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electrode positioning strategies
chemaverdaguer
Posted on 07/17/07 21:03:06
Number of posts:

Posted: Wed Jun 02, 2004 11:17 pm    Post subject: electrode positioning strategies

Hello to everyone in the forum
My hospital has just bought your system, and i am in charge of setting it up. I am having troubles with the positioning of the electrodes. Could you please explain to me the correct position? Do I need some kind of conducting gel to lower the impedances?
regards

Replies:

from andrew
andydimitri
Posted on 07/17/07 21:04:34
Number of posts: 0
andydimitri replies:

Hi Chemaverdaguer,

Posted: Thu Jun 03, 2004 10:36 pm  Post subject: electrodes...

The electrode montage is the same as what you would use for an ABR.

We've typically used an electrode at CZ, reference at the nape of the neck (i.e. 1 cm below the hair line; midline), and ground electrode on the collar bone.

You can use forehead instead of CZ as well.

As for conducting gel - same as ABR. We've used Grass Electrode Cream EC2.

Make sure you scrub with the areas clean.... to get the impedances down.... same as ABR....

Hope this helps Very Happy
_________________
Andrew Dimitrijevic PhD
Postdoctoral fellow
University of California, Irvine
Department of Neurology
adimitri@uci.edu


Untitled Post
luissv
Posted on 07/17/07 21:07:26
Number of posts: 0
luissv replies:

Posted: Fri Sep 24, 2004 9:51 pm Post subject:

Hi, I use the Bio-Logic system. Is ok to use the Fz - ear lobe (R and L) electrode position?


from Sasha John

Posted on 07/17/07 21:09:22
Number of posts:
replies:

Posted: Sat Oct 16, 2004 11:37 pm��� Post subject: Electrode Strategy

Fz-Ear is okay, but will not give as large a response as Fz to just below the inion. In the 70 Hz range, the majority of the ASSR is coming from the brainstem, so the best way to record this dipole source is Cz-inion. Having the active and reference electrodes in those positions, when the signals are subtracted by the differential amplifier, will lead to the largest result. As we know, Fz-Ear is better for getting a good Wave I, in transient ABR since this is generated in primary auditory nerve, while Fz-Inion is better for getting Wave V...accordingly, since ASSR is derived more from the brainstem structures related to Wave V generation, the Fz-Ear will lead to some attenuation of response in case of the ASSR. That's the formal answer....in the clinic, however, it is likely fine to record using either scenario, but it is important to remember there may be slightly worse SNR.


electrodes with infants
skbrennan
Posted on 07/17/07 21:11:27
Number of posts: 4
skbrennan replies:

Posted: Thu Nov 24, 2005 11:43 am Post subject: electrodes with infants

A study by van der Reijden and colleagues published in Ear and Hearing this year ("EEG derivations providing ASSRs with High SNRs in Infants") suggests that the inion-Cz placements result in very low SNRs. Does anyone have any thoughts why this result may have occured in such contrast with other studies who have used the inion-Cz positions in infants successfully?


from Sasaha8

Posted on 07/17/07 21:13:10
Number of posts:
replies:

PostPosted: Wed Dec 21, 2005 12:29 am��� Post subject: Electrode locations �� �

The study didn't say Cz-inion was bad...just that it was not as good as lateralized electrode positions. In adults the dipole from brainstem is maximal at Cz, while in infants it seems to be lateralized...this can be a developmental change in the brainstem nuclei which are generating the response or possibly a different proportion of the generators are responding..but it is likely the prior explanation....in any case, the study offers some evidence that it might be useful to rely upon 2 electrodes when testing both ears and evaluating the response to each ear only in one electrode.


Untitled Post
Alejandro
Posted on 07/17/07 21:14:25
Number of posts: 0
Alejandro replies:

Posted: Sat Mar 25, 2006 2:34 pm Post subject:

Luissv, the Fz-earlobe is a good electrode position in case you are recording newborn, but not in children or adults



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