[Eeglablist] Fw: Re: ECG Channel Inclusion in ICA and ICLabel Steps

Mon Aug 5 14:53:42 PDT 2024

Hi Cedric and John,

> It does not inherently assume that all sources must be of the same nature
or originate from EPSP/IPSPs from pyramidal neurons in cortical gyri, does
it?

I mean "If ICA were to inherently assume that all sources must be of the
same nature or originate from ERSP/IPST from pyramidal neurons in cortical
gyri", it would not identify non-brain artifacts.

If the heartbeat-evoked potential is completely synchronized with the ECG,
ICA must capture the mixed cortical activation pattern as a single
component and there is no way to separate the cortical contribution from
the heart's contribution.

John, what's the relation of the timings between ECG and HEP--are they
always synchronized (i.e. the functional connectivity), or the latter
delays/jitters the onset of ECG (the effective connectivity)? ICA may
capture the former under favorable conditions, but it cannot capture the
latter.

Makoto

On Mon, Aug 5, 2024 at 4:55 PM Cedric Cannard via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> Hi Makoto,
>
> Sorry for the typo. As you can guess, I meant "I do not believe including
> auxiliary channels violates ICA assumptions."
>
>
> > Tony Bell is a legend
>
> haha :)
>
>
> > For example, concatenating millivolt-range signals with microvolt-range
> signals for decomposition may cause unexpected trouble.
>
> Yes, I generally rescale the ECG signal to the EEG range if the ECG scale
> is vastly different, so ICA does not prioritize the larger ECG signals over
> the smaller EEG ones, which gives better results.
>
>
> > Then ICA would not identify non-brain artifacts, right?
>
> Why? Non-brain artifacts have independent sources. My point was that, as
> you summarized, ICA assumes sources to be independent, mixed, and
> non-gaussian, not that the sources of all signals are EPSP/IPSPs from
> pyramidal neurons.
>
>
> > I'm rather curious to know if heartbeat-evoked potential is a real
> thing. For example, if I decompose a heartbeat IC which typically has a
> broad and dipolar projection from the depth. Is there any neuronal
> contribution there? If yes, then the heartbeat IC is contributed by both
> the heart and the brain. If no, it is generated only by the heart. Which is
> the case?
>
> I agree and am wondering the same thing. And I don't think there is an
> answer to this yet. removing heart ICs may remove both the CFAs and the
> relevant neuronal-related HEP. Ideally, heart ICs would capture the cardiac
> field artifacts (CFA) which travel by volume conduction (e.g., skin) and
> are picked up by scalp EEG electrodes. The broad and dipolar spatial
> properties of the heart ICs reflect these CFAs (i.e., the source is
> non-neuronal). And HEPs (after removing these CFAs) would only reflect
> neuronal processing of heart activity.
> I think one potential way of answering this would be to have intracranial
> electrodes time-locked to scalp electrodes, mark the R-peaks in both, and
> compare. But even then, heart activity can travel to the brain via various
> direct and indirect pathways: directly via the vagus nerve, indirectly via
> volume conduction through the spinal cord (surrounded by conductive CSF)
> and conductive arteries, or via blood pressure-related activity detected by
> baroreceptors/chemoreceptors.
>
> I am currently developing a multivariate method that would provide more
> information on the synchronization (coherence & partial coherence), system
> response (transfer function matrix, spectral matrix, inverse spectral
> matrix), and causal interactions (directed coherence, directed transfer
> function, partial directed coherence) between heart and EEG signals.
> hopefully, that can provide some insights (direct, indirect interactions
> and direction of the interaction).
>
> I think what provides some answer is the growing body of literature
> showing meaningful associations between HEP and interoception and
> integration of internal bodily states, highlighting brain areas known to be
> involved in these processes from the neuroimaging literature, e.g. insula,
> ACC, somatosensory cortex.
>
> Some good references for HEP:
>
> https://urldefense.com/v3/__https://pubmed.ncbi.nlm.nih.gov/31051293/__;!!Mih3wA!A7XPAnqNlQiz9pvotlbJTJbG2_n0TrNLB20H1cJLZDjdmMz8JsfHFIdXHQufx-wO2xcvGmCGkuOn8VQfYj8XKL4HCQ$
>
>
> https://urldefense.com/v3/__https://pubmed.ncbi.nlm.nih.gov/22541740/__;!!Mih3wA!A7XPAnqNlQiz9pvotlbJTJbG2_n0TrNLB20H1cJLZDjdmMz8JsfHFIdXHQufx-wO2xcvGmCGkuOn8VQfYj8D2qUf-A$
>
>
> https://urldefense.com/v3/__https://pubmed.ncbi.nlm.nih.gov/28651745/__;!!Mih3wA!A7XPAnqNlQiz9pvotlbJTJbG2_n0TrNLB20H1cJLZDjdmMz8JsfHFIdXHQufx-wO2xcvGmCGkuOn8VQfYj9BgOZjfw$
>
>
> Cedric
>
>
>
> ------- Forwarded Message -------
> From: Makoto Miyakoshi via eeglablist <eeglablist at sccn.ucsd.edu>
> Date: On Monday, August 5th, 2024 at 7:59 AM
> Subject: Re: [Eeglablist] ECG Channel Inclusion in ICA and ICLabel Steps
> To: EEGLAB List <eeglablist at sccn.ucsd.edu>
>
>
> > Hello John and
> >
> > Cedric
> >
> >
> > ,
> >
> > This double negative makes it difficult to understand what you are trying
> > to say, Cedric.
> >
> > > I do not believe including auxiliary channels does not violate ICA
> >
> > assumptions.
> >
> > You are saying that including ECG violates ICA's assumption, but your
> > claim seems opposite.
> >
> > ICA's assumptions are, off the top of the head,
> >
> > - The sources are non-Gaussian
> > - The sources are linearly independent
> > - The sources are linearly and instantly mixed
> > - Tony Bell is a legend
> >
> > So ECG channels may be included in ICA with no problem in theory.
> However,
> > if empirical observations recommend otherwise, there may be some reason
> > that is specific to each application which is worth investigating. For
> > example, concatenating millivolt-range signals with microvolt-range
> signals
> > for decomposition may cause unexpected trouble.
> >
> > > It does not inherently assume that all sources must be of the same
> nature
> >
> > or originate from EPSP/IPSPs from pyramidal neurons in cortical gyri,
> does
> > it?
> >
> > Then ICA would not identify non-brain artifacts, right?
> >
> > I'm rather curious to know if heartbeat-evoked potential is a real thing.
> > For example, if I decompose a heartbeat IC which typically has a broad
> and
> > dipolar projection from the depth. Is there any neuronal contribution
> > there? If yes, then the heartbeat IC is contributed by both the heart and
> > the brain. If no, it is generated only by the heart. Which is the case?
> >
> > Makoto
> >
> >
> >
> > On Mon, Aug 5, 2024 at 12:58 AM Cedric Cannard via eeglablist <
> > eeglablist at sccn.ucsd.edu> wrote:
> >
> > > Dear John,
> > >
> > > This is the same debate as including EOG for separating and extracting
> > > ocular components (isn't that common practice?). The only reason why
> you
> > > can get away without EOG channels is that ocular activity is so large
> > > compared to EEG, so easy to identify as an independent source. However,
> > > cardiac artifacts are difficult to identify without an explicit
> reference
> > > signal (except occasionally in some individuals where you can see them
> > > visually in the raw time series).
> > >
> > > Someone will correct me if I'm wrong, but I do not believe including
> > > auxiliary channels does not violate ICA assumptions. ICA is an
> algorithm
> > > designed to separate a mixture of signals into statistically
> independent
> > > components. It does not inherently assume that all sources must be of
> the
> > > same nature or originate from EPSP/IPSPs from pyramidal neurons in
> cortical
> > > gyri, does it?
> > >
> > > By providing a clear reference for ECG artifacts, ECG channels can
> enhance
> > > the accuracy of this separation in my experience, in line with Sofia's
> > > observation. In fact, this is a method supported by my new BrainBeats
> > > plugin (along with HEP/HEO and HRV analysis which implements validated
> > > algorithms and guidelines via command line or GUI). See here for a
> > > step-by-step tutorial:
> > >
> https://urldefense.com/v3/__https://www.jove.com/t/65829/author-spotlight-advancing-study-brain-heart-interplay-with__;!!Mih3wA!CWCJFZKu2zYD1n7sKo1ur_bO9g_iWhAy9vSTS18Bf-jfmH6errEXOVCDaXANh_5ukcj1Wajfh_MIn3CPFGGRV09qjA$
> > > And Github repo:
> > >
> https://urldefense.com/v3/__https://github.com/amisepa/BrainBeats__;!!Mih3wA!CWCJFZKu2zYD1n7sKo1ur_bO9g_iWhAy9vSTS18Bf-jfmH6errEXOVCDaXANh_5ukcj1Wajfh_MIn3CPFGGKS9yf5A$
> > >
> > > Sofia, my question is: Why are you using ICA in the context of HEP? You
> > > generally want to keep ECG-related activity for HEP. Do you suspect
> the HEP
> > > is a CFA? I have wondered about that but haven't found a work-around.
> > >
> > > Curious to hear more on this!
> > >
> > > Cedric Cannard
> > >
> > > On Thursday, August 1st, 2024 at 7:08 AM, Richards, John via
> eeglablist <
> > > eeglablist at sccn.ucsd.edu> wrote:
> > >
> > > > Don't include ECG in the EEG signal for ICA. For various technical
> > > > reasons (amplitude, frequency, signal spikes, location) and
> theoretical
> > > > ones (its NOT a brain signal; you want to correlate ECG and EEG).
> > > >
> > > > See poster by Wanze Xie at ICIS, or contact him. He has synchronized
> > > > cardiac cycles and ERPs. His techniques might be useful and he has
> some
> > > > very interesting VEP/cardiac cycle data.
> > > >
> > > > John
> > > >
> > > > ***********************************************
> > > > John E. Richards
> > > > Carolina Distinguished Professor
> > > > Department of Psychology
> > > > University of South Carolina
> > > > Columbia, SC 29208
> > > > Dept Phone: 803 777 2079
> > > > Fax: 803 777 9558
> > > > Email: richards-john at sc.edu
> > >
> > >
> https://urldefense.com/v3/__https://jerlab.sc.edu/__;!!Mih3wA!B4rXaMGVhHYr_2oHmmQc94PJcfhiYYPWsZNqJtpm0CRKhOTeHaXWrkUCGI-mcxaW1b2qR1YWJv1lJrPrNV29FIao1z4gCQ$
> > >
> > > > ***********************************************
> > > >
> > > > -----Original Message-----
> > > > From: eeglablist eeglablist-bounces at sccn.ucsd.edu On Behalf Of Sofia
> > > > Amaoui via eeglablist
> > > >
> > > > Sent: Thursday, August 1, 2024 8:54 AM
> > > > To: eeglablist at sccn.ucsd.edu
> > > > Subject: [Eeglablist] ECG Channel Inclusion in ICA and ICLabel Steps
> > > >
> > > > Dear all,
> > > >
> > > > We are conducting a Heart-Evoked Potential (HEP) study using EEG
> signals
> > > > that are time-locked to R-peak via ECG. Our preprocessing pipeline
> is being
> > > > implemented with EEGLAB, including the ERPLAB and HEPLAB plugins. As
> part
> > > > of this process, we employ Independent Component Analysis (ICA) and
> ICLabel
> > > > to identify ocular and cardiac field artefacts (CFA).
> > > >
> > > > A key question has arisen regarding including the ECG channel in the
> ICA
> > > > and ICLabel steps. Our preliminary findings show that when we
> include it,
> > > > CFA classification is much higher.
> > > >
> > > > We are seeking your insights on whether the inclusion of the ECG
> channel
> > > > is aiding in the identification of CFA components or if it might be
> > > > compromising EEG information of interest by focusing on identifying
> and
> > > > removing CFA.
> > > >
> > > > Thank you for your time and assistance.
> > > >
> > > > Best regards,
> > > >
> > > > Sofia Amaoui,
> > > > _______________________________________________
> > > > Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> > > > To unsubscribe, send an empty email to
> > > > eeglablist-unsubscribe at sccn.ucsd.edu
> > > > For digest mode, send an email with the subject "set digest mime" to
> > > > eeglablist-request at sccn.ucsd.edu
> > > > _______________________________________________
> > > > Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> > > > To unsubscribe, send an empty email to
> > > > eeglablist-unsubscribe at sccn.ucsd.edu
> > > > For digest mode, send an email with the subject "set digest mime" to
> > > > eeglablist-request at sccn.ucsd.edu
> > > > _______________________________________________
> > > > Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> > > > To unsubscribe, send an empty email to
> > > > eeglablist-unsubscribe at sccn.ucsd.edu
> > > > For digest mode, send an email with the subject "set digest mime" to
> > > > eeglablist-request at sccn.ucsd.edu
> >
> > _______________________________________________
> > Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> > To unsubscribe, send an empty email to
> eeglablist-unsubscribe at sccn.ucsd.edu
> > For digest mode, send an email with the subject "set digest mime" to
> eeglablist-request at sccn.ucsd.edu
> _______________________________________________
> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> To unsubscribe, send an empty email to
> eeglablist-unsubscribe at sccn.ucsd.edu
> For digest mode, send an email with the subject "set digest mime" to
> eeglablist-request at sccn.ucsd.edu