Inaccurate saccades within the deadline had no time out. However, monkeys had difficulty discriminating lack of reward from an inaccurate saccade and lack of reward from slow responding. Hence, the display was removed on 25%–50% of missed-deadline trials. Monkeys quickly learned that reinforcement was only available prior to this time. All patterns of results and conclusions were unchanged by these trials. Monkeys respected the response deadlines (proportion of missed deadlines: Q Accurate: 0.18, Fast: 0.16; S Accurate: 0.19, Fast: 0.13). Some sessions included only the Fast and BAY 73-4506 manufacturer Accurate conditions; for that

reason, variability should be expected to be higher in the Neutral condition. We recorded neurons in FEF, located on the anterior bank of the arcuate sulcus, using tungsten microelectrodes (2–4 MΩ, FHC) referenced to a guide tube in contact with the dura. Location was verified by evoking eye movements though low-threshold (<50 μA) microstimulation. The number of electrodes lowered on a given session ranged from one to eight. Single-unit waveforms were isolated online, sampled at 40 kHz, and resorted offline (Offline Sorter; Plexon). All surgical and experimental procedures were in accordance with the National Institutes of Health Guide for the

Care and Use of Laboratory Animals and approved by the Vanderbilt Institutional Animal Care and Use Committee. Stem Cell Compound Library cell line Neurons are categorized into three major types: visual, visuomovement, Thiamine-diphosphate kinase and movement. Though classification

operates along a continuum, many observations demonstrate that these populations are functionally distinct (Cohen et al., 2009; Ray et al., 2009; Gregoriou et al., 2012). Visual neurons increase discharge rates significantly immediately after array presentation but have no saccade-related modulation. Movement neurons increase discharge rate significantly before saccade initiation but have no visual response. Visuomovement neurons exhibit both periods of modulation. To classify neurons, we used activity from a memory-guided saccade task. To test for visual responses, we used t tests to compare the average activity in the interval 75–100 ms after target presentation to the activity in the 100 ms interval preceding target presentation. To test for presaccadic activity, we used t tests to compare the average activity in the 100 ms interval before saccade initiation to the activity in the interval 500–400 ms before saccade initiation. To determine when neurons responded differently to two SAT conditions or when the target as compared to distractors appeared in the RF, we computed ms-by-ms Wilcoxon rank-sum tests, evaluating the null hypothesis that target-in-RF activity was significantly different from distractor-in-RF activity. Target selection time (TST) was the first of ten successive time points significant at the p < 0.01 level. Population TST was computed using jackknifing.