Browsing by Author "Herrero Silva, Joaquín Alfonso"

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    Mind wandering: Investigating the role of low-frequency oscillations and cortical connectivity with intracranial human recordings
    (2025) Herrero Silva, Joaquín Alfonso; Aboitiz, Francisco; Pontificia Universidad Católica de Chile. Facultad de Medicina; Pontificia Universidad Católica de Chile. Facultad de Ciencias Biológicas; Pontificia Universidad Católica de Chile. Facultad de Química y Farmacias; Pontificia Universidad Católica de Chile. Facultad de Ciencias Sociales
    Mind wandering (MW) is a mental state characterized by attentional decoupling from external stimuli and ongoing tasks. At the neural level, MW has been associated with a decrease in the power of high-frequency oscillations in both the ventral and dorsal attentional networks (VAN and DAN). Concurrently, there is an increase in power within the Default Mode Network (DMN). However, contradictory evidence exists regarding the role of low-frequency oscillations in the neural dynamics underlying the emergence of MW. It has been suggested that changes in the power of theta and alpha frequency bands occur simultaneously with attentional decoupling, potentially facilitating its regulation. Moreover, while low-frequency bands are pertinent to the emergence of high-frequency oscillations, the specifics of their cortical distribution during the onset of MW remain uncertain. Additionally, homeostatic variations related to the inhibitory/excitatory balance within attentional networks and the DMN have yet to be adequately described. Therefore, our aim is to elucidate the neural signature associated with low-frequency oscillations that differentiate selective attention from MW. To achieve our objectives, we present the results from nine epileptic patients with electrocortical recordings (ECoG) who were candidates for surgical intervention. Participants completed a modified Sustained Attention to Response Task (SART), previously developed by our team (Henríquez et al., 2016) , to evaluate attentional states classified as sustained attention (ON state), somnolence (SL state), and MW conditions (OFF state). As anticipated, we observed a high proportion of ON responses (78.9%) compared to OFF (12.4%) and SL responses (8.7%). Furthermore, we found that behavioral variability, calculated across four trials preceding questions, increased before OFF responses. This behavioral variability supports the hypothesis that attentional lapses may unfold several seconds prior to thought sampling questions (TSQ). To understand the oscillatory contributions leading to OFF states, we characterized the electrodes of each participant within their respective networks of interest (VAN, DAN, and DMN). We then conducted spectral analysis of each independent electrode to identify differences in brain activity between the ON and OFF states. During OFF states, we observed a decrease in low-frequency power during both spontaneous and time-evoked windows, with non-specific network patterns. Simultaneously, we noted a decrease in aperiodic components that weredriven solely by the DMN. Connectivity dynamics at low frequencies were found to be heightened within the DMN and between the VAN and DAN. Finally, we linked behavioral data with ongoing brain activity to discern how cortical activity influences spontaneous attentional cycling. We found a significant correlation between behavioral variability and the instantaneous phase of theta oscillations immediately prior to trial onset, but only for OFF responses. Consequently, OFF states appear to be influenced by the phase consistency of the trial start. Overall, during mind wandering, we have documented changes in low_x0002_frequency oscillations that presumably guide inhibitory processes in the parietotemporal areas beyond the DMN. Thus, the inhibitory/excitatory balance at a large-scale cortical level is crucial during shifts in attentional fluctuations.