Identifying functional networks using endogenous connectivity in gamma band electrocorticography
Andrew L Ko1, Kurt E Weaver, Shahin Hakimian
11 Department of Neurological Surgery, University of Washington , Seattle, Washington.
Brain Connectivity
|July 25, 2013
Summary
Brain connectivity can be mapped using spontaneous electrocorticography (ECoG) signals. This method identifies functional networks, like motor and visual cortex, without needing electrical cortical stimulation (ECS) or task-evoked responses.
Area of Science:
- Neuroscience
- Systems Neuroscience
- Computational Neuroscience
Background:
- Spontaneous, infra-slow (<0.1 Hz) fluctuations in gamma band (70-100 Hz) power, recorded via electrocorticography (ECoG), reflect functional brain organization across various cortical areas.
- These fluctuations are observed in sensory cortices, motor cortex, and the default mode network (DMN), suggesting their role in large-scale network dynamics.
Purpose of the Study:
- To develop and validate a data-driven method for characterizing cortical connectivity using spontaneous ECoG signals.
- To compare the networks identified by the novel method with established clinical mapping results from electrocortical stimulation (ECS).
- To investigate the potential of using resting-state ECoG for functional brain mapping, reducing reliance on behavioral tasks or direct stimulation.
Main Methods:
- A data-driven approach utilizing co-modulation analysis of infra-slow and gamma band power fluctuations in ECoG data.
- Application of a graph spectral clustering algorithm to identify consistent functional networks from spontaneous activity.
- Comparison of algorithmically identified networks with clinical mapping data obtained through electrocortical stimulation (ECS).
Main Results:
- The developed method successfully identified networks corresponding to the motor and visual cortex with high specificity.
- Anatomical and functional evidence supports the identification of other networks, including the default mode network (DMN).
- The findings demonstrate that functional cortical mapping is achievable using only spontaneous ECoG recordings, independent of behavioral tasks or ECS.
Conclusions:
- Infra-slow co-modulations of gamma band power represent a neurophysiological basis for resting-state networks.
- This spontaneous ECoG-based mapping technique offers a promising alternative to traditional methods like ECS or task-based functional imaging.
- The methodology provides a valuable tool for studying alterations in brain connectivity across different behavioral states and clinical conditions.
