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analysis:task:lineartracktone [2015/01/12 21:14]
mvdm created
analysis:task:lineartracktone [2018/07/07 10:19]
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-LinearTrackTone task description,​ from the Methods section of the paper: 
-=== Overview and timeline === 
-Four male Long-Evans rats (Harlan; Mississauga,​ Canada), 6-10 months old at the beginning of behavioral 
-training, were first habituated to wearing a LED backpack, used for video tracking during behavioral sessions. 
-During this first week, rats were food- restricted such that they gradually approached approximately 
-90%, but never less than 85%, of their free-feeding weight. Next, rats were introduced to the apparatus, 
-an elevated linear track 1.8m in length with food pellet reward receptacles at both ends (Figure 1). On this 
-track, different audio cues were associated with different reward outcome distributions (described in detail 
-in the next section). Reward receptacles were equipped with photobeams, such that delays could be imposed 
-between rats nosepoking into the receptacle and the time of reward delivery. As rats learned the task, this 
-delay was gradually increased to 500ms. 
-Once rats reliably ran >100 trials in a daily 40-minute session (average 11.25 daily sessions from start of 
-track training, range 5-21 sessions), they were surgically implanted with an array of tetrodes targeting the 
-ventral striatum. Following recovery, rats were re-trained on the task. Once they were running >100 trials 
-reliably and recording electrodes reached their targets, neural data acquisition during behavior commenced 
-(average 11.5 sessions after surgery, range 6-18 sessions); at this stage video tracking relied on LEDs attached 
-to the recording headstage rather than the backpack. 
-Recording sessions with (1) at least one recording electrode in the vStr, and (2) in which rats ran at least 
-100 trials, were eligible for initial behavioral analysis (25 sessions total: 3 from R014, 7 from R016, 8 
-from R018, and 7 from R020, where R014-020 are subject IDs). As described in the Results, in 16 of 
-these 25 sessions there was behavioral evidence for successful discrimination between the reward-predictive 
-cues; neural data from these sessions only was analyzed further. All procedures were pre-approved by the 
-University of Waterloo Animal Care Committee, and performed in accordance with Canadian Council for 
-Animal Care (CCAC) guidelines. 
-=== Behavioral task === 
-The behavioral task design had two objectives: first, to elicit behavioral evidence that rats distinguished 
-between different reward outcomes, and second, to include a stereotyped period during which neural signals 
-could be compared without confounding overt behavioral differences. To accomplish both in a setting in 
-which vStr gamma oscillations have been previously found, we constructed an elevated linear track from 
-wood, painted matte black, 1.8m in length and 10cm wide. The ends of the linear track were equipped with 
-custom- built food pellet reward receptacles,​ into which rats could nosepoke to break an infrared photobeam 
-(Coulbourn; Figure 1A). 
-To trigger reward delivery, rats had to hold the nosepoke for 500ms, at which point an automated pellet 
-dispenser (Coulbourn) released a number of food pellets (described below; pellets are 45mg Test Diet 5TUL). 
-The first pellet arrived in the receptacle between 750 and 1000ms after reward delivery is triggered, resulting 
-in a period of at least 1250ms during which rats await reward delivery while stationary at the reward sites. 
-A run from one receptacle to the other was defined as a trial, which could be successful (if nosepoke held 
-for at least 500ms) or error (no nosepoke made, or withdrawn before 500ms; no reward dispensed). Only 
-successful trials were included for analysis. 
-//Figure 1: Behavioral apparatus. A: Rats shuttled back and forth on an 1.8m linear 
-track, with food pellet reward receptacles at each end. To obtain reward, rats were required to hold 
-a nosepoke for 500ms. The number of pellets received was signaled by audio cues, presented 
-when rats traversed a specific location near the center of the track (jittered by a random distance 
-of up to 15 cm on a trial by trial basis, to prevent cue onset from being predictable to the rats), 
-and played from a speaker placed behind the currently rewarded receptacle.//​ 
-The number of pellets delivered on a given trial was signaled by one of five audio cues, triggered when rats 
-entered the center zone of the track (Figure 1A). Random jitter between +15 to -15cm was added to the cue 
-presentation trigger zone on each trial, to prevent cue onset from being predictable by the rats. The five audio cues were: 
-  *  Cue 1: 2kHz tone, turning on/off at 10Hz 
-  *  Cue 2: 15kHz tone 
-  *  Cue 3: white noise 
-  *  Cue 4: 8kHz tone, amplitude-modulated with a 2Hz sine wave 
-  *  Cue 5: 3 different mixed tones (1, 2 and 4kHz) alternating at 15Hz 
-Cues were played from a speaker placed behind the currently armed receptacle, such that the average sound 
-intensity at the center of the track was measured at 75 dB. Cues remained on until either (1) an unsuccessful 
-(early unpoke) nosepoke was made, (2) one second after a successful nosepoke, or (3) the rat re-entering the 
-trigger zone in the center of the track. Each cue was associated with a different reward outcome distribution:​ 
-  *  Outcome 1: 1 pellet (100% of trials) 
-  *  Outcome 2: 3 pellets (100%) 
-  *  Outcome 3: 5 pellets (100%) 
-  *  Outcome 4: 2 pellets (50%) or 4 pellets (50%) 
-  *  Outcome 5: 1 pellet (50%) or 5 pellets (50%) 
-The mapping between audio cues to outcome distributions was counterbalanced between subjects to ensure 
-that differences in behavior between cues could not be the result of intrinsic salience or unconditioned responding 
-to specific cues. To determine if rats learned the association between cue and outcome distribution,​ 
-we computed their running speed in the ”run” epoch between cue onset and nosepoke; based on classic 
-results (e.g. Crespi 1942) we expected rats to run faster in response to the 5-pellet cue than to the 1-pellet 
-Daily training and recording sessions included two 20-minute blocks: a ”value” block and a ”risk” block. 
-During the ”value” block, outcomes with certain reward of 1 (low value), 3 and 5 (high value) pellets were 
-pseudorandomly assigned to trials with a frequency of 0.4, 0.2 and 0.4 respectively (i.e. of 100 total trials, 40 
-are 1-pellet, 20 are 3-pellet, and 40 are 5-pellet) such that the same cue could not occur more than twice in 
-succession. Similarly, the ”risk” block consisted of low risk (2 or 4 pellets, frequency 0.4), no- risk (certain 3 
-pellets, frequency 0.2) and high risk (1 or 5 pellets, frequency 0.4). The certain 3-pellet cue was included in 
-both blocks to provide a consistent reference point for tracking possible changes in behavior across blocks; 
-the comparisons of interest are between low and high value, and between low and high risk. Recording 
-sessions additionally included 5 minutes of ”off-task” recording in a separate container (a terra cotta flower 
-pot filled with towels) before and after running on the track. 
analysis/task/lineartracktone.txt · Last modified: 2018/07/07 10:19 (external edit)