Complex network analysis and topology-based data analysis for identifying risk factors of delirium

의과대학/박사Objective The human brain is a complex network of interlinked regions and composed of the structural (or backbone) network and dynamic functional networks. Studies revealed that the abnormal brain network has associated with the emergence of brain diseases. Delirium is one of brain diseases, and its etiologies are multifactorial. To identify risk factors of delirium, this study aimed to investigate neural substrates of delirium using complex network analysis and investigate phenotypic subgroups of delirium using topology-based data analysis Materials and Methods A total of fifty-eight hip fracture patients were recruited in this study. Structural and functional neuroimaging data from all participants were acquired before hip fracture surgery. Among the participants, only thirty-two patients were scanned for postoperative MRI data acquisition. Neural substrates in preoperative delirium, and functional connectivity re-organization during an episode of delirium were studied using a framework of complex network analysis. In topological data analysis, cognitive impairment, personality scales such as neuroticism and conscientiousness, and delirium rating scale were considered to identify phenotypic subgroups of delirium. Results Among fifty-eight patients, twenty-five patients were identified as delirium after hip fracture surgery. In the study of neural substrates of delirium, the significant increase of characteristic path length in structural network was observed in preoperative delirium (P<0.05). Also, increased structural path length densities connecting frontal to subcortical and visual sensory regions were played a pivotal role in characterizing delirious patients (corrected P<0.05). Furthermore, functional connectivity density between the prefrontal cortex and audiovisual sensory areas were significantly increased in preoperative delirium (corrected P<0.05). Interestingly, functional connectivity density between the visual cortex and the frontal and auditory areas were strongly suppressed in during-delirum patients (P<0.05). Finally, topology-based data analysis identified three subgroups of delirium in dimensions of cognitive function and personality. Conclusion This study investigated neuroimaging-based neural risk factors for delirium. The increased path length of structural network in preoperative delirium implies that there existed disruptions of the connection weights such as a fractional anisotropy and the number of streamlines in the backbone network. The significantly suppressed functional connectivity from the visual cortex to the auditory cortex and frontal regions may play a pivotal role in characterizing the delirious phenomena such as dysfunction in perception, a deficit in sustaining the conscious mental state, and hallucination. Lastly, topological data analysis suggests that neural substrates of delirium could be different for phenotypic subgroups of delirium.ope

Gait pattern analysis and clinical subgroup identification: a retrospective observational study

To identify basic gait features and abnormal gait patterns that are common to different neurological or musculoskeletal conditions, such as cerebral stroke, Parkinsonian disorders, radiculopathy, and musculoskeletal pain. In this retrospective study, temporal-spatial, kinematic, and kinetic gait parameters were analyzed in 424 patients with hemiplegia after stroke, 205 patients with Parkinsonian disorders, 216 patients with radiculopathy, 167 patients with musculoskeletal pain, and 316 normal controls (total, 1328 subjects). We assessed differences according to the condition and used a community detection algorithm to identify subgroups within each condition. Additionally, we developed a prediction model for subgroup classification according to gait speed and maximal hip extension in the stance phase. The main findings can be summarized as follows. First, there was an asymmetric decrease of the knee/ankle flexion angles in hemiplegia and a marked reduction of the hip/knee range of motion with increased moment in Parkinsonian disorders. Second, three abnormal gait patterns, including fast gait speed with adequate maximal hip extension, fast gait speed with inadequate maximal hip extension, and slow gait speed, were found throughout the conditions examined. Third, our simple prediction model based on gait speed and maximal hip extension angle was characterized by a high degree of accuracy in predicting subgroups within a condition. Our findings suggest the existence of specific gait patterns within and across conditions. Our novel subgrouping algorithm can be employed in routine clinical settings to classify abnormal gait patterns in various neurological disorders and guide the therapeutic approach and monitoring.ope

The effects of positive or negative self-talk on the alteration of brain functional connectivity by performing cognitive tasks

Self-talk can improve cognitive performance, but the underlying mechanism of such improvement has not been investigated. This study aimed to elucidate the effects of self-talks on functional connectivity associated with cognitive performance. We used the short form of Progressive Matrices Test (sRPM) to measure differences in performance improvements between self-respect and self-criticism. Participants were scanned using functional magnetic resonance imaging in the following order: baseline, during-sRPM1, post-sRPM1, self-respect or self-criticism, during-sRPM2, and post-sRPM2. Analysis was conducted to identify the self-talks' modulatory effects on the reward-motivation, default mode, and central-executive networks. Increase in sRPM2 score compared to sRPM1 score was observed only after self-criticism. The self-talk-by-repetition interaction effect was not found for during-sRPM, but found for post-sRPM; decreased nucleus accumbens-based connectivity was shown after self-criticism compared with self-respect. However, the significant correlations between the connectivity change and performance change appeared only in the self-respect group. Our findings showed that positive self-talk and negative self-talk differently modulate brain states concerning cognitive performance. Self-respect may have both positive and negative effects due to enhanced executive functions and inaccurate confidence, respectively, whereas self-criticism may positively affect cognitive performance by inducing a less confident state that increases internal motivation and attention.ope

Effects of gratitude meditation on neural network functional connectivity and brain-heart coupling

A sense of gratitude is a powerful and positive experience that can promote a happier life, whereas resentment is associated with life dissatisfaction. To explore the effects of gratitude and resentment on mental well-being, we acquired functional magnetic resonance imaging and heart rate (HR) data before, during, and after the gratitude and resentment interventions. Functional connectivity (FC) analysis was conducted to identify the modulatory effects of gratitude on the default mode, emotion, and reward-motivation networks. The average HR was significantly lower during the gratitude intervention than during the resentment intervention. Temporostriatal FC showed a positive correlation with HR during the gratitude intervention, but not during the resentment intervention. Temporostriatal resting-state FC was significantly decreased after the gratitude intervention compared to the resentment intervention. After the gratitude intervention, resting-state FC of the amygdala with the right dorsomedial prefrontal cortex and left dorsal anterior cingulate cortex were positively correlated with anxiety scale and depression scale, respectively. Taken together, our findings shed light on the effect of gratitude meditation on an individual's mental well-being, and indicate that it may be a means of improving both emotion regulation and self-motivation by modulating resting-state FC in emotion and motivation-related brain regions.ope

Structural Integrity and Functional Neural Activity Associated with Oral Language Function after Stroke

(1) Background: The impairment of language function after a stroke is common. It is unclear how the brain reorganizes for language function after cerebral infarction. The aim of this observational study is to investigate the association of structural integrity and functional neural activity with language function in aphasic patients with middle cerebral artery infarction. (2) Methods: Magnetic resonance images and scores from the Western Aphasia Battery on 20 patients were retrieved from medical records. A Voxel-wise linear regression analysis was performed using fractional anisotropy maps or the fractional amplitude of low-frequency fluctuation maps as dependent variables and scores of oral language function as independent variables while controlling for age and time elapsed after stroke. (3) Results: Spontaneous speech was positively associated with fractional anisotropy in the left dorsal stream and the right posterior corpus callosum and with the fractional amplitude of the low-frequency fluctuation of cranial nuclei in the pontomedullary junction. Comprehension was positively associated with the left ventral stream. Naming was positively associated with the left ventral stream and the bilateral occipitofrontal fasciculus, as well as with the fractional amplitude of low-frequency fluctuation of the supramarginal gyrus in the left hemisphere. (4) Conclusions: The dorsal and ventral streams are important for articulation and meaning after the reorganization of neural circuits following stroke. Subdomains of oral language function with a visual component are dependent on the visual association areas located in the right hemisphere.ope

Neural basis of romantic partners’ decisions about participation in leisure activity

Leisure activity is one of key ingredients for individual happiness and life satisfaction. Enjoying leisure activity with one’s partner can increase marital satisfaction. This study aimed to identify the neural basis of making decisions on participation in a leisure activity with one’s romantic partner as well as the relationship between leisure activity and satisfaction with life. Thirty-seven soon-to-be married heterosexual couples were participated in functional MRI while deciding participation in specific leisure activities in the individual, partner, with-friend, and with-partner conditions. We constructed analysis of variance models and investigated couple characteristics such as personality similarity, leisure activity matching rate, and spatial similarity in the bilateral frontoparietal network. The results showed decreased activity in the bilateral hippocampus during the task in the with-partner condition. Individual leisure activity was correlated with quality of life in males, whereas participation in leisure activity might require more cognitive loading on the dorsolateral prefrontal cortex in females. The leisure activity matching rate was correlated with courtship period, personality similarity, and spatial similarity of the right frontoparietal network during the task. These findings suggest that although there are different activation pattern in making decisions on leisure activity between romantic couples, spatial similarity of the partner’s social brain networks may be a marker that predicts how well the couple enjoys leisure activity together. In addition, our couples’ data analysis provides a scientific basis for the saying that romantic couples become more similar the longer they are together.ope

Subtypes of breast cancer show different spatial distributions of brain metastases.

The aim of our study was to test the hypothesis that the spatial distribution of breast cancer brain metastases (BM) differ according to their biological subtypes. MR images of 100 patients with BM from primary breast cancer were retrospectively reviewed. Patients were divided according to the biological subtype of the primary tumor, (triple-negative: 24, HER2 positive: 48, luminal: 28). All images marked with BMs were standardized to the human brain MRI atlas provided by the Montreal Neurological Institute 152 database. Distribution pattern of BM was evaluated with intra-group and intergroup analysis. In intra-group analysis, hot spots of metastases from triple-negative are evenly distributed in the brain, meanwhile BMs from HER2 positive and luminal type occur dominantly in occipital lobe and cerebellum. In intergroup analysis, BMs from triple-negative type occurred more often in frontal lobe, limbic region, and parietal lobe, compared with other types (P < .05). Breast cancer subtypes tend to demonstrate different spatial distributions of their BMs. These findings may have direct implications for dose modulation in prophylactic irradiation as well as for differential diagnoses. Thus, this result should be validated in future study with a larger population.ope

Neural Basis of Professional Pride in the Reaction to Uniform Wear

Professional pride is a positive emotion that includes self-reflection or evaluation and attitude toward one's own occupational group. Uniforms can encourage the wearer to have professional pride. The current study aimed to elucidate the neural basis of professional pride using an experimental task related to the self in uniform and functional magnetic resonance imaging (fMRI). The person-adjective matching task, in which a participant or other in uniform or casual wear was presented with positive and negative words, was used for scanning fMRI. Imaging data from 21 adults who had an occupation requiring a uniform were analyzed to identify the main and interaction effects of individual (self vs. other), clothes (uniform vs. casual wear), and valence (positive vs. negative). Identified brain activities were correlated with psychological scales including the Rosenberg Self-esteem Scale and Group Environment Questionnaire. Whole brain analyses found that the interaction between individual and clothes was present in multiple regions such as the right ventrolateral prefrontal cortex (VLPFC), left dorsolateral prefrontal cortex, left middle and inferior temporal gyri, left posterior superior temporal sulcus, right temporoparietal junction, left lingual gyrus, left calcarine cortex, right insula, left caudate, and right putamen. In particular, activities in the right VLPFC, left calcarine cortex, and right putamen in the self/uniform condition were positively correlated with several psychological scales. These results suggest that professional pride may be represented through multiple brain networks related to empathy, reward, and emotion regulation as well as the theory-of-mind network. The neural basis of professional pride is closely related to positive self-evaluation and group cohesion.ope

Neural Basis of Ambivalence towards Ideal Self-Image in Schizophrenia

Objective: Little has been explored about a reflection towards self-image in schizophrenia, though it can be related to heterogeneous symptoms of the illness. We identified the neural basis of ambivalence towards ideal self-image in patients with schizophrenia. Methods: 20 patients with schizophrenia and 20 healthy controls underwent functional MRI while the self-image reflection tasks of determining whether to agree with sentences describing their actual or ideal self-image that contained one of the adjective pairs with opposite valence. The interaction between the group and ideal ambivalence score was examined, and group differences in functional connectivity related to ambivalence towards ideal self-image were further studied. Results: The interaction of group-by-ideal ambivalence score was shown in the dorsal anterior cingulate cortex and dorsolateral prefrontal cortex, where activities were positively correlated with the level of ideal self-image ambivalence in patients, but not in controls. Task-related decrease in functional connectivity was shown between the orbitofrontal cortex and cerebellum in patients. Conclusion: The process of reflecting on ambivalent ideal self-image in schizophrenia may be related to aberrant prefrontal activity and connectivity. Abnormality in the prefrontal regions that take part in cognitive conflict monitoring and value judgment may underlie the pathophysiology of increased ambivalence towards ideal self-image.ope

Characteristics of Ambivalence of Self-image in Patients with Schizophrenia

Objectives: Ambivalence of self-image is considered to be important in patients with schizophrenia since impairment of self-referential processing and increment in ambivalence are illness-related symptoms. This study aimed to evaluate quantitative and qualitative properties of ambivalence of self-image in patients with schizophrenia. Methods: Twenty patients with schizophrenia and 20 normal controls performed a set of ’self-image reflection task’ and then the level of ambivalence towards actual and ideal self-image were numerically scored. Ambivalence scores were compared between groups and correlation analyses with psychometric scales were done in each group. Results: Patients with schizophrenia had higher level of ambivalence towards both actual and ideal self-image (p<0.001). Normal controls showed significant correlations with the scales representing level of self-concept clarity (r=-0.480, p=0.033), depression (r=0.479, p=0.033), and self-esteem (r=-0.555, p=0.011 ; R=-0.600, p=0.005) while the patients did not. Conclusion: Ambivalence towards one’s self-image is more intense in patients with schizophrenia. This symptom may be considered to exist as an independent symptom in schizophrenia.ope