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

Tue Aug 6 15:06:10 PDT 2024

Hi all,

If HEP

1. is recorded from the scalp,
2. is synchronized to ECG (R peak, for example),
3. has semi-constant delay (300-600 ms) relative to the heart beat,

then I think the HEP may be an EEG, but you say the delay is accounted by
the blood vessel's inflation in the head following the heart beat?
So are you saying HEP is a brain signal, or not? I'm still confused.

An ICA-decomposed heart-related component, if it is ever present (I agree
to John that it is rather rare), always shows tangential dipole angle when
fitted. Have you seen any radial (i.e. vertex-oriented) dipole for a
heart-related component? This observation makes me think that the source of
the heart-related ICs must be arteries and veins in the depth of the head.
Maybe Stefan Debener discussed it already in one of his fMRI-EEG works from
the mid 2000's which Scott mentioned.

Makoto

On Tue, Aug 6, 2024 at 10:01 AM McCleery, Amanda <amanda-mccleery at uiowa.edu>
wrote:

> Hi all,
> Just chiming in to say that this discussion is very timely (I sent an
> email to Arnaud Delorme about a week ago asking for guidance re: whether or
> not to include ECG channels in ICA), and I hope a consensus opinion from
> the ICA gurus will be posted to the EEGlab wiki page!
> Thanks
> Amanda McCleery, Ph.D. (she/her/hers)
> Assistant Professor, Department of Psychological and Brain Sciences
> The University of Iowa
> 473 Psychological and Brain Sciences Building, Iowa City IA 52242
>
>
>
>
> -----Original Message-----
> From: Makoto Miyakoshi <mmiyakoshi at ucsd.edu>
> Sent: Monday, August 5, 2024 4:54 PM
> To: EEGLAB List <eeglablist at sccn.ucsd.edu>
> Subject: Re: [Eeglablist] Fw: Re: ECG Channel Inclusion in ICA and ICLabel
> Steps
>
> 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_n0TrNLB20H1cJLZDjdmMz8JsfHFIdXHQu
> > fx-wO2xcvGmCGkuOn8VQfYj8XKL4HCQ$
> >
> >
> > https://urldefense.com/v3/__https://pubmed.ncbi.nlm.nih.gov/22541740/_
> > _;!!Mih3wA!A7XPAnqNlQiz9pvotlbJTJbG2_n0TrNLB20H1cJLZDjdmMz8JsfHFIdXHQu
> > fx-wO2xcvGmCGkuOn8VQfYj8D2qUf-A$
> >
> >
> > https://urldefense.com/v3/__https://pubmed.ncbi.nlm.nih.gov/28651745/_
> > _;!!Mih3wA!A7XPAnqNlQiz9pvotlbJTJbG2_n0TrNLB20H1cJLZDjdmMz8JsfHFIdXHQu
> > fx-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-spotli
> > ght-advancing-study-brain-heart-interplay-with__;!!Mih3wA!CWCJFZKu2zYD
> > 1n7sKo1ur_bO9g_iWhAy9vSTS18Bf-jfmH6errEXOVCDaXANh_5ukcj1Wajfh_MIn3CPFG
> > GRV09qjA$
> > > > And Github repo:
> > > >
> > https://urldefense.com/v3/__https://github.com/amisepa/BrainBeats__;!!
> > Mih3wA!CWCJFZKu2zYD1n7sKo1ur_bO9g_iWhAy9vSTS18Bf-jfmH6errEXOVCDaXANh_5
> > ukcj1Wajfh_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!B4rXaMGV
> > hHYr_2oHmmQc94PJcfhiYYPWsZNqJtpm0CRKhOTeHaXWrkUCGI-mcxaW1b2qR1YWJv1lJr
> > PrNV29FIao1z4gCQ$
> > > >
> > > > > ***********************************************
> > > > >
> > > > > -----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,
> > > > > _______________________________________________
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