A fundamental goal of system neuroscience is to understand how the brain processes sensory information. In this project we go beyond the classical open-loop approach and study the visual system in a closed-loop manner by using advanced optimization algorithms developed the field of evolutionary computation.
Final Report Abstract
Light and darks visual stimuli are separately processed by the ON and OFF channels in the retina and visual thalamus. The ON and OFF channels converge the, for the first time, on neurons in the primary visual cortex. In this project we have advanced our understanding of the functional properties and the functional architecture of the responses to lights and darks in the early visual system, i.e. visual thalamus and primary visual cortex. The following are the three main findings of the project: 1) Our results reveal fundamental differences in the way lights and darks are processed in the visual system. We demonstrate a pronounced difference between ON and OFF luminance response functions and we show that these differences can explain a phenomenon first described by Galileo almost 400 years ago that was still puzzling astronomers today. 2) Our results demonstrate the existence of OFF-dominated columns, in which OFF responses are stronger than ON responses through the depth of the primary visual cortex, and ON-dominated columns, in which ON responses are stronger. Furthermore, our results reveal a robust columnar organization for absolute spatial phase. 3) Our results show that OFF-dominated cortical neurons respond faster to visual stimuli than ON-dominated neurons. Importantly we also show that ON-OFF temporal differences measured in visual cortex have a psychophysical correlate in the detection of lights and darks in humans. The study Kremkow et al. “Neuronal nonlinearity explains greater visual spatial resolution for darks than lights” published in 2014 in PNAS received worldwide press coverage from more than 30 news outlets, including: National Geographic, TIME Magazine, LA Times, Der Spiegel, El Mundo, ABC, La Repubblica, The Christian Science Monitor, FrenchTribune, The New Zealand Herald, etc. and it is mentioned in the PNAS First View Blog. It has an altmetric score of over 300 and is in the 99%ile of all articles ever tracked by altmetric. For detailed information regarding the press coverage please refer to: http://www.altmetric.com/details.php?domain=www.pnas.org&citation_id=2111132
Publications
- Neuronal and perceptual differences in the temporal processing of darks and lights. (2014) Neuron, 82:224–234
Komban, Kremkow et al.
(See online at https://doi.org/10.1016/j.neuron.2014.02.020) - Neuronal nonlinearity explains greater visual spatial resolution for darks than lights. (2014) PNAS, 111:3170–3175
Kremkow et al.
- The role of thalamic population synchrony in the emergence of cortical feature selectivity. (2014) PLoS Computational Biology, 10:e1003418
Kelly, Kremkow et al.
(See online at https://doi.org/10.1371/journal.pcbi.1003418) - Columnar organization of spatial phase in visual cortex. (2015) Nature Neuroscience, 18:97–103
Wang, Jin, Kremkow et al.
(See online at https://doi.org/10.1038/nn.3878)
