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Citation |
Blangero A, Kelly SP. J. Neurosci. 2017; 37(44): 10725-10737. |
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Affiliation |
School of Electrical and Electronic Engineering, University College Dublin, Dublin, Ireland. |
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Copyright |
(Copyright © 2017, Society for Neuroscience) |
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DOI |
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PMID |
28982706 |
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Abstract |
In situations where impending sensory events demand fast action choices, we must be ready to prioritize higher-value courses of action in order to avoid missed opportunities. When such a situation first presents itself, stimulus-action contingencies and their relative value must be encoded in order to establish a value-biased state of preparation for an impending sensorimotor decision. Here we sought to identify neurophysiological signatures of such processes in the human brain (both female and male). We devised a task requiring fast action choices based on the discrimination of a simple visual cue, in which the differently-valued sensory alternatives were presented 750-800 msec beforehand as peripheral "targets" that specified the stimulus-action mapping for the upcoming decision. In response to the targets, we identified a discrete, transient, spatially-selective signal in the event-related potential (ERP), which scaled with relative value and strongly predicted the degree of behavioral bias in the upcoming decision both across and within subjects. This signal is not compatible with any hitherto known ERP signature of spatial selection, and also bears novel distinctions with respect to characterizations of value-sensitive, spatially-selective activity found in sensorimotor areas of non-human primates. Specifically, a series of follow-up experiments revealed that the signal was reliably invoked regardless of response laterality, response modality, sensory feature, and reward valence. It was absent, however, when the response deadline was relaxed and the strategic need for biasing removed. Thus, more than passively representing value or salience, the signal appears to play a versatile and active role in adaptive sensorimotor prioritization.SIGNIFICANCE STATEMENTIn many situations such as fast-moving sports, we must be ready to act fast in response to sensory events, and in our preparation, prioritize courses of action that lead to greater rewards. Although behavioral effects of value-biases in sensorimotor decision making have been widely studied, little is known about the neural processes that set these biases in place beforehand. Here we report the discovery of a transient, spatially-selective neural signal in humans, which encodes the relative value of competing decision alternatives and strongly predicts behavioral value biases in decisions made ∼500 ms later. Follow-up manipulations of value differential, reward valence, response modality, sensory feature and time constraints, establish that the signal reflects an active, feature- and effector-general preparatory mechanism for value-based prioritization. Language: en |