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

Mon Aug 5 20:24:27 PDT 2024

Jason and all -

There is a heartbeat signal - in EEG-in-fMRI (the 'ballistocardiogram').
Averaging on the R wave and visualizing the scap channels result in
animation shows a  potential that flows (up) the carotid and then up and
across the scalp diagonally.  The 'ballistic' title came from the
supposition that the scalp electrodes moving in the high-magnetic field of
the scanner.  But I hard a physicist speculate that it might (also) be some
sort of vascular 'Hall effect' [Wikipedia: The *Hall effect* is the
production of a potential difference <https://urldefense.com/v3/__https://en.wikipedia.org/wiki/Voltage__;!!Mih3wA!H7P0TN4v61HpukPPHO4oCDg4r8cshREkr_v0lzNnQH-DxBXkkVcNby7FFJxeIUVMkmPC_32Qo3AB73ZwPDTB$ >
 (the *Hall voltage*) across an electrical conductor
<https://urldefense.com/v3/__https://en.wikipedia.org/wiki/Electrical_conductor__;!!Mih3wA!H7P0TN4v61HpukPPHO4oCDg4r8cshREkr_v0lzNnQH-DxBXkkVcNby7FFJxeIUVMkmPC_32Qo3AB7_MN23_f$ > that is transverse
<https://urldefense.com/v3/__https://en.wiktionary.org/wiki/transverse__;!!Mih3wA!H7P0TN4v61HpukPPHO4oCDg4r8cshREkr_v0lzNnQH-DxBXkkVcNby7FFJxeIUVMkmPC_32Qo3AB7ykdV50-$ > to an electric current
<https://urldefense.com/v3/__https://en.wikipedia.org/wiki/Electric_current__;!!Mih3wA!H7P0TN4v61HpukPPHO4oCDg4r8cshREkr_v0lzNnQH-DxBXkkVcNby7FFJxeIUVMkmPC_32Qo3AB78wnhxtz$ > in the conductor and to an
applied magnetic field <https://urldefense.com/v3/__https://en.wikipedia.org/wiki/Magnetic_field__;!!Mih3wA!H7P0TN4v61HpukPPHO4oCDg4r8cshREkr_v0lzNnQH-DxBXkkVcNby7FFJxeIUVMkmPC_32Qo3AB74w7f9gR$ >
perpendicular <https://urldefense.com/v3/__https://en.wiktionary.org/wiki/perpendicular__;!!Mih3wA!H7P0TN4v61HpukPPHO4oCDg4r8cshREkr_v0lzNnQH-DxBXkkVcNby7FFJxeIUVMkmPC_32Qo3AB7yr5JZDb$ > to the
current. It was discovered by Edwin Hall
<https://urldefense.com/v3/__https://en.wikipedia.org/wiki/Edwin_Hall__;!!Mih3wA!H7P0TN4v61HpukPPHO4oCDg4r8cshREkr_v0lzNnQH-DxBXkkVcNby7FFJxeIUVMkmPC_32Qo3AB75Q9wqA3$ > in 1879]. Scalp maps for
ECG-account independent components look similar - though I don't believe
that the averaged scalp potential movie for an EEG session should exhibit
the same moving map....

Scott

On Mon, Aug 5, 2024 at 5:13 PM japalmer29--- via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> Hi Cedric and Makoto,
>
> My thoughts re the heartbeat source--I believe the heartbeat itself is
> mainly dipolar viewed from the "far field" of the scalp electrodes, which
> is why it shows up as a rainbow looking map. The actual dynamics of the EM
> field are more complex, but we mainly see only one component if any for the
> heartbeat.
>
> If there is a heartbeat related brain signal, I think it would likely be
> blood flow related, but we don't really see such components. I don't think
> such a component would be part of the heart located component since the
> blood flow would not be instantaneously synched to the heartbeat. All
> standard ICA components are only supposed to be instantaneously independent.
>
> Best,
> Jason
>
> -----Original Message-----
> From: eeglablist <eeglablist-bounces at sccn.ucsd.edu> On Behalf Of Cedric
> Cannard via eeglablist
> Sent: Monday, August 5, 2024 4:47 PM
> To: EEGLAB List <eeglablist at sccn.ucsd.edu>
> Subject: [Eeglablist] Fw: Re: ECG Channel Inclusion in ICA and ICLabel
> Steps
>
> 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-spot
> > > light-advancing-study-brain-heart-interplay-with__;!!Mih3wA!CWCJFZKu
> > > 2zYD1n7sKo1ur_bO9g_iWhAy9vSTS18Bf-jfmH6errEXOVCDaXANh_5ukcj1Wajfh_MI
> > > n3CPFGGRV09qjA$
> > > And Github repo:
> > > https://urldefense.com/v3/__https://github.com/amisepa/BrainBeats__;
> > > !!Mih3wA!CWCJFZKu2zYD1n7sKo1ur_bO9g_iWhAy9vSTS18Bf-jfmH6errEXOVCDaXA
> > > Nh_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!B4rXaM
> > > GVhHYr_2oHmmQc94PJcfhiYYPWsZNqJtpm0CRKhOTeHaXWrkUCGI-mcxaW1b2qR1YWJv
> > > 1lJrPrNV29FIao1z4gCQ$
> > >
> > > > ***********************************************
> > > >
> > > > -----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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-- 
Scott Makeig, Research Scientist and Director, Swartz Center for
Computational Neuroscience, Institute for Neural Computation, University of
California San Diego, La Jolla CA 92093-0559, http://sccn.ucsd.edu/~scott