Single photoreceptor mapping of visual neurons in vivo with adaptive optics microscopy.

• Applicant: Dr. Philipp Tellers
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2016 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 319029450

Our understanding of the neural basis of human visual perception remains startlingly incomplete, because humans and Old World primates are in many ways unique among mammals in their visual anatomy and physiology, making experimental and genetic research quite challenging. Research at the retinal level has been almost exclusively performed in tissue explants, where it is unclear how close to normal the retina is operating. At the cortical level, researchers have had to rely on assumptions about photoreceptor populations and sensitivities in each subject studied, assumptions that lately have become less tenable. A new multi-wavelength microstimulator outfitted with adaptive optics (AO) correction now circumvents these hurdles. The microstimulator allows to image the photoreceptor mosaic in real time, while simultaneously stimulating single cone photoreceptors in the living eye. Thus, not only the position but also the wavelength sensitivity (S, M and L) as well as the contribution of single photoreceptors to neural or behavioral responses can be determined. For my project, I will record extracellularly from neurons in the thalamus or cortex of macaques while activating single cones, to create the first 'cone maps' that underlie the long-familiar receptive fields of central visual neurons. The advantages of mapping at the cellular level will be (1) to learn how the signals derived from single photoreceptors are combined or transformed at various levels of the visual system, (2) to resolve several current controversies in color vision physiology (e.g. cone opponency), and (3) to provide the foundation for advances in microperimetric assessment of retinal disease and associated therapies

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Lawrence Sincich, Ph.D.