Measuring a fly’s head direction while walking

Behaviour is the way in which the nervous system interacts with the world. In order to understand how the brain controls behaviour, we need tightly controlled conditions in the lab with well-defined stimuli. Insects exhibit largely deterministic responses in experiments, which allows us to examine the underlying processing of a behavioural input — through the visual senses, or through movement of the body — which leads to an output. We mainly study equilibrium responses: reflexes which correct for changes in the external environment.

The example below (left) shows a typical behavioural experiment in which the thorax of a tethered fly is oscillated at a fixed frequency (TR). The animal responds by moving its head (HR) to counteract the roll movement of the body, in an attempt to stabilize the images perceived by the eyes.

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We can use control engineering methods to understand the operation of this input-output system and to probe the contribution of individual sensory organs that are involved in a feedback loop (above right and below).

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As frequency increases, performance drops can be measured.

Selected recent publications

Review: Evolution of biological image stabilization
Ben J Hardcastle, Holger G Krapp
Current Biology  (2016)

Bimodal optomotor response to plaids in blowflies: mechanisms of component selectivity and evidence for pattern selectivity
Aman B Saleem, Kit D Longden, Daniel A Schwyn, Holger G Krapp, Simon R Schultz
The Journal of Neuroscience  (2012)

Interplay between feedback and feedforward control in fly gaze stabilization
Daniel A Schwyn, Francisco JH Heras, Gino Bolliger, Matthew M Parsons, Holger G Krapp, Reiko J Tanaka
IFAC World Congress  (2011)

Review: Sensory systems and flight stability: what do insects measure and why?
Graham K Taylor, Holger G Krapp
Advances in insect physiology  (2007)