monitoring brain wave activity and localizing sources of ionic currents

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23 views

Why my Time-Frequency plot is time reversed?

I'm trying to build my own code implementation for Continuous Wavelet Fourier Transform. But when I compare the time-frequency plot created with my function with time-frequency plot created with the ...
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1answer
23 views

What Is Meant by Clustering of ICA (Independent Component Analysis) Components?

I'm following the EEGLAB tutorial about STUDY creation and manipulation of the datasets, and came across the concept of clustering of ICA components. I'm not too familiar with processing of ICA ...
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120 views

Python tool for time-frequency analysis

I am trying to perform time-frequency analyses using the PyWavelets (pywt) toolkit for python. My ultimate goal is to perform time-frequency analyses for EEG signals but I am starting with something ...
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1answer
94 views

Can Kalman filter remove 50 Hz noise?

I'm dealing with a brain stimulation. My EEG contains large spikes (>3 mV) when stimulation occurs. I want to remove the 50 Hz noise, but I can't use notch filter because it creates large artifacts. ...
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66 views

How to find Coefficients of Autoregressive (AR) model using least means square (LMS) Algorithm without having future signal?

I want to do two things. Estimating Coefficients of AR model using LMS Using Coefficients found in step 1 and predict future samples of a signal using AR equation. I don't have a desired signal so I ...
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1answer
35 views

How to apply baseline methods to MNE preprocessed raw EEG signals?

I am new at EEG preprocessing and classification. I have followed Clemens Brunner's blog https://cbrnr.github.io/2018/01/29/removing-eog-ica/ as a tutorial for MNE. This is how I have preprocessed ...
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2answers
44 views

Augmentation for EEG signal classification using Deep Learning

Augmentation is a technique that we use in deep learning for expanding the training dataset. It includes different ways of modifying an image and adding it to the training dataset. My question is if ...
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85 views

MNE-python time frequency analysis

I usually use Brain Vision analyzer for EEG analysis. Recently, I also do MNE-python. I have already done ERP and time-frequency analysis.I'm trying to get time-frequency power from MNE-python now. ...
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35 views

How to account for number of electrodes in EEG data while converting to frequency domain?

I have raw data from 64 electrode EEG in CSV format where there are multiple rows and 64 columns. I am using the following Python code to separate the data into frequency bands: ...
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2answers
132 views

May I know how to find Time frequency power spectrogram of a signal?

I am analyzing EEG signal and I am unable to understand the term Time-Frequency Power Spectrogram. Please Can anyone help me? Thank you in advance.
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3answers
49 views

Can an EEG be re-sampled to fix a poor voltage resolution?

I’ve made quite a bad mistake in ca. 14 EEG recordings – I recorded at 10uV resolution @ 5000 Hz instead of 0.1 uV @ 500 Hz. I’m conducting an ERP experiment, and the signals of interest are on the ...
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1answer
105 views

Manual filter or digital filter first for EEG?

I am getting conflicting advise regarding how to clean my EEG data: 1) Manually remove artefacts first and then apply digital filters OR 2) Apply digital filters first and then manually remove ...
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1answer
227 views

Wavelet transform and FFT using to extract feature power bands with EEG signals

I am using 5 channels [ fz , cz , c3 , c4 , pz] to detect drowsiness of driver My First Question is, what is the right input to get feature power band ( Theta , alpha , gamma , beta ) to wavelet ...
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1answer
266 views

Common Spatial Pattern for EEG Signals

I am having difficulty in understanding the use of CSP for EEG signal feature extraction and subsequently. Since I am using two classes, this query will be restricted to it. In essence CSP requires 2 ...
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1answer
113 views

Spatial spectrum of EEG data: non-uniform DFT?

I want to compute the spatial spectrum of EEG data collected using a non-uniformly sampled grid of sensors (as in the figure below). One way to do this would be to interpolate the data on a ...
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242 views

output shape of STFT

I cant figure out why our output image is 257 * 32 , 32 I know why , but 257 I cant understand ? this is the exact word of this paper wich applied STFT on 3 channel of eeg signal : Short time Fourier ...
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1answer
649 views

How to apply Hamming Window and compute FFT?

I'm borrowing an EEG device whose accompanying software also computes the FFT of the data it collects. The software provides the user with a file of EEG values and a file of FFT values computed from ...
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1answer
78 views

EEG, PSI interpretation

My colleague and I started exploring EEG processing and, especially, functional connectivity. We decided to try the Phase Slope Index (PSI) and conducted a simple experiment as follows: it consists of ...
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2answers
102 views

How do I know if my EEG signal need denoising?

I recently started working on sleep study. For my research I download sleep EEG data from physionet. The EEG data has 100 Hz sampling rate and was recorded from 2 bipolar EEG site. When I start the ...
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3answers
5k views

How to correctly compute the EEG Frequency Bands with Python?

so I am trying to compute the EEG(25 channels, 512 sampling rate, 248832/channel) bands (alpha, beta, gamma, etc.) with Python. I managed to do so by: firstly filtering the signal with a butterworth ...
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1answer
2k views

How to compute the power bands of an eeg signal using python?

so I have an eeg signal (edf format) that has 25 channels and 248832 entries, sampling frequency of 512Hz. I have to compute the frequency bands: – Delta: 0.1-4Hz – Theta: 4-8Hz – Alpha: 8-12Hz – ...
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1answer
353 views

DWT versus band-pass filter

Which technique gives better result in extracting a band from a signal, let's say the alpha band (8-13 Hz): using a band-pass-filter or a DWT (Discrete Wavelet Transformation)? P.S.: I am working in ...
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1answer
41 views

What is the meaning of negative second for a Morlet wavelet?

I kind of familiar with wavelet transform (I just used it in code but do not have a deep understanding about it). I've been reading an article and came across this sentence: where 4Fs is the ...
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1answer
2k views

why butterworth bandpass filter changes signal in the passband?

I want to apply a butterworth bandpass filter to EEG signals and it's not working so I tried with a simple signal: t=[0:0.01:10]; s3= 9*sin(2*pi*4*t); Still ...
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2answers
340 views

Compute absolute power spectrum in MATLAB

I have EEG signals. Is there a way to compute the absolute power spectrum in MATLAB within a frequency band? I know I have to use the fft function but I can't find any details about the absolute power ...
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1answer
2k views

Compute phase coherence between two eeg signals

I have two EEG signals/channels and I would like to compute phase coherence in MATLAB. I have this paper: https://www.nature.com/npp/journal/v39/n5/full/npp2013330a.html but it does not say what Sij ...
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2answers
9k views

What does epoch mean in EEG?

I need to understand the meaning of an epoch in EEG signal. I have an EEG signal. Then how can I get the epoch?
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0answers
334 views

How to choose notch frequencies for filtering line noise?

I'm using the function to filter out line noise at 60 Hz (and 120, 180 Hz) caused by electrical noise: ecogNotch In the case below I can effectively filter out the line noise with a notch filter at ...
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0answers
336 views

What's the suitable specifications for the FIR filter?

i have EEG signal,the sampling frequency is 256 HZ .The wavelet decomposition that i will use does not allow the extraction of specific frequency bands without additional filtering. Thus, in order to ...
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1answer
727 views

Low pass FIR filter for EEG signal

I'm trying to do Analysis of EEG Signal for the Detection of epileptic seizure so in the pre-processing of the EEG signal I use a low pass FIR filter ...
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0answers
34 views

Reduce impact of outliners for frequency analysis by increasing signal length?

I am working on a project to detect drivers drowsiness with EEG signals. I am using the frequency values retrieved by FFT. I have some outliners (artifacts) in my signals, which I don't want to remove ...
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1answer
150 views

What do certain terms mean in EEG processing describing frequency bands?

I've recently started a project about detecting driver drowsiness with an EEG and came across some terms I didn't quite understood: ...increase in theta activity occur... - ...low voltage theta ...
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1answer
852 views

Bandpass filter to get EEG frequency bands?

I'm doing a project with an EEG to detect driver drowsiness and learned about EEG frequency bands (alpha, beta, gamma...). As the frequency bands are simple frequency ranges, I wonder if I can use ...
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1answer
90 views

What is QEEG technically, and how is it computed?

I've been working with EEG signals for a while. I wonder how to compute QEEG (or Brain Map) representation. I think it is extracted from raw EEG and I want to know what is technical method for QEEg ...
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131 views

EOG artifacts turn up in several ICA source signals

I try to remove EOG artifacts from my EEG signals (I am using a EPOC+ for recording and MNE Python for processing). Therefore I've recorded test data with blinks every 5 seconds. The blinks can be ...
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2answers
2k views

Which order to perform downsampling and filtering?

I have EEG data recorded with 128Hz sampling rate. As my goal is to reduce the amount of data (and maybe noise), I want to downsample the data to 64Hz (I am only interested in range 0.5 - 30Hz). I ...
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1answer
4k views

Cross correlate a 2D array

I have a 2D array of eeg data with shape (64,512) - 64 electrodes, 512 timepoints I want to calculate the maximum cross correlation (irrespective of lag/time shift) between every single electrode, so ...
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1answer
2k views

How to segment frequency bands after FFT and calculate power?

I have been working with EEG signal. I have raw EEG data for a 2-second (i.e. $t=2$) duration. My objectives are: Transforming these raw data from time domain to frequency domain. Segmentation into ...
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1answer
2k views

How is the topo / scalp map from an EEG Signal with ICA created?

I am lately experimenting with an EEG and found this Library: MNE Python. I am using an ICA to find and correct artifacts - this is working fine. It's now possible to plot a topo / scalp map for the ...
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1answer
3k views

How do we use signal::filter and signal::butter in R for EEG data?

I am trying to design an experiment to determine the peak amplitude of an EEG signal in response to a stimulus. Till now, our team has been using MATLAB and since we wish to go open source, we are ...
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1answer
373 views

Origin of artifacts 12 Hz away from electrical line noise (50 Hz)?

I made electroencephalographic measurements from people while they were sleeping. When plotting the frequencies, I see that I do not only have an expected 50 Hz (and 150 Hz and 250 Hz...) artifact (...
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1answer
87 views

What could be causing these humps every 10 Hz on my PSD estimate data?

I am working with EEG recordings about 1,000,000 data pts long, recorded at 4,000 Hz. I'm generating PSD estimates for these recordings using the matlab "periodogram" function like so: ...
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2answers
3k views

How to identify and differentiate frequency and time in EEG data using python?

I have an EEG data of 200 Hz and sampled at 4097. I have few doubts and questions related to this data: What does it mean by sampling in EEG data? I am getting the sample rate and the frequency when ...
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1answer
311 views

AR model order selection for half second EEG fragments

I am using MATLAB to evaluate power spectral density estimates of half second EEG signals, using modified covariance method. Can anyone suggest me how to select the AR model order for this process? Is ...
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1answer
1k views

Python MNE - reading EEG data from array

I have EEG data that comes in the form of a 3D numpy array (epoch * channel * timepoint). timepoint is a 256 element array containing each sampled timepoint (1s total, at 256Hz). epoch is an ...
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3answers
2k views

Phase locking value / phase synchronization

I have pairs of EEG signals filtered to give me just alpha bands. For a machine learning problem I have found that calculating the phase locking value between the alpha signals of these 2 channels ...
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2answers
271 views

EEG Power at specific time points

I'm in the process of building features for an EEG machine learning problem and have been doing some reading about what features may be useful. Turns out, that alpha band (8-12Hz) power can make a ...
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2answers
603 views

Signal power without FFT

I have an EEG signal thats about 1second long, sampling frequency of 256Hz, measured in microvolts, and I want to calculate the power of a specific frequency band (8-12Hz) I believe the correct way ...
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1answer
8k views

Python - time frequency spectrogram

I have some 64 channel EEG data sampled at 256Hz and I'm trying to conduct a time frequency analysis for each channel and plot a spectrogram. The data is stored in a numpy 3d array, where one of the ...
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1answer
710 views

Python bandpass filter - singular matrix error

I've been trying to design a bandpass filter using scipy but I keep getting a LinAlg Singular Matrix error. I read that a singular matrix is one that is not invertable, but I'm not sure how that error ...