title: Thinking about thinking: Neural mechanisms and effects on memory.
abstract: It is a well-established finding that memory encoding is impaired if an external secondary task (e.g. tone discrimination) is performed simultaneously. Yet, while studying we are also often engaged in internal secondary tasks such as planning, ruminating, or daydreaming. It remains unclear whether such a secondary internal task has similar effects on memory and what the neural mechanisms underlying such an influence are. We therefore measured participants' blood oxygenation level dependent responses while they learned word-pairs and simultaneously performed different types of secondary tasks (i.e., internal, external, and control). Memory performance decreased in both internal and external secondary tasks compared to the easy control condition. However, while the external task reduced activity in memory-encoding related regions (hippocampus), the internal task increased neural activity in brain regions associated with self-reflection (anterior medial prefrontal cortex), as well as in regions associated with performance monitoring and the perception of salience (anterior insula, dorsal anterior cingulate cortex). Resting-state functional connectivity analyses confirmed that anterior medial prefrontal cortex and anterior insula/dorsal anterior cingulate cortex are part of the default mode network and salience network, respectively. In sum, a secondary internal task impairs memory performance just as a secondary external task, but operates through different neural mechanisms.
authors.affiliation: Neurolinguistics Department, Institute of Cognitive Science, University of Osnabruck, Germany; Department of Neuropsychology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany. Electronic address: corinna.bonhage@uos.de.
authors.forename: Corinna
authors.initials: C
authors.lastname: Bonhage
authors.affiliation: Department of Clinical Psychology and Psychotherapy, University of Leipzig, Germany.
authors.forename: Friederike
authors.initials: F
authors.lastname: Weber
authors.affiliation: Department of Clinical Psychology and Psychotherapy, University of Leipzig, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Exner
authors.affiliation: Department of Social Neuroscience, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Kanske
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology*; D013850:Thinking / Q000502:physiology*; D055815:Young Adult
keywords: Attention; Cognitive self-consciousness; Default mode network; Proactive interference/ memory; Salience network; fMRI