title: Neural Coding for Instruction-Based Task Sets in Human Frontoparietal and Visual Cortex.
abstract: Task preparation has traditionally been thought to rely upon persistent representations of instructions that permit their execution after delays. Accumulating evidence suggests, however, that accurate retention of task knowledge can be insufficient for successful performance. Here, we hypothesized that instructed facts would be organized into a task set; a temporary coding scheme that proactively tunes sensorimotor pathways according to instructions to enable highly efficient "reflex-like" performance. We devised a paradigm requiring either implementation or memorization of novel stimulus-response mapping instructions, and used multivoxel pattern analysis of neuroimaging data to compare neural coding of instructions during the pretarget phase. Although participants could retain instructions under both demands, we observed striking differences in their representation. To-be-memorized instructions could only be decoded from mid-occipital and posterior parietal cortices, consistent with previous work on visual short-term memory storage. In contrast, to-be-implemented instructions could also be decoded from frontoparietal "multiple-demand" regions, and dedicated visual areas, implicated in processing instructed stimuli. Neural specificity in the latter moreover correlated with performance speed only when instructions were prepared, likely reflecting the preconfiguration of instructed decision circuits. Together, these data illuminate how the brain proactively optimizes performance, and help dissociate neural mechanisms supporting task control and short-term memory storage.
authors.affiliation: Department of Experimental Psychology, Ghent University, Gent, Belgium.|Center for Cognitive Neuroscience, Duke University, Durham, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Muhle-Karbe
authors.affiliation: MRC Cognition and Brain Sciences Unit, Cambridge University, Cambridge, UK.
authors.forename: John
authors.initials: J
authors.lastname: Duncan
authors.affiliation: Department of Experimental Psychology, Ghent University, Gent, Belgium.|Department of Cognitive Neuropsychology, Tilburg University, Tilburg, The Netherlands.
authors.forename: Wouter
authors.initials: W
authors.lastname: De Baene
authors.affiliation: MRC Cognition and Brain Sciences Unit, Cambridge University, Cambridge, UK.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Mitchell
authors.affiliation: Department of Experimental Psychology, Ghent University, Gent, Belgium.
authors.forename: Marcel
authors.initials: M
authors.lastname: Brass
mesh_terms: D059031:Anticipation, Psychological / Q000502:physiology*; D001931:Brain Mapping; D056344:Executive Function / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006040:Goals; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000502:physiology*; D011930:Reaction Time; D021641:Recognition, Psychology / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
keywords: MVPA; cognitive control; frontoparietal cortex; task preparation; visual cortex; working memory