Terminology
Place memory When an animal can remember the location of something (eg food, nest).
Visual cues Symbols or landmarks that the animal can see and recognise.
Gryllus bimaculatus
Trial
Morris water maze
A species of cricket.
Each time the experiment was run.
A popular experimental method. In brief, a rat is placed in a pool of water (2 metres in diameter) and has to swim until it finds a hidden platform that it can stand on. Each time the rat is subsequently put in the pool it finds the platform faster because it remembers where it is.
Ablation Removal (often by chemical means).
Mushroom body neuropils A specific region for learning and memory in the insect brain.
Paper summary
In this paper the authors tested a large number of crickets for place memory.
This involved placing a single cricket each time in an arena with a heated floor that had one cold spot. The walls of the arena contain symbols (visual cues) that the cricket can learn and remember. The cricket finds the heated floor unpleasant and moves around the arena until it finds the cool spot to stand on. When the same cricket is placed in the arena for a second, third, fourth, etc time it can look at the symbols on the walls and use them as a navigational guide to remember where the cool spot is in relation to them.
In addition to measuring the time taken for the cricket to reach the cool spot each time, the authors recorded the path around the arena taken by the cricket and the time each cricket spent ‘wall following’. The wall-following behaviour could be
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viewed as the cricket trying to escape and not actually trying to find the cool spot. The paths were useful in demonstrating how directly (or not) the cricket approached the cool spot target.
The authors then performed rotation trials. These involved placing the cricket in the arena as normal and letting it search for the cool spot. However , on second exposure to the arena the walls were rotated 180 ° so that the visual cues were no longer indicating the accurate position of the cool spot. Crickets were then tested to see if they went to the place they remembered the cool spot to be (fictive), to the actual cool spot (original) or a random cool spot.
The results showed that the cricket can successful ly use visual cues to locate the cool spot target. Even when the arena walls were rotated the cricket initially targeted the position it thought the cool spot should be.
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© Learning and Teaching Scotland 2011