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Questions tagged [signal-processing]

For questions about signal processing theory and its applications in psychology and cognitive neuroscience.

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1answer
21 views

Reference signal when measuring EEG

When performing EEG, a number of electrodes are placed on the scalp to measure the electric potential difference between those locations and a reference. In the unipolar configuration, the reference ...
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19 views

Recovering P300 information from raw EEG data [duplicate]

I am trying to recover P300 information from raw EEG data. I have information from 23 electrodes in my EEG cap and have several files form which I will need to recover this information. However, I am ...
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1answer
46 views

The number of things we can focus on at once

In terms of computer science, a programming runtime like JavaScript can be assumed to have 1 thread, or one thing to focus on at a time. The processor moves sequentially through instructions, ...
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1answer
107 views

What does fMRI data look like after pre-processing?

I wish to know what fMRI data looks like after preprocessing. My Understanding My understanding is that fMRI is MRI in time dimension that is we have repeated scans of brain volume. A voxel is a ...
4
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1answer
52 views

Features for blink detection in real-time single channel EEG

I am looking to detect blink events in real-time single channel EEG. Classification of a moving window of samples to determine whether a blink artifact exists requires feature extraction (except when ...
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1answer
43 views

EEG segmentation and denoising which one should done first?

Because of EEG nature, in EEG analysis often researcher use Windowing/segmentation method. As i currently work on sleep study, and in my study i need to analysis EEG data, i came to a problem. ...
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1answer
61 views

How do I determine whether my EEG signal needs denoising?

I recently start to work 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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1answer
126 views

Can a bipolar EEG signal be converted to a monopolar (unipolar) one?

I have bipolar EEG signal of Fpz-Cz of EEG sleep data which I have downloaded from physionet. I would like to have Fpz signal for my sleep study. Is there any way I could convert a bipolar EEG signal ...
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2answers
930 views

What happens at sampling rates lower or higher that the Nyquist rate?

I do understand that for a signal to be properly sampled, it has to be done on the Nyquist sampling rate. What I do not understand is, what happens at sampling rates lower rate than the Nyquist rate, ...
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1answer
61 views

How do I measure ratio of EEG frequency band for a few electrodes in decibels?

I wanted to calculate the ratio of Theta/Beta ($\Theta$/$\beta$) in decibels for a couple of electrodes in AF3 AF4 and Cz I was able to get these in microvolts, but would like to convert them to ...
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206 views

EEGlab: power spectral density from a single eeg lead

I was trying to get FFT power of an interval in a record. The sleep recording software we use doesn't allow to export EDF format of an interval, only of the whole record, but it allows to extract an ...
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79 views

Noise free EEG signal data base

I am working on a research paper regarding EEG signal preprocessing. The first stage includes denoising the signal. However, since I need to evaluate the performance of the method I am using, I ...
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0answers
102 views

Window and noverlap values in pwelch function of Matlab

Could anyone please suggest what values to be used for Window and noverlap inputs of pwelch function in Matlab. I am using a 200 ms EEG signal with sampling frequency 1000 (so total samples 200) to ...
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2answers
156 views

How is the biological error signal in predictive coding computed?

I am quite inspired by the results obtained by PredNet, which implements a predictive coding model using artificial neural networks. They compute the prediction error as a simple subtraction, and then ...
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0answers
44 views

Oblique EPI in afni

It is my very first time with afni and I am having problems with the creation of the afni dataset from dicom images. I runned: ...
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1answer
37 views

What are the methods to reject ocular artifacts in the EEG?

Is there any way to remove ocular artifacts from an EEG signal, other than applying independent component analysis, or manual rejection?
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1answer
286 views

What is the meaning of the peak polarity in EEG data?

I wish to define neuronal activities by analyzing the peaks of each channel in EEG signals. Some papers use the negative peaks as a measure of neuronal activity and others deploy the positive peaks. ...
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0answers
31 views

Library (or manual creation) of ERP components

I'm looking to test some computational models using ERP components as inputs (eg. p300, n170) I'm wondering if there is an existing library anywhere that would have a bank of wave/component examples ...
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0answers
103 views

Is there a reasonably easy way to get emotions from EEG?

I am building a project to visualise brain data from EEG, specifically emotions. I have found a significant numbers of papers that describe methods that include pre-processing, feature extraction and ...
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2answers
113 views

Method/Unit for measuring activity in specific frequency band for EEG

This may be more of a signal processing question but I'm looking to measure and compare activity in different frequency bands for each sensor. Unfortunately, all papers I've looked at simply refer to "...
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1answer
56 views

High Density Signal Meaning

When I was reading an article, I found that it describes the EEG signal as a high-density signal. So what is that mean? EMG is high temporal resolution and moderate spatial resolution (...
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0answers
301 views

Python MNE - reading EEG data from array [closed]

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 ...
7
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1answer
313 views

What are proper EEG frequency bands and electrode placements for imagined speech?

I am doing an EEG experiment about imagined speech recognition. Which frequencies will have the most relevant information? I chose the frequency band [4-40] Hz as a start, mainly because of signal ...
6
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1answer
133 views

How to analyze auditory steady state responses?

How does one usually go about analyzing the auditory steady state response (ASSR)? I have data where speech was amplitude modulated to a 40 Hz sine tone. There's 3.5 minutes of data; should I just ...