[Eeglablist] Multivariate Interaction Measure (MIM): ROIconnect

[Tyson Perez]

Thank you, Cedric!  Much appreciated.  🤓

Cheers,
Tyson Perez, DC, PhD

> On Jul 7, 2025, at 13:51, Cedric Cannard <ccannard at protonmail.com> wrote:
> 
> Hi Tyson,
> 
> My understanding is that the MIM used in ROIconnect is designed to quantify the strength and consistency of phase-to-phase coupling between multivariate signals from different brain regions. It ranges from 0 to 1, with higher values indicating stronger consistent coupling, but it is insensitive to the sign of the phase difference (that is, it does not differentiate between in-phase and anti-phase relationships). Instead, it captures the magnitude of linear dependencies between multivariate time series across regions, regardless of their polarity. Not all FC metrics are constrained to [0, 1]. For instance, Pearson correlation ranges from -1 to 1, reflecting both direction and strength of linear association. However, many coherence-based and information-theoretic FC measures, including MIM, are non-negative and often bounded between 0 and 1, because they assess magnitude or shared variance/information, rather than direction or sign.
> 
> In short, MIM measures how strongly, not how directionally, the multivariate phase dynamics of two regions are related. It's a robust choice for undirected FC in the presence of source mixing and is not meant to infer polarity (like in-phase vs. anti-phase), only consistency of interaction.
> 
> 
> Cedric
> 
> 
> 
>> On Sunday, 6 July 2025 at 10:08, Dr Tyson Perez DC via eeglablist <eeglablist at sccn.ucsd.edu> wrote:
>> 
>> Hi,
>> 
>> When I create my functional connectivity/correlation matrices using
>> ROIconnect, MIM values range from 0 to 1 (i.e., no negative values). Is the
>> MIM essentially computing the *consistency *of phase relationship between
>> brain regions irrespective of whether they are in-phase or out-of-phase?
>> 
>> Cheers,
>> Tyson Perez, DC, PhD
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>