Hernández-Navarro, LluísHermoso Mendizábal, AinhoaDuque, DanielDe la Rocha, JaimeHyafil, Alexandre2023-06-202023-06-202021Hernández-Navarro L, Hermoso-Mendizabal A, Duque D, de la Rocha J, Hyafil A. Proactive and reactive accumulation-to-bound processes compete during perceptual decisions. Nat Commun. 2021;12:7148. DOI: 10.1038/s41467-021-27302-82041-1723http://hdl.handle.net/10230/57272Standard models of perceptual decision-making postulate that a response is triggered in reaction to stimulus presentation when the accumulated stimulus evidence reaches a decision threshold. This framework excludes however the possibility that informed responses are generated proactively at a time independent of stimulus. Here, we find that, in a free reaction time auditory task in rats, reactive and proactive responses coexist, suggesting that choice selection and motor initiation, commonly viewed as serial processes, are decoupled in general. We capture this behavior by a novel model in which proactive and reactive responses are triggered whenever either of two competing processes, respectively Action Initiation or Evidence Accumulation, reaches a bound. In both types of response, the choice is ultimately informed by the Evidence Accumulation process. The Action Initiation process readily explains premature responses, contributes to urgency effects at long reaction times and mediates the slowing of the responses as animals get satiated and tired during sessions. Moreover, it successfully predicts reaction time distributions when the stimulus was either delayed, advanced or omitted. Overall, these results fundamentally extend standard models of evidence accumulation in decision making by showing that proactive and reactive processes compete for the generation of responses.application/pdfeng© The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/ licenses/by/4.0/info:eu-repo/semantics/articlehttp://dx.doi.org/10.1038/s41467-021-27302-8Computational neuroscienceDecisionMotor controlSensory processinginfo:eu-repo/semantics/openAccess