Table 2.

Summary of physiological studies of retinal degeneration effects on the visual cortex.

Model	Study	Effects	References
S334TER-3 Rats (age: 2–3 months of age)	Changes in electrophysiological properties in V1 such as orientation tuning, spatial and temporal frequency, receptive field (RF)	Weakening of orientation selectivity, reduced spatial and temporal frequency, decrease in receptive field size	Chen et al., 2016 Scientific reports
S334TER-3 Rats (age: 2–3 months of age)	Changes in spontaneous activity, firing rate, interspike interval (ISI) and Lempel-Ziv (LZ) complexity were analyzed	Increased firing rate, decrease in ISI and lower LZ complexity	Wang et al., 2016 Neuroscience Letters
S334TER-3 Rats (age: 2 months)	Efficiency of information transmission was quantified in V1 by determining the mutual information (MI)	Decrease in MI between visual stimulation and neural response in V1	Wang et al., 2017 IEEE
S334TER-3 Rats (age: 3–4 months)	Efficiency of information transmission was quantified in V1 by determining the mutual information (MI). The analysis was based on both spikes and local field potential (LFP) signals	Decrease in MI between visual stimulation and neural responses for spiking activity, whereas for LFP the MI was similar to control group implying the ability of the visual system to capture information at population level	Wang et al., 2018 Neuroscience
S334TER-3 Rats (Age: 3–4 months)	Evaluation of residual contrast response properties after retinal degeneration	The spontaneous activity was strong and evoked responses was weaker observed at medium and high contrast level. No significant difference in C50 (semi-saturation contrast) was observed	Chen et al., 2020 Vision Research
Humans (patients with RP; age: 23–57 years)	Evaluation of residual visual function by measuring pattern reversal evoked potential (PVEPs) using different sizes of black and white checks of different contrast levels	A decrease in amplitude (P100) and increase in latency at lower contrast but not at higher contrast.	Mancebo-Azor et al., 2020 MDPI
Royal College of Surgeons (RCS) rat; age- P (28–35), P (49–56), P (98–105)	Determine loss of pattern vision by measuring (a) optical imaging responses using grating stimulus (b) Multi unit activity (MUA) and Local field potentials (LFPs) were measured in response to light stimulus in different layers of cortex	A marked decrease in amplitude of cortical signals were observed in rats for a wide range of spatial frequencies and for all groups. The MUA responses showed a decrease in older age group with reduced firing rate. The amplitude and latency of the LPFs that decreased at early ages increased progressively with age. The effect was similar in all cortical layers.	Gias et al., 2011 Vision Research
rd10 mice Age: P60, P120, P180	Functional changes in the visual cortex circuit during progressive retinal degeneration	Significant alteration in the excitation/ inhibition balance resulting from increased inhibition in local circuits.	Pietra et al., 2021 Visual Neuroscience
Humans patients with inherited RD (age: 36-57 years)	Contrast sensitivity deficits in patients with inherited retinal degeneration	Patients with IRD exhibit significant deficits in contrast sensitivity despite having normal visual acuity. The contrast sensitivity was measured by a new method named as Quick Contrast Sensitivity Function (QCSF) that allows a more comprehensive evaluation using a greater number of contrast and spatial frequency evaluation.	Alahmadi et al., 2018 BMC Opththalmology