Cortical Inactivation Does Not Block Response Enhancement in the Superior Colliculus.

Katarzyna Kordecka,Wioletta J Waleszczyk,Agnieszka Wierzbicka,Andrzej T Foik

doi:10.3389/fnsys.2020.00059

Abstract

Repetitive visual stimulation is successfully used in a study on the visual evoked potential (VEP) plasticity in the visual system in mammals. Practicing visual tasks or repeated exposure to sensory stimuli can induce neuronal network changes in the cortical circuits and improve the perception of these stimuli. However, little is known about the effect of visual training at the subcortical level. In the present study, we extend the knowledge showing positive results of this training in the rat’s Superior colliculus (SC). In electrophysiological experiments, we showed that a single training session lasting several hours induces a response enhancement both in the primary visual cortex (V1) and in the SC. Further, we tested if collicular responses will be enhanced without V1 input. For this reason, we inactivated the V1 by applying xylocaine solution onto the cortical surface during visual training. Our results revealed that SC’s response enhancement was present even without V1 inputs and showed no difference in amplitude comparing to VEPs enhancement while the V1 was active. These data suggest that the visual system plasticity and facilitation can develop independently but simultaneously in different parts of the visual system.

Highlights

Repetitive visual training is a rapidly developing tool to modulate neuronal plasticity in the visual system for both research and clinical application (Sabel, 2008)
Our results showed that the 3 h visual training evoked strong enhancement of the visually evoked potential (VEP) both in the V1 and the Superior colliculus (SC)
We confirm that visual training causes enhancement of VEP amplitude in the V1 as it was described before (Sawtell et al, 2003; Teyler et al, 2005; Frenkel et al, 2006; Ross et al, 2008; Cooke and Bear, 2010, 2012) and extends the knowledge showing positive results of this training in the rat’s SC

Summary

Introduction

Repetitive visual training is a rapidly developing tool to modulate neuronal plasticity in the visual system for both research and clinical application (Sabel, 2008). Repetitive visual training is successfully used in studies on the visually evoked potential (VEP) plasticity in the visual system of mammals. Repeated exposure to sensory stimuli can induce neuronal plasticity and leads to an enhanced visual response of these stimuli. Numerous researches have shown that the VEP enhancement might reflect synaptic plasticity (Heynen and Bear, 2001; Sawtell et al, 2003; Teyler et al, 2005; Frenkel et al, 2006; Ross et al, 2008; Cooke and Bear, 2010, 2012). A few days long, repeated presentation of gratings with a single orientation resulted in a potentiation of the cortical VEPs amplitude to the presented stimuli

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Results

Conclusion