| Description |
Analyzing patterns of intracranial electroencephalographic (EEG) recordings can provide insight into how temporal and spatial components of brain activity are related on a trial-by-trial basis. Research on fMRI resting state networks has clarified the role of the default mode network (DMN) in internally directed cognition (e.g., mind-wandering), and the frontoparietal network (FPN) in externally directed cognition (e.g., working memory tasks); however, the relation of these networks to similar functional properties of neuroelectric activity is not yet understood. Recently, it has been suggested that the scalp EEG phenomena of alpha event-related desynchronization (ERD) and theta-band eventrelated synchronization (ERS) during simple cognitive tasks might represent neuroelectric parallels of DMN down-regulation and FPN activity, respectively. This study addressed this question by investigating task-related patterns of alpha ERD and theta ERS at intracranial sites within the DMN and FPN networks while participants completed multiple trials of the Multi-Source Interference Task (MSIT), containing three levels of task difficulty. The intracranial EEG patterns of 8 patients who underwent presurgical mapping for treatment of epilepsy were examined. Alpha ERD was expected to be preferentially observed at sites corresponding to the DMN while theta ERS was expected to be preferentially observed at FPN sites, dependent upon task difficulty. Additionally, higher task difficulty was expected to be related to slower reaction time. In support of these hypotheses, increased task difficulty was positively related to rection time. Contrary to these hypotheses, electrodes within the default mode and frontoparietal networks showed no significant differences in theta or alpha power; however, exploratory findings direct future work to investigate potential theta and alpha power differences within and between the frontoparietal, default mode, visual, and dorsal attention networks. Specific hypotheses for alpha and theta ERD/ERS within these networks are discussed. These results indicate that intracranial electroencephalography can be used to analyze the spatial and temporal patterns of neural networks. With replication, it is likely that increased task difficulty will elicit differing mechanisms of cognitive engagement within these four networks, supported by the found ERD/ERS trends of alpha and theta power, dependent upon task difficulty. These findings focus the exploration of cognitive information processing towards the dorsal attention and visual networks, strengthen the drive to understand the distinct classification of the frontoparietal and dorsal attention networks, and support new ways to study these networks using neuroelectric recordings. |
