RT Journal Article
SR Electronic
T1 Representation of task episodes in human cortical networks
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 582858
DO 10.1101/582858
A1 Tanya Wen
A1 John Duncan
A1 Daniel J Mitchell
YR 2019
UL http://biorxiv.org/content/early/2019/03/21/582858.abstract
AB Task episodes consist of sequences of steps that are performed to achieve a goal. The current study used fMRI to examine which regions of the brain represent full episodes, items, and current step. Participants learned 6 tasks each consisting of 4 steps. Inside the scanner, participants were cued which task to perform and then sequentially identified the target item of each step in the correct order. The multiple demand (MD) network and the visual cortex exhibited phasic responses to each task step, suggesting that they are sensitive to the fine structure of the episode. In contrast, default mode (DMN) regions showed a phasic response predominantly to onset of the entire task episode. Beyond these phasic responses, gradually increasing activity across each task episode was seen throughout most of the brain. Representational similarity analysis of episode and item coding revealed a significant dissociation between MD and DMN networks. Compared to MD regions, which showed strong coding of individual items but not the entire episode, the DMN showed representation of both item and episode, with coding for the episode localized to the parahippocampal cortex. The data hint that the most abstract level of task structure may be encoded in medial frontal cortex.