Tracking the emergence of attentional control in prefrontal cortex and hippocampus
Zusammenfassung der Projektergebnisse
Covert attentional stimulus selection is a key mechanism to prioritize neuronal processing to the most relevant stimulus before an actual behavioral choice is made by an organism. But how does neuronal circuitry identify the most relevant, i.e. most valuable, stimulus among multiple available alternatives at any moment in time ? To identify an object as behaviorally relevant, and shift attention towards it, the brain needs to integrate information about stimulus-value associations with top-down information that specifies the sensory feature and location of a target stimulus. This project showed that subdivisions of the prefrontal cortex (PFC - ventromedial prefrontal cortex (vmPFC), anterior cingulate cortex (ACC), and lateral prefrontal cortex (lPFC)) play specific functional roles in this integration. To dissociate stimulus-associated value from sensory top-down target information the location and associated value of the to be attended target stimulus was independently manipulated during the recording of extracellular activity from a large extent of the fronto-cingulate axis. The topography of stimulus valuation signals was largely separated from the topography of spatial attention effects. Stimulus associated value selectivity clustered predominantly in the ventromedial PFC, whereas spatial selectivity predicting the shift of attention was evident across the complete medial-to-lateral extent of the fronto-cingulate cortex, spanning the ACC and the LPFC. LPFC responses were enhanced for the attention contralateral condition and showed early onset selectivity. A large proportion of ACC neurons was selective for target location, and ACC responses were highly heterogeneous, with about an equal proportion of neurons whose responses were increased and decreased by attending the contralateral target. We found that neurons at the intersection of vmPFC and ACC conjunctively represented the target’s associated value and location, and that there was an interaction between their target value and target location selectivities,, suggesting a role of these neurons in integrating valuation signals with sensory top-down target information at the time of covert attentional shifts. These results illustrate that single neurons in fronto-cingulate cortex are not only monitoring outcomes, but are likewise recruited for covert shifts of the attentional focus. As such these findings strongly support reinforcement-learning and predictive coding accounts of fronto-cingulate function: Value expectancies are not only updated when newly arriving feedback violates prior expectancies, but selectively reactivate when reward predicting cues become available in the environment to guide covert stimulus selection and behavioral choice.
Projektbezogene Publikationen (Auswahl)
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(2011). Specific Contributions of Ventromedial, Anterior Cingulate, and Lateral Prefrontal Cortex for Attentional Selection and Stimulus Valuation. PLoS Biol 9(12): e1001224
Kaping, D., Vinck, M., Hutchison, R., Everling, S., Womelsdorf, T.
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(2013). Beta coherence within human ventromedial prefrontal cortex precedes affective value choices. Neuroimage
Lipsman N., Kaping D., Westendorff S., Sankar T., Lozano A.M., Womelsdorf T.
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(2014) Anterior Cingulate Cortex Cells Identify Process-Specific Errors of Attentional Control prior to transient Prefrontal-Cingulate Inhibition. Cerebral Cortex
Shen C., Ardid, S., Kaping D., Westendorff, S., Everling, S., Womelsdorf, T.
