Dr. Johan Pahlberg received his Ph.D. from the University of Helsinki, Finland, in 2007. His doctoral work, under the supervision of Professor Kristian Donner, focused on the adaptive evolution of visual pigments, and molecular mechanisms optimizing signaling in rod photoreceptors. His postdoctoral work with Dr. A.P. Sampath at the University of Southern California and University of California Los Angeles, focused on how mechanisms in rod bipolar cells is modulated for optimal signal detection in the retina. His current work is aimed at elucidating how rod photoresponses are processed and parsed into the retinal circuitry, and thus how optimization of response transmission already at the first visual synapse is achieved, by integrating physiology with genetics.
The photoreceptors of the retina have been studied extensively over the past decades. However, much of the downstream processing from photoreceptors remains to be determined. Textbooks and review articles have argued that the function of the retina is to simply convey the visual stimulus to the brain, where complex computations can take place. However, the neural circuitry of the retina has a marvelous complexity consisting of ~130-140 clearly distinct cell types. How these cells process the visual information from the photoreceptors is a fascinating enigma and answering these questions will reveal fundamental mechanisms and strategies used in neural processing and sensory signaling. Research on visual disorders such as Stationary Night Blindness, Retinal Degeneration and other impairments in low light level vision will benefit greatly from a general understanding of the rod photoreceptors and their retinal circuitry.
The long-term goal is to have a substantial impact on vision rescue therapies and artificial vision. Research methods will include single cell patch-clamp recordings, whole retina electroretinogram recordings and behavioral experiments.
Ulisse Bocchero, Ph.D., Postdoc Fellow
Irina Ignatova, Ph.D., Postdoc Fellow
Lior Levy, B.Sc., Postbac Fellow
Lab_1.pdf(pdf, 223 KB)
Corinne Beier, Ulisse Bocchero, Zhijing Zhang, Nange Jin, Stephen C. Massey, Christophe P. Ribelayga, Kirill Martemyanov, Samer Hattar, Johan Pahlberg. Retinal circuits driving non-image forming visual behaviors. bioRxiv 2020.09.08.288373
Tian Wang, Johan Pahlberg, Jon Cafaro, Rikard Frederiksen, AJ Cooper, Alapakkam P. Sampath, Greg D. Field, Jennie Chen. Activation of rod input in a model of retinal degeneration reverses retinal remodeling and induces formation of functional synapses and recovery of visual signaling in the adult retina. J Neurosci (2019) 39(34):6798-6810.
Johan Pahlberg, Anurima Majumder, Nikolai O. Artemyev. Ex vivo functional evaluation of synaptic transmission from rods to rod bipolar cells in mice. In Methods in Molecular Biology: Mouse Retinal Phenotyping (2018) 1753:203-216.
Johan Pahlberg*, Rikard Frederiksen*, Gabriel Pollock, Kiyoharu Miayagishima, Alapakkam P. Sampath, Carter Cornwall. Voltage-sensitive conductances increase the sensitivity of rod photoresponses following pigment bleaching. J Physiol (2017) 595: 3459–3469.
Johan Pahlberg*, Anurima Majumder*, Hakim Muradov, Kimberly K. Boyd, Alapakkam P. Sampath, Nikolai O. Artemyev. Exchange of cone for rod phosphodiesterase 6 catalytic subunits in rod photoreceptors mimics in part features of light adaptation. Journal of Neuroscience (2015) 35(24): 9225-35.
Johan Pahlberg*, Anurima Majumder*, Kimberly K. Boyd, Vasily Kerov, Saravanan Kolandaivelu, Visvanathan Ramamurthy, Alapakkam P. Sampath, Nikolai O. Artemyev. Transducin translocation contributes to rod survival and enhance synaptic transmission from rods to rod bipolar cells. Proc Natl Acad Sci (2013) 110(30): 12468-12473
Johan Pahlberg*, Yan Cao*, Ignacio Sarria, Naomi Kamasawa, Alapakkam P. Sampath, Kirill A. Martemyanov. RGS7 and RGS11 provide the main GAP for the Gαo and set the sensitivity and time scale of rod ON bipolar light responses. Proc Natl Acad Sci (2012) 09(20): 7905-10.
Johan Pahlberg, Alapakkam Sampath. The mitigation of transduction and synaptic noise in sensory systems is key to setting detection threshold. Bioessays (2011) 33(6): 438-477.