Selection for action in fruit fly

The mechanism of action selection is a widely shared fundamental process required by animals to interact with the environment and adapt to it. A key step in this process is the filtering of many "distracting" sensory inputs which may disturb action selection. Because it has been suggested that, beyond sharing common mechanisms, action selection may also be processed by shared circuits in vertebrates and invertebrates we wondered whether invertebrates showed the ability to filter out "distracting" stimuli to maintain a goal directed action, as seen in vertebrates. Therefore, we studied action selection in wild-type Drosophila melanogaster, by investigating their reaction to the abrupt appearance of a visual distractor during an ongoing locomotor action directed to a specific visual target. We found that flies tended to shift the original trajectory towards the distractor, thus acknowledging it's presence, but did not appear to commit to it, suggesting that an inhibition process took place in order to continue to carry out the original goal-directed action. To some extent flies appeared to take into account the level of salience of the abrupt distractor appearance as a basis for the ensuing motor program. However, they did not engage in a complete change in their initial motor program in favour of the distractor. These results provide interesting insights into the selection-for-action mechanism, in a context requiring action-centered attention which might have appeared rather early in the course of evolution.