complex systems and brain sciences
Please follow our latest work on the lab website!
Publications before Fall 2023 are here organized by topic. See CV for a chronological list.
| Brain Stimulation |
| Geometry and Topology of Large-Scale Brain Dynamics |
| Multiagent Coordination Dynamics |
| Human Dynamic Clamp |
| Other |
| † : co-first author | ‡ : co-last author |
My work at UNC-Chapel Hill focuses on understanding the causal roles of neural oscillations across multiple scales, from neuronal spiking to behavioral dynamics, using various brain stimulation and computational techniques.
My first work conceptualizing the treatment of major depressive disorder using closed-loop deep brain stimulation as a control problem for multistable nonlinear dynamical systems.
My first animal work (ferrets), using optogenetic stimulation to understand how alpha oscillations control cortical excitability – a long-standing question in human non-invasive brain stimulation literature, for which this paper provides the cellular mechanism.
My first clinical-trial paper showing how rhythmic alpha stimulation can be used to treat depressive symptom in people with schizophrenia.
First paper by an undergraduate mentee (L.S.), associating the dynamics of individual alpha frequency with anxiety. Innovative work using mobile EEG device.
My work and continued collaboration at Stanford University involves developing large-scale biophysical network models and new computational topology/geometry techniques to characterize complex brain dynamics observed in human fMRI.
A Mapper-inspired computational method to capture phase transitions in biophysical network models of and real human fMRI dynamics. This method differs from earlier Mapper-based topological data analysis methods by taking advantage of temporal information.
A novel computational framework for characterizing brain dynamics as landmarks (attractors) of a multistable dynamic landscape. We show the relation between attractors better capture human brain functional connectivity patterns than any specific attractor.
An earlier draft of Zhang, Sun & Saggar (2022) that may be read as a stand-alone theoretical paper, analyzing how the distribution of attractors is affected by various structural parameters.
A follow up work of Zhang, Sun & Saggar (2022) with clinical applications.
How can multiple components form complex structure/dynamics on multiple levels/scales in natural complex adaptive systems (e.g., living, social systems)? In my doctoral work, I approached this problem by integrating empirical, theoretical, and methodological research, which I call the Human Firefly Trilogy. The Trilogy is a series of three papers:
The “Human Firefly” experiment.
The theoretical model derived from experimental observations in the Human Firefly experiment reported in Zhang, Kelso, Tognoli (2018).
Methodological paper on a topological approach to complex coordination patterns with multiple characteristic spatiotemporal scales. The method was based on exploratory analyses of single-trial dynamics recorded in the Human Firefly experiment.
Together, they make up my dissertation:
More recent theoretical developments:
Continues the some theoretical questions posed by the model of Zhang et al (2019), in particular, how bistability in a pair of oscillators can be restored by bidirectional coupling to a third oscillator.
A follow-up of McKinley et al (2021), addressing the case of symmetry breaking in frequnecy and coupling. More applicable to brain stimulation.
A historical review of related models of rhythmic coordination:
This group of studies investigates the neural and physiological changes in humans during social coordination with a “Virtual Partner” whose social coordinative behavior can be parametrically manipulated through modifying its governing equation. This was based on a new paradigm named the Human Dynamic Clamp (here’s a paper).
A summary of the methodology.
We found elevated emotional responses for stable coordination and perceived humanness in the Virtual Partner.
Emmanuelle Tognoli, Mengsen Zhang, and J. A. Scott Kelso (2018). On the Nature of Coordination in Nature. Advances in Cognitive Neurodynamics VI (Ed. JM Delgado-Garcia). DOI | pdf
Mengsen Zhang, Craig Nordham, and J. A. Scott Kelso (2015). Deterministic versus probabilistic causality in the brain: to cut or not to cut. Physics of Life Reviews, 15: 136-138. DOI | pdf
