Jens Kremkow (State University of New York and Humboldt-Universität zu Berlin) | Principles underlying sensory map topography in primary visual cortex

Abstract

The primary visual cortex contains a detailed map of the visual scene, which is represented according to multiple stimulus dimensions including spatial location, ocular dominance and stimulus orientation. While it is known that the maps for spatial location and ocular dominance arise from the spatial arrangement of thalamic afferent axons in the cortex, the origin of the orientation map remain unclear. A possible anatomical substrate for orientation maps could be the axonal arrangement of ON and OFF thalamic afferents in the cortex just as the substrate for ocular dominance maps is the arrangement of thalamic afferents from the contralateral and ipsilateral eyes. In this talk I will discuss our latest experimental results that support this hypothesis.

Our results [1] show that the cortical maps for orientation, direction and retinal disparity in the cat are all strongly related to the organization of the map for spatial location of light (ON) and dark (OFF) stimuli. We show that this organization is OFF-dominated and OFF-centric, i.e. OFF retinotopy is more precise than ON retinotopy and OFF acts as the anchor of the cortical retinotopic map [2]. These unexpected results have now also been shown in tree shrew visual cortex [3], seem to be present in primate [1] and therefore are likely a common design principle in species with orientation maps. Because the ON/OFF organization originates from clustering of ON and OFF thalamic afferents in the cat visual cortex [4], we conclude that all main features of visual cortical topography, including orientation, direction and retinal disparity, follow a common organizing principle that arranges thalamic axons with similar retinotopy and ON–OFF polarity in neighbouring cortical regions.

Literature

[1] Kremkow, J., Jin, J., Wang, Y., and Alonso, J-M. (2016) Principles underlying sensory map topography in primary visual cortex. Nature, 533:52-57

[2] Kremkow, J., Jin, J., Komban, S.J., Wang, J., and Alonso (2013) Asymmetries in ON and OFF cortical retinotopy: are OFF receptive fields the anchors of cortical retinotopic maps? Soc. Neurosci. abstr. 639.09.

[3] Lee, K-S., Huang, X., and Fitzpatrick, D. (2016) Topology of ON and OFF inputs in visual cortex enables an invariant columnar architecture. Nature, 533:90-04

[4] Jin, J., Wang, Y., Swadlow, H. A., and Alonso, J-M. (2011) Population receptive fields of ON and OFF thalamic inputs to an orientation column in visual cortex. Nature Neurosci. 14, 232–238