A Corollary Discharge Modulates Sensory Processing in Singing Crickets
"How do animals process self-generated sensory information as compared to sensory stimuli perceived from their external environment?" This is a fundamental question in sensory neuroscience. In 1950 Sperry and von Holst and Mittelstaedt proposed that a corollary discharge or efference copies is generated by the motor areas of the central nervous system to interact with the processing of the expected self-generated sensory feedback. Recently we identified the cellular mechanisms underlying a corollary discharge mechanism in the cricket, which is an ideal model to analyse this problem. While males sing their calling song at an intensity of about 100 dB SPL their own auditory system is exposed to the self-generated sound signals and also the wind sensitive cerci are stimulated by air currents due to the wing movements. This could have a detrimental effect on the sensitivity of these sensory pathways - unless they process self-generated sensory signals differently to sounds perceived from the environment.
We identified a large Corollary Discharge Interneuron that stretches all along the CNS of crickets. Its dendrites are located in the mesothoracic ganglion, but axonal; arborisations occur in all other ganglia.
This interneuron inhibits the auditory pathway in singing crickets. It causes IPSPs in phase with the sound pulses in central interneurons and presynaptic inhibition of auditory afferents. Due to its widespread arborisations, it might also modulate the activity of other sensory pathways. We analysed the activity of wind sensitive cercal interneurons in fictively singing crickets. Also these interneurons clearly receive IPSPs in phase with the singing pattern, a situation that is highly similar to the auditory interneurons. We now analyse if this inhibition in the cercal pathway is also mediated by the same Corollary Discharge Interneuron.
Group Members
Dr Berthold Hedwig (Group Leader)
bh202@cam.ac.uk
Dr Fabienne Dupuy
Research: Auditory motor interface
fyd20@cam.ac.uk
Dr Kostas Kostarakos
Research: Auditory brain neurons
kk437@cam.ac.uk
Dr Stefan Schoeneich
Research:Song pattern generation
ss817@cam.ac.uk
Kelly Seagraves
Research: Directional sensitivity
ks584@cam.ac.uk
Part II Zoology Project Students
Tanya Gunnarsdottir
Gemma Longson