Binocular properties of lobula giant motion-sensitive neurons of crabs

SCARANO F.; SZTARKER J; TOMSIC D.

Lucca

Congreso; Gordon Research Conferences; 2015

Gordon Research Conferences

Many important behaviors of insects and crabs are guided visually, for which the information obtained separately from each eye must be combined and processed. We know little about how the images of an object seen by the two eyes merge in the arthropod brain. Motion-sensitive giant neurons from the lobula (third optic neuropil) of insects and crabs are thought to be central elements in the organization of different visually-guided behaviors in these animals. By performing in vivo intracellular recording, we explored the ability of 47 lobula giant (LG) neurons of the crab Neohelice to process binocular information. We took advantage that in crabs the visual field of each eye encompass 360°, i.e. the visual field of both eyes completely overlap. By using a removable division between the two eyes, we evaluated LG responses under binocular or monocular sight of a stimulus, consisting of a black bar moved in the front-lateral visual field, ipsilateral or contralateral to the recording side. In the binocular condition, 43 of the 47 neurons responded to the stimulus presented at both sides independently, while 4 responded only to the ipsilateral side. When the division between the eyes was present all the neurons (47) continued responding to the ipsilateral side, while from the 43 that responded to the contralateral side 39 continued responding. Therefore, 90% of the recorded LGs showed to be binocular. However, the intensity of binocular vs. monocular responses varied among neurons. Additionally, in some cases responses to horizontal or vertical moving bars were differentially affected. Surprisingly, 3 additional neurons that in the binocular condition exhibited receptive fields restricted to one side only, showed a complete inversion of their receptive field side when tested with the division.