Short-term Monocular Deprivation Induced Brain Structural Plasticity In Adult Visual Cortex

In order to adapt to the constantly changing external environment,our brain needs to adjust its function and structure.This key characteristic of the brain is called neuroplasticity.It is generally believed that neuroplasticity is at its peak during growth and development,and as the age increases,neuroplasticity gradually weakens.Recent studies have found that the adult brain still retains a certain degree of neuroplasticity,and the neuroplasticity often occurs quickly through short-term training.Visual plasticity is a classic paradigm of neuroplasticity research.A large number of animal experiments have proved that the visual system of adult animals still maintains rapid microstructural plasticity,such as synaptic regeneration and elimination.This type of experiment mainly relies on high-resolution imaging equipment,such as two-photon fluorescence imaging,and is not suitable for human experiments.Therefore,the rapid microstructural plasticity of the visual system still lacks direct evidence in human adults.Magnetic resonance imaging is an imaging method that is highly sensitive to soft tissues.With the continuous advancement of diffusion weighted-magnetic resonance imaging(DW-MRI),a non-invasive,whole-brain,and highly sensitive imaging method of tissue microstructures,researchers were able to obtain brain tissue's microstructural information that highly fits the histology.In terms of neuroplasticity,the mean diffusivity(MD)obtained based on diffusion tensor imaging(DTI)has proved to be an index that is highly sensitive to microstructure plasticity,which has been applied in the study of learning,memory and other neural mechanisms,and produced a series of important scientific achievements.This article focuses on the rapid microstructure plasticity of adult visual system.We looked forward to using MD,a very sensitive indicator of brain microstructure changes,to explore where and how fast the microstructure plasticity of the adult visual system occurs,and how long this change will last,under short-term monocular deprivation interventions.Our research found that the two-hour monocular deprivation intervention on the dominant eye would cause changes in the eye dominance index and changes in the brain microstructure of the subjects,and the significant microstructure changes only occur in visual and vision-related brain areas.The brain regions with significant MD changes included not only the V1,but also the V5/MT,the hippocampus associated with spatial learning,and the primary motor cortex subregions with strong functional connections to the visual cortex.And there are functional connections or synergy of microstructure changes in these brain regions.Finally,we found that the behavioral and microstructure changes caused by monocular deprivation are recoverable.This study provides direct evidence for the plasticity of the microstructure of the adult visual system.At the same time,this study is expected to provide a potential diagnosis and treatment evaluation method for patients with visual impairment.