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- Adams, Rick A., et al.
(author)
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Variability in Action Selection Relates to Striatal Dopamine 2/3 Receptor Availability in Humans : A PET Neuroimaging Study Using Reinforcement Learning and Active Inference Models
- 2020
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In: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 30:6, s. 3573-3589
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Journal article (peer-reviewed)abstract
- Choosing actions that result in advantageous outcomes is a fundamental function of nervous systems. All computational decision-making models contain a mechanism that controls the variability of (or confidence in) action selection, but its neural implementation is unclear-especially in humans. We investigated this mechanism using two influential decision-making frameworks: active inference (AI) and reinforcement learning (RL). In AI, the precision (inverse variance) of beliefs about policies controls action selection variability-similar to decision 'noise' parameters in RL-and is thought to be encoded by striatal dopamine signaling. We tested this hypothesis by administering a 'go/no-go' task to 75 healthy participants, and measuring striatal dopamine 2/3 receptor (D2/3R) availability in a subset (n = 25) using [C-11]-(+)-PHNO positron emission tomography. In behavioral model comparison, RL performed best across the whole group but AI performed best in participants performing above chance levels. Limbic striatal D2/3R availability had linear relationships with AI policy precision (P = 0.029) as well as with RL irreducible decision 'noise' (P = 0.020), and this relationship with D2/3R availability was confirmed with a 'decision stochasticity' factor that aggregated across both models (P = 0.0006). These findings are consistent with occupancy of inhibitory striatal D(2/3)Rs decreasing the variability of action selection in humans.
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| 2. |
- Engel, Andreas K., et al.
(author)
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Introduction Where's the Action?
- 2015
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In: PRAGMATIC TURN. - : MIT PRESS. - 9780262034326 ; , s. 1-
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Conference paper (peer-reviewed)abstract
- Cognitive science is witnessing a pragmatic turn away from the traditional representation-centered framework of cognition toward one that focuses on understanding cognition as being "enactive." The enactive view holds that cognition does not produce models of the world but rather subserves action, as it is grounded in sensorimotor skills. The conclusions of this Ernst Strungmann Forum suggest that strong conceptual advances are possible when cognition is framed by an action-oriented paradigm. Experimental evidence from cognitive science, neuroscience, psychology, robotics, and philosophy of mind supports this position. This chapter provides an overview of the discourse surrounding this collaborative effort. Core topics which guided this multidisciplinary perusal are identified and challenges that emerged are highlighted. Action-oriented views from a variety of disciplines have started to cross-fertilize, thus promoting an integration of concepts and creating fertile ground for a novel theory of cognition to emerge.
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