Whole blood serotonin levels in healthy elderly are negatively associated with the functional activity of emotion-related brain regions

The consequences of an unilateral electrolytic entorhinal lesion on the functional activity in all major anatomically defined brain regions were evaluated in the rat. The 14C-2-deoxyglucose method served as a tool to quantify alterations of local cerebral glucose utilization (LCGU) ipsilateral and contralateral to the lesion at 4 days, 2 weeks, or 3 months after stereotaxic surgery. Apart from a few minor increases in the contralateral hemisphere, the predominant pattern consisted of reductions in the range of 10–40% in the ipsilateral hemisphere. Ipsilaterally, in extrahippocampal areas, LCGU had regained control levels at 2 weeks postlesion in contrast to hippocampal regions, where reductions were more pronounced than in other brain areas and partially persisted for up to 3 months. Interestingly, the termination zones of entorhinal fibers in the dentate gyrus did not regain control levels within 3 months. We conclude from the data that functional recovery of denervated primary target areas does not occur within 3 months after entorhinal lesions and that altered functional activity may be found beyond the primary target areas predominantly during the acute recovery period after the lesion. The data suggest that sprouting fibers do not reestablish a fully functional neuronal network during the recovery period.

Download Full-text

Aberrant White Matter Networks Mediate Cognitive Impairment in Patients with Silent Lacunar Infarcts in Basal Ganglia Territory

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.2015.67 ◽

2015 ◽

Vol 35 (9) ◽

pp. 1426-1434 ◽

Cited By ~ 9

Author(s):

Jinfu Tang ◽

Suyu Zhong ◽

Yaojing Chen ◽

Kewei Chen ◽

Junying Zhang ◽

...

Keyword(s):

White Matter ◽

Basal Ganglia ◽

Cognitive Deficits ◽

Large Scale ◽

Diffusion Tensor ◽

Brain Regions ◽

Lacunar Infarcts ◽

Healthy Elderly ◽

Brain White Matter ◽

Diffusion Tensor Imaging Tractography

Silent lacunar infarcts, which are present in over 20% of healthy elderly individuals, are associated with subtle deficits in cognitive functions. However, it remains largely unclear how these silent brain infarcts lead to cognitive deficits and even dementia. Here, we used diffusion tensor imaging tractography and graph theory to examine the topological organization of white matter networks in 27 patients with silent lacunar infarcts in the basal ganglia territory and 30 healthy controls. A whole-brain white matter network was constructed for each subject, where the graph nodes represented brain regions and the edges represented interregional white matter tracts. Compared with the controls, the patients exhibited a significant reduction in local efficiency and global efficiency. In addition, a total of eighteen brain regions showed significantly reduced nodal efficiency in patients. Intriguingly, nodal efficiency–behavior associations were significantly different between the two groups. The present findings provide new aspects into our understanding of silent infarcts that even small lesions in subcortical brain regions may affect large-scale cortical white matter network, as such may be the link between subcortical silent infarcts and the associated cognitive impairments. Our findings highlight the need for network-level neuroimaging assessment and more medical care for individuals with silent subcortical infarcts.

Download Full-text