Neuroscience Seminar Series for Rising Scholars (Hybrid): Li Xin Lim, PhD (PI: Andrew Westbrook, PhD)

“From cognitive demand to TMS perturbation: EEG markers of neural criticality”

Speaker: Li Xin Lim, PhD
Postdoctoral Associate, PI: Andrew Westbrook, PhD

Date and Time: Monday, September 14, 2026 12:00 PM

In-Person: Room 127, Staged Research Building (SRB), Busch Campus

Join via Zoom: Please email the host, Dr. Noelle Stiles (noelle.stiles@rutgers.edu), or check the CAHBIR Slack #General thread for the link

Abstract: The critical brain hypothesis proposes that the brain operates near a transition point where excitation and inhibition are balanced, allowing neural activity to flexibly reorganize in response to changing demands. We use a time-resolved EEG measure of scale invariance, d2 to estimate distance from this critical regime: lower d2 indicates neural dynamics closer to criticality. We benchmark d2 using ground-truth simulations of a neural mass model and show that d2 is lowest when excitation and inhibition are balanced. d2 is then applied to a task-switching paradigm, showing more demanding trials shifted neural activity farther from criticality, whereas faster, more accurate, and more flexible behavior tended to occur closer to criticality. These relationships also differed across brain regions, suggesting that deviations from criticality can reflect both cognitive effort and adaptive control. Because excitation-inhibition balance is thought to govern proximity to criticality, a key next question is whether experimentally perturbing cortical excitability changes critical dynamics and behavior. Transcranial magnetic stimulation (TMS) offers a noninvasive means to test this proposed causal mechanism. Participants received continuous theta-burst stimulation (cTBS; inhibitory), intermittent theta-burst stimulation (iTBS; excitatory), and sham stimulation in three separate sessions. Relative to sham, iTBS is associated with lower post-stimulation resting-stated2, consistent with a shift toward criticality. During a memory-guided saccade task, cTBS increases d2 across fixations, visually guided-, and memory-guided saccade periods, indicating a shift away from criticality; it also reduces memory-guided saccade velocity. These findings suggest that theta-burst stimulation can differentially reshape neural criticality, with consequences for cognitive control and memory-guided behavior.