Liu C-L, Chiau H-Y, Tseng P, Hung DL, Tzeng OJL, Muggleton NG, Juan C-H. Antisaccade cost is modulated by contextual experience of location probability. J Neurophysiol 103: 1438 -1447, 2010. First published December 23, 2009 doi:10.1152/jn.00815.2009. It is well known that pro-and antisaccades may deploy different cognitive processes. However, the specific reason why antisaccades have longer latencies than prosaccades is still under debate. In three experiments, we studied the factors contributing to the antisaccade cost by taking attentional orienting and target location probabilities into account. In experiment 1, using a new antisaccade paradigm, we directly tested Olk and Kingstone's hypothesis, which attributes longer antisaccade latency to the time it takes to reorient from the visual target to the opposite saccadic target. By eliminating the reorienting component in our paradigm, we found no significant difference between the latencies of the two saccade types. In experiment 2, we varied the proportion of prosaccades made to certain locations and found that latencies in the high location-probability (75%) condition were faster than those in the low location-probability condition. Moreover, antisaccade latencies were significantly longer when location probability was high. This pattern can be explained by the notion of competing pathways for pro-and antisaccades in findings of others. In experiment 3, we further explored the degrees of modulation of location probability by decreasing the magnitude of high probability from 75 to 65%. We again observed a pattern similar to that seen in experiment 2 but with smaller modulation effects. Together, these experiments indicate that the reorienting process is a critical factor in producing the antisaccade cost. Furthermore, the antisaccade cost can be modulated by probabilistic contextual information such as location probabilities. I N T R O D U C T I O NThe saccadic eye movement system is an excellent model for studying the flexibility of human behaviors because of its extensively investigated neurophysiological basis (Basso and Wurtz 1997;Carpenter 1999;Schall 2004;Schall and Hanes 1993;Schiller and Kendall 2004; for review see Schall 2001 for review see Schall , 2009Schall and Thompson 1999). It is well known that pro-and antisaccades reflect the operation of different cognitive components. Over the last decade, researchers have shown that the saccadic eye movement system can be influenced by a wide range of cognitive factors, including attention (Baldauf and Deubel

Chiau HY, Tseng P, Su JH, Tzeng OJ, Hung DL, Muggleton NG, Juan CH. Trial type probability modulates the cost of antisaccades. J Neurophysiol 106: 515-526, 2011. First published May 4, 2011 doi:10.1152/jn.00399.2010The antisaccade task, where eye movements are made away from a target, has been used to investigate the flexibility of cognitive control of behavior. Antisaccades usually have longer saccade latencies than prosaccades, the so-called antisaccade cost. Recent studies have shown that this antisaccade cost can be modulated by event probability. This may mean that the antisaccade cost can be reduced, or even reversed, if the probability of surrounding events favors the execution of antisaccades. The probabilities of prosaccades and antisaccades were systematically manipulated by changing the proportion of a certain type of trial in an interleaved pro/antisaccades task. We aimed to disentangle the intertwined relationship between trial type probabilities and the antisaccade cost with the ultimate goal of elucidating how probabilities of trial types modulate human flexible behaviors, as well as the characteristics of such modulation effects. To this end, we examined whether implicit trial type probability can influence saccade latencies and also manipulated the difficulty of cue discriminability to see how effects of trial type probability would change when the demand on visual perceptual analysis was high or low. A mixed-effects model was applied to the analysis to dissect the factors contributing to the modulation effects of trial type probabilities. Our results suggest that the trial type probability is one robust determinant of antisaccade cost. These findings highlight the importance of implicit probability in the flexibility of cognitive control of behavior.saccade; visual attention; voluntary control IN THE EVER-CHANGING WORLD, probabilistic information relating to the surrounding environment is actively utilized by individuals to adapt their behaviors flexibly to achieve their goals. The saccadic eye movement system is an excellent model for studying the flexibility of human behavior because it is conducive to measurement in the laboratory and has been well characterized on a neurophysiological basis (Hutton 2008;Munoz and Everling 2004). The effects of prior probabilistic information on saccadic performance have been well documented. For example, gaze is directed to specific locations faster when they represent higher likelihoods of target presence based on past experience (e.g., Carpenter and Williams 1995;Gmeindl et al. 2005;Liu et al. 2010;Miller 1988;Milstein and Dorris 2007; for recent reviews see Angelaki et al. 2009;Summerfield and Egner 2009). Most importantly, this utilization of probabilistic information is not constrained at the simple stimulus-and-response level, because it can also be observed when the task requires visual analysis and response selection. Recently, Liu et al. (2010) used a central cue to indicate to participants whether they should saccade to (prosaccade) or away from ...

It is widely accepted that the supplementary eye fields (SEF) are involved in the control of voluntary eye movements. However, recent evidence suggests that SEF may also be important for unconscious and involuntary motor processes. Indeed, Sumner et al. ([2007]: Neuron 54:697-711) showed that patients with micro-lesions of the SEF demonstrated an absence of subliminal inhibition as evoked by masked-prime stimuli. Here, we used double-pulse transcranial magnetic stimulation (TMS) in healthy volunteers to investigate the role of SEF in subliminal priming. We applied double-pulse TMS at two time windows in a masked-prime task: the first during an early phase, 20-70 ms after the onset of the mask but before target presentation, during which subliminal inhibition is present; and the second during a late phase, 20-70 ms after target onset, during which the saccade is being prepared. We found no effect of TMS with the early time window of stimulation, whereas a reduction in the benefit of an incompatible subliminal prime stimulus was found when SEF TMS was applied at the late time window. These findings suggest that there is a role for SEF related to the effects of subliminal primes on eye movements, but the results do not support a role in inhibiting the primed tendency. Hum Brain Mapp 38:339-351, 2017. © 2016 Wiley Periodicals, Inc.