| For decades, people had been researching the relationship between the acial expressions,emotions and the brain by various means in order to understand the mechanisms of brain that. generates and maintains depression. Although the etiology of depression States have been done a lot of by scholars, but the exact mechanism is still unclear, and there are many conflicting views. Depression in patients have very complex psychological structure,including emotional depression, frustration, and the slow association, anxiety and inattention, which result in cognitive function in different degrees. A lot of research has shown that depression exists significant cognitive impairment and the implementation of frontal lobe dysfunction is.one of the main performance in depression and its cognitive impairment. In recent years, cognitive dysfunction in depression patients was more and more be concerned by scholars home and abroad, Some studies show that depression may be independent of cognitive impairment in depression symptoms, which is one of the main reason that depression patients in remission still can not even restore.Neuropsychological testing is a brain disorder diagnosis and assessment of mental activities, the tools to quantify, can reflect the person's cognitive function. Event-related potentials (Event related potentials, ERP) from different time course of the processing of emotional and cognitive changes in brain activity, with its superior temporal resolution (up to milliseconds) and relatively low hardware requirements are widely used. Which is relatively stable indicators of P300 can be used to evaluate depression, cognitive dysfunction, particularly the implementation of the extent of potential clinical value.Many studies show that abnormal emotional and cognitive aspects in patients with depression result in the abnormality metabolism of corresponding brain structure and could be reflected by anatomy in the central nervous system, the hippocampus and amygdala of the limbic system might be involved in the formation of emotional behavior, locomotor activity and endocrine integration and plays a very important role in the pathogenesis of depression. MR diffusion tensor imaging (Diffusion tensor imaging DTI) technology can show nerve fiber pathways and fiber bundles traveling direction, track non-invasively brain white matter fiber, detect anatomical connectivity among every brain region, so it is a new technique for neuroscience research in recent years。Based on blood oxygen level dependent (BOLD) functional magnetic resonance imaging (FMRI) technology can distinguish among different types of emotional facial stimuli, separate from different emotions, and observe the stimuli of functional areas of brain related to the implementation of tasks .so that it have great potential in the pathological positioning,in depression and its cognitive impairment, in the monitoring of depression, in the antidepressant treatment and prognosis, and it is very important to study depression.because of its characteristics of high time, spatial resolution, non-invasive and easily repeatableWe will study the brain structure and function of depression patients by the morphology, DTI technique, BOLD-FMRI technology system, and explore the pathogenesis of depression and cognitive impairment based on brain function by fine structure analysis gray matter and white matter of the whole brain and comparison between patients and healthy controls, so that we can explore whether MRI can be used as an objective biological indicators for clinical diagnosis and provide new evidence, methods and ideas that improve prognosis and prediction, treatment of patients. of depression.This topic includes five parts:the first part, the study of cognitive function and event related potentialsof patients with depression; the second part; the study of the hippocampal and amygdala morphology of depression; the third part the study of diffusion tensor imaging MRI of depression; the fourth section, the study of emotional processing of depression by functional magnetic resonance imaging; the fifth section, the study of cognitive function of depression by functional magnetic resonance imagingThe first part, the study of cognitive function and event related potentialsof patients with depressionObjective:To investigate cognitive damage characteristics in patients with depression.Methods:24 cases of depression were assessed by the Hamilton Depression Rating Scale, Wisconsin Card Sorting Test (WCST), N-BACK task, P3OO tools. Complete the categories number (cc), the error response number (Re), the number of respondents that complete of the first category (Rlst), persistent errors (Rpe), no maintain the integrity of the number of categories (Fm) of wcst, latency and amplitude of P300 and reaction time (mRT) of N-back task are the measures,the patient were statistically analyzed to 24 normal controls.Results:1) Neuropsychological test scores WCST (including error responses, continuity errors, complete the first category the number of required responses), reaction time(mRT) of N-back task and latency,and amplitude of P300 of depression group had significant statistical difference compared with the control group.2) There are no significant correlation between Severity of depression and neuropsychological test scores, but there are positively correlated between the duration and continuity errors and reaction time (mRT).3) There are positively correlated,between latency of P300 and error responses, there are negatively correlated.between eaction time (mRT) P300 amplitude and completed categories. Conclusion:1) Depressed patients have cognitive dysfunction, and show cognitive impairment based perform functions.2) The course of disease rather than the severity of depression was correlated to the severity of cognitive impairment, that is, the longer duration, more severe cognitive impairment.3) WCST, N-back, P300 are three ways to respond from a different perspective of cognitive impairment of depression, which P3OO latency, reaction time (mRT) and continuity errors (Rpe) are indicators reflecting the sensitivity of frontal executive function.The second part; the study of the hippocampal and amygdala morphology of depression;Objective 1To measure the bilateral hippocampus and amygdala size of depression group and control group, explore the basis of depression in brain morphology, and analysis the relationship.between depression and bilateral hippocampus and amygdala size,2 To explore the correlation between the cognitive impairment in patients with depression and bilateral hippocampus and amygdala size, and analysis the neuropathological basis of memory impairment of depression. Methods To measuret on volumes of both sides of the hippocampus and amygdala. of 24 patients with depression and 24 control patients, by volume analysis software and analysis the relationship between the. size of bilateral hippocampus and amygdala and cognitive impairment (three indicators:latency of P300, reaction time and persistent error.Results 1) Volume of both sides of the depression group in the hippocampal was significantly Less than control group, but the volume on both sides in the amygdala was no significant difference between the two groups.2), bilateral hippocampus in patients with was no correlation between duration and depression HAMD depression scale and depression.3) Hippocampal volume in patients with depression was positively correlated with P300 amplitude, but no correlated with rpe, mRT and latency.Conclusion 1) Hippocampal volume of depression appears reduced, but with depression course and severity of depression independent of hippocampal volume abnormalities, it may be the basis of the neurobiology of depression, but not yet clear changes in brain structure and function isthe cause or results of depression.2) the hippocampus involved in the emotional process, mainly involved in memory function3)The hippocampus hhas no relationship with the executive function response to.frontal lobe function..The third part the study of diffusion tensor imaging MRI of depressionObjective 1To study the white matter FA values and its significance of depression by magnetic resonance diffusion tensor imaging (DTI) Technology.2To explore the correlation between cognitive impairment and the DTI anisotropy in patients with depression and to analyze the neuropathological basis of cognitive impairment.Methods To measure and compare white matter FA values in different parts of patients with depression and controls by DTI regions of interest (ROI) method, and to analysis statistically by the SPSS 13.0 statistical package, and the measurement data was expresser byx±SD) and compared between the two groups by independent samples t test, P<0.05 for the difference was statistically significant. Cognitive impairment FA values by DTI imaging between depression patients and the control group, were statistically analyzed..Result.1. There was significant (P<0.05) between the depression group and the control group, FA value of different anatomical contrast of the site are:frontal, anterior cingulate gyrus, corpus callosum the knee.。2. FA values of bilateral frontal, anterior cingulate cortex, genu of corpus callosum has nothing to do with the HAMD depression scale, the left frontal FA values was moderate negative correlation with duration (r=-0.566, P<0.01).3.FA values of bilateral frontal white matter, cingulate gyrus, genu of corpus callosum were significantly negatively correlated with latency of P300 and Rpe (P<0.05), FA values of left frontal white matter, anterior cingulate cortex, genu of corpus callosum were moderate correlation with mRT (P<0.05).) Conclusion 1. The significantly different site in FA values between the depression and control groups mainly was frontal, anterior cingulate gyrus, genu of corpus callosum.。2. Long-term depression may have contributed to the injury site, resulting in important neural circuit or bilateral contact in the abnormal middle cerebral hemisphere, so affective disorder symptoms and some cognitive impairment increased. 3, DTI can reveal the damagement of the integrity of the myelin sheath of nerve fibers including of frontal, anterior cingulate cortex, genu of corpus callosum and other in patients with depression, It is to ensure that the basis of axonal conduction function if the myelin sheath is intact, which may affect the pathological basis of cognitive function.4, The damage of integrity of these areas is mainly due to abnormal executive function.The fourth section, the study of emotional processing of depression by functional magnetic resonance imagingObjective To study different brain activation response to different emotional pictures by functional magnetic resonance imaging in patients with depression and to explore the characteristics of brain activity in patients with depressionMethods 15 patients with depression and 15 cases of control group were stimulated by International Affective Picture System pictures to the brain functional magnetic resonance imaging (fMRI) scans, Task-block design, processing image data with neurological image analysis (AFNI) software.Result 1 The activated brain regions of identificating of the neutral control group, image, positive image, negative image is bilateral frontal, middle and next time, the central gyrus, angular gyrus, supramarginal gyrus, anterior cingulate gyrus and the pressure, the hippocampus, amygdala, occipital visual cortex, pons and cerebellum.2. Compared with neutral images, the activated area by positive and negative pictures was observed in overlap activation of bilateral inferior parietal lobule, superior temporal gyrus and basal ganglia area, while the positive image and the negative image of the activation is different. Significant activation of bilateral frontal brain regions of Negative-Positive differences are radiation crown area, anterior cingulate gyrus and press department, middle temporal gyrus, internal capsule, insula, and cerebellar vermis, right thalamus, pons. Negative brain activation in only the left brain.3.There are differences between the two groups to identify of neutral, positive and negative pictures。3.When recognizing of neutral images (depression group by control group), there had significantly negative activation of brain regions in bilateral superior parietal lobule, cingulate gyrus and corpus callosum, left middle frontal gyrus, hippocampus, right parahippocampal gyrus, Right supramarginal gyrus, thalamus and had significantly positive activation of brain regions in occipital visual cortex brain area, the right wedge leaf, the left cerebellar hemisphere.2 When recognizing of positive images (depression group by control group), there had significantly negative activation of brain regions in bilateral parahippocampal gyrus, hippocampus, dorsal thalamus and the superior parietal lobule, middle temporal, inferior gyrus, precuneus, in the cerebral and cerebellar hemispheres, putamen, the right amount, the next time, insula and had significantly positive activation of brain regions in bilateral cerebellar hemispheres, occipital visual cortex and right parietal lobe.3 When recognizing of negative images (depression group by control group), there had significantly positive activation of brain regions in Bilateral parahippocampal gyrus, wedge leaf, thalamus, occipital visual cortex and cerebellar hemisphere, amygdala, right hippocampus, middle temporal, inferior gyrus and parietal and had significantly negaitive activation of brain regions in Cerebellar hemisphere and left frontal, the next time, right inferior parietal lobule, superior parietal lobule。Conclusions Depression involved in such damage closely related to frontal lobe, cingulate gyrus and the limbic system (hippocampus, parahippocampal gyrus, amygdala, and may be involved in limbic system-the cortex-striatum-the globus pallidus-thalamus neural circuit-based multiple neural circuit structure and function abnormalities.The fifth section, the study of cognitive function of depression by functional magnetic resonance imaging Objective To study the characteristics of brain activation.function in patients with depression and cognitive impairmentMethods 10 patients with depression and 10 age and education level equivalent control group performanced the number of working memory tasks simultaneously by functional magnetic resonance imaging (fMRI). AFNI software analysis the data of FMR I locatedly and quantitatively。Result 1. the implementation of the correct rate is less, the reaction time is longer in Depression group than in the control group, there are statistically significant 2 working memory brain activation of two groups:Digital working memory brain activation in normal include bilateral frontal, middle, next time, next time temporal parietal lobule, inferior parietal lobule, precuneus, medial frontal gyrus, insula, anterior cingulate gyrus, occipital visual cortex area, dorsal thalamus. Digital working memory activation in patients group and control group activate the same brain regions.Conclusion 1 prefrontal and cingulate are the basis of working memory of brain function. parietal is an important part of attention system 2 decreased activation of prefrontal cortex is one of the pathological mechanisms that patients with depression have working memory impairment.Summary1 This is the first time at home and abroad to study prospectively the spatial and temporal patterns of depression and its cognitive dysfunction in combination with event-related potentials from the time and magnetic resonance of technology from space (including the Hippocampus and Amygdala size, shape white matter, cerebral gray matter function).Pathological basis of depression generally have their reasons and incentives that may be due to congenital myelin and neurons themselves dysplasia, or more sensitive to external stimuli, are vulnerable to damage. Acquired generally related to stress, stress caused biochemical changes in vivo, mainly glutamate system has led to other parts of the prefrontal and hippocampal neurons sustained damage; Such damage makes these parts of the neurons release in resting state to reduce nerve impulses, so emotional and cognitive neural circuit damage. when the external stimulation of emotional pictures, or the performance of the compensatory over-activation (early), or showed less activation (late), such as higher nervous activity during working memory performance in the prefrontal cortex at an early stage, activities of compensatory increase in the limbic system, the late show prefrontal cortex, the limbic system activity decrease, the same impulse as payment reduction led to a decline in executive function, which can be reflected on the functional magnetic resonance; Neuronal damage reduction due issuing nerve impulses, nerve fibers themselves can cause nutritional changes of myelin, leading to nerve fiber damage; At the same time as the release of neurons to reduce nerve impulses may lead to reduction in the number of myelin and the nerve synapse reduction (changes in these nerve fibers can be displayed on the DTI, showed decreased FA value), and nerve fiber changes will affect the neural pathway (several important pathway) links between the (leading to the latent period and the N-back task reaction time extension), which links the reduction will affect the frontal and hippocampal neurons in the integrity of the loop, damage the integrity of neurons led to a lack of functional stimulation, so that further damage neurons, and possible structural changes such as shrinkage of the hippocampus, neurons and nerve fibers in brain morphology. The space in time exception will be shown, electrophysiological event-related potential P300 latency will appear on the extension, N-BACK reaction time occurs and the error rate of increase, while WCST decline in executive function occurs, such as sustained increase in the number of errors, the patient showed abnormal symptoms such as emotional and cognitive. Such as depression (frontal, temporal lobe) attention disorder (parietal lobe), and memory impairment (temporal lobe), reduced capacity and the work plan hesitation (frontal lobe), work efficiency decreased (association cortex), etc. These emotional and cognitive as neurons and neural pathways are crossed, and therefore depression and cognitive function in a common injury, manifested in behavioral depression, cognitive decline and other symptoms 2. This is the first time at home and abroad to propose the pathogenesis of depression combined with cognitive dysfunction from the anatomy angle,that is state and trait there.The results show that in the exercise of duties, the activation of brain regions showed positive patients were lower than the control group as to bilateral superior frontal gyrus, left middle frontal gyrus was significant, while we found that frontal lobe in depressed mood also plays an important role in processing and contrast positive image, in the observation of neutral, negative picture of bilateral frontal activation are mainly negative, Combined with previous neuroimaging studies, indicating the prefrontal cortex of depressed patients neurophysiological abnormalities and emotional, language, attention selection, visual spatial memory, and depression onset dorsal prefrontal cortex decreased physical activity, depressive state function of these brain regions passivation, reflecting the common cognitive and emotional barriers, emotional and cognitive processing described neurophysiological link between. We also found that depressive mood and cognitive use of different brain regions, they are the basis of the existence of different brain functions, it also confirmed from the anatomy of depression depression and cognitive impairment in the state of nature are there. Some studies found that patients with depression symptoms in the treatment of depression were relieved, but cognitive function compared with the control group, there were a significant statistical difference. This suggests that depression, cognitive impairment trait, indicating that depressive mood and cognitive impairment in brain function based on the existence of different brain regions, which in our study had been confirmed; but the study also found that after treatment, with the condition of remission, the patient's cognitive function has significantly improved; WCST performance improvement and depression improved significantly correlated, suggesting that the cognitive state of depression the presence of patients with recognized depression known function of the extent of damage and depression are related. Analyze the reasons that we found in the DTI study of depression in patients with bilateral frontal white matter, cingulate gyrus, corpus callosum, the integrity of the knee down, and with depression, a positive correlation between duration, and continuity errors and the percentage (Rpe) negative correlation, which confirmed the damage to white matter fibers may be depression, mood and cognitive impairment in the common pathological basis, such as damage to white matter fibers in the mood of depression and cognitive function plays an important role in the development, combined with depression have a common emotional and cognitive brain areas, such as frontal lobe, the positive control of depressive symptoms, cognitive function can promote the recovery of patients.3. Depression, emotional disorders and cognitive impairment based on a similar pathology, the joint damage of white matter and gray matter lead to depression and the occurrence of cognitive impairment.4.There is no relationship between the severity of Depression and cognitive function, but the duration of Depression were positively correlated to cognitive function. Depression on the left middle frontal gyrus white matter FA values were negatively correlated with the duration, suggesting that prolonged course may increase the injury of brain white matter in depression patients.
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