/sci/ - Science & Math

>>3956771
can you read my mind with that?

how do you get information from the inner brain cells?

Can evoked potentials be explained in terms of event-related phase resetting of ongoing oscillatory dynamics?

>2011
>using only 32 electrodes

>>3956771
At first I was like " I don't see any capacitors", then I was like "oh, he meant hats".

Can you give me your opinion on those EEG toys you see in some science museums. They display a screen of data indicating your emotions and how hard you're concentrating, but with only a few electrodes and no conductive gel I don't see how they can get that level of information. I think they're just putting on a show.

>>3956777
first question: depends what you mean by "read". i can see your brain waves. i can see how they respond to stimulus i provide. i can't see if you cheated on your girlfriend.

2nd: it's EEG. we're not directly recording from your thalamus. information on inner brain activity is based on inference.

>>3956791
evoked potentials are potentials (e.g. brain waves) that are caused by stim. event-related phasing is stim being related to a time duration of some sort. phasing is a vague term, but usually describes the wave itself and is usually contrasting two types of brain waves (e.g. gamma and delta being in phase-synchrony with each other). oscillatory dynamics is just EEG wave forms.

if the question is "can you see stimulus affect the waveform of two wave bands using EP techniques?" the answer is yes. i do that right now.

>>3956801
>seeing papers try to correlate findings with 256 electrode caps
>laughing as null results

i'd say the majority of presentations i see at conferences map topography of the central electrodes anyway (F3, Fz, F4, C3, Cz, C4, P3, Pz, P4).

regardless of types of caps, i'm actually working with wireless EEG right now... far fewer nodes (12 sites only).

>>3956833
>evoked potentials are (...)
Not exactly. Event related potentials are averages over large trial amounts to filter out the wave-like nature of the continuous signal, so that voltage deflections stand out. Supposedly they reflect changes in mass neural activity. There has however been discussion about whether ERPs actually reflect resetting of oscillatory activity. Suppose there is high power in the theta band, and a visual stimulus causes the phase of the wave to reset to, for example, 0. If you average over large amounts of trials, this will be reflected in the ERP, as the waveform is time-locked to the stimulus.

I asked the question just to probe your knowledge. Seems like you have a bit to learn still. Good luck though.

>>3956817
they are. gel or saline (depending on what kind of application method you use) helps to eliminate any issues with controllable connection problems (e.g. hair and sloughing skin) but that doesn't mean you don't have eletrical impulses coming off of your scalp at any given time. they are just harder to see what's going on due to low impedence. you can still see high frequency things like eye blinking or jaw clinching even with the slightest amount of conducting solution... it's just not really that exciting to see unless you've never done EEG before.

or, what would make more sense... if the cap at those museums was actually an MEG. then, there would be no need for conducting gel since it's all done with magnets. i don't know, i personally have never seen that sort of set up. i usually go to the natural science ones to see penguins and giant octopi.

>>3956867
> if the cap at those museums was actually an MEG
Lol, MEG requires an array of superconducting quantum-interference devices. An MEG scanner is not a cap, it's more like an MRI scanner.

bump

>>3956864
yeah, i haven't gone through a time-locking lab yet. however, evoked potentials doesn't necessarily imply an ERP study. phase-locking studies have been done using EPs (like the study i've been working on). The main difference between ERP studies and EP studies being ERP studies usually imply an active task and is usually measured (as you said) over a lot of trials. EP studies (aka evoked potential studies) aren't as deadlocked as ERP studies but aren't necessarily trigger based. like meditation studies or effects of music studies are usually EP studies.

definitely had a lot more to learn though.

>>3956931
http://www.sciencedirect.com/science/article/pii/S0149763407000334

>>3956880
actually, more like a salon thing that goes over your head. it's also loud as fuck. but it's more of a cap than fMRI since you are sitting and it goes over your head, versus laying down and being trapped in what sounds like a jet engine.

but an MEG would make more sense than an EEG cap since having hundreds of people wear the same cap is pretty unsanitary. i don't think a museum would be really into spreading lice. MEG (especially now) is a lot more compact and doesn't have to rely on conducting gels of any sort.

almost got me though. maybe if this were the 90s then you'd be right in saying they are closer to fMRI in size than EEG. but it's the future, bro.

>>3956960
>almost got me though. maybe if this were the 90s then you'd be right in saying they are closer to fMRI in size than EEG. but it's the future, bro.
...
First, MEG is silent. The noise of an MRI scanner comes from the gradient coils. There are no gradient coils in an MEG scanner. Second, you don't necessarily sit. Some MEG require you to lie down. Third, they're fucking expensive, because of the SQUIDS, and because of the magnetically shielded room they require. There's no way a museum would have one just for shits and giggles.

Seriously. Read the wiki page or something.

>>3956943
thanks for the article. i'm a klimesch fan. a good amount of klimesch is used in this lab to deal with experience related effects with alpha and theta.