Corticosterone measurements indicates a growing stress in the animal for each timepoints, with peaks at fear acquisition (T1) and fear teasting (T3) and a drop 24 hours after acquisition (T2). Unfortunately, physiological stress response does not predict fearful behavioural response, as shown by other studies. Therefore, no correlation between the behavioural fear reaction and a physiological stress reaction.


Rats exhibited freezing after one month from fear acquisition, in comparison to one week which was the previous experimental procedure. This shows that rats are capable of resurfacing a fear memory even after a long period of time. Rats also exhibited freezing behaviour majorly in the aftermath of the tone, showing that the conditioning does work as anticipation of the shock. As a response, the animal does not leave the freezing position even after the tone. Furthermore, the inclusion of additional behaviours showed vigilant behaviours as indicative of imminent freezing, sometimes acting as a substitute reaction.

Operant supression

The administration of saccharine as a replacement for alcohol was successful, with the rats learning the operant behaviour within the allocated time. As for the suppression ratio, both the shock intensity and the injections of diazepam had an effect on it: for the shock, a higher intensity would cause a major suppression. On the other hand, a greater concentration of diazepam tamper the suppression ratio, reducing it.

The conducted study served as ground work for subsequent molecular analysis of the neural circuits revolving around fear memory in rats. A face -recognition AI-based software is being developed to fasten the behavioural scoring, that otherwise take great portions of time to be made. The behavioural scoring done in this experiment will be fed to the software for machine learning.

If you want to learn more about my project, click for the last time on the right button to access the project manuscript, a poster summarising the project and my thesis presentation. Thank you for reading