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Cereb Cortex. 2015 Dec;25(12):4715-26. doi: 10.1093/cercor/bhu155. Epub 2014 Jul 17.

The Neural Representation of Voluntary Task-Set Selection in Dynamic Environments.

Author information

1
Bernstein Center for Computational Neuroscience Berlin Berlin Center for Advanced Neuroimaging SFB 940 Volition and Cognitive Control, Technische Universität Dresden, Dresden, Germany Berlin School of Mind and Brain.
2
Bernstein Center for Computational Neuroscience Berlin Psychology Department, Università Milano-Bicocca, Milan, Italy Milan Center for Neuroscience, Milan, Italy.
3
Bernstein Center for Computational Neuroscience Berlin Department of Social Neuroscience, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany Division of the Humanities and Social Sciences, California Institute of Technology, CA, USA.
4
Bernstein Center for Computational Neuroscience Berlin Berlin Center for Advanced Neuroimaging Cluster of Excellence NeuroCure Department of Neurology, Charité - Universitätsmedizin Berlin, Berlin, Germany SFB 940 Volition and Cognitive Control, Technische Universität Dresden, Dresden, Germany Berlin School of Mind and Brain Department of Psychology, Humboldt-Universität zu Berlin, Berlin, Germany.

Abstract

When choosing actions, humans have to balance carefully between different task demands. On the one hand, they should perform tasks repeatedly to avoid frequent and effortful switching between different tasks. On the other hand, subjects have to retain their flexibility to adapt to changes in external task demands such as switching away from an increasingly difficult task. Here, we developed a difficulty-based choice task to investigate how subjects voluntarily select task-sets in predictably changing environments. Subjects were free to choose 1 of the 3 task-sets on a trial-by-trial basis, while the task difficulty changed dynamically over time. Subjects self-sequenced their behavior in this environment while we measured brain responses with functional magnetic resonance imaging (fMRI). Using multivariate decoding, we found that task choices were encoded in the medial prefrontal cortex (dorso-medial prefrontal cortex, dmPFC, and dorsal anterior cingulate cortex, dACC). The same regions were found to encode task difficulty, a major factor influencing choices. Importantly, the present paradigm allowed us to disentangle the neural code for task choices and task difficulty, ensuring that activation patterns in dmPFC/dACC independently encode these 2 factors. This finding provides new evidence for the importance of the dmPFC/dACC for task-selection and motivational functions in highly dynamic environments.

KEYWORDS:

fMRI; multivariate decoding; prefrontal cortex; task difficulty; task-set

PMID:
25037922
DOI:
10.1093/cercor/bhu155
[Indexed for MEDLINE]

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