Polarity Rules

[@midnajo437]

This is the best explanation of the polarity rules. Thank you very much to upload.

[@Yeahwecanplaythat]

Great video. You missed the 7th difference...the small patch of grass present next to the rock.

[@jessicahergert8513]

can you do more examples of polarity?

[@dawnlightening]

@Jeremy Moeller This so-called Polarity Rule is merely a Tautology: for example at 4:20 in the video, you say that EITHER Fp2 is positive wrt F8 OR F8 is negative wrt Fp2. Both these two statements are equivalent. It is impossible for Fp2 to be positive wrt F8 AND F8 to be positive wrt Fp2. Also, even though the differential amplifier output depends on the difference in voltages at the two inputs, each of the input voltages is treated by the amplifier with respect to a common reference or ground potential. EEGers commonly connect the ground lead to some part of the head away from the brain, eg the mastoid process. The problem, is that such a "ground", itself has a potential difference with respect to 'Global Ground' (eg a metal pole buried into the earth, as used by electric utilities, radio transmitters etc). So, choosing another "ground" on the body will change the shape of the EEG, because the new "ground" will be at a different potential to the mastoid process. It would be best that whichever ground is chosen is also connected to Global Ground, then this 'Ground Placement Artifact' would disappear. EDIT: The best method would be to use miniature coaxial leads, with the electrode connected to the central conductor & the outer braid free. Then connect the braid & central conductor to the two Diff_amp inputs. That way you get the Absolute voltage at the electrode site, without any dependence on a secondary site AND ALSO you benefit from Common Mode Rejection.

[@magedabuldahab7481]

3:00 not counterintuitive at all, it's quite logical, downward deflectionas if i go down a mountain from input one " peak"to input 2 " base" anc the positive deflection as if climbing a mountain where input1 is base and input 2 is the peak of mountain، so the question is : is the electricity climbing up or down the mountain, which will be answered by tracing the other channels

[@shayaanp9207]

best video

[@swatN1]

God bless you!

[@tachatirelus4164]

EEGtechnician