This shows you the differences between two versions of the page.
analysis:task:lineartracktone [2015/01/12 21:42] mvdm |
analysis:task:lineartracktone [2018/07/07 10:19] |
||
---|---|---|---|
Line 1: | Line 1: | ||
- | ==== 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. | ||
- | |||
- | {{:analysis:task:lineartracktone_figure1.png?600|}} | ||
- | |||
- | //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 | ||
- | cue. | ||
- | |||
- | 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. | ||
- | |||
- | ==== Metadata fields ==== | ||
- | |||
- | * FeederLocation: (x,y) video tracker coordinates with location of reward sites (feeders) | ||
- | * TimeOnTrack1, TimeOffTrack1: times (in seconds, on same timebase as spike and CSC data) on track for value block; TimeOnTrack2 and TimeOffTrack2 same but for risk block | ||
- | * All other fields are times of corresponding event | ||