Cheng, P. Z. | Search bioRxiv

bioRxiv2025

Neural correlates of transitions between internal and external cognitive domains

Human cognition involves continuous transitions between processing information guided by the external world and engaging with internally-generated thoughts, yet research has predominantly investigated switching based on external rules. We therefore examined neural mechanisms underlying external and internal domain switching using independent groups of EEG (N=46) and fMRI (N=60) in a colour judgement task requiring evaluations based on either colour similarity (external domain) or colour preference (internal domain) through switching on a trial-by-trial basis. ERPs revealed amplitude differences between the two judgements as well as switching and repeated trials. EEG analysis revealed a sustained neural differentiation between switch and repeated trials, specifically during similarity judgements, with effects lasting from early time points through the entire trial duration. fMRI showed similarity judgements engaged visual and motor regions during switching, while preference judgements showed minimal subcortical activation for repeated trials. These findings demonstrate that external and internal cognitive domain switching effects are asymmetrical. These findings provide the first temporal and spatial neural characterisation of domain switching between processing information guided by the external world and internally-generated thoughts, indicating that shifting between internal and external domains involves mechanisms distinct from traditional external rule-switching paradigms.

neuroscience↗

bioRxiv2019

Intrinsic activity temporal structure reactivity to behavioural state change is correlated with depressive rumination

The brains intrinsic activity plays a fundamental role in its function. In normal conditions this activity is responsive to behavioural context, changing as an individual switches between directed tasks and task-free conditions. A key feature of such changes is the movement of the brain between corresponding critical and sub-critical states, with these dynamics supporting efficient cognitive processing. Breakdowns in processing efficiency can occur, however, in brain disorders such as depression. It was therefore hypothesised that depressive symptoms would be related to reduced intrinsic activity responsiveness to changes in behavioural state. This was tested in a mixed group of major depressive disorder patients (n = 26) and healthy participants (n = 37) by measuring intrinsic EEG activity temporal structure, quantified with detrended fluctuation analysis (DFA), in eyes-closed and eyes-open task-free states and contrasting between the conditions. The degree to which DFA values changed between the states was found to be negatively correlated with depressive symptoms. DFA values did not differ between states at all in those with high symptom levels, meaning that the brain remained in a less flexible sub-critical condition. This sub-critical condition in the eyes-closed state was further found to correlate with levels of maladaptive rumination. This may reflect a general cognitive inflexibility resulting from a lack in neural activity reactivity that may predispose people to overly engage in self-directed attention. These results provide an initial link between intrinsic activity reactivity and psychological features found in psychiatric disorders.

neuroscience↗