About our work
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. Traditionally 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.
We use comprehensive approach spanning from molecules to behavior and utilize a variety of very specific animal models. To answer our research questions, we use state-of-the art electrophysiological and behavioral experiments combined with molecular and genetic methods of the highest standard. Our experiments are performed on several unique genetically modified mouse lines that display altered photoresponses and signaling properties, as well as other species whose variations in retinal anatomy and physiology can further inform these questions. Thus, our research will greatly benefit our understanding of visual disorders such as Stationary Night Blindness, Retinal Degeneration and other impairments in low light level vision affecting 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.
Corinne Beier*, Ulisse Bocchero*, Lior Levy, Zhijing Zhang, Nange Jin, Stephen Massey, Cristophe Ribelayga, Kirill Martemyanov, Samer Hattar, Johan Pahlberg. Divergent outer retinal circuits drive image and non-image visual behaviors. Cell Reports(2022) 39(13):111003.
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*, 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. J Neurosci (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.
Invited Peer-Reviewed Book chapters and Review Articles:
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, Alapakkam Sampath. The mitigation of transduction and synaptic noise in sensory systems is key to setting detection threshold. Bioessays (2011) 33(6): 438-477.