The Ant Visual Discrimination Y-Maze is used to study visual discrimination in ants.
The Visual Discrimination Y-Maze creates a simple two-choice environment to allow the evaluation of foraging behaviors in the presence of different visual cues. The apparatus consists of a longitudinal start arm that branches into two choice arms, creating a Y-Maze wherein cues can be placed within the choice arms or at the ends of the arms.
Mazeengineers offers the Ant Visual Discrimination Y-Maze.
The Ant Visual Discrimination Y-Maze is used to study visual discrimination in ants. Ants are ecologically diverse insects that can be found habituating various environments. Thus, ants rely on different strategies, such as path integration, and cues to navigate their environment (Schwarz & Cheng, 2010). Apart from pheromone trails, visual cues also play a crucial role in navigation.
Visual discrimination assays, such as the Visual Discrimination Chamber used in rodent models, are popular in assessing visual learning and memory-related behaviors. The Ant Visual Discrimination Y-Maze creates a simple two-choice environment to allow the evaluation of foraging behaviors in the presence of different visual cues. The apparatus consists of a longitudinal start arm that branches into two choice arms, creating a Y-Maze wherein cues can be placed within the choice arms or at the ends of the arms. Studies have shown that visual learning can vary with the color, shape, and size of the visual cue, as well as the species and caste being evaluated (Fernandes, Buckley, & Nevin, 2017; Cammaerts, 2013). The Ant Visual Discrimination Y-Maze has provisions for placement of large-sized cues as well as other non-2D visual cues. The maze can also be used to study how morphological variations of the eye in different ant species affect visual perception and learning and in the assessment of choice behaviors.
Other Y-mazes used in the evaluation of choice behaviors across different animals include the Honeybee Y-maze, the Bumblebee Y-maze, the Bat Y-maze, and the Zebrafish Y-maze.
The Ant Visual Discrimination Y-Maze is a Y shaped maze made of black opaque acrylic mounted on a white Plexiglas plate. It consists of a longitudinal start arm that branches into two choice arms. All three arms of the maze measure 20 cm in length, 4 cm in width, and 4 cm in height. The two choice arms are connected to each other at an angle of 120 at the decision point. Each arm has provisions for placing either small-field visual stimuli or large-field visual stimuli. The small-field visual stimuli can be placed 4.5 cm from the decision point, while the large-field visual stimuli can be placed 20 cm from the decision point. Visual stimuli include 2D patterns and LED lights.
Clean the maze after every trial. Appropriately light the maze. A tracking and recording system such as the Noldus Ethovision XT can be used to assist with observations.
Pre-training
Conduct pre-training without the presence of visual stimuli. Place food rewards at the starting arm, decision point, and in each lateral arm. Place the subject in the starting arm and allow it to explore the maze. Select the subjects that return to the setup in less than 3-4 minutes to perform in the training phase.
Visual Discrimination Task
Place the visual cues in the respective arms along with their corresponding reinforcement stimuli (rewarded and punished stimuli). Initiate trials by placing the subject in the starting arm of the maze and observe its choice behaviors. Swap the stimuli pairings pseudo-randomly between the arms of the maze between trials. Conduct 18 consecutive trials for each subject with an inter-trial interval of 2-4 minutes.
Investigation of the effect of innate color preferences on learning and memory behaviors in ants
Yilmaz, Dyer, Rössler, and Spaethe (2017) investigated innate color preferences and learning and memory retention of Camponotus blandus. The subjects had to discriminate a combination of different monochromatic light stimuli [365 nm (ultraviolet, UV), 450 nm (blue), and 528 nm (green)] on the Ant Visual Discrimination Y-Maze. The spectral stimuli were provided by three light-emitting diodes (LEDs) mounted on a UV transparent Plexiglas plate connected to a power supply. In each trial, 3 µl of sucrose solution was provided as a reward while water was provided with the distractor stimulus. The subject’s innate color preferences were first tested, and they were presented with two monochromatic lights at various intensities. The results obtained indicated that the ants exhibited a strong innate preference for UV over blue and green stimuli. Color learning and discrimination tests were then conducted, which consisted of two different learning groups. In the first group, the ants had to discriminate between two out of three monochromatic light stimuli. Based on chromatic information only, and irrespective of intensity changes, the results indicated that although the subjects had a strong preference for UV, they learned how to discriminate blue or green stimuli from UV. However, the ants could not discriminate between the blue or green stimuli when they were presented as opposing stimuli. In the second group, the ants were tested to determine if they learned the rewarded association or simply learned to avoid UV. Testing involved the unrewarded stimulus (UV) being replaced by a novel stimulus (blue or green). It was observed that the ants failed to choose the correct arm. However, when given a choice between UV and a novel stimulus, the ants chose the novel stimulus, indicating that they learned to avoid UV light but not the rewarded stimulus. Memory tests were performed to test how long ants maintained the learned association. Results indicated that learning performance during training and memory tests did not differ.
Investigation of visual pattern discrimination of two sympatric ant species
Yilmaz, Aksoy, Camlitepe, and Giurfa (2014) investigated visual pattern discrimination of Formica cunicularia and Camponotus aethiops in the Ant Visual Discrimination Y-Maze. The two species possess apposition eyes but differ in the characteristics of their visual environment. The experiment involved discrimination between using two-small field and two large-field visual stimuli on the Ant Visual Discrimination Y-Maze. The small field stimuli included two small black triangles, one pointing upward and the other pointing downward on a white background. The large field stimuli included two black and white gratings, one horizontal and the other vertical, exceeding the back walls of the maze. Sucrose solution (2 μl) was provided with the correct visual stimulus, and a 5% quinine solution (2 μl) was provided with the incorrect visual stimulus. Results for the small field stimuli indicated that F. cunicularia learned to discriminate between the upright and downright triangle. In contrast, C. aethiops were unable to discriminate between the two visual stimuli. During the large-field stimuli testing, the horizontal and vertical gratings of the stimuli were shifted from up- to downward or left- to rightward pseudo-randomly across trials. F. cunicularia continued to learn to discriminate between the two stimuli regardless of the position of the gratings. However, C. aethiops showed a difference in performance between the horizontal and vertical gratings. Discrimination learning was better when the horizontal grating was being rewarded.
Investigation of chromatic and achromatic vision in ants
Aksoy and Camlitepe (2012) investigated behavioral responses of Formica cunicularia foragers to monochromatic spectral stimuli on the Ant Visual Discrimination Y-Maze. Each choice arm of the Y-Maze terminated in a clear perspex feeding box from which escape was prevented with a fluon barrier. Lightboxes were attached to the backside of the feeding box that delivered spectral stimuli to the maze. The subjects’ discrimination abilities between different wavelengths were tested. Experiments involved the pairing of 370 vs. 540 nm; 440 vs. 540 nm; 540 vs. 370 nm, and 640 vs. 540 nm. It was observed that the subjects could discriminate between 370 nm and 540 nm in both control and critical tests. The subjects were also able to discriminate 640 nm from 540 nm in the control test but failed in the critical test. In contrast, the subjects were unable to discriminate 440 nm from 540 nm. The subjects’ discrimination abilities between the same wavelengths having different intensities were then tested. Control tests involved spectral pairs of the same wavelengths, but the intensity of unrewarding one was reduced by 2 log units. Results indicated that the subjects could discriminate against the 2-log unit intensity difference for all wavelengths except for 640 nm. In critical tests, the 2-log unit training intensity was then decreased to 1-log unit by increasing the intensities of unrewarding ones. It was observed that the subjects failed in all wavelength pairs except 440 nm. In addition to the Y-Maze testing, the subjects’ responses to decreasing intensities of different wavelengths were also tested on an orientation platform. The orientation platform consisted of a circular plastic vessel (170 mm diameter) connected to the nest via a pipe. The subjects were trained in turn to 370, 440, 540, and 640 nm. It was observed that all wavelengths caused a significant homeward orientation response by foragers. Critical tests were then performed where intensities were reduced. It was observed that foragers continued to orient to 370 and 540 nm when the intensity decrease was 1-log and 2-log units but dispersed randomly below these values. The foragers’ significant orientation to 440 and 640 nm disappeared when their intensities were decreased by 1-log unit.
The following can be observed on the Ant Visual Discrimination Y-Maze:
Strengths
The Ant Visual Discrimination Y-Maze can be used to observe visual discrimination between two different visual stimuli in ants. Visual stimuli can vary in color, size, shape, or pattern. Large visual stimuli can be placed exceeding the extent of the maze back walls. Minimum training of the subjects is needed, which makes the testing procedure short. In addition to condition learning protocols, other behaviors such as social behaviors, reproductive behaviors, and preference behaviors can also be evaluated in the maze.
Limitations
The subject’s motivation to perform the task and its appetitive condition may affect task performance. In task involving appetitive stimuli, changes in the quantity and quality of the reward may impact performances. The presence of previous trails or other unintentional stimuli may interfere with task performance. Factors such as age, gender, and strain of the subject may affect task performances.
