A major acute function of dopamine may be to encourage gate opening (Ivry and Spencer, 2004) so that cues appropriately energize/motivate behavior (Hikosaka, 2007 and Mazzoni selleck products et al., 2007). In PD, dopaminergic medication suppresses

beta power and facilitates movement, but also causes problems including impulsivity and difficulty ignoring distracting cues (Cools et al., 2003 and Moustafa et al., 2008). Similarly, in rats, enhancement of dopamine signaling with amphetamine or apomorphine causes suppression of beta power (Berke, 2009) and abnormalities in sensorimotor gating, as assessed by prepulse inhibition of acoustic startle (Ralph-Williams et al., 2002). As one possible test of our gating hypothesis, we predict an inverse relationship between beta

power evoked by a prepulse and the startle response to the subsequent cue. All animal procedures were approved by the University of Michigan Committee on Use and Care of Animals. Each group of rats was identically food-restricted during training and behavioral testing, receiving 15 g of standard laboratory rat chow daily (in addition to rewards received during task performance). To start each trial one of the three central nose-ports was lit randomly, indicating that the rat should poke and hold its nose in that port (Figure 1B). selleck inhibitor After a variable delay, a cue tone (∼65 dB) instructed the rat to move promptly into the immediately adjacent nose-port to the left (1 kHz tone) or right (4 kHz tone). Failure to hold until cue tone onset

led to houselight illumination and a 10–15 s aminophylline timeout. Successful trials were rewarded with a 45 mg fruit punch flavored sucrose pellet at the back of the chamber. This task was identical to the immediate-GO task, except that after the instructional cue tone, the rats had to continue holding in the initial nose-port until a second “GO” cue (Gaussian white noise, 125 ms duration, intensity ∼65 dB) played. The intervals between “Nose In” and the instructional cue, as well as between the instructional and GO cues, were variable. Individual rats were tested on these tasks in separate sessions on alternating days. In both tasks, 70% of trials were “GO” trials, which were identical to the Immediate-GO task with minor exceptions (in particular, the instruction cue lasted just 50 ms). Other trials were either “NOGO” or “STOP” trials depending on the session. To encourage rats to respond as quickly as possible, on GO trials rats had to initiate the movement within a “limited hold” period (Table S1). Rats were also required to poke the adjacent port within a period tuned to the performance of each rat (termed the “movement hold”) after leaving the initial nose-port. Incorrect performance caused houselight illumination for an 8 s timeout. On NOGO trials, a white noise burst (125 ms duration) played instead of the pure tone; on STOP trials, the white noise burst played at a fixed interval (the stop-signal delay, SSD) after the pure tone (“GO” cue).