Electrophysiology Alterations In Primary Visual Cortex Neurons Of Retinal Degeneration Rats

Retinal degeneration will result in the reconstruction of visual circuit and it can also cause the loss of visual signals, which will lead to many visual diseases. Retinitis pigmentosa(RP) and age-related macular degeneration are typical retinal degenerative diseases. People have been working on the treatment of these diseases, but we don’t find a satisfactory treatment now. Knowing the properties of neurons in the visual pathway is critical for finding the treatments. Electrophysiological properties at the retina level have been investigated during the progression of retinal degeneration; however, little is known about the changes in electrophysiological properties that occur in the primary visual cortex(V1) during the course of retinal degeneration. V1 is the essential area for visual information transmission. The visual information has to go through V1 before entering a high-level recognizition. Therefore, it is necessary to understand electrophysiological properties that occur in V1 and it can provide theoretical basis for finding better treatments in the future.In this experiment, rats were divided into degenerated group and control group. S334ter-line-3(S334ter-3) is a transgenic model of retinal degeneration developed to express a rhodopsin mutation similar to that found in human RP patients, so we choose S334ter-3 as degenerated group rats. Retina in Long Evans(LE) rats has pigments which is close to the human retina. LE rats have relatively complete visual functions, so we choose LE as control group rats. We collected 127 V1 neurons from 11 S334ter-3 rats and 10 LE rats, including 58 S334ter-3 cells and 69 LE cells. By conducting extracellular recording, we examined the electrophysiological properties of V1 in S334ter-3 and LE, then compared their electrophysiological properties. The results indicated that V1 neurons in the S334ter-3 rats showed weaker orientation selectivity, lower optimal spatial and temporal frequency values and a smaller receptive field size compared to the LE rats. The rats have smaller sensitivity of orientation and temporary frequency, besides the ability of spatial resolution was decreased during retinal degeneration. These results indicate that there is a great attenuation of visual features processing in V1 during retinal degeneration.