Path Regularity Mazes

Introduction

Path Regularity Maze is a learning paradigm that investigates navigational mechanisms and the underlying orientation in honeybees. It explores maze-learning by combining four types of mazes; constant-turn maze, zig-zag maze, irregular maze, and variable irregular maze.

Bees are known to navigate through complex labyrinths by using colors or marks as symbolic indicators; however, this phenomenon has largely been investigated in vertebrates such as rats only. Shaowu, Akiko, and Mandyam (2000) have developed Path Regularity Maze to study whether honeybees possess the ability to recognize and differentiate between regular pattern mazes from the unmarked mazes of various configurations.

Path Regularity maze consists of a number of cylinders containing entrance and exit holes. A bee flying a correct path enters a cylinder through one hole and leaves through one of two exit holes. One of these holes represents the correct path and continues through the maze, while the other leads to the dead end. A bee treading the correct path flies to the final cylinder containing a reward.

Apparatus and equipment

The apparatus consists of an array of vertically-oriented cylinders (diameter: 22.5cm, height: 25cm) used as modules to construct mazes. Each cylinder has three holes (diameter: 4cm), each positioned 12.5cm above the floor. The exit holes are located at 45º to the right or left of the other direction. All cylinders are covered with transparent Perspex cover.

Training protocol

House bees in a glasshouse with the temperature maintained at 24° ±5°C during the day and 17° ±3°C at night. Mount a beehive in the glasshouse with holes allowing entry and exit into the glasshouse. For each experiment, mark and train 10 bees by carrying out reinforcements, i.e., allowing navigation through the selected maze. The experiments can be recorded with (Noldus Etho Vision® XT).

Complex Maze Learning & Navigation Training in Honeybees Using Variable Mazes

Place the reward feeder just outside the entrance to the maze and train 8-10 bees to fly toward it. Slowly move the feeder through the maze step by step (after 1h in each decision chamber). After the feeder reaches its final position, score performance of each bee in terms of choices made and the total duration of flight through the maze. Continue training for 6 hours.

Test of Bee Performance Using Constant-Turn Maze

Put the maze on a 30cm high table with castors. Allow each bee to enter the maze configured in two settings; right-turn maze and the left-turn maze. Here, the bee has to turn in one direction only to reach the exit and receive a reward on right-hand or left-hand exit.

Test of Bee Performance Using Zig-zag Maze

Here the bee has to turn alternately left and right in the series of cylinders to reach the feeder.

Test of Bee Performance Using Irregular Maze

This maze lacks a pattern and can be arranged randomly. The bee has to learn the sequence through repeated training for a fixed irregular maze. Train the bee to fly through the randomly-sequenced cylinders.

Test of Bee Performance Using Variable Irregular Maze

Allow the bee to fly through four variable irregular maze configurations in turn to reach the reward.

Analysis of Maze Navigation and Path Regularity Learning in Honeybees Using Complex Mazes

Shaowu et al. (2000) explored the ability of honeybees to navigate through mazes of various structures and symmetry. They found that bees are better at learning mazes with a regular pattern, such as a constant-turn maze. Constant-turn maze possessed a simple single rule that bees learned and mastered quickly. Where navigational algorithms were more complex, such as in the zig-zag maze, the bees had difficulty following alternations; however, they demonstrated the ability to learn the path and use it to their advantage ultimately. Irregular mazes, on the other hand, were hard to learn. Nonetheless, the trained bees were nearly as good in memorizing the irregular 6-turn sequence as they were in the zig-zag sequence. Learning and navigational performances in the variable irregular mazes were significantly poor, which was not surprising since it required both memorization of the paths of all four mazes and recognition of the type of maze the bee had entered in order to recall the appropriate memory.

Data analysis

The bee performance is evaluated by group flights into four categories:

• C1: number of flights in which a bee arrives at the feeder without making any mistakes.
• C2: number of flights in which the bee retraces path but remains on the correct path and successfully arrives at the goal.
• C3: number of flights in which a bee makes at least one wrong turn but manages to arrive at the goal within 5 min. This category is divided into three subcategories: C3a, C3b, and C3c, representing one, two, and three or more wrong turns, respectively.
• C4: number of flights in which the bee does not reach the goal within 5 min of flight, irrespective of path choice. Such bees get trapped and require entry into the maze to start anew.

C1 denotes the best performance and C4 the worst.

Other measures assessed during each task include:

• Duration of Flight: Time in seconds required to reach the feeder. Flight duration is measured as T1 (1–30 sec), T2 (31–60 sec), T3 (61–90 sec), T4 (91–120 sec), and T5 (120–300 sec).
• Bee Choice in Each Chamber: measured by plotting performance histograms.

Strengths and limitations

Strengths

Path Regularity Maze is a reliable tool to study navigational and memory patterns in honeybees. It is an amalgam of four different tests that are sufficient to gauge various aspects of honeybee performance. The four configurations of the maze with varied architecture provide a detailed look at how bees memorize, learn, and recall spatial memory.

The difficulty level of the maze increases gradually, allowing the bee to develop memory and strategic skills at its own pace. The bees are given an appropriate break after each test, which reduces the chances of stress and fatigue. Furthermore, bees are not food deprived at any stage. Hunger can affect bee performance.

Limitations

The complexity of the maze design does not allow bees to develop navigational strategies fully. In the constant-turn maze, bees had trouble flying to the goal despite the strategy requiring constant turning. The extent to which bees can develop navigational strategies and master irregular mazes needs to be further explored.

Summary

• Path regularity maze determines complex maze learning in honeybees.
• This concept has been studied in vertebrates.
• Honeybees navigate through surroundings with the help of cues and symmetry.
• Path regularity maze uses four types of maze to test complex maze learning in honeybees.
• These mazes include constant-turn maze, zig-zag maze, irregular maze and variable irregular maze.
• The honeybee enters the maze through one hole and flies to exit to receive the reward.
• The maze is developed by Shaowu et al. (2000)

References

Mizutani, A., Srinivasan, M.V., & Zhang, S. (2000). Maze Navigation by Honeybees: Learning Path Regularity. Learn Mem, 7(6), 363–374.