Neural Circuits BIO 344 Fall 2024 PDF

BIO 344 Fall 2024 Neural circuits Esther Stoeckli Map formation What is a map? Are there different kinds of maps? What is the fundamental difference between different types of maps?  Inputs from the retina form a topographic map in the tectum Sanes, Reh, Harris, 2006 The topographic m...

BIO 344 Fall 2024 Neural circuits Esther Stoeckli Map formation What is a map? Are there different kinds of maps? What is the fundamental difference between different types of maps?  Inputs from the retina form a topographic map in the tectum Sanes, Reh, Harris, 2006 The topographic map of the visual system preserves also spatial information, whereas the olfactory map preserves only quality of the stimulus In the visual system of mammals, projections from the retina are relayed in the lateral geniculate nucleus on their way to the visual cortex  In the topographic map of the visual system the exact positional information of stimuli is preserved Tessier-Lavigne, Cell 82(1995)345  dorsal dorsal eye tectum ventral ventral eye tectum Use a simpler visual system to learn about neural circuit formation Forming a topographic map The Bonhoeffer stripe assay Sanes, Reh, Harris, 2012 Axonal targeting in the tectum is determined by repulsive cues Sanes, Reh, Harris, 2012 Gradients of Eph-receptors and Ephrins control retinal axon targeting Sanes, Reh, Harris, 2012 Temporal axons are repelled by high concentrations of Ephrins Building Brains, 2011 Eph receptors and Ephrins do not interact specifically Axon-axon competition contributes to topopgraphic map formation Stoeckli, Neuron 84(2014)655 Wiring the olfactory system Building Brains, 2011 Spatial information is not included in the olfactory map Axons from olfactory sensory neurons that respond to the same odorant target the same glomerulus One neuron – one receptor Takeuchi & Sakano, 2014 The olfactory map is established in a stepwise manner activity independent Nishizumi & Sakano, 2015 Timing and expression of repellants is crucial for axonal targeting Nishizumi & Sakano, 2015 In contrast to the visual system, the repulsive ligand is not expressed in the target in the olfactory system Nishizumi & Sakano, 2015 Sema3F is expressed by axons not by the target Nishizumi & Sakano, 2015 Ligand-independent differences in receptor activity explain Nrp1/PlexinA1 expression gradients along the A-P axis Nishizumi & Sakano, 2015 Local wiring – segregation of glomeruli – is regulated by sorting molecules Nishizumi & Sakano, 2015 Olfactory receptors are involved in the regulation of different stages of olfactory system wiring Nishizumi & Sakano, 2015