| Description |
In order to understand how our brains produce our visual experience of the world, a mechanistic understanding of the circuitry of the visual system is necessary. Neural circuits in the brain extract a 3D image of the world by executing computations on 2D information gathered by the eye. Area V1 in visual cortex receives information from the eye and re-distributes it into the dorsal and ventral pathways of the visual system. Somehow, the dorsal pathway enables us to perceive motion and locate objects in space, while the ventral pathway enables us to perceive and recognize what the object is. Developing a comprehensive circuit diagram of V1 would be a significant step towards understanding how information from the eye is re-combined and routed into the dorsal and ventral streams. In this study, we investigated the neurons that project from layer 4B (L4B) in V1 to the adjacent visual area V2. We specifically examined neurons in L4B that provide information to the thick (dorsal pathway) and thin (ventral pathway) stripes within V2. We also investigated the local (intra-V1) axonal branching patterns of L4B neurons projecting to thick stripes in order to understand where they are distributing information to within V1. We first find evidence that there is a greater contribution of motion information (magnocellular) from L4B than previously reported to both thin and thick stripes. Further, we find that the information relayed to these V2 stripes comes from a variety of cell sizes, which differs from previous descriptions and suggests further specialization in the connectivity between these two areas. Finally, we find evidence for different circuits within V1 for the L4B neurons projecting to V2 thick stripes. We show that the pattern of information distribution within V1 is not homogenous, as has been previously described. We also show that L4B neurons provide information to functional areas (interblobs) that were previously considered devoid of L4B input. Overall, our findings reveal different morphological cell types and circuits in L4B of V1, which we attribute to the identification of these neurons’ projection targets outside of V1, which was lacking in previous studies. |
