Characterization of the activity of lobula columnar elements evoked by different parameters of visual stimulation that influence evasive behaviour in crabs.

BERÓN DE ASTRADA M; BENGOCHEA M; OLIVA D

Montevideo

Congreso; XII Congress International Society for Neuroethology; 2016

Object motiondetection provides essential cues for a wide variety of behaviors such as mate,prey, or predator detection. In insects and decapod crustaceans, encoding ofobject motion is associated to visual processing in the third retinotopic opticneuropil, the lobula. Due to the thin caliber of the small-field lobulacolumnar neurons, almost all we know about object motion detection arises fromstudies on their postsynaptic and larger lobula output neurons. Here we usedcalcium imaging to study the activity of the columnar neurons that feed ontothe crab?s lobula when stimulated by different parameters of object motion. Wepresented vertical edges translating horizontally that varied in speed,contrast and direction of motion. The high-speed edges produced the strongestcalcium responses; the dark edges evoked greater responses than the clear ones;and calcium responses adapted to motion in one direction partially recoveredwhen confronted to an edge running in the opposite direction. As lobula outputneurons have been implicated in driving evasive behaviors, we also studied themodulation of the crab escape behavior to variations in the same visualparameters. We found a high correlation between the activity of the columnarneurons and the intensity of escaping. These results are consistent with theinvolvement of the lobula in object motion coding. Moreover, as the neurons studiedoriginate in the second optic neuropil, the medulla, object motioninformation would indeed begin to be encoded in the medulla.