Abstract
The dynamic nature of the brain is critical for the success of treatments aimed at restoring vision at the retinal level. The success of these treatments relies highly on the functionality of the surviving neurons along the entire visual pathway. 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. By conducting extracellular recording, we examined the electrophysiological properties of V1 in S334ter-line-3 rats (a transgenic model of retinal degeneration developed to express a rhodopsin mutation similar to that found in human retinitis pigmentosa patients). We measured the orientation tuning, spatial and temporal frequency tunings and the receptive field (RF) size for 127 V1 neurons from 11 S334ter-3 rats and 10 Long-Evans (LE) rats. 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. These results suggest that the visual cognitive ability significantly changes during retinal degeneration.
Highlights
Several major outer retinal diseases, such as retinitis pigmentosa (RP) and age-related macular degeneration, are caused by the degeneration of photoreceptors, which results in the loss of visual signals and major remodelling of the retinal circuitry[1,2,3,4]
The present study focused on the comparison between receptive field properties in V1 cells from S334ter-3 and LE rats
The results showed that the V1 cells in the S334ter-3 rats exhibited weaker orientation selectivity, lower optimal spatial and temporal frequency values, and smaller receptive field (RF) compared to the cells in LE rats
Summary
Several major outer retinal diseases, such as retinitis pigmentosa (RP) and age-related macular degeneration, are caused by the degeneration of photoreceptors, which results in the loss of visual signals and major remodelling of the retinal circuitry[1,2,3,4]. The S334ter-3 rat is considered a suitable animal model to investigate the progression of degeneration in outer retinal diseases. Many previous studies have investigated the morphological and functional changes that occur in retinal cells in different degeneration models[11,12,13,14,15,16,17,18]. Investigations in LE rats discovered that the majority of neurons showed sharply tuned orientation selectivity with a bias for horizontal stimuli. Had the same orientation[20,21] In this present study we measured functional changes in V1 using grating stimuli in the degenerated group (S334ter-3). Our results showed the V1 neurons in the degenerated group exhibited weaker orientation selectivity, lower optimal spatial and temporal frequency values, and smaller RFs compared to the control group
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