Target detection in visual clutter

Many animals use visual cues when navigating through the surrounding environment. For example, an animal’s own motion through the world creates self-generated optic flow across the retina, which can be used to stay on a straight path, and to avoid obstacles. However, some features in the surround will move inconsistently with the self-generated optic flow. For example, a bird flying past will move independently of any self-generated optic flow. Such target motion, or small-field motion, is important for detecting e.g. predators, prey and conspecifics. In hoverflies, target detection is especially important in territorial defence and conspecific interactions. This behaviour is believed to be subserved by small target motion detector (STMD) neurons found in the optic lobes. These neurons respond robustly to target motion, even against velocity matched optic flow. STMDs are believed to synapse with target selective descending neurons (TSDNs), which project to the motor command centers. While TSDNs show similar specificity to small targets, unlike STMDs, TSDNs do not respond robustly to targets moving against velocity matched optic flow. In addition, when targets are displayed against counter-directional optic flow, the TSDN response to target motion is facilitated. This suggests an interaction between the target detection system, and the neurons optimized for detecting optic flow, making our findings difficult to reconcile with current models for target selectivity.

Short Bio

Karin Nordström defended her PhD in 2003, supervised by Dan Nilsson in the Lund Vision Group and Dan at Uppsala University, followed by a post doc with David O’Carroll at Adelaide University. She spent 2009-2015 at Uppsala University, as an independently funded Research Fellow establishing the Motion Vision group.

Karin has been at Flinders University since 2015. She is currently an ARC funded Future Fellow and a Matthew Flinders Professor in Neuroscience. Karin uses hoverflies to understand the mechanisms underlying motion vision. She is particularly interested in understanding how neural selectivity is achieved, and uses a range of techniques, including electrophysiology, quantitative behavior, field work, image manipulation and modelling.

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