Gain Modulation by an Urgency Signal Controls the Speed–Accuracy Trade-Off in a Network Model of a Cortical Decision Circuit

Standage, Dominic; You, Hongzhi; Wang, Dahui; Dorris, Michael C.

doi:10.3389/fncom.2011.00007

Cited by 61 publications

(103 citation statements)

References 81 publications

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“…24) and a clear evidence-independent increase in firing rates with greater elapsed time. It has been proposed that these contextually-sensitive influences combine to form a neural urgency signal that expedites the evolving decision process by driving it closer to a fixed threshold, which translates to a dynamic criterion on evidence19222325262728.…”

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confidence: 99%

Global gain modulation generates time-dependent urgency during perceptual choice in humans

2016

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Decision-makers must often balance the desire to accumulate information with the costs of protracted deliberation. Optimal, reward-maximizing decision-making can require dynamic adjustment of this speed/accuracy trade-off over the course of a single decision. However, it is unclear whether humans are capable of such time-dependent adjustments. Here, we identify several signatures of time-dependency in human perceptual decision-making and highlight their possible neural source. Behavioural and model-based analyses reveal that subjects respond to deadline-induced speed pressure by lowering their criterion on accumulated perceptual evidence as the deadline approaches. In the brain, this effect is reflected in evidence-independent urgency that pushes decision-related motor preparation signals closer to a fixed threshold. Moreover, we show that global modulation of neural gain, as indexed by task-related fluctuations in pupil diameter, is a plausible biophysical mechanism for the generation of this urgency. These findings establish context-sensitive time-dependency as a critical feature of human decision-making.

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confidence: 99%

Global gain modulation generates time-dependent urgency during perceptual choice in humans

2016

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“…Two obvious possibilities include changes in the final firing rate or the initial firing rate of the neurons that represent evidence accumulation. A less obvious but computationally effective alternative is to adjust the total evidence needed to reach the bound through a dynamic stimulus-independent rise of the accumulators, referred to as urgency (Churchland et al, 2008; Standage et al., 2011; Thura et al, 2014). Because urgency equally increases the firing rates of neurons representing all potential choices, it reduces the total evidence that must be accumulated for committing to a choice, as if the bound had changed although the start- and end-points remain fixed.…”

Section: Resultsmentioning

confidence: 99%

Neural Mechanisms of Post-error Adjustments of Decision Policy in Parietal Cortex

Purcell

Kiani

2016

Neuron

139

184

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SUMMARY Humans often slow down after mistakes (post-error slowing, PES), but the neural mechanism and adaptive role of PES remains controversial. We studied changes in the neural mechanisms of decision-making after errors in humans and monkeys that performed a motion-direction discrimination task. We found that PES is mediated by two factors: a reduction in sensitivity to sensory information and an increase in the decision bound. Both effects are implemented through dynamic changes in the decision-making process. Neuronal responses in the monkey lateral intraparietal area (LIP) revealed that bound changes are implemented by decreasing an evidence-independent urgency signal. They also revealed a reduction in the rate of evidence accumulation, reflecting reduced sensitivity. These changes in the bound and sensitivity provide a quantitative account of choices and response times. We suggest that PES reflects an adaptive increase of decision bound in anticipation of maladaptive reductions in sensitivity to incoming evidence.

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“…In addition to BSI and decision threshold tuning, several theoretical studies have suggested that the behavioral performance can also be controlled by various mechanisms, including locus coeruleus modulated gain transients (Shea-Brown et al 2008), the urgency or timing signals (Churchland et al 2008;Hanks et al 2014;Standage et al 2011Standage et al , 2013, and common excitatory input to the decision neural populations (Furman and Wang 2008;Roxin and Ledberg 2008;Standage et al 2011). The urgency signal plays a top-down modulatory role that is similar to the BSI mechanism.…”

Section: Discussionmentioning

confidence: 99%

Speed-accuracy tradeoff by a control signal with balanced excitation and inhibition

Wang

2015

Journal of Neurophysiology

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Lo CC, Wang CT, Wang XJ. Speed-accuracy tradeoff by a control signal with balanced excitation and inhibition. J Neurophysiol 114: 650-661, 2015. First published May 20, 2015 doi:10.1152/jn.00845.2013.-A hallmark of flexible behavior is the brain's ability to dynamically adjust speed and accuracy in decision-making. Recent studies suggested that such adjustments modulate not only the decision threshold, but also the rate of evidence accumulation. However, the underlying neuronallevel mechanism of the rate change remains unclear. In this work, using a spiking neural network model of perceptual decision, we demonstrate that speed and accuracy of a decision process can be effectively adjusted by manipulating a top-down control signal with balanced excitation and inhibition [balanced synaptic input (BSI)]. Our model predicts that emphasizing accuracy over speed leads to reduced rate of ramping activity and reduced baseline activity of decision neurons, which have been observed recently at the level of single neurons recorded from behaving monkeys in speed-accuracy tradeoff tasks. Moreover, we found that an increased inhibitory component of BSI skews the decision time distribution and produces a pronounced exponential tail, which is commonly observed in human studies. Our findings suggest that BSI can serve as a top-down control mechanism to rapidly and parametrically trade between speed and accuracy, and such a cognitive control signal presents both when the subjects emphasize accuracy or speed in perceptual decisions. decision making; speed-accuracy tradeoff; top-down control; balanced input THE ABILITY TO DYNAMICALLY adjust speed vs. accuracy is a salient feature of decision-making (Bogacz et al. 2010; Gold and Shadlen 2002;Heitz 2014;Wang 2008;Wickelgren 1977): if "to get it right" is the priority, we slow down to gather more information and gain a better performance. On the other hand, if time is at a premium (e.g., when detecting a predator), we make a quick judgment at the potential cost of accuracy. Speed-accuracy tradeoff (SAT) can result from a trial-by-trial learning process, which is believed to depend on synaptic plasticity and reward information in the cortex and basal ganglia (Balci et al. 2010; Gold and Shadlen 2002;Lo and Wang 2006;Wang et al. 2013). However, adjustment can often be made quickly, "on the fly," based on either task instruction, a changing environment, or a subject's own will (Edwards 1965;Forstmann et al. 2008;Luce 1986;Palmer et al. 2005;Wickelgren 1977).SAT is commonly considered in terms of adjusting a decision threshold of an integrator (Bogacz et al. 2006;Edwards 1965), such as that described by the drift diffusion model (DDM) (Luce 1986;Ratcliff 1978). In this framework, under speed emphasis the decision threshold is decreased, so it can be reached faster to trigger a response, whereas accuracy emphasis is instantiated by an increase of the decision threshold to integrate more information before a decision is made. The idea of changing decision threshold is intuitively appealin...

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Gain Modulation by an Urgency Signal Controls the Speed–Accuracy Trade-Off in a Network Model of a Cortical Decision Circuit

Cited by 61 publications

References 81 publications

Global gain modulation generates time-dependent urgency during perceptual choice in humans

Global gain modulation generates time-dependent urgency during perceptual choice in humans

Neural Mechanisms of Post-error Adjustments of Decision Policy in Parietal Cortex

Speed-accuracy tradeoff by a control signal with balanced excitation and inhibition

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