[Eeglablist] P and N values in EEG data

[Dr Cyril, Pernet]

To follow up on Makoto making fun of N-P naming, these are just 
conventions and you can read more about this here 
https://urldefense.com/v3/__https://cobidasmeeg.wordpress.com/2018/08/07/result-reporting/__;!!Mih3wA!D6s__mhdUCPc5gfu1ZORNKBYv1tcbWw_k6Ev-5U4grJ7kbovHyCheaAVUiOIByNHqLX7-y6_kpmoGCFvMyJLSQ$ 

Traditionally, event-related response components have been named using 
an established nomenclature, where the polarity of the (EEG) response 
and its/nominal/latency form the elements of the name (e.g., N100, N170, 
P300, N400, etc.). This convention appears in guidelines first published 
by the International Federation for Clinical Neurophysiology (IFCN) in 
1983, and those updated in 1999 
(https://urldefense.com/v3/__http://www.clinph-journal.com/content/guidelinesIFCN__;!!Mih3wA!D6s__mhdUCPc5gfu1ZORNKBYv1tcbWw_k6Ev-5U4grJ7kbovHyCheaAVUiOIByNHqLX7-y6_kpmoGCH6NQ-kXQ$  
<https://urldefense.com/v3/__http://www.clinph-journal.com/content/guidelinesIFCN__;!!Mih3wA!D6s__mhdUCPc5gfu1ZORNKBYv1tcbWw_k6Ev-5U4grJ7kbovHyCheaAVUiOIByNHqLX7-y6_kpmoGCH6NQ-kXQ$ >).

 From a neurophysiological perspective, peaks mark a transition in terms 
of neural processing, but ERP polarity has no direct link to synaptic 
activity (excitation or inhibition) since, even if you measure it on the 
brain, it is an integral measure of cortical layers (and if measured on 
the scalp, integrate many sources altogether)


> Hi Humera,
>
> Now your question makes sense to me. Thank you for your patience and
> revising your question.
>
> The answer is: The polarity (i.e. positive or negative) of an ERP
> component, such as P300 or N100, has nothing to do with emotional valence
> ('negative stimulus' which may be disgusting or 'positive stimulus' which
> may be pleasing). P or N as in P300 and N100 represent ERP polarity (i.e.
> the peak amplitude) is positive or negative (i.e. minus).
>
> Note also that ERP polarity changes as you change reference electrode. P300
> can be N300 depending on your choice of reference.
>
> In the future I will propose P3000000000 (p-three-billion) to make fun of
> ERP researchers.
>
> Makoto
>
> On Wed, Oct 11, 2023 at 10:31 AM Humera Sharif via eeglablist <
> eeglablist at sccn.ucsd.edu> wrote:
>
>> Hi,
>>
>> Could anyone please explain what P and N (such as P300/N100 etc.) peaks in
>> EEG data in response to negative stimuli (Event) indicate? P is a
>> positive peak, so P in a negative stimulus means 'less disgusting, less
>> negative, less hated' compared to the N peak. And does the same apply to
>> the N peak for positive stimuli?
>>
>> Thanks in advance.
>>
>> Best regards,
>> Humera Sharif
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-- 
Dr Cyril Pernet, PhD, OHBM fellow, SSI fellow
Neurobiology Research Unit,
Building 8057, Blegdamsvej 9
Copenhagen University Hospital, Rigshospitalet
DK-2100 Copenhagen, Denmark

wamcyril at gmail.com
https://urldefense.com/v3/__https://cpernet.github.io/__;!!Mih3wA!D6s__mhdUCPc5gfu1ZORNKBYv1tcbWw_k6Ev-5U4grJ7kbovHyCheaAVUiOIByNHqLX7-y6_kpmoGCG6NNvlDw$ 
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