Codification of visual cues by parallel channels in the third optic ganglion of an arthropod

MERCEDES BENGOCHEA, MARTIN BERÓN DE ASTRADA

Congreso; Congreso argentino de Neurociencias; 2015

Sociedad Argentina de Neurociencias

Visual scenes comprise enormous amounts of information from which nervous systems extract and process behaviorally relevant cues. Here, we study how visual information is segregated in high order visual centre in a highly visual crab. Crab's optic lobe encompasses three serially arranged ganglia built from repetitive neuronal columns transected by horizontal neuronal layers. Studies in flies show that outer horizontal layers of the second optic ganlgion differentially codify light-On/Off stimuli while layers of the third ganglion codify the four cardinal directions of optic flow motion. Here we study through calcium imaging if the three horizontal input layers of the crab´s third optic ganglion differentially codify light-On/Off stimuli or motion direction. On and Off step changes in light intensity evoked similar calcium peak responses and similar times of recovery of the signal in the three input layers. However, both peak and times of recovery differed between the On and Off stimuli. To study the codification of motion direction we presented 14 black edges translating horizontally in one direction and the 15th one in the opposite direction, thus, we expected to reveal the strata involved in coding direction. The calcium response in the 15th trial was similar for the three input strata. However, this response is significantly higher than the response to a 15th with no change in direction. Our results suggest the existence of deferential visual coding at crab's lobula.