Decisions are expedited through multiple neural adjustments spanning the sensorimotor hierarchy

• Published in: Nature communications Vol. 9; no. 1; pp. 3627 - 13
• Main Authors: Steinemann, Natalie A., O’Connell, Redmond G., Kelly, Simon P.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07.09.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 631/378/2629/1409; 631/378/2649/1409; 9/26; Accuracy; Activation; Adult; Brain; Coding; Cortex; Decision making; Decisions; Discrimination, Psychological - physiology; Electroencephalography; Electromyography; Evoked Potentials, Visual; Female; Humanities and Social Sciences; Humans; Male; Motors; multidisciplinary; Muscle contraction; Muscle, Skeletal - physiology; Muscles; Pressure; Pupil - physiology; Reaction Time - physiology; Science; Science (multidisciplinary); Sensorimotor Cortex - physiology; Sensorimotor system; Young Adult
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-06117-0

When decisions are made under speed pressure, “urgency” signals elevate neural activity toward action-triggering thresholds independent of the sensory evidence, thus incurring a cost to choice accuracy. While urgency signals have been observed in brain circuits involved in preparing actions, their influence at other levels of the sensorimotor pathway remains unknown. We used a novel contrast-comparison paradigm to simultaneously trace the dynamics of sensory evidence encoding, evidence accumulation, motor preparation, and muscle activation in humans. Results indicate speed pressure impacts multiple sensorimotor levels but in crucially distinct ways. Evidence-independent urgency was applied to cortical action-preparation signals and downstream muscle activation, but not directly to upstream levels. Instead, differential sensory evidence encoding was enhanced in a way that partially countered the negative impact of motor-level urgency on accuracy, and these opposing sensory-boost and motor-urgency effects had knock-on effects on the buildup and pre-response amplitude of a motor-independent representation of cumulative evidence. When needed, we can speed up our decisions at the expense of accuracy. Here, the authors employ a novel human electrophysiology paradigm to show that hastened decisions are implemented through multiple, fundamentally distinct neural process adjustments across the sensorimotor hierarchy.