The Resting State FMRI Research Of Sleep Deprivation

Sleep can promote organism growth and maintain organism survival.It is more important that sleep maintain cognitive functions like caution, memory, learning, et al normally.So good sleep is important to individual's body and mind health.Sleep deprivation (SD) is a state which lose of sleep by resons of many kinds.It usually means that people have less than 4hs sleep in 24h, which cause changes of emotion, learning memory, immunity function, et al.When people become tired, SD make changes of physiology, psychology and behavior. We use functional magnetic resonance imaging to investigate the effects of SD on executive function and different components and processes of working memory.The functional connectivity in resting state is now a popular method of fMRI, so we use it to impove our understanding of the effect of SD on brain function.According to a self-controlled design, 14 healthy young males (25.9±2.3 years) attended the experiment four times on their own wills.The experiment was divided into three parts. Firstly, visual Go/no-go test were used to investigate the effects of SD on attention. Secondly, effects of SD on working memory were studied. Based on the model by Bandeley, we chose n-back pattern to investigate verbal working memory, spatial working memory and object working memory. Lastly, in resting state, we took ACC and ACC&PCC as seed regions base on the results of the above two parts.Functional connectivity was used to investigate the effect of SD on connectivity between these specific brain regions.Main results and conclusions are the followings:SD induced decrease of executive control function. TSD induced positive and negative BOLD signal include the superior prefrontal cortex, inferior prefrontal cortex, et al. and with negative BOLD signal in the anterior cingulated cortex (ACC) and right lingual gyrus et al. These results suggested that the increased activation may be related to the compensatory response since more attention resources are needed to perform the Go/No-go task after 36 h TSD and the decreased activation in the ACC may reflect the impact on response inhibition by the TSD.Working memory was impaired after SD. The brain areas which have close relationship with the working memory are prefrontal cortex, posterior parietal cortex and anterior cingulated gyrus, parietal cortex, cuneus, cerebellum and supplementary motor area, et al. SD has different influence on the working memory tasks. The influence of SD on object and spatial working memory mainly are deactivating of brain areas related to working memory storage and process. As far as verbal working memory is concerned, besides the deactivation of brain areas related to working memory storage and process, the areas related the attention system activated which has close relationship with fatigue. The individual adaptation to SD is mainly demonstrated by the prefrontal compenstion. The increase of prefrontal cortex function for compensation is an important characteristic after SD.Recently, it was found that the brain remained active in an organized fashion during the resting state: this was called the 'default mode network' of brain function.The default mode network contained prefrontal lobe, parietal cortex, anterior and posterior cortex, et al.This network maintained the sober state and had a close relationship with the attention system. The resting state fMRI research of SD found that the functional connectivity of default mode network was increased.This reflected the consistent functional change of the default mode network.and correlated the decline of attention, executive control function and wake state. Along with the SD, the functional connectivity of thalamus had opposite changes of ACC and posterior cingulated cortex (PCC), which meant that the thalamus stayed over-activated state.After SD, the descent of attention level correlated with functional descent of default mode network. The subcortical regions like thamus remain over-activated state and took PFC part in maintaining the sober state, especially it couldn't maintain the sober state independently.In recently, the resting state fMRI research is very popular.This paper study the influence of SD on brain function in resting state.It is a supplement and progress to traditional task research, and is beneficial to our further understanding of SD on human brain function.