Talk:Electroencephalography

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Contents 1 Merge Electroencephalography and Electroencephalogram? 2 Voltages 3 Voltages again 4 Is it really useful for Astral Projection? 5 References 6 research on EEG training 7 Note 12 8 Check your notes! 9 Image 10 Monroe Institute Critique 11 Bias regarding neurofeedback 12 POV and Clean-Up 13 Ideas for future work 14 Other Brainwaves? 15 Brain wave and sex 16 Requested move 16.1 Discussion and voting 16.1.1 Voting 16.1.2 Discussion 17 Silver electrodes 18 Gamma and Schizophrenics 19 Four types of waves? 20 Construction of electroencephelograph 21 Corticography 22 First human EEG record published in America. 23 Electrode placement diagram 24 forensic method? 25 Merge Kappa rhythm into Electroencephalography 26 Removed opinion on electrode placement 27 Removed EEG-marketing-spam 28 qEEG? 29 Did You Know 30 Event Related Potentials 31 Sound Cancellation 32 the amount of brain wave (Hertz) the brain generates 33 Dense Array EEG (daEEG) 34 EEG/Brainwave Of Ego Death 35 underlying theory of EEG missing? 36 Confusing section

[edit] Merge Electroencephalography and Electroencephalogram?

should this be merged with electroencephalogram? - Omegatron 13:30, Sep 15, 2004 (UTC)

Done 14:46, Sep 15, 2004 (UTC)

Yes. There's no difference. electroencephalography is the technique of making EEG recordings; an electroencephalogram is one such recording. I don't have a handle yet. jerry@neuromon.com 10/26/04 10:17 PDT

Yeah, but like photography and photograph deserve separate articles. I think the merge is good, though. - Omegatron 19:15, Dec 17, 2004 (UTC)

[edit] Voltages

I know that the electrodes are measuring voltages at the scalp, but what is the reference? Is the voltage measured between pairs of electrodes? What is the electrical model of the scalp as related to the brain? - Omegatron 19:15, Dec 17, 2004 (UTC)

I found an answer here: http://www.ebme.co.uk/arts/eegintro/eeg2.htm - Omegatron

Differential amplification is more complex than the explanation offered above. Take for example an EEG channel called C3-A1 (C3 as active, A1 as reference).

To produce a single EEG signal (the wavy line or "trace" showing values over time), requires not one but three differential amplifiers. In the example of C3-A1, the first amplifier receives values from C3 and Ground, amplifying the difference. The second receives A1 and ground, amplifying that defference. Finally the third receives the output of amp 1 and amp 2, amplifying that difference and producing the EEG trace. Thus there are no less than three wires attached to the head to define one EEG channel of data: the active, the reference and the ground sites must be measured.

There is an international convention called the "10-20 System" that specifies the locations of active and reference sites in a fully replicable manner. It also is conventional to regard the specific location of ground as immaterial so long as it is on the skin. (I expect that this convention will prove to be wrong.)

The three differential amplifiers produce common-mode rejection, the very important effect of removing most artifact, or non-brain sources of voltage variation. We live in a sea of electromagnetic flux from outside the body, and parts of the body outside the brain produce voltages as well. For example muscle contractions, heart activity, eye-movements, and swallowing are common sources of artifact voltage changes in EEG. Simply, common-mode rejection occurs when an electromagnetic fluctuation is detected by both first-stage amps simultaneously, and the fluctuation is removed when only the difference between those values is passed on by the second stage amp.Psydoc 07:25, Apr 8, 2005 (UTC)

So one amplifier produces C3-ground, and the second produces A1-ground, and the third produces (C3-ground)-(A1-ground) = C3-A1. So it's still a differential amplifier amplifying the difference between C3 and A1 (regardless of how many op-amps and transistors are actually involved). It sounds like there's some practical common-mode rejection aspect to measuring relative to ground? I'm not really sure how this would work, though.

I am not an expert (and you seem like you are), but every "Common reference derivation" schematic I have seen uses:

• 1 reference/common electrode - all signals are measured relative to this
• 1 DRL (driven right leg) amplifier - an active output that is connected to the patient
• As many signal electrodes as desired

http://www.biosemi.com/faq/limit_current.htm

http://www.biosemi.com/pics/zero_ref1_big.gif

http://www.biomedical-engineering-online.com/content/figures/1475-925X-3-25-6.jpg

This schematic http://circuitos.tripod.cl/schem/r24.gif shows the DRL driving the average of the ("signal" and "reference") electrodes back into the person.

So by "ground" do you mean the active DRL output? - Omegatron 16:25, Apr 8, 2005 (UTC)

I really appreciate this interchange. Your expertise apparently is electronics. My experience includes comprehending the EEG, but I particularly focus on clinical applications of operant conditioning of EEG - commonly called "Neurofeedback" - based on quantitative analysis of EEG and database comparisons. So I'm a clinician, but I have been interested in the electronics too, the better to comprehend the EEG.

I agree with your first paragraph summarizing the differential amplifier. To better answer your puzzlement about the benifits of common mode rejection I have referred to "Spehlmann's EEG Primer 2nd Ed.", B.E.Fisch, 1991. (Ouch that is old!) That common textbook describes the following rationale. Potentials from brain tissue distributed across the brain seldom are precisely the same in amplitude and timing. In contrast, potential changes arising from the environment strike the electrods essentially simultaneously and are cancelled by the amplification scheme. That effect requires low impedances and relatively equal impedances for each electrode. Technicians are tought to assure that condition, and the very high front-end impedances of modern EEGs (10 plus gigohm) make the problem less critical.

When it comes to reading electronic diagrams I am a novice, but those you provide do not look familiar or similar to the simplified versions in my texts. I have not seen one that shows an output driven into the person, other than those you provided (was it really an EEG?) I do see your reasoning, and as far as it goes I see why you think the "ground" is a DRL. The biomed engineer who tought me EEG emphacised that no signal is driven into the person, so I wonder. The "ground" is clearly described by Fisch as destinct from the amplifier ground, and as the basis for inverting the phase of the signal from the second electode in the pair. I think I will pose the question to a manufactuter (I do know several) and get back to you on that.Psydoc 05:14, Apr 12, 2005 (UTC)

Excellent. Well I'm just starting to learn about it, helping out with the OpenEEG project. I haven't really gotten into the actual EEG part of the circuitry; focusing on the signal parts of the circuit first. Their circuits are based around this paper, which uses a design with DRL amplifiers. - Omegatron 13:19, Apr 12, 2005 (UTC)

The electrical model of the scalp as related to the brain has been worked out in very extensive medical research. To simplify, voltages at the scalp are most influenced by voltage changes in large groups of pirimidal neurons at the brain surface directly beneath the electrode. Voltages are attenuated about 100-fold by the skull and other interveining tissue. In addition to that local signal source, there is "volume conduction" to the electrode from across the brain. Three-dimensional mathmatic procedures exist that identify major signal sources deeper within the brain.Psydoc 07:25, Apr 8, 2005 (UTC)

Is there a circuit model (with capacitance/resistance, etc.)? - Omegatron 16:25, Apr 8, 2005 (UTC)

Not that I have seen. The research I have seen has focussed on the level of individual neurons, postsynaptic potentials, and summated fields. I do expect that others have modeled it in detail, given the sophistication of the industry worldwide. Remember that very high-density-array brain-surface EEG is used to guide brain tissue ablation to treat severe intractable epelepsy. They model the seizure focus in 3D using EEG, then incert micro devices with precision. When I did a brief search I found only a discussion of the need for the EEG in that process, but it is informative.

• http://www.psychiatry24x7.com/medline/details.jhtml?id=12627809&product=none

Psydoc 05:14, Apr 12, 2005 (UTC)

Aha! "Active DC suppression is superior because it biases the output stage towards zero, allowing for higher gains." It's used to prevent premature clipping in the amplifiers?

"First, Huhta and Webster assumed that the subject was connected to earth ground. This simplification reduces the number of variables in the calculations, but it is no longer appropriate. Grounding the subject is unsafe because it increases the risk of electric shock. Modern safety regulations require that the subject must be isolated from ground so that contact with an electric source would not result in the subject creating a path to ground. Furthermore, grounding also allows more 60 Hz noise to enter the measurements. Modern amplifiers use an “isolated common” electrode which is electrically isolated from the ground of the power supply. In this configuration, the potential of both measurement and reference leads are measured relative to this common electrode and only their difference is amplified. Since the subject is only capacitively coupled to ground, the 60 Hz noise due to electric fields is greatly reduced."[1] - Omegatron 14:31, Apr 15, 2005 (UTC)

Regarding the scalp-brain connection, here is the very wonderful way that Bruce Fisch puts it in his "EEG Primer," which I recommend to anyone interested in EEG: He points out that there are two questions that people interested in the scalp voltages may ask. The first question is, if the electric fields of the brain are in a certain state, what will the fields be at the scalp? He calls this the forward problem, and he points out that there is only one answer to this question for any state of the brain. The other question is what EEGers would like to know the answer to: if the electric fields at the scalp are thus-and-so, what is the underlying state of the electric fields in the brain? This is the reverse problem and there are an infinite number of possible answers to it. The computer programs that Psydoc refers to use mathematical modeling to propose plausible answers to the reverse problem; they benefit from their programmers' physiologic understanding of the cortical generators, as well as the knowledge of the general average size and permissivity/permittivity of the skull, scalp, and so on. (For instance, IPSPs hyperpolarize in the millivolt range; there are no volt, or megavolt generators in the brain and so the computer can quickly rule out solutions that would require them.) - Ikkyu2 09:39, 28 August 2005 (UTC)

[edit] Voltages again

The EEG is a collection of biopotential measurements. The EEG measures potential (voltages, SI unit Volt) between two sites on the scalp. Since the signal is very small compared to other massive sources of noise, one uses a differential amplifier system. There is one reference electrode (often erroneously called ground) (Ref), and two active electrodes (e.g. A1, A2). The biopotential amplifier measures the difference between A1 and Ref, and between A2 and Ref. The biopotential amplifier has a high common mode rejection ratio, which means that signals (e.g. noise) that are common to A1-Ref and A2-Ref are cancelled. You need three electrodes and one amplifier to get one useful raw EEG signal.

The raw EEG thus consist of a collection of potential measurements (voltages) of Fp1,Fp2,T3,T4 etc., all versus the reference. This is different from the montages.

What is usually analyzed in clinical EEG is at one further level of abstraction. Conventional EEG looks at bipolar montages, where Fp1 is compared to another electrode such as F3 - the Fp1-F3 lead, or an average reference where Fp1 is compared to the average all the other electrodes. One can also link to a "neutral site", which is just a bipolar montage but with a fixed comparison electrode such as A1, A2 or an average of A1+A2. Thus, you need four electrodes and two amplifiers (each of which takes input from three electrodes), to get a conventional EEG signal.

Hope this clears things up. Janbrogger 08:35, 22 March 2007 (UTC)

[edit] Is it really useful for Astral Projection?

The article states, "Altering the brain's electrical activity can be useful for ... astral projection ..." Is that an NPOV statement? Or is it instead someone's belief that it can be useful for astral projection? If so, shouldn't Wikipedia instead report that someone (preferably identified) believes it to be the case?

Given that the Astral projection article states, "Neither this technique, nor OBEs in general, are accepted by the overwhelming majority of scientists," I would think that something needs to be modified about this statement in the Electroencephalography article. 170.35.224.63 15:36, 17 Jan 2005 (UTC)

changed to astral projection experiments.  :-) - Omegatron 21:13, Jan 17, 2005 (UTC)

I have noticed there are claims made about such things. Part of the interest in brainwaves is the speculation about what is possible. It may be absolute nonsense according to my reasoning, but it still makes interesting and encyclopedic reading. It would be right to document what people claim, and what has been found by various forms of investigation. I'll have a good scout around for more of the same. There's so much stuff out there, but I'll try to keep it balanced and concise. Regs D.Right 11:25, 30 Mar 2005 (UTC)

Of the several hundred practitioners of neurofeedback I have met, I think probably there are only a few who comfortably makes such statements, the author of the article prominent among them. For more common uses, see the professional sites devoted to this field.Psydoc 05:21, Apr 12, 2005 (UTC)

[edit] References

"Computer programs such as Noromaa Solutions Oy's Brainwave Generator (http://www.bwgen.com) are able to stimulate the brain and alter the brain's frequency via an audio stimulus."

Have there been any article's in peer-reviewed journals that support this statement? If so we should probably note them. If not we probably shouldn't make it sound like it is necessarily a fact. — Asbestos | Talk 14:56, 24 Feb 2005 (UTC)

Hmmm, doing some search myself, I guess there is some peer-reviewed research out there. An article in Psychology and Behavior is the only peer-reviewed source I could find. Outside of that there are various other articles, [2] [3], but they are connected to the Monroe Institute which I'm not certain would be a neutral source. Anyway, I'm putting up the first link.

My only remaining question is putting up the name and link for Noromaa Solutions Oy's Brainwave Generator. Looks like advertising. Should we just say that binaural sound generators exist, and maybe link in External Links? — Asbestos | Talk 17:37, 24 Feb 2005 (UTC)

I read the psych and behaviour paper in full. I'm afraid it really only says that the experiment effected mood, and they cannot conclude that it balances the brain in any way. Similar effects can be achieved with cheaper alternatives. Research on brain training really is mostly manufacturer's hyperbole. JuneD 22:48, 23 Mar 2005 (UTC)

[edit] research on EEG training

There is a growing collection of peer reviewed articles on EEG operant conditioning, AKA neurofeedback, if one knows where to look. The overall implication is of robust efficacy. Try these for a start: they are profesional organization sites. www.isnr.org www.aapb.org www.ecnsweb.com

68.102.135.215 19:46, 27 Mar 2005 (UTC)tvm drmatthews@optimumperformance.info

The research is there alright. But I can't seem to find any findings that neurofeedback leads to any lasting beneficial changes. The research seems to me to be focussed on measuring what happens in the brains of various people with injuries vs normal etc. I cannot find anything that concludes brain entrainment will improve performance. Perhaps we could have some more specific references? Cheers EBlack 09:28, 29 Mar 2005 (UTC)

The "Training the brain to a desired state" section has become a mismash of claims and counterclaims. I've tried to reorganize this section to give a clearer veiw of the debate. This is a rather difficult area to wade into, since there is some degree of pseudoscience along with some legitimate research. The best bet is to stick with PubMed-referenced articles, but there isn't yet a clear picture on what works and what is baseless, as far as I can tell. Sayeth 21:34, Mar 28, 2005 (UTC)

It does look better. I will continue looking for references to clarify any myths. Regs EBlack 09:28, 29 Mar 2005 (UTC)

Sorry I conributed to the "mismash of claims and counterclaims" in my first forey into Wikiland. Psydoc 07:28, Apr 8, 2005 (UTC)

I am concerned that the caracterization of the neurofeedback research as "this research is still at the earliest pilot stage" is technically incorrect. A pilot study is a well-defined and very limited form of research. Few if any of the studies referenced at the ISNR site are pilot study designs. There are well-honored scientific methods and criteria for peer-review and adequacy of research design, including statistical tesing of hypotheses. Those criteria are being followed by the scientists in the societies to which the readers were directed. I will try later to provide you with speciffic citations on longer term efficacy for neurofeedback. But please be thoughtful in this matter.Psydoc 07:28, Apr 8, 2005 (UTC)

The term "brain entrainment" does not actualy apply to neurofeedback, but is speciffic to the "following' response found when a person is stimulated with light, sound or tactile activity at a given frequency. I find the section is a mishmash of neurofeedback and light-sound stimulation. Would it be better to discuss the efficacy of each at its own section? There is markedly more research on neurofeedback than on stimulation/ entrainment. Also whereas stimulation devices are sold to the public, neurofeedback devices are FDA controlled devices used by licensed professionals. The area for EEG would in my opinion be better if it included the medical uses more prominently too.Psydoc 07:26, Apr 8, 2005 (UTC)

Some studies: After looking back at the ISNR bibliography, there are a number of case studies included. I will begin here to point to a few of the more solid studies.

Lubar et al, 1995. www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7786929&dopt=Abstract

Monastra et al, 2002. www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12557451&dopt=Abstract

Vernon et al, 2003. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12543448&dopt=Abstract

Psydoc 06:34, Apr 12, 2005 (UTC)

I did an overall edit on the "training the brain" section. Hope it seems ballanced.Psydoc 06:59, Apr 12, 2005 (UTC)

I adjusted the Dr Berkley critique. Of course he is wedded to something that works. I'm sure brain training companies don't like him saying that brain training doesn't work for attention deficit disorder. I wonder about some of those links to "professional" brain training cert people. Its starting to look a bit like wikispam. EBlack 04:36, 27 Apr 2005 (UTC)

I think thats right. The whole section on "training the brain" could be relabeled "Mind Machines and Snake Oil". The "institutes" that are involved in electroencephalography are generally only measuring the brain, not actually trying to alter it. The results that show inconclusive or negative effects of brain training, vastly outweigh the studies showing positive results. BTW, the positive ones are generally assessed to be sloppy. As far as I can see, some party with a vested interest is on the soapbox. D.Right 07:03, 29 Apr 2005 (UTC)

I tidied it up a bit, removing the redundant para on "following", and put some of the minor references as links in the link section. I have a database of references which counters the research entailed in those small references and minor brain machine conventions. However, if I place them in the same paragraphs as the moved links, the page will become ridiculously large. So I suggest we stick with conclusive reviews or meta-analyses in the main body, rather than argumentative or speculative little conference papers. As much of brain training it related to quackery, I think the section should include more claims of brain training companies (balancing left and right, development of psychic abilities, photographic memory, and hypnosis machines etc) I am putting a brief para together, if anyone else has some interesting additions, that'd be great. Regards D.Right 05:07, 4 May 2005 (UTC)

[edit] Note 12

This note does not have source. There is no link: ref|12 "See for example this commercial site reporting university research"

[edit] Check your notes!

Folks, check you own notes (11-15) please!--Shooravi 17:40, 5 May 2005 (UTC)

[edit] Image

User:A.Warner's only contributions were uploading and posting Image:Neurofeedback_and_Remote_Seduction.JPG to this article. The image didn't make much sense, so I removed it until a better image can be found. Sayeth 21:28, May 4, 2005 (UTC)

Well, I was working on it! The image makes a great deal of sense when you read the additional references about brain training claims, remote seduction, hypnosis, esteem etc. If you can find a better image that has copyright permission, then feel free to replace it. Regards A.Warner 04:18, 5 May 2005 (UTC)

[edit] Monroe Institute Critique

Perhaps it doesn't belong in this article, but an article on the Monroe Institute would be appropriate, I think. I've used their products and personally think they work, but I've not found any studies other than TMI's own in which to form an objective opinion.

[edit] Bias regarding neurofeedback

It appears a proponent of neurofeedback, someone who sells this stuff, has come on here and is now trying to insert POV information. There are others who also appear interested in inserted the exact opposite POV. Please try to remove the bias and rewrite the neurofeedback section in a clean and NPOV manner. This includes avoiding putting in links to commercial vendors, this is not supposed to be an advertisement. Please also see neurofeedback as it is suffering from POV problems as well.

And regarding the section title "training the brain": this seems like a very odd, POV and unprofessional choice for a section. It should be changed to something more acceptable for an encyclopedia.

-Nathan J. Yoder 17:01, 11 May 2005 (UTC)

I think there are several different people doing both, actually. It will settle out eventually. Maybe we should break it up into "for" and "against" sections thuogh. Really that stuff should be in neurofeedback, though. - Omegatron 19:48, May 11, 2005 (UTC)

And, um... WTF is this: Image:Neurofeedback and Remote Seduction.JPG? "How to zap the walking peanuts with only your mind"? - Omegatron 12:47, May 12, 2005 (UTC)

Agreed. The picture is silly and badly drawn. I removed it once (see talk section "Image" above), but someone apparently replaced it. Sayeth 14:10, May 12, 2005 (UTC)

I've removed it and am listing it on WP:IFD. — Asbestos | Talk 14:19, 12 May 2005 (UTC)

Well, if you really think so! I thought it was kind of colourful. I think the peanuts were there to illustrate a pun that the article it was taken from included (nuts and brains etc). And there was a passage about increasing penis size (hence the banana), that I could clarify in the wikipage. I still think it does a good job of representing brain training/neurofeedback's state in the world. But I will leave it up to another neutral and aesthetically aware individual to post it back up in the future:) A.Warner 19:46, 13 May 2005 (UTC)

Well this isn't the article it was drawn for, so it really makes no sense here.

Also, I assume you have the right to reproduce it under the GFDL license? - Omegatron 21:49, May 13, 2005 (UTC)

As I mentioned: http://en.wikipedia.org/wiki/Image:Neurofeedback_and_Remote_Seduction.JPG

Would you prefer some kind of monochrome? A.Warner 17:16, 14 May 2005 (UTC)

[edit] POV and Clean-Up

This seems easy to resolve: The main field of Electroencephalography is medical diagnosis. So this article should primary talk about this, pointing to neurofeedback and brain computer interface for other, and maybe emerging, fields. --Pjacobi 23:48, 2005 May 14 (UTC)

Done. --Pjacobi 00:21, 2005 May 15 (UTC)

Good. - Omegatron 00:52, May 15, 2005 (UTC)

Nice work,Pjacobi. Sayeth 03:00, May 16, 2005 (UTC)

[edit] Ideas for future work

• The roles of the IPSP and EPSP as the primary generators of the recorded potentials should be described, in addition to the currently-present statement that the action potential is not a generator of same.

• The History section is very wonderful, and would be more so with a brief discussion of, or at least a pointer to, the contributions of Herbert Jasper and Wilder Penfield.

-Ikkyu2 23:14, 27 August 2005 (UTC)

[edit] Other Brainwaves?

 I'm going to add in a bit about Epsilon brainwaves and site a link.

[edit] Brain wave and sex

What brain wave would be most likely to be active during sex? Beta is what I think.

[edit] Silver electrodes

Why are skin-surface electrodes made of silver (silver chloride) or gold? Do these make a better connection? Do they prevent galvanic DC voltages when the metals mix with skin fluids? It seems like every professional electrode for EEG and EKG is silver/silver chloride, but I can't find an explanation why. — Omegatron 18:24, 15 March 2006 (UTC)

Au and AgCl don't interact with scalp electrolytes. This avoids creating a salt bridge between electrodes that would totally screw up the voltage recordings, so yeah, you're pretty much dead on with your guess. Sn and Pt can also be used, but are pretty rare in EEG from what I've seen. Semiconscious • talk 21:02, 30 March 2006 (UTC)

Don't interact with the scalp electrodes? I'm talking about scalp electrodes made from these metals. — Omegatron 05:42, 31 March 2006 (UTC)

Huh? You misread what I wrote. It says "electrolytes". Gold and silver elctrodes don't interact with scalp electrolytes. Semiconscious • talk 06:30, 31 March 2006 (UTC)

In audio/video, connectors are silver or gold plated because this reduces corrosion and noise.Elamita 01:03, 12 January 2007 (UTC)

[edit] Gamma and Schizophrenics

here's an Interesting question. I recall one of my psychology teachers in college referring to the gamma state often being seen in schizophrenics. If anyone knows anything about this I would suggest they add it under the gamma section. —The preceding unsigned comment was added by Malicide (talk • contribs) 08:14, 10 August 2006 (UTC)

[edit] Four types of waves?

The article states that historically, there are four types of brain wave patterns, and then proceeds to list 6 patterns. Minor issue, but maybe it should be changed? Good article overall though.

Delta, theta, alpha, and beta are the traditional Berger bands. Mu rhythm is an alpha rhythm; it is generally considered to be a "normal variant." Gamma is a frequency-defined rhythm like D/T/A/B, but it is not generally seen on the scalp EEG (because of the properties of the skull/scalp). Most gamma research is done with intracranial electrodes. 76.100.89.50 11:17, 24 July 2007 (UTC)

[edit] Construction of electroencephelograph

What is the construction and working of electroencephelograph?

[edit] Corticography

The electrical activity recorded from inside the skull (intracranial electrophysiology) yields information that is radically different from EEG. This is because EEG provides a big picture of brain dynamics, while elecrodes on the cortex, for example, provide detailed local information. The latter technique should therefore be reffered to as corticography.

[edit] First human EEG record published in America.

This image may be useful in the article. Figure 2: First human EEG record published in America. Upper line shows alpha waves waxing and waning; bottom two lines show blocking of the alpha waves with visual stimulation (Jasper and Carmichael, 1935). Taken from the article Herbert Henri Jasper (1906-1999): An Appreciation

[edit] Electrode placement diagram

A most useful addition would be an electrode site diagram, something of the type found here: [4] It could be accompanied by a list describing electrode sites for typical montages, something one would think would be essential to the article. Can anyone provide? Robert K S 17:08, 16 August 2006 (UTC)

Done. 10-20_system_(EEG) What do you think about it ? XApple 23:09, 10 February 2007 (UTC)

Just what the doctor ordered. Robert K S 02:04, 11 February 2007 (UTC)

[edit] forensic method?

could it be considered a forensic method?

[edit] Merge Kappa rhythm into Electroencephalography

I'm not seeing how Kappa rhythm can become more than a stub; even the original author thinks it should be merged into this. If someone can expand it, please do, otherwise it probably shouldn't be more than a paragraph in electroencephalography. Kathy A. 18:24, 3 December 2006 (UTC)

Merged.--Poorman1 23:08, 6 December 2006 (UTC)

[edit] Removed opinion on electrode placement

An anonymous user (using a computer at the University Library in Groningen, the Netherlands) added the following under methods, regarding localization:

"... This involved a complicated systyem of adding electrodes in specific locations known as localization and polarity. This is of limited utility in todays atmosphere of MRI and CT scans and is rarely used in the field except in specialized research applications. It follows then if placement is accomplished without measuring and marking but with attention to equal spacing to avoid asymetries, this time consuming part of the testing proceedure may be safely omitted as it has no relevance. In fact in clinical practice in many hospitals measuring and marking is not done on portable patients such as in the various ICUs but may be done in the lab with primarily out patients. If in fact the use of the 10-20 system was of importance it would be mandated for all patients. The fact is the patients where measuring and marking is not used in ICUs are the sickest and would need the most accurate recordings possible. However the de facto reduction of the 10-20 system in such cases would seem to demphasise the importance of the proceedure and would beg the question why does such a out moded procedure still occupy such a position of emphasis. "

This seems to be a little opinionated, without any references. Accurate placement of electrodes is still very important for many focal non-tumor pathologies and especially for focal epileptic seizure activity. Many patients with epilepsy have refractory epilepsy (approx 1/3 depending on your cutoff), and current guidelines indicate that within a scope of a few years they should be considered for epilepsy surgery. Localizing the site of the lesion over the history of the patient then becomes quite important. It is perhaps outmoded as a general brain health test and for tumor localization, but not at all for epilepsy syndrome diagnosis and monitoring. Janbrogger 09:30, 19 December 2006 (UTC)

[edit] Removed EEG-marketing-spam

Removed commercial spam regarding EEG and marketing (user originating from U.S.-based DCI Marketing according to arin.net/whois). As far as I can see, some effort has been put into correlations between EEG and advertising in controlled experiments. But the reference given is commercial spam. Janbrogger 08:57, 22 December 2006 (UTC)

"+ In recent years there has been increased interest in electroencephalographic (EEG) measurement of brain activity as a way to measure advertising effects. [5] "

[edit] qEEG?

Quantitative Electroencephalography is apparently, from what I can tell, just normal EEG with use of computers over simple analog means (paper). I was thinking we might want to include it into this article since it just seems to just be a minor branch from normal EEG, and probably couldn't make a whole article on it's own. Does anyone know more about qEEG so as to either write a whole article or place it within this one coherently? Tonerman 20:27, 27 February 2007 (UTC)

qEEG is not only computerized/digital EEG. I'm going to add a section to it. "qEEG provide new ways to view to view data that are different from traditional visual analysis...Digital analysis techniques, however, are accompanied by considerable difficulty in routine use". Janbrogger

"Digital EEG" refers to EEG recorded on computer, rather than on paper. "Quantitative EEG" refers to signal processing that quantifies features of the EEG (rather than the typical way of reading an EEG, which is by ("qualitative") visual inspection of the waveform. It is the same idea as an EKG monitor that gives a numerical heart rate from the EKG tracing. I look forward to your review and would be happy to share ideas. I would caution that there is a major dichotomy in the EEG world when it comes to qEEG. I am new to Wikipedia, so I apologize if any of my comments are inappropriate to this forum, but let me share my experience so that the ultimate article is actually as factual as possible. There are some with a good grounding in basic neurophysiology, clinical neurophysiology, engineering and physics who work to quantify the EEG--which is read with much "art"--and relate the findings to broader research into brain function. This is very much a research situation. There are limited ways in which qEEG has been used in a a way that is generally agreed upon scientifically--like anesthesia measurements (though I don't know much about that topic), spike detection (always as a "pointer"--need to be reviewed by an EEGer, and some new developments in critical care neuromonitoring. The group from Australia (Johnstone, Barry, Clarke) has a number of publications on qEEG/ERP in ADHD, but it hasn't caught on as a clinical test for some reason (see their review in Clinical Neurophysiology, 2003). On the other hand, there are a number of companies who sell equipment for quantitative EEG equipment which uses proprietary databases to discriminate between "normal" and certain conditions (like mild traumatic brain injury, depression or learning disabilities). As far as the scientific process is concerned, it is problematic that the research is done commercially and not generally as peer-reviewed work. (Much of what is published is in journals specific to "Neurotherapy"--so there is a good chance that the reviewers are already convinced that there is something to the whole proces--and much less so in broader neurology/psychiatry/neuroscience publications.) Also, there are a lot of difficulties in doing research on conditions that are "mild" (not for the people suffering from them, but what I mean is that there are not as many objective signs as in other neurological conditions). I recently read a qEEG "clinical report," and the conclusions that were made were far from what can possibly concluded from the data at hand. I am also looking at the websites of these companies (and the clinics that employ them) for a talk I am writing, and my general impression is that they have lots of neuroscience language, but the content of their statements is not supported by current knowledge. Let me recommend also Nuwer's statement on behalf of the American Academy of Neurology and the American Clinical Neurophysiology Society. Shwmtpf 02:13, 24 July 2007 (UTC)

[edit] Did You Know

Not to take up too much space, but did you know that a plate of Jell-o registers similarly to an adult's brain on an eeg? User:Planes&Mustangs510

I find that very unlikely. It may be that there is a constant DC electrochemical potential in a plate of Jell-o but it is extremely unlikely that there are rhytmical generators of sufficient amplitude to remotely resemble a human EEG. Janbrogger 08:35, 22 March 2007 (UTC)

Maybe if the Jell-o it self is vibrating at an alpha rythm it could be possible. Anyways, what are your sources Planes ? XApple 22:11, 19 July 2007 (UTC)

[edit] Event Related Potentials

The ERP page should be merged into the EEG page. EEG is not just used as a clinical tool. The majority of EEG based Cognitive Neuroscience rsearch involves Evoked Potentials. Terry Toweling 14:00, 12 August 2007 (UTC)

I respectfully disagree about merging ERP and EEG. Although it is true that the majority of cognitive neurophysiology is done with event-related potentials rather than spontaneouns EEG, I think there is more than enough to be said about ERPs that would clutter the EEG page. The ERP page needs work (though I don't have the time at the moment to work on it)....perhaps once it is a little more fleshed-out, it would be apparent that there is enough to warrant 2 separate pages. Shwmtpf 18:31, 14 August 2007 (UTC)

You're probably right, but there is currently no mention on the EEG page of its cognitive research applications.Terry Toweling 21:24, 14 August 2007 (UTC)

Since cognitive EEG research is what I do for a living, I should probably add something... 12.110.104.135 21:59, 17 August 2007 (UTC)

[edit] Sound Cancellation

Question, is there a way to cancel sound waves out with brain wave transfers? Also - along with feeling, and the rest of the senses? I have a feeling sound waves can be cancelled out, but how about sight stored in the mind after seeing? Or other interactions like that? —The preceding unsigned comment was added by 65.31.122.176 (talk • contribs) 00:20, 15 August 2007 (UTC)

As far as I know, these are not possible. Do not make speculative edits to articles, the way you did to this article. The talk page is the place for speculation. Hu 06:55, 15 August 2007 (UTC)

[edit] the amount of brain wave (Hertz) the brain generates

Should there be a list of the amounts of hertz the brain generates as well as how much the brain can generate? - RVDDP2501 13:12, 23 August 2007 (UTC)

[edit] Dense Array EEG (daEEG)

Should Dense Array EEG be added to the EEG page or should it have it's own page?

Dense Array EEG is an improvement on standard approaches to EEG, as it uses a much larger number of “electrodes” (small saline soaked sponges that are able to record the electrical activity of the brain) so that there is better accuracy and localization of the source of any abnormal electrical activity.

Dense Array EEG applies a large number of electrodes (128 or 256) by using a “net” that can apply the electrodes in minutes. The application is painless, reduces patient anxiety about the test and, therefore, increases compliance. Additionally, the net application does not require the need for sedation, and since there is no abrasion of the scalp as is used with standard EEG, there is a reduced risk of infection.

Just as Magnetic Resonance Imagining (MRI) and Computed Tomography (CT) allow a structural image of the brain, Dense Array EEG is a way to electrically “image” the brain, as the electrical information that is gathered is run through a powerful computer that allows the location of the electrical activity to be determined with great accuracy. Recent software advances in this technology now provides for the electrical source to be mapped right on to a MRI.

Dense Array EEG has been used for many years for research applications investigating aspects of brain function and mind control, and has been featured on the cover of National Geographic and Newsweek. Dense Array EEG is a useful clinical tool for the detection of electrical abnormalities associated with seizure activity (i.e. Epilepsy,) but also for “subclinical” electrical activity that might be interfering with attention or learning, sleep disorders and more.

Goodspace 22:40, 2 October 2007 (UTC)

Could add something on high-density EEG to this page... Even though there is a qualitative improvement in validity of the topographical data provided by high-density EEG arrays, the fundamental issues associated with the inverse problem of localizing cerebral sources of scalp EEG data are still present.

High density systems are rarely used for long-term EEG monitoring; they are however sometimes used to "localize" seizure foci by determining where inter-ictal discharges are coming from (and inter-ictal discharges are less reliable than ictal onsets). Jean Gottman presented some work with inter-ictal localization using high density EEG at the American Epilepsy Society 1-2 years ago.

High density EEG is no more accepted by the neurological community as a clinical tool in ADHD/learning disabilities, sleep disorders, etc., than "standard" EEG is, though it is a helpful research tool.

Most high-density EEG systems use a cap with the same metalic electrodes and electrode paste as used with standard EEG. The system that uses saline-soaked sponges is produced by Electric Geodesics, Inc. It is a little different in that it uses a high-input-impedance amplifier.Shwmtpf 20:41, 17 October 2007 (UTC)

[edit] EEG/Brainwave Of Ego Death

Does anyone know the brainwave pattern of psychedelic (LSD, shrooms, mesc, DMT, ect.) ego death? Has there been a specific studies on the brainwave pattern of ego death? Ken Wilber did some experiments some time ago on different meditative states of mind and he managed to stop his brain waves completely and according to him this is a state of pure non-dual awareness with no feeling of the mind-body limitations on perception. This description seems similar to ego death so is ego death brought upon by having no brain waves? Zachorious 18:15, 29 October 2007 (UTC)

[edit] underlying theory of EEG missing?

Why is there no discussion regarding the underlying neuronal activity which generates the EEG wave? Is that on a different page? I would add some of it, but I figure that if this article has lasted so long without it being there, maybe there's a reason. -- eykanal talk 17:33, 2 December 2007 (UTC)

[edit] Confusing section

The section titled "Source of EEG Activity" makes use of a bucket load of jargon without explaining any of it. I learned absolutely nothing from that section, it should probably be re written so mere mortals can comprehend it. --69.86.151.144 (talk) 06:16, 20 January 2008 (UTC)