Developing an automated apparatus for continual trials recognition memory in rodents

Spontaneous recognition tasks are widely used as a laboratory measure of different memory types in animals. These studies are often run such that only one trial a day is collected for each rodent, with the animal being handled during delays (whilst objects are being changed) and between trials (which are typically run on different days), increasing anxiety in the animals and affecting reproducibility of the data. This leads to high levels of behavioural noise which results either in the use of large numbers of animals to produce sufficient statistical power or ambiguous results that can be misinterpreted.

Dr Alex Easton (Durham University), together with Campden Instruments (a commercial developer of behavioural testing equipment) has developed the semi-automated continual trials apparatus that includes a testing chamber in which the animal can explore objects and a holding chamber where the animal rests undisturbed whilst objects are changed. An automatic door opens between the two chambers to allow the animal to shuttle between them without being handled. The apparatus also incorporates a camera to capture the animal’s behaviour throughout its time in the testing chamber for scoring later and a prototype behaviour scoring app. The apparatus allows the use of substantial (24h) delays between sample phase (familiarisation with objects) and test phase (introduction of novel object), whilst retaining the benefits of the continual trials approach, by running all sample phases on day 1 and all test phases on day 2.

Having validated the effectiveness of the technology in both rats and mice on object recognition and object location memory, Dr Alex Easton sought collaborators to expand the application of the apparatus. With the support of CRACK IT Solutions funding Alex and Campden Instruments are now working with researchers across four universities (St Andrews University, University of Edinburgh, Open University and Bristol University) to:

• Assess the potential for running multiple apparatus simultaneously.
• Increase the amount of data extracted from a session using the integrated camera.
• Improve data scoring.
• Develop the apparatus for use in different experimental settings such as electrophysiology or optogenetic experiments.

The apparatus provides a marked refinement in procedure, as animals do not undergo handling between or within trials. The reduced handling and reduced inter-animal variability makes performance more reliable, reducing the number of animals required to achieve statistical significance in studies of spontaneous recognition. In both rats and mice, the researchers have shown that they can reduce the number of animals required for standard tasks from 16 animals per group to eight. This has reduced the number of animals used in their research group by approximately 100 animals in the last three years. The apparatus also provides a marked refinement in procedure, as animals do not undergo handling between or within trials.