DOI: 10.5061/dryad.pg4f4qrmf
title: Dopamine axon population Ca signals in the striatum during odor cue- and reward-based choice tasks in mice

description: Dopamine axon activity in the ventral, dorsomedial, and dorsolateral
 striatum was recorded, while mice performed a perceptual and value-based
 decision-making task. In one experiment, thirsty mice performed a
 perceptual decision-making task using mixtures of odor A and B (100/0,
 90/10, 65/35, 35/65, 10/90, 0/100), in which identity of a dominant odor
 determined an available water port, and odor C which signaled no outcome.
 A fixed amount of water was always delivered with a correct choice. In the
 next experiment, mice performed a perceptual and value-based
 decision-making task using mixtures of odor A and B (100/0, 65/35, 35/65,
 0/100), in which identity of a dominant odor determined an available water
 port, with probabilistic water reward. In this task, a fixed amount of
 water was delivered in block 1, and then in block 2, one water port
 delivered big or medium size of water in a pseudo-random order, and
 another water port delivered medium or small size of water in a
 pseudo-random order. In both tasks, odor-water port (left or right) rule
 was held constant throughout training and recording in each animal.
description: Fiber fluorometry (photometry) was performed as previously
 reported (Menegas et al., 2018) with a few modification. The optic fiber
 (400 µm diameter, Doric Lenses) allows chronic, stable, minimally
 disruptive access to deep brain regions and interfaces with a flexible
 patch cord (Doric Lenses, Canada) on the skull surface to simultaneously
 deliver excitation light (473 nm, Laserglow Technologies, Canada; 561 nm,
 Opto Engine LLC, UT) and collect GCaMP and tdTomato fluorescence
 emissions. Activity-dependent fluorescence emitted by cells in the
 vicinity of the implanted fiber’s tip was spectrally separated from the
 excitation light using a dichroic, passed through a single band filter,
 and focused onto a photodetector connected to a current preamplifier
 (SR570, Stanford Research Systems, CA). During recording, optic fibers
 were connected to a magnetic patch cable (Doric Lesnses, MFP_400/430)
 which delivered excitation light (473 nm and 561 nm) and collected all
 emitted light. The emitted light was subsequently filtered using a 493/574
 nm beam-splitter (Semrock, NY) followed by a 500 ± 20 nm (Chroma, VT) and
 661 ± 20 nm (Semrock, NY) bandpass filters and collected by a
 photodetector (FDS10x10 silicone photodiode, Thorlabs, NJ) connected to a
 current preamplifier (SR570, Stanford Research Systems, CA). This
 preamplifier output a voltage signal which was collected by a NIDAQ board
 (National Instruments, TX) and Labview software (National Instruments,
 TX). To synchronize behavioral events and
 fluorometry signals, TTL signals were sent every 10 s from a computer that
 was used to control and record task events using Labview, to a NIDAQ board
 that collects fluorometry voltage signals. GCaMP and tdTom signals were
 collected as voltage measurements from current preamplifiers. Green and
 red signals were cleaned by removing 60Hz noise with bandstop FIR filter
 58-62Hz and smoothing with moving average of signals in 50ms. The global
 change within a session was normalized using a moving median of 100s.
 Then, the correlation between green and red signals during ITI was
 examined by linear regression. If the correlation is significant
 (p&lt;0.05), fitted tdTom signals were subtracted from green
 signals. Mice were first trained only with
 pure odors and with the same amounts of water reward (~6 ul). After mice
 achieved greater than 90% accuracy, mice received a surgery for viral
 injection and fiber implantation. Following a 1-week recovery period, mice
 received re-training and then, mixtures of odor A and B (100/0, 90/10,
 65/35, 35/65, 10/90, 0/100) were gradually introduced. After the accuracy
 of all the mixture odors achieved more than 50%, neuronal recording with
 fiber fluorometry was performed for 5 sessions. Subsequently, a task with
 different amounts of water was introduced. Mixtures of odor A and B
 (100/0, 65/35, 35/65, 0/100) but no odor C were used in this task. Each
 recording session started with 88-120 trials with an equal amount of water
 (~6 ul, the standard amount) in the first block to calibrate any potential
 bias on the day. In the second block, different amounts of reward were
 delivered in each water port. In order to make the water amounts
 unpredictable, one water port delivered big or medium size of water (2.2
 and 0.8 times of the standard, ~13.2 and 4.8 ml, BIG side) in a
 pseudo-random order, and another water port delivered medium or small size
 of water (0.8 and 0.2 times of the standard, ~4.8 and 1.2 ml, SMALL side)
 in a pseudo-random order. Block 2 continued for 200 trials or until the
 end of recording sessions, whichever came earlier. A mouse performed 134.3
 ± 3.4 (mean ± SEM) trials in block 2. The water condition (BIG or SMALL)
 was assigned to a left or right water port in a pseudo-random order across
 sessions. Recording was conducted for 40 min every other day to avoid
 potential bleaching. On days with no recording, animals were trained with
 pure odors A and B with the standard amount of water.