Neuroscience & Non-Communicable Diseases Seminar Series
A/Prof Karin Nordström - Flinders University, Adelaide
Despite being equipped with low-resolution eyes and tiny brains, many insects show exquisite abilities to detect and use visual information. For example, the optic flow generated by a flying insect can be used to maintain a straight flight course, or to avoid obstacles. Many insects, such as killer flies, dragonflies and hoverflies, are also amazingly good at pursuing small moving targets, such as prey or conspecifics, even in highly complex surrounds. Subsequently, animals whose survival depends on early target detection are often equipped with a sharply tuned visual system, yielding robust performance in challenging conditions. Indeed, in the insect brain we find some neurons tuned to the detection of optic flow, and others tuned to the visualization of target motion. We have found that the target neurons found in the optic lobes respond robustly to the motion of small moving objects, even when displayed against syn-directional background clutter.
Importantly, in diptera, the encoding of visual information by the descending neurons, which are more directly involved in generating the behavioral output, has received less attention. To redress this deficiency we have characterized target selective neurons and optic flow sensitive neurons in their ventral nerve cord. We find that target-selective descending neurons only respond to target motion if the background is stationary or moving slowly, moves in the opposite direction, or has un-naturalistic spatial characteristics, which is strikingly different to the response of target neurons in the optic lobes. As the descending neurons are pre-motor, these findings affect our interpretation of the neurophysiology underlying target-tracking behaviors.
All welcome. Drinks and nibbles from 3:30pm, seminar starts at 4pm.
Enquiries: Ingvars Birznieks , Natasha Kumar , Greg Smith