Central post-stroke pain due to injury of the spinothalamic tract in patients with cerebral infarction： a diffusion tensor tractography imaging study

Many studies using diffusion tensor tractography（DTT） have demonstrated that injury of the spinothalamic tract（STT） is the pathogenetic mechanism of central post-stroke pain（CPSP） in intracerebral hemorrhage; however, there is no DTT study reporting the pathogenetic mechanism of CPSP in cerebral infarction. In this study, we investigated injury of the STT in patients with CPSP following cerebral infarction, using DTT. Five patients with CPSP following cerebral infarction and eight age-and sex-matched healthy control subjects were recruited for this study. STT was examined using DTT. Among DTT parameters of the affected STT, fractional anisotropy and tract volume were decreased by more than two standard deviations in two patients（patients 1 and 2） and three patients（patients 3, 4, and 5）, respectively, compared with those of the control subjects, while mean diffusivity value was increased by more than two standard deviations in one patient（patient 2）. Regarding DTT configuration, all affected STTs passed through adjacent part of the infarct and three STTs showed narrowing. These findings suggest that injury of the STT might be a pathogenetic etiology of CPSP in patients with cerebral infarction.

Structural and functional connectivity in traumatic brain injury

Traumatic brain injury survivors often experience cognitive deficits and neuropsychiatric symptoms.However,the neurobiological mechanisms underlying specific impairments are not fully understood.Advances in neuroimaging techniques（such as diffusion tensor imaging and functional MRI）have given us new insights on structural and functional connectivity patterns of the human brain in both health and disease.The connectome derived from connectivity maps reflects the entire constellation of distributed brain networks.Using these powerful neuroimaging approaches,changes at the microstructural level can be detected through regional and global properties of neuronal networks.Here we will review recent developments in the study of brain network abnormalities in traumatic brain injury,mainly focusing on structural and functional connectivity.Some connectomic studies have provided interesting insights into the neurological dysfunction that occurs following traumatic brain injury.These techniques could eventually be helpful in developing imaging biomarkers of cognitive and neurobehavioral sequelae,as well as predicting outcome and prognosis.

Compromised small-world efficiency of structural brain networks in schizophrenic patients and their unaffected parents

Several lines of evidence suggest that efficient information integration between brain regions is disrupted in schizophrenia. Abnormalities in white matter tracts that interconnect brain regions may be directly relevant to this pathophysiological process. As a complex mental disorder with high heritability, mapping abnormalities in patients and their first- degree relatives may help to disentangle the risk factors for schizophrenia. We established a weighted network model of white matter connections using diffusion tensor imaging in 25 nuclear families with schizophrenic probands （19 patients and 41 unaffected parents） and two unrelated groups of normal controls （24 controls matched with patients and 26 controls matched with relatives）. The patient group showed lower global efficiency and local efficiency. The decreased regional efficiency was localized in hubs such as the bilateral frontal cortices, bilateral anterior cingulate cortices, and left precuneus. The global efficiency was negatively correlated with cognition scores derived from a 5-factor model of schizophrenic psychopathology.We also found that unaffected parents displayed decreased regional efficiency in the right temporal cortices, left supplementary motor area, left superior temporal pole, and left thalamus. The global efficiency tended to be lower in unaffected parents. Our data suggest that （1） the global efficiency loss in neuroanatomical networks may be associated with the cognitive disturbances in schizophrenia; and （2） genetic vulnerability to schizophrenia may influence the anatomical organization of an individual＇s brain networks.