Orbitofrontalkortex-Netzwerke verantwortlich für Entscheidungssicherheit
Zusammenfassung der Projektergebnisse
How confident are you in the decision you just took? We are readily able to answer this question, providing an estimate of our certainty that the choice we made was correct. In the face of an uncertain world, humans and other animals must use their sense of confidence to guide adaptive behavior such as investment and learning. Previous work has shown that single neurons in rat orbitofrontal cortex (OFC), a sub region of frontal cortex, signal decision confidence. Different types of neurons make up the circuitry within OFC by projecting to other brain areas or locally inhibiting other neurons. The goal of this project was to determine the contribution of two major cell types in OFC to confidence-guided behavior – local inhibitory interneurons and brainstem projection neurons – thereby establishing a cortical circuit map for decision confidence. In psychophysical experiments, rats learned to make a choice about the identity of a sensory stimulus by entering a choice port, in which they had to wait for a delayed reward. Rats expressed their confidence in the choice by the amount of time they are willing to wait for a reward before leaving the choice port, providing a post-decision confidence report. I first developed quantitative models to assess to what degree rats used decision confidence to adjust investment decisions. Rats invested time close to optimality predictions, i.e., they used decision confidence to maximize reward intake. I then mapped the major projection cell types in rat OFC and found that neurons projecting to different subcortical regions are located in distinct cortical sublayers and primarily target a single area, such as neurons projecting to the ventral tegmental area, superior colliculus, and dorsal raphe. I recorded single neurons in rat OFC using tetrode drives and found that many neurons signaled decision confidence and predicted trial-by-trial time investment. Further, neurons showed diverse dynamic activity patterns that were not randomly distributed but clustered into a small set of typical response profiles that spanned the entire duration of a trial. Many neurons encoded decision confidence immediately after making a choice, irrespective of the sensory modality used to make a choice. Another group of neurons showed ramping activity during the time investment period, predicting the rats’ time investment, while different neurons sharply increased their activity just before leaving decisions. To test whether major neuronal cell type show functional specialization, I used optical tagging to identify the neuronal cell type of extracellularly recorded single neurons. Technical challenges limited these experiments to a single cell type, the major type of local inhibitory neurons expressing parvalbumin (PV). Using a transgenic rat line, I found that many PV-positive neurons became active just when rats decided to abort time investment. These neurons therefore predicted leaving decisions and encoded trial outcome. Together, this work provides evidence for a specialized cortical circuit that links confidence signals with subsequent leaving decisions driving adaptive behavior.
Projektbezogene Publikationen (Auswahl)
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2020. Behavior- and Modality-General Representation of Confidence in Orbitofrontal Cortex. Cell 182(9): 112-126e18
Masset P, Ott T, Lak A, Hirokawa J, Kepecs A
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2021. Striatal dopamine mediates hallucination-like perception in mice. Science 372(6537):1-9
Schmack K, Bosc M, Ott T, Sturgill J, Kepecs A
