The primary visual cortex has the most accurate map of visual space in the brain and devotes about a square millimeter of its surface to represent all stimulus parameters needed to process a single point in an image. The list of stimulus parameters represented for each point is extensive and includes spatial position, contrast polarity (light or dark), orientation, direction of motion, binocular disparity, eye input, and spatial frequency. Research over the past decades has revealed with increasingly more detail the cortical representation of different stimulus parameters, however, the precision of the current visual cortical maps is still closer to a 150 AD Ptolemy-map of the world than a Google map. We still have a limited understanding of the precise arrangement of different stimulus representations and relations between representations within the map and we still do not know why animals with high visual acuity have cortical maps arranged in intriguing topographic patterns (e.g. orientation pinwheels) that are not existent in animals with poorer vision. Our work over the past years started to reveal the principles underlying visual cortical topography and their possible functional implications. Based on this work, we recently proposed that the topography for all stimulus parameters originate from the arrangement of four different types of thalamic afferents in visual cortex, which convey information about light-dark polarity (ON and OFF) and eye input (contralateral and ipsilateral). The orderly arrangement of these afferents by spatial position, eye input and contrast polarity provides a smooth and accurate map of visual space but at the expense of representing some stimulus parameters more accurately than others (e.g. darks better than lights) and compromising the representation of multiple stimulus parameters when the visual field is large. This proposal takes advantage of novel multielectrode-arrays to map with unprecedented precision the topography of primary visual cortex representing a point of visual space. We combine multielectrode recordings from thalamus and cortex with pharmacological methods and computational modeling to dissect the thalamic and cortical networks underlying cortical topography and the relative contribution of ON and OFF pathways to the structure and function of visual cortical maps.
A complete understanding of how sensory maps are organized in the cerebral cortex is essential to guide future therapeutic approaches aimed at repairing or replacing cortical microcircuits. The future of electrical cortical prosthesis not only requires solving problems of tissue damage and electrode interface but also knowing with enough detail the cortical topography where the electrodes need to be implanted. A detailed understanding of map organization is also important to identify cortical changes caused by visual diseases such as amblyopia, which may be restricted to specific cortical regions that may be missed without accurate knowledge of cortical topography. Revealing the stimulus combinations that are best represented in primary visual cortex also provides an opportunity to improve our understanding of image processing in the brain and the neuronal processes used to parse information from visual scenes.
| Luo-Li, Gloria; Mazade, Reece; Zaidi, Qasim et al. (2018) Motion changes response balance between ON and OFF visual pathways. Commun Biol 1:60 |
| Kremkow, Jens; Alonso, Jose-Manuel (2018) Thalamocortical Circuits and Functional Architecture. Annu Rev Vis Sci 4:263-285 |
| Alonso, Jose Manuel (2018) Motion processing picks up speed in the brain. Nature 558:38-39 |
| Pons, Carmen; Mazade, Reece; Jin, Jianzhong et al. (2017) Neuronal mechanisms underlying differences in spatial resolution between darks and lights in human vision. J Vis 17:5 |
| Mazade, Reece; Alonso, Jose Manuel (2017) Thalamocortical processing in vision. Vis Neurosci 34:E007 |
| Koch, Erin; Jin, Jianzhong; Alonso, Jose M et al. (2016) Functional implications of orientation maps in primary visual cortex. Nat Commun 7:13529 |
| Kremkow, Jens; Perrinet, Laurent U; Monier, Cyril et al. (2016) Push-Pull Receptive Field Organization and Synaptic Depression: Mechanisms for Reliably Encoding Naturalistic Stimuli in V1. Front Neural Circuits 10:37 |
| Kremkow, Jens; Jin, Jianzhong; Wang, Yushi et al. (2016) Principles underlying sensory map topography in primary visual cortex. Nature 533:52-7 |
| Wool, Lauren E; Komban, Stanley J; Kremkow, Jens et al. (2015) Salience of unique hues and implications for color theory. J Vis 15: |
| Zhao, Linxi; Sendek, Caroline; Davoodnia, Vandad et al. (2015) Effect of Age and Glaucoma on the Detection of Darks and Lights. Invest Ophthalmol Vis Sci 56:7000-6 |
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