New FMRI Study From China: Brain Dynamics in a Criticality Framework

Out on PubMed, from investigators in China, is this study:

Electroconvulsive therapy modulates critical brain dynamics in major depressive disorder patients.

Xin Y, Bai T, Zhang T, Chen Y, Wang K, Yu S, Liu N, Tian Y.Brain Stimul. 2021 Dec 22:S1935-861X(21)00843-3. doi: 10.1016/j.brs.2021.12.008. Online ahead of print.PMID: 34954084

The abstract is copied below:

Background: Electroconvulsive therapy (ECT) is widely considered as an effective and fast-acting option for treating patients with major depressive disorder (MDD). However, the neural basis underlying this powerful therapy remains uncertain. Recent studies have suggested that the healthy brain may operate near a critical state, which may reflect a balance between neuronal excitation and inhibition.


Objective: In the present study, we investigated whether there are any changes regarding criticality in MDD and, if so, whether ECT can reverse them. Critical dynamics analysis was performed on resting-state functional magnetic resonance imaging (rs-fMRI) data collected from 39 MDD patients and 38 healthy controls (HCs).

Results: We found that compared with HCs, MDD patients, especially those who responded positively to ECT, tended to have smaller avalanches and lower branching ratios, suggesting a sub-critical state, at both the whole-brain and functional network levels. Importantly, ECT effectively corrected such anomalies, accompanied by enhanced degree centrality and functional connectivity of high-degree nodes located in the networks like the default-mode network.

Conclusion: These results indicate that ECT can modulate large-scale brain dynamics of MDD patients to be closer to criticality. Our study sheds new light on the pathology of MDD and the network mechanism by which ECT influences treatment.

Keywords: Criticality; Electroconvulsive therapy; Major depressive disorder; Neuronal avalanches.

The paper is here.

This paper looks at brain dynamics from a criticality framework and concludes that abnormal baseline dynamics in MDD are restored to normal in ECT responders. 

Now, I wrote that sentence tongue-in-cheek, pretending I had drunk the Kool-Aid of all the underlying assumptions of the methods in this paper. There is so much arcane mathematics and physics in the paper, that (with the exception of a few understandable paragraphs) it might as well have been written for a mathematics journal.

Here is an example: 

Huh? And how can you trust that all this is real, if they can also write the following sentence?

Patient diagnosis was determined by a trained psychiatrist according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition)(DSM-5).

If you can't tell 4 from 5, how can you keep avalanches in power-law distributions straight?

But seriously, if all this is real, and I am just woefully Ludditic, then maybe it holds the keys to understanding the mechanism of action of ECT and also the pathophysiology of depressive illness. First, let's start with a replication...

More power to you if you can read through this whole paper, ~ 25 minutes.