| Population aging is one of the major problems in current society.The aging of the brain will cause memory decline,executive function decline,cognitive function decline and other problems,and may lead into neurodegenerative diseases,thus greatly affecting the life of the elderly.Brain functional connectivity technology using magnetic resonance imaging(MRI)has been widely used in the study of brain function and brain disease network mechanism.Its methodology is based on correlation and synchronization analysis of brain blood oxygen level-dependent signal(BOLD)obtained by f MRI to characterize brain functional networks and activation.Therefore,from the perspective of brain network,it can be more straightforward to find the connections between brain regions.At the same time,the study of brain network is helpful to provide accurate targets and circuits for brain intervention.The thalamus is a key node in the cognitive function network,connecting the cortex,subcortex and cerebellum.Structural magnetic resonance imaging and diffusion tensor imaging studies have shown that some subregions of the thalamus exhibit volume shrinkage and microstructure degradation with age,and the anterior thalamus is usually more vulnerable than the posterior region.In terms of brain function,age-related differences in thalamocortical connectivity may lead to age-related changes in attention,working memory,and episodic memory processes.In addition,the nucleus mass in the thalamus is associated with circadian rhythm and plays a key role in the regulation of light sensitivity.However,the brain aging mechanism of thala-hippocampus light sensitive pathway is still unclear.Therefore,using functional magnetic resonance imaging(f MRI),we first explored the differences in the cortex-thalamic-hippocampal directed network between the elderly and the young.Secondly,blue-green light intervention therapy is given to people with subjective cognitive impairment to further explore the mechanism of blue-green light intervention and provide an important theoretical reference for the intervention of brain aging.Secondly,blue-green light intervention was given to people with subjective cognitive impairment to further validate the brain ageing mechanism of blue-green light acting on photosensitive pathways,providing an important theoretical reference for the intervention of brain ageing.First,using a regression dynamic causal model to construct a directed network,we analyze the differences between the cortex-thalamic-hippocampal network between the elderly and the young.The relationship between the network and cognitive behavioral scores was also explored.The results showed that the excitatory connections between the posterior thalamus and the hippocampus in the elderly were significantly lower than those in the young population,and the difference was not found in other parts of the thalamus and the inhibitory connections were not different.In the connections between the posterior thalamus and the cortex,excitatory connections between the posterior thalamus and the visual,sensorimotor and dorsal attention networks were found to be reduced,while inhibitory connections with the frontoparietal and default mode networks were significantly stronger than in younger people.It also showed stronger directed connections between the posterior and anterior thalamus within the thalamus.The directed connection strength at the differences all correlated with the cognitive behavioral scores.Secondly,this paper recruited people with subjective cognitive impairment for blue-green light intervention treatment,collected functional magnetic resonance before and after treatment,and explored the influence of blue-green light on functional connections of three light-sensitive nodes of hypothalamus suprachiasmatic nucleus(SCN),amygdala and thalamus before and after intervention by using functional connections.The results showed that light intervention had specific effects on the whole brain functional connections of the three light nodes.Specifically,significant changes were found in the global functional connections of the lateral geniculate nucleus in the left hemisphere,which was mainly related to the improvement of the patient’s cognitive ability.At the same time,the whole-brain functional connections of the amygdala in the right hemisphere also showed significant changes,and this change was mainly related to the improvement of the mood of the patients.Secondly,we also found that light intervention also caused common changes in the brain functional connections of the lateral geniculate of the thalamus,the amygdala,and the SCN.The specific manifestations are in the middle occipital gyrus,inferior temporal gyrus and middle frontal gyrus.In summary,this paper finds that the information interaction between the thalamus and its connections to the cerebral cortex and hippocampus may guide the study of brain ageing,and suggests that the thalamus is one of the key targets for intervention in brain ageing. |
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