Understanding the neural mechanisms of memory is key to being able to produce effective treatment of memory loss in an ageing population, as well as in diseases such as Alzheimer's disease. A common task used in laboratory animals, both in research and in drug development, is spontaneous object recognition. This task assesses the innate preference of animals for exploring novel items over familiar items, in order to determine their memory for objects they have seen before. The task is easy and quick to administer and requires no special training as it relies on normal exploratory behaviour. However, whilst the use of this task is increasingly common, it has the disadvantage of requiring relatively large numbers of animals in order to produce reliable data because of the normal variability between animals in exploration of objects.
Researchers at Durham University, with funding from the NC3Rs, have developed a modification of this widely used memory task - the continual trials apparatus. Using this new apparatus, Dr Easton and colleagues showed that rats can be assessed for their memory of multiple objects over several consecutive trials. This improves the reliability of the data gained from each animal, and therefore reduces the number of animals required to produce meaningful data from the task.
The work, recently published in the Journal of Neuroscience Methods, indicates that the number of animals required in the task can be reduced from the typical group size of 12-20 animals in current experiments to between 4 and 6 using the new methodology. The authors calculate that over the past five years the new apparatus could have reduced the number of animals required in published experiments using this task by over 15,000. As the task is also widely used for screening of new drugs, the possibility of reducing animal use in these tasks is even greater.
The recently published paper also shows that the new methodology can be applied to more sophisticated tasks of memory with a similar reduction in animal numbers, meaning a range of studies worldwide could benefit from the new approach, helping to reduce animal usage whilst improving understanding of the mechanisms of memory.
Dr Easton's team is continuing to develop the task in order to determine whether the same reduction in animals can be made in an even wider range of behavioural tasks, as well as utilising the new methodology to develop their own work on understanding the role of structures in the medial temporal lobe in memory.
Picture (left) of the continual trials apparatus. The rat starts each trial in the centre of the black part of the apparatus before a central door opens and it can explore objects in the grey part of the arena. After a period of exploration, it returns to the black area (though side doors) to await the start of the next trial.
The apparatus (right) has multiple test environments arranged at 90 degrees to each other which can be slotted into place between trials, whilst the rat
waits in the black area. This allows more complex tasks to be run assessing memory for more than just objects, whilst still allowing multiple trials to be run in a single session.
Ameen-Ali KE, Eacott MJ, Easton A (2012) A new behavioural apparatus to reduce animal numbers in multiple types of spontaneous object recognition paradigms in rats. Journal of Neuroscience Methods 211 (1): 66-76