High resolution 3D-neuroanatomy of the retina - investigation of wiring rules in different contrast mechanisms

• Applicant: Professor Dr. Martin Heß
• Subject Area: Cognitive, Systems and Behavioural Neurobiology ; Systematics and Morphology (Zoology)
• Term: from 2012 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 226127164

The vertebrate retina is a prime example for the investigation of structure-function-correlations of complex sensory organs and their species-specific adaptation in the context of visual ecology. Histology and fine structure of the outer retina (pigment epithelium + photoreceptors) are indicative for visual acuity, sensitivity and contrast mechanisms (e.g. photoreceptor morphotypes), that have to be specified via cell number ratios and neuroanatomical findings from the inner retina. Both, a fundamental understanding of architecture and function of a neuronal net, and insights about variations (e.g. mono-, di-, tri, tetrachromatic contrast formation) stand and fall with the availability and quality of high resolution structure data of shape and wiring rules of all cell types involved - contributions that can be received better and better from morphological retina research via light- and electron-microscopical 3D imaging. The “break through” within retinal connectomics, however, are the latest methods of serial block face scanning electron microscopy (SBFSEM) with mechanical cutting (Heidelberger Hobel) or ion beam milling (FIB-FESEM), that give us for the first time almost distortion-free ultrathin layer series for 3D reconstruction and morphometry of entire neuronal nets in nm-resolution. In the previous project we investigated numerous cell types and some connectivity rules of a teleost retina with FIB-FESEM for the first time and demonstrated possibilities and limits of this method. To overcome these limits and to be able to interpret the zoological/neuroanatomical findings in an adequate context, the connectoms of 4 teleost species with different retinal connection schemes will be investigated as complete as possible. For this purpose FIB-FESEM (for the extremely fine ramifications of the outer plexiform layer) and the Heidelberger Hobel (for the remaining inner retina incl. inner plexiform layer) shall be combined.

• DFG Programme: Research Grants