Dissociable theta networks underlie the switch and mixing costs during task switching

Abstract

During task‐switching paradigms, both event‐related potentials and time‐frequency analyses show switch and mixing effects at frontal and parietal sites. Switch and mixing effects are associated with increased power in broad frontoparietal networks, typically stronger in the theta band (~4–8 Hz). However, it is not yet known whether mixing and switch costs rely upon common or distinct networks. In this study, we examine proactive and reactive control networks linked to task switching and mixing effects, and whether strength of connectivity in these networks is associated with behavioural outcomes. Participants (n = 197) completed a cued‐trials task‐switching paradigm with concurrent electroencephalography, after substantial task practice to establish strong cue‐stimulus–response representations. We used inter‐site phase clustering, a measure of functional connectivity across electrode sites, to establish cross‐site connectivity from a frontal and a parietal seed. Distinct theta networks were activated during proactive and reactive control periods. During the preparation interval, mixing effects were associated with connectivity from the frontal seed to parietal sites, and switch effects with connectivity from the parietal seed to occipital sites. Lateralised occipital connectivity was common to both switch and mixing effects. After target onset, frontal and parietal seeds showed a similar pattern of connectivity across trial types. These findings are consistent with distinct and common proactive control networks and common reactive networks in highly practised task‐switching performers.

Too much or not enough? Optimal level of human intracranial theta activity for rule-switching in the subthalamo-medio-prefrontal circuit

“…The modulation of theta amplitude found in the dmPFC and in the STN during switching is consistent with previous EEG studies in healthy participants 23,25 and with previous iEEG studies on executive control functions recording LFP across several cortical or subcortical targets 10,13 . Critically, we also found that theta activity magnitude further increased during unsuccessful trials compared to correct switches in both brain structures.…”

Temporally and functionally distinct large-scale brain network dynamics supporting task switching

“…Further studies involving iEEG oscillations other than high-gamma activity are warranted to determine the network dynamics supporting cognitive flexibility. Prior scalp EEG studies reported that the theta amplitude and coherence across frontal and parietal regions differed between switch and repeat trials ( Cooper et al, 2015 ; Capizzi et al, 2020 ; McKewen et al, 2021 ).…”

Theta power and functional connectivity as neurophysiological markers of executive functions in individuals with cognitive complaints in daily life

“…Depending on the specific EF task, neuronal assemblies in different brain regions within the superordinate network (and additional regions) synchronise, thereby serving control mechanisms more efficiently (Cavanagh & Frank, 2014). In healthy individuals, increased theta functional connectivity has been observed in fronto-parietal brain regions during conflict monitoring (e.g., Cohen, 2014a), response inhibition (e.g., Harmony et al, 2009), set-shifting (e.g., McKewen et al, 2021), and working memory updating (e.g., Mizuhara & Yamaguchi, 2007). The distinction between the two neurophysiological markers is important, because an increase in power is considered to reflect engagement of a cortical region, whereas functional connectivity (i.e., phase synchronization) is thought to reflect communication between cortical hubs (Cooper et al, 2017).…”