Visual intensity ratio modulates operant learning responses in larval zebrafish

Abstract

13Larval zebrafish is a promising vertebrate model for understanding neural 14 mechanisms underlying learning and memory. Here, we report on a high-throughput 15 operant learning system for zebrafish larvae and demonstrate that lower visual 16 intensity ratio of the conditioned stimulus to the background can enhance learning 17 ability, highlighted by several behavioral metrics. We further characterize the learning 18 curves as well as memory extinction for each conditioned pattern. Finally, we show 19 how this learning process developed from 7 days old to 10 days old zebrafish. 20 Highlights 21  Conditioned visual patterns with lower intensity ratio to the background elicited 22 stronger operant learning responses 23  Memory extinction was modulated by the visual intensity ratio of the conditioned 24 stimulus to the background 25  A high-throughput automated system for acquiring and analyzing behavioral data 26 27 2 Material and Methods 61 2.1 Ethical statement of animals-using 62 Handling and care of all animals were conducted in strict accordance with the 63 guidelines and regulations set forth by University of Science and Technology of 64 China (USTC) Animal Resources Center, and University Animal Care and Use 65 Committee. Both raising and training protocols were approved by the Committee on 66 the Ethics of Animal Experiments of the USTC (permit number: 67 USTCACUC1103013). 68 2.2 Animals and raising 69 Zebrafish (Danio rerio) of the genotype huc:h2b-gcamp6f were used in all 70 experiments. All tested fish were from 7 to 10 dpf (day past fertilization) larvae. They 71 were bred, raised and housed in the same environment. Fish were fed two times per 72 day from 6 dpf with paramecium in the morning (8-9 A.M.) and evening (6-7 P.M.) 73 until used in the experiments. Water was replaced with E2 medium (Cunliffe, 2003) 74 in the morning (8-9 A.M.) and evening (6-7 P.M.). Water temperature was maintained 75 at 28.5 °C. Illumination was provided by fluorescent light tubes from the ceiling with 76 lights turned on at 08:00 A.M. and off at 10:00 P.M. 77 2.3 Experimental Setup 78 The behavioral system with custom software suites and supported hardware were built 79 to achieve an end-to-end high-throughput experimental workflow. (Figure 1A) 80 2.3.1 Hardware 81Zebrafish swam freely in custom-built acrylic containers with transparent bottoms. 82Each container was divided into four arenas separated by opaque walls. The arena's 83 size is 3 cm × 3 cm × 1 cm, with water filled (Fig. S2.a). Each arena held one fish. 84 Three CMOS cameras (Basler aca2000-165umNIR, Germany) with adjustable lens 85 (Canon, Model EF-S 18-55mm f/3.5-5.6 IS II, Japan) simultaneously captured 86 swimming behavior at ten frames per second. Three infrared LED light sources 87 (Kemai Vision, China, model HF-FX90, wavelength 940 nm) illuminated each 88 container from below. A 700 nm long-pass filter (Thorlabs FEL0700, US.) was 89 positioned in front of each camera to block visible light to facilitate online imaging 90 processing with custom soft...

From Stimulus to Behavioral Decision-Making

“…One of the authors also thank the Neuroscience Pioneer Club (NPC) for inspiring discussions. This manuscript has been released as a pre-print at BioRxiv (Yang W. et al, 2018).…”

Visual Contrast Modulates Operant Learning Responses in Larval Zebrafish

“…One of the authors also thank the Neuroscience Pioneer Club (NPC) for inspiring discussions. This manuscript has been released as a pre-print at BioRxiv (Yang W. et al, 2018).…”