• Octopamine and initial fear response

In species such as beetles, spiders, and crickets, octopamine manipulation decreased the magnitude of the initial fear response. In my study, this was not observed. This discrepancy could be explained by different threats used to induce the fear response. It is thought that threats could exist within a hierarchy, hence the stimulus I used to induce the fear response may not have been so threatening to shift the fear response. Another explanation could be related to the link between octopamine and fear response being more complex than expected, with species differences.

  • Octopamine and repeated fear responses

The role of octopamine on changes in fear responses to repeated stimuli has never been investigated before. Hence, this is the first study that observes octopamine increasing the fear response to repeated stimuli inducing sensitisation. Octopamine could increase the overall responsiveness to stimuli, similarly to glucocorticoids, or underlying the process of sensitisation, which has been associated only with serotonin.

  • Personality and fear response

Boldness has been linked to variation in fear response in other species of invertebrates. This link was also found in my study, with further interesting results showing individuals with different personalities responding differently to octopamine manipulation. Boldness could be linked with cognition, with bolder individuals interpreting environmental information differently from shyer individuals, resulting in using different types and magnitude of fear responses. This result suggests that personality has to be considered to study fear responses.

Picture by Kristoffer Lundgren.