Beyond the evoked/intrinsic neural process dichotomy

Abstract

Contemporary functional neuroimaging research has increasingly focused on characterization of intrinsic or “spontaneous” brain activity. Analysis of intrinsic activity is often contrasted with analysis of task-evoked activity that has traditionally been the focus of cognitive neuroscience. But does this evoked/intrinsic dichotomy adequately characterize human brain function? Based on empirical data demonstrating a close functional interdependence between intrinsic and task-evoked activity, we argue that the dichotomy between intrinsic and task-evoked activity as unobserved contributions to brain activity is artificial. We present an alternative picture of brain function in which the brain’s spatiotemporal dynamics do not consist of separable intrinsic and task-evoked components, but reflect the enaction of a system of mutual constraints to move the brain into and out of task-appropriate functional configurations. According to this alternative picture, cognitive neuroscientists are tasked with describing both the temporal trajectory of brain activity patterns across time, and the modulation of this trajectory by task states, without separating this process into intrinsic and task-evoked components. We argue that this alternative picture of brain function is best captured in a novel explanatory framework called enabling constraint. Overall, these insights call for a reconceptualization of functional brain activity, and should drive future methodological and empirical efforts.

Dynamic brain network configurations during rest and an attention task with frequent occurrence of mind wandering

“…Thus, so far, we have presented the DFC states revealed in the present study by discussing the relationship between core network components as they relate to task and rest. An alternative approach is to adopt a more global or holistic view of brain function that does not necessarily subscribe to dichotomies such as task versus rest, task‐evoked versus intrinsic, task‐positive brain network versus task‐negative brain network, CEN versus DN (Bolt, Anderson, & Uddin, ). Following a more holistic perspective, brain states can be seen as the repertoire of more or less flexible brain network configurations that emerge dynamically to enable context‐appropriate behavior based on the skillful interchange between external and internal needs.…”

From eyes‐closed to eyes‐open: Role of cholinergic projections in EC‐to‐EO alpha reactivity revealed by combining EEG and MRI

“…Although we took steps to minimize the impact of task‐evoked activities of the preceding task block on resting state data, task‐evoked responses may not be eliminated from resting state blocks. Moreover, past work has shown that BOLD signals can be affected by a prior task even minutes after the cessation of the task (Bolt, Anderson, & Uddin, ; Yao et al, ). Fourth, some of the interpretations above are quite speculative owing to the dearth of knowledge in this area, which is partly attributable to our lack of the ability to directly manipulate pertinent variables in noninvasive human imaging.…”

Metastable neural dynamics underlies cognitive performance across multiple behavioural paradigms

“…Specifically, subjects whose resting state was similar to the taskgeneral architecture garnered the highest cognitive scores. Successful cognition is likely predicated on an adequate a priori dynamic configuration before the onset of task-relevant stimuli, as opposed to simple ad hoc adjustments after the fact (Bolt et al, 2018). Thus, resting state activity may reflect the brain's predictive engagement with the environment (Sadaghiani, 2010;Sadaghiani and Kleinschmidt, 2013;Clark, 2016).…”

“…Potential limitations of the findings presented here should be noted. Firstly, it is worth emphasising that the division of neural activity into intrinsic and task-evoked activity may be an artificial distinction and not an actual division respected by neural properties (Bolt et al, 2018). Moreover, the finding of increased metastability during task relative to rest may, to some extent, be dependent on factors related to experimental design including: (1) the time frame considered; and (2) the temporal resolution of the imaging modality used.…”