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4 votes

Why are biosignals from the body said to be continuous?

Biological signals are analogues and hence continuous. Early EEG systems simply recorded the analogue signals and displayed it as a continuous signal graphically as wiggly lines written by little pens ...
AliceD's user avatar
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4 votes

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

Short answer The peak polarity of an EEG is arbitrary. Background Positive and negative in an EEG measure is arbitrary. If you measure the EEG between two electrodes and you flip the wires, the ...
AliceD's user avatar
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3 votes
Accepted

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

Short practical answer for a signal to be properly sampled, it has to be done [at] the Nyquist sampling rate Up front: sampling at the Nyquist frequency is the bare minimum rate to reproduce the ...
AliceD's user avatar
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2 votes

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

Here is the 10 KHz signal (the maximum frequency of the signal is 10 KHz): Now, if we sample the signal at 5 KHz and 10 KHz, the signal will look like as shown below (the brown points): It is clear ...
Pankaj Singh's user avatar
2 votes

How is the biological error signal in predictive coding computed?

TL;DR: We don't know whether the brain really uses predictive coding or not. But neurally computing an error signal on a small scale is possible (see below). Predictive coding is an hypothesis for a ...
Dylan Richard Muir's user avatar
2 votes

How is the biological error signal in predictive coding computed?

I provided an answer to a similar question here that limitedly deals with the role of biological prediction errors. Here's an excerpt of that answer: ...to answer this properly, we must first make it ...
aiwyn's user avatar
  • 503
2 votes
Accepted

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

According to a review by Croft & Barry (2000), a number of possible methods exist to prevent, or reject ocular artifacts in the EEG; Prevention/reduction of artifact instances Recording with ...
AliceD's user avatar
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2 votes

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

How you analyse your data depends a bit on how you did your time-frequency decomposition. If you're using a fast Fourier transform, you will likely cut out the temporal window of interest prior to ...
Ana's user avatar
  • 2,553
2 votes

What does fMRI data look like after pre-processing?

The MRI signal is a small electrical current induced in the receiver coil by the precession of magnetization during resonance, i.e., a manifestation of Faraday's Law of Induction, wherein a changing ...
AliceD's user avatar
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2 votes

Features for blink detection in real-time single channel EEG

The EEG signature of eye blinks is typically visible for about 200ms of data. When you want to move a window of 50 to 200 samples, I assume that your sampling frequency is 1000Hz (you should specify ...
S.A.'s user avatar
  • 310
2 votes

EEG segmentation and denoising which one should done first?

Depending on whom you ask, you get both answers. That's mostly dependent on the denoising algorithm. If you're using an adaption of GST, you are segmenting first with an n-1 overlap. If you're using ...
Doc_Dormicum's user avatar
2 votes

Reference signal when measuring EEG

For the unipolar configuration, why can't we just use Earth ground as our reference instead of having a reference electrode or performing an average of measurements on all the electrodes? The ...
AliceD's user avatar
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2 votes
Accepted

Slow-wave EEG artifact removal

It all depends: '...do we need to remove artifacts from the whole EEG signal' - yes you have to in case you are using the entire EEG trace for spectral analysis and if there are artifacts in the ...
AliceD's user avatar
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1 vote

Frequency band comparison between two groups

I would be wary about treating your data differently. If you have 64 recording sites, you can possibly use all 64 channels to get to 32 "less noisy" channels and use that data optimally, but ...
Bryan Krause's user avatar
  • 7,586
1 vote

Why is Electric Artefact still present in my recording?

There are many many reasons why interference can occur so it's almost impossible to give a direct answer with the details provided. You should at least give details like a spectrogram and experimental ...
Eric Lee's user avatar
1 vote

How to handle single trial ERP (P300)

I remember trying using single-epoch measurements with electroretinogram (ERG) recordings. Basically, ERG responses are electrical potential recordings from the neural activity in the retina. ERGs are ...
AliceD's user avatar
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1 vote

Why are biosignals from the body said to be continuous?

To add to the answer provided by @AliceD, pure digital waveforms are square waveforms as they represent steps between 1s and 0s and are therefore not continuous. Analogue waveforms are not. They are ...
Chris Rogers's user avatar
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1 vote
Accepted

The number of things we can focus on at once

You already seem to be making the difference between a point of focus, versus "things in the back of ones mind". I think that's quite apt. Different authors have come up with different theories about ...
AliceD's user avatar
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1 vote
Accepted

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

Short answer As far as I can see - no you can't. Background In EEG systems, unipolar signals are measurements against a distant reference electrode, for example Fpz (Fig. 1). So suppose I have ...
AliceD's user avatar
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1 vote

How to map EEG time-series and visualize meditative states frequencies?

Thank you for your interesting question! Generally, there are three types of methods to process your EEG time-series data: Time domain methods (e.g., regression, statistical analysis on your EEG ...
Emma's user avatar
  • 115
1 vote

How to analyze auditory steady state responses?

ASSR analysis is based on the fact that the electrophysiological responses are time locked with the stimulus repetition rate. There is not one possible method of analysis. Generally spoken, ASSR ...
AliceD's user avatar
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