Integrating Visual Psychophysical Assays within a Y-Maze to Isolate the Role that Visual Features Play in Navigational Decisions

Summary

Here, we present a protocol to demonstrate a behavioral assay that quantifies how alternative visual features, such as motion cues, influence directional decisions in fish. Representative data are presented on the speed and accuracy where Golden Shiner (Notemigonus crysoleucas) follow virtual fish movements.

Abstract

Collective animal behavior arises from individual motivations and social interactions that are critical for individual fitness. Fish have long inspired investigations into collective motion, specifically, their ability to integrate environmental and social information across ecological contexts. This demonstration illustrates techniques used for quantifying behavioral responses of fish, in this case, Golden Shiner (Notemigonus crysoleucas), to visual stimuli using computer visualization and digital image analysis. Recent advancements in computer visualization allow for empirical testing in the lab where visual features can be controlled and finely manipulated to isolate the mechanisms of social interactions. The purpose of this method is to isolate visual features that can influence the directional decisions of the individual, whether solitary or with groups. This protocol provides specifics on the physical Y-maze domain, recording equipment, settings and calibrations of the projector and animation, experimental steps and data analyses. These techniques demonstrate that computer animation can elicit biologically-meaningful responses. Moreover, the techniques are easily adaptable to test alternative hypotheses, domains, and species for a broad range of experimental applications. The use of virtual stimuli allows for the reduction and replacement of the number of live animals required, and consequently reduces laboratory overhead.

This demonstration tests the hypothesis that small relative differences in the movement speeds (2 body lengths per second) of virtual conspecifics will improve the speed and accuracy with which shiners follow the directional cues provided by the virtual silhouettes. Results show that shiners directional decisions are significantly affected by increases in the speed of the visual cues, even in the presence of background noise (67% image coherency). In the absence of any motion cues, subjects chose their directions at random. The relationship between decision speed and cue speed was variable and increases in cue speed had a modestly disproportionate influence on directional accuracy.

Introduction

Animals sense and interpret their habitat continuously to make informed decisions when interacting with others and navigating noisy surroundings. Individuals can enhance their situational awareness and decision making by integrating social information into their actions. Social information, however, largely stems from inference through unintended cues (i.e., sudden maneuvers to avoid a predator), which can be unreliable, rather than through direct signals that have evolved to communicate specific messages (e.g., the waggle dance in honey bees)¹. Identifying how individuals rapidly assess the value of social cues, or any sensory information, can....

Protocol

All experimental protocols were approved by the Institutional Animal Care and Use Committee of the Environmental Laboratory, US Army Engineer and Research and Development Center, Vicksburg, MS, USA (IACUC# 2013-3284-01).

1. Sensory maze design

1. Conduct the experiment in a watertight poly methyl methacrylate Y-maze platform (made in-house) set atop of a transparent support platform in a dedicated room. Here the platform is 1.9 cm thick and is supported by 4 7.62 cm beams of extruded aluminum that is 1.3 m in width, 1.3 m in length, and 0.19 m in height.
2. Construct the holding and decision areas to be identical in co....

Results

Hypothesis and design

To demonstrate the utility of this experimental system we tested the hypothesis that the accuracy with which Golden Shiner follow a visual cue will improve with the speed of that cue. Wild type Golden Shiner were used (N = 16, body lengths, BL, and wet weights, WW, were 63.4 ± 3.5 mm and 1.8 ± 0.3 g, respectfully). The coherency of the visual stimuli (leader/distractor r.......

Discussion

Visual cues are known to trigger an optomotor response in fish exposed to black and white gratings¹³ and there is increasing theoretical and empirical evidence that neighbor speed plays an influential role in governing the dynamical interactions observed in fish schools^{7,14,15,16,17}. Contrasting hypotheses exist to explain how individua.......

Materials

Name	Company	Catalog Number	Comments
Black and white IP camera	Noldus, Leesburg, VA, USA		https://www.noldus.com/
Extruded aluminum	80/20 Inc., Columbia City, IN, USA	3030-S	https://www.8020.net 3.00" X 3.00" Smooth T-Slotted Profile, Eight Open T-Slots
Finfish Starter with Vpak, 1.5 mm extruded pellets	Zeigler Bros. Inc., Gardners, PA, USA		http://www.zeiglerfeed.com/
Golden shiners	Saul Minnow Farm, AR, USA		http://saulminnow.com/
ImageJ (v 1.52h) freeware	National Institute for Health (NIH), USA		https://imagej.nih.gov/ij/
LED track lighting	Lithonia Lightening, Conyers, GA, USA	BR20MW-M4	https://lithonia.acuitybrands.com/residential-track
Oracle 651 white cut vinyl	651Vinyl, Louisville, KY, USA	651-010M-12:5ft	http://www.651vinyl.com. Can order various sizes.
PowerLite 570 overhead projector	Epson, Long Beach CA, USA	V11H605020	https://epson.com/For-Work/Projectors/Classroom/PowerLite-570-XGA-3LCD-Projector/p/V11H605020
Processing (v 3) freeware	Processing Foundation		https://processing.org/
R (3.5.1) freeware	The R Project for Statistical Computing		https://www.r-project.org/
Ultra-white 360 theater screen	Alternative Screen Solutions, Clinton, MI, USA	1950	https://www.gooscreen.com. Must call for special cut size
Z-Hab system	Pentair Aquatic Ecosystems, Apopka, FL, USA		https://pentairaes.com/. Call for details and sizing.