title: Altered effective connectivity network of the basal ganglia in low-grade hepatic encephalopathy: a resting-state fMRI study with Granger causality analysis.
abstract: BACKGROUND
  The basal ganglia often show abnormal metabolism and intracranial hemodynamics in cirrhotic patients with hepatic encephalopathy (HE). Little is known about how the basal ganglia affect other brain system and is affected by other brain regions in HE. The purpose of this study was to investigate whether the effective connectivity network associated with the basal ganglia is disturbed in HE patients by using resting-state functional magnetic resonance imaging (rs-fMRI).
  
  
  RESULTS
  Thirty five low-grade HE patients and thirty five age- and gender- matched healthy controls participated in the rs-fMRI scans. The effective connectivity networks associated with the globus pallidus, the primarily affected region within basal ganglia in HE, were characterized by using the Granger causality analysis and compared between HE patients and healthy controls. Pearson correlation analysis was performed between the abnormal effective connectivity and venous blood ammonia levels and neuropsychological performances of all HE patients. Compared with the healthy controls, patients with low-grade HE demonstrated mutually decreased influence between the globus pallidus and the anterior cingulate cortex (ACC), cuneus, bi-directionally increased influence between the globus pallidus and the precuneus, and either decreased or increased influence from and to the globus pallidus in many other frontal, temporal, parietal gyri, and cerebellum. Pearson correlation analyses revealed that the blood ammonia levels in HE patients negatively correlated with effective connectivity from the globus pallidus to ACC, and positively correlated with that from the globus pallidus to precuneus; and the number connectivity test scores in patients negatively correlated with the effective connectivity from the globus pallidus to ACC, and from superior frontal gyrus to globus pallidus.
  
  
  CONCLUSIONS
  Low-grade HE patients had disrupted effective connectivity network of basal ganglia. Our findings may help to understand the neurophysiological mechanisms underlying the HE.
authors: Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu Province, China.
authors: Rongfeng
authors: R
authors: Qi
authors: Long Jiang
authors: LJ
authors: Zhang
authors: Jianhui
authors: J
authors: Zhong
authors: Zhiqiang
authors: Z
authors: Zhang
authors: Ling
authors: L
authors: Ni
authors: Qing
authors: Q
authors: Jiao
authors: Wei
authors: W
authors: Liao
authors: Gang
authors: G
authors: Zheng
authors: Guangming
authors: G
authors: Lu
mesh_terms: D000641:Ammonia / Q000097:blood; D001479:Basal Ganglia / Q000503:physiopathology*; D016022:Case-Control Studies; D003710:Demography; D005260:Female; D005917:Globus Pallidus / Q000473:pathology / Q000503:physiopathology; D006501:Hepatic Encephalopathy / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology*; D009483:Neuropsychological Tests; D012146:Rest / Q000502:physiology*; D013223:Statistics as Topic
chemical_list: D000641:Ammonia