Monetary reward speeds up voluntary saccades

Abstract

Past studies have shown that reward contingency is critical for sensorimotor learning, and reward expectation speeds up saccades in animals. Whether monetary reward speeds up saccades in human remains unknown. Here we addressed this issue by employing a conditional saccade task, in which human subjects performed a series of non-reflexive, visually-guided horizontal saccades. The subjects were (or were not) financially compensated for making a saccade in response to a centrally-displayed visual congruent (or incongruent) stimulus. Reward modulation of saccadic velocities was quantified independently of the amplitude-velocity coupling. We found that reward expectation significantly sped up voluntary saccades up to 30°/s, and the reward modulation was consistent across tests. These findings suggest that monetary reward speeds up saccades in human in a fashion analogous to how juice reward sped up saccades in monkeys. We further noticed that the idiosyncratic nasal-temporal velocity asymmetry was highly consistent regardless of test order, and its magnitude was not correlated with the magnitude of reward modulation. This suggests that reward modulation and the intrinsic velocity asymmetry may be governed by separate mechanisms that regulate saccade generation.

Reward sensitivity deficits modulated by dopamine are associated with apathy in Parkinson’s disease

“…Our next stage of analysis was to examine differences in eye movement parameters between groups. The major focus of interest was peak velocity, a marker of invigoration of response which has been shown to be sensitive to rewards in both human and monkey studies ( Chen et al , 2013 , 2014 ; Manohar et al , 2015 ). We also analysed reaction times and saccadic variability, which are discussed later.…”

“…Parkinson’s disease patients often suffer from executive deficits ( Dirnberger and Jahanshahi, 2013 ; Gratwicke et al , 2015 ). The use of physiological measures like pupillometry to index value placed on monetary incentives minimizes executive function requirements ( Hong and Hikosaka, 2008 ; Chen et al , 2014 ; Rudebeck et al , 2014 ; Manohar and Husain, 2015 ; Manohar et al , 2015 ). Our findings suggest that apathetic Parkinson’s disease patients place less value on rewards in the evaluation stage of goal-directed action.…”

“…A few recent studies have suggested that reward sensitivity might be an important component of apathy in health and disease ( Czernecki et al , 2002 ; Adam et al , 2013 ; Bonnelle et al , 2015 a , b ). Investigations in both monkeys and humans show that a simple way to measure such sensitivity is to use eye movement and pupillary indices ( Hong and Hikosaka, 2008 ; Chen et al , 2014 ; Rudebeck et al , 2014 ; Manohar and Husain, 2015 ; Manohar et al , 2015 ). We developed a novel eye-tracking paradigm to index reward sensitivity in Parkinson’s disease using saccadic and pupillary properties and sought to determine if dysfunctional reward processing contributes to clinical apathy.…”

Strategic allocation of working memory resource

“…Consider that we find minimizing the errors of our memory intrinsically rewarding. Indeed, extrinsic rewards influence the metrics of saccades in humans and monkeys (Chen, Chen, Zhou, & Mustain, 2014;Takikawa, Kawagoe, Itoh, Nakahara, & Hikosaka, 2002). For instance, extrinsic rewards affect both the velocity of saccades as well as neural activity in dopamine-associated reward circuits (Kato et al, 1995), and they modulate neural activity in cortical areas that represent the goals of saccade plans (Platt & Glimcher, 1999).…”

It Pays to Prepare: Human Motor Preparation Depends on the Relative Value of Potential Response Options

“…Shorter reaction times to rewarding stimuli indeed suggest that we prioritise the preparation of more rewarding actions. Work on humans (Chen LL et al, 2014;Manohar SG et al, 2017;Xu-Wilson M et al, 2009) and non-human primates (Bendiksby MS and Platt ML, 2006;Hikosaka O, 2007;Lauwereyns J et al, 2002;Takikawa Y et al, 2002) has shown that saccades are faster to stimuli associated with relatively larger rewards and their trajectories are biased towards previously rewarded locations (e.g. Hickey C and van Zoest W, 2012;Theeuwes J and Belopolsky AV, 2012).…”