![]() ![]() In addition to intrinsic programs, extrinsic cues and substrate interactions direct dendrite orientation, growth, and layering in vivo, with accumulating evidence showing that several molecular pathways contribute to neuronal subtype-specific layering and receptive field formation ( Dong et al., 2015). In vertebrates, clustered protocadherins serve a similar function in space-filling neurons, including retinal ganglion and Purkinje cells ( Lefebvre et al., 2012). In Drosophila, dendritic self-avoidance is mediated by the immunoglobulin superfamily member Dscam (Down syndrome cell adhesion molecule) through recognition and repulsion of isoneuronal dendrites ( Hughes et al., 2007 Matthews et al., 2007 Soba et al., 2007). Prominently, self-avoidance is a major mechanism for recognition and repulsion of isoneuronal dendrites to prevent overlapping innervation ( Zipursky and Grueber, 2013). Moreover, proper dendrite patterning is aided by like-repels-like mechanisms to ensure even and non-redundant receptive field formation. The cell-intrinsic capacity to grow dendrites relies on specific transcriptional ( Dong et al., 2015) and translational programs ( Lin et al., 2015) that ensure sufficient growth capacity of neurons to acquire their defined subtype-specific morphology. Although space-filling dendrite growth and tiling ensure proper synaptic or sensory input processing, it remains largely enigmatic how such complete field coverage is achieved during development. This phenomenon of space-filling dendrite growth and tiling requires even spreading of dendrites and, in the case of tiling, non-redundant partitioning of the innervated layer by dendrites of the same neuronal subtype. In addition, the dendritic fields of some types of neurons, including retinal ganglion cells and somatosensory neurons of both vertebrates and invertebrates, feature complete but non-redundant dendritic field coverage ( Gallegos and Bargmann, 2004 Grueber et al., 2002 Sagasti et al., 2005 Wässle and Boycott, 1991). Many neuronal classes establish subtype-specific, highly stereotyped dendritic branching patterns to cover their receptive field ( Lefebvre et al., 2015). Sensory perception relies on properly differentiated and connected neurons for accurate processing of inputs. ![]()
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