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Visual sensitivity of giant neurons to the size of moving objects in the crab Neohelice granulata.

Estela Manuela Lanza

  • CABA,
  • Argentina
  • Estela Lanza ¹𝄒²
  • , Daniel Tomsic ¹𝄒²
  • 1 Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular, Pabellón 2, Ciudad Universitaria, CP1428, Buenos Aires, Argentina. 
  • 2 CONICET-Universidad de Buenos Aires

The semiterrestrial crab Neohelice (previously Chasmagnathus) granulata is proven to be a remarkable model to study the neurobiology behind visualy guided behaviors. Crabs allow the possibility of intracellular recording from neurons located in high visual centers of living animals. As this crab is preyed upon by gulls, large objects elicit a scape response. In the past we have extensively recorded giant neurons from the lobula (third optic neuropil), which are sensitive to large moving objects and are involved in the scape behavior. These animals also prey upon smaller crabs. Recent experiments revealed that a small dummy moving at ground level elicits strong chasing responses, whereas the same dummy elevated 10 cm above the ground elicits reliable escape responses. With the aim of characterize the sensitivity of lobula giant (LG) neurons to size and elevation of moving objects we recorded the electrophysiological responses of LG neurons to large, medium and small translational visual stimulus with linear trajectories at the equator of the eye and small objects with linear trajectories above and below the equator.