Clear and concise information on Electrode Montage

In eeg and neurofeedback terms the + electrode is also called the
"active" electrode. This active electrode is connected to the place
you want to measure. The other - electrode serves as a reference
electrode. Most of the time this one is connected to a "neutral" place
like the mastoid bone behind the ear, or an earlobe.
If you choose to place the - electrode to a neutral place, then you've
got what is called a "mono polar" montage. The signal you'll obtain
will be absolute since the site on the scalp will be some micro volts
against the theoretical 0 micro volts from the neutral site.
If your place the - electrode also on the scalp, you've then got a
"bipolar" montage. You're values will then be "incremental" since
you're know including another site with electrical activity going on.
If you google on these montages you'll often notice they include a
"ground" electrode which is often attached to another neutral place,
like the other earlobe. With the modulareeg, we don't have such a
"ground" electrode. We do have the DRL which is an entirely different
thing, but can also be attached to an earlobe. I normally choose the
right wrist though. Or just hold it in your hand, between two fingers.
I have a small metal disc which I can hold or attach to a wristband.
So all in all for one channel a possible (monopolar) setup could be: +
electrode to the site O1 or O2, - electrode to neutral place like an
earlobe, DRL to the other earlobe or places mentioned above. In case
of two channel setup do the same with the other electrodes and then
just hold the DRL or something like that. There also an option to
share the same - electrode for both channels. Make a Y splitting cable
so one - electrode can go into your two - sockets on your modeeg
device.

Detailed Signal Format (from Dr T. Collins)

The 16 bit sample values are stored as unsigned integers with a range from 0 to 1023.

A zero volt signal is sampled as 512.

As 1023 is the maximum, the six most significant bits are never used and so are always zero.


High Byte Low Byte
000000XX XXXXXXXX
MSB

Where X= 1/0

The EEG digital board samples at a rate of 256 samples per second so a frame of samples is transmitted every 1/256 seconds.

As there are 17 bytes in each frame packet this means that 256x17 = 4352 bytes are transmitted every second.

size of metal box

http://www.maplin.co.uk/module.aspx?moduleno=43713

Metal box with size 120x95x30 from Maplin is suitable for analgoue board.

Tips for using budgets

Hi everyone,

Today Jack and I had a go of buying items using budgets in the serving window in the building of material and metallurgy. And the process is simple.

Just go there and tell the guy that you want to use final year project budgets to buy some items and then you'll get a white-paper form to fill in. You'll need to know your project number and there is a category there in which you can find out.

Today we've got a PP3 battery but we haven't searched the boxes yet because we're not sure about the exact size of box we need. So I'm not quite sure whether we can get the boxes there. But there's lots of items and hopefully we can find the boxes. Just go there and search the index. Looking forward to your good news!

Victor

ElectricGuru Screenshots

We had a go at using ElectricGuru on the lab PCs with a modular EEG board wired up with the calibration signal to channel 1 and channel 2 shorted to ground. The .exe file runs fine although for some reason the time-domain plot didn't work for us. To try it out, download from http://www.realization.org/page/topics/electric_guru.htm and set the Machine under the preferences menu to RS232EEG

OpenEEG Software

1.Electric Guru : It is a very simple but powerful application that is good for troubleshooting and checking that your electrodes are reading valid signals.
Electric Guru includes the signal plotted in the time domain along with frequency response and phase differences.

ABI BCI : Is a small windows application that implements a neural network for biofeedback training.It works by taking a raw EEG signal and filtering it down to frequencies that you specify.It then sends those specific filtered signals into two layer feed-forward neural network that learn how to differentiate between two or more different types of signals.

BioEra:
One of the best program that interact with openEEG. It allows the user to build designs out of a large list of components. BioEra also provides the user with enormous control of each component.

Expected Features of an Awake EEG

Dear All,

Please find a link describing the common features of a normal awake EEG

http://emedicine.medscape.com/article/1140143-overview

Also describes locations where the particular waveforms are best found which is useful since we are only using a few channels and need to concentrate them in the correct area.

Steve

OpenEEG screenshots

Hi all

We had a go at hooking up an OpenEEG board to some electrodes and got some measurements. The screengrabs are all of a 0.5 second time-frame:

1. Lots of activity on channel 2 - so much that it is clipping

2. Typical Output. Some mains hum visible (50Hz = 25 cycles in this 1/2 second time-frame)

3. This is without the right-leg driver ear-clip connected. Lots of mains hum!

4. Some very clear eeg activity on channel 2 (approx 9Hz)

Neural Wheelchair Control

http://www.youtube.com/watch?v=0at3NzNRySg

Cables and connectors

I am purchasing 3 off of the following to test out ..
1m audio cable with a jack on one end and bare on the other
Jack Socket

Farnell details:
Code Qty Description
1219360 3 LEAD, 3.5MM S JACK-BARE END,1M PRO SIGNAL-AUDL-73-1M £5.76
1267374 3 SOCKET, 3.5MM JACK, 3POLE MULTICOMP - MJ-074N £2.13

For enclosures there are amny to choose from - though some seem expensive for what they are:
Enclosures from RS
Enclosures from Farnell
Our boards are 100mmx800mm BUT we need to be sure they fit INSIDE the box and that there is room for any screws/connectors so 1 or 2 cm spare could be useful.
This board is 120x120mm
(I would prefer a painted version of the same dimensions. The flanges may be handy for fixing inside the surrounding box).

Electrode Placement

Enclosures for our boards

We will need to place our analgoue board in a metal box. This can then be placed with the digital board in a plastic box. (See Nelo's picture below. Note the analgue board is boxed at the bottom).

Boxing is mentioned in the modular OpenEEG FAQ
http://openeeg.sourceforge.net/doc/faq.html
"Q: Why is putting both boards in the same metal box a safety issue?
A: It is because you need to let the power and output signals pass through the box wall somewhere. There you have to ensure that the connectors are isolated from the box, or you will end up connecting isolated ground to PC ground, which is a bad thing. Even if the connector housings are made of plastic, you risk lowering the isolation voltage.

It is possible to use a metal box, if you create wide enough gaps between the connectors and the metal wall. Problem is, you still end up with an outer surface connected to isolated ground, so it is safer to avoid the subject entirely.

It is recommended that you put the amplifier board in a metal box, which is in turn placed in a plastic box along with the digital board. Look here for an example."

A multi-event brain-controlled game

http://www.webkitchen.com/brainathlon/

OpenEEG Calibration/Testing

This was what I was hoping to see.

The first attempt was corrupted due to a small error in the original version of my openEEG class library. After re-examining the firmware code, I've fixed the bug in version 1.0.0.1. This screenshot was taken using the new version of openEEG.dll and looks fine!

The new version is in the shared dropbox folder.

OpenEEG Calibration/Testing

This is a screenshot taken whilst using the calibration output of the analogue openEEG board connected to channel 1 and with channel 2 grounded. The calibration signal is a square-wave at around 14 Hz.

Note that the analogue boards have coupling capacitors forming high-pass filters cutting off at about 0.1 Hz. This means that it can take up to around 10 seconds for the output data to settle down and become meaningful after changing the input connections. So you need to be patient!

The grounded channel seems to float towards the negative saturation level and stay there with occasional "noise" spikes. I'm not sure yet why it does this but it seems consistent from board to board.

Journal Of Clinical neurophysiology

http://journals.lww.com/clinicalneurophys/pages/default.aspx

Short Presentation Subjects

These are some suggestions for very, very short informal talks at our meetings.
The presentations should be only 4-5 minutes and you can sit and chat and wave your arms or stand and use a couple of powerpoint slides. Whatever is best for you.

Please make a comment to indicate which title you have selected.

What is a neuron and how does it work?
What are the frequencies of the brain?
An overview of modular OpenEEG (something very high level)
Dealing with noise - I(calibrating the board and the recommended enclosure)
Dealing with noise - II (mains hum and sheilded cables)
The digital signal output from the modular board (p2 format and sample rate)
Passive vs. active electrodes
Where and how to fit electrodes?
Application software (thoughts on, for example, C#, VB, Matlab, OpenVibe)
Signal processing (filtering and Fourier)
Neurofeedback in games (what's new and/or how it is used)
Neurofeedback/EEG in control applications (any examples whether helicopters or wheelchairs or robots)
Commercial Neurofeedback systems (any examples of real systems, costs and applications)
Neurofeedback with 2 channels (examples of what is possible)
Neurofeedback in therapy

(or perhaps you would like to suggest a title)

BCI software developers Open Source

http://openvibe.inria.fr/?q=about

This is like a software version of The OpenEEG.

Advanced Visualization in Biofeedback

http://www.sciencegl.com/EEG_3D_spectrum/biofeedback_3D.htm

biomedical articles

http://www.ncbi.nlm.nih.gov/pubmed/

Biofeedback Journals

This is a link to an on-line Biofeedback Journal - . It looks very good. There is a 1997 special issue on neurofeedback. (Click on the text for the full articles).

There is also a Journal of Applied Psychophysiology - I'm not sure if this link will work. If not search our ejournal library with "Biofeedback".

Also - here's a link to an IEEXPLORE search on "biofeedback" and "EEG" sorted by date (newest first).
(Note - older references are fine for background but try to use more newer references to put your work in context.)

Selling Electrodes site in UK

http://unimed-electrodes.co.uk

EEG Lab In MATLAB

http://sccn.ucsd.edu/eeglab/

EEGLAB - Open Source Matlab Toolbox for Electrophysiological Research

Notes about the OpenEEG data format

It's actually not quite so easy to glean information on the data format at OpenEEG (unless I'm missing something). These notes and links may help.

The data (packet) format we get off our digital boards is called "p2" (packet format 2).
Details are under "Firmware 2" right at the bottom of the
main Modular OpenEEG page. This is the format of our data.

This link has it formatted better. Also see Tim's blog.

We are only using channels 1 and 2 (i.e., not 3-6). Note each channel is allocated 2 bytes; a high byte and a low byte. 10 bits of these 16 bits record the signal values (ie. we would expect the upper 6 bits to be zero).

Neurofeedback Links

EEG Frequncies:


An interesting website on Brain and Health
Wikipedia on "Neuromarketing" Brain and Health (!!)

Neurofeedback for ADHD:


Faces of Neurofeedback:


Neurofeedback controlled helicopter:

Welcome to Neurofeedback Projects

This blog was designed as a place to share information on our Electronic Engineering neurofeedback projects at Birmingham University, UK.

We are using OpenEEG equipment.
http://www.olimex.com/gadgets/openeeg.html