Schedule of Events | Symposia

Concurrent multimodal imaging reveals that EEG measures of excitation/inhibition balance are compatible with MRS-based measures

Poster Session F - Tuesday, April 1, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Aaron Cochrane¹ (aaron_cochrane@brown.edu), Luke Rosedahl¹, Takeo Watanabe¹, Yuka Sasaki¹; ¹Brown University

A fundamental feature of the human nervous system is the dynamic interaction between excitation and inhibition. The relative degree of these factors, expressed as excitation/inhibition (E/I) balance, has been used to study a wide range of processes including neuroplasticity, cognition, and disordered neural functioning. While magnetic resonance spectroscopy (MRS) has been effective in quantifying concentrations of excitatory and inhibitory neurotransmitters, and by extension their ratio, MRS methods are greatly limited in their spatial and temporal resolution while also carrying high expenses. Alternative EEG-based measures of E/I balance, such as those derived from criticality theory, have been proposed and validated in several domains, yet these measures have not been directly compared to MRS-based E/I balance. Here, we used concurrent electroencephalography (EEG) and MRS in humans during a 90-minute post-learning nap and tested whether occipital EEG-based E/I balance and MRS-based E/I balances were reliably associated. We found that EEG-based estimates of E/I balance, derived from criticality theory, were positively and reliably associated with MRS-based estimates of E/I balance. These associations were especially strong when examining E/I balance estimated from alpha band. The two methods of assessing E/I balance were reliably linked when examining both within-subjects correlations (i.e., controlling for between-subject variations) and between-subjects correlations (i.e., controlling for within-subject variations). As expected, between-subjects correlations showed stronger associations. These results provide a critical validation for the use of low-cost EEG-based and criticality-informed E/I balance to measure the underlying ratio of excitatory and inhibitory transmitters at multiple brain locations and with high temporal precision.

Topic Area: METHODS: Electrophysiology