Topographical disorientation after ischemic mini infarct in the dorsal hippocampus: whispers in silence
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Date
2014
Authors
Faraji, Jamshid
Soltanpour, Nabiollah
Moeeini, Reza
Roudaki, Shabnam
Soltanpour, Nasrin
Abdollahi, Ali-Akbar
Metz, Gerlinde A. S.
Journal Title
Journal ISSN
Volume Title
Publisher
Frontiers Research Foundation
Abstract
Silent focal ischemic mini infarcts in the brain are thought to cause no clinically overt
symptoms. Some populations of hippocampal cells are particularly sensitive to ischemic
events, however, rendering hippocampal functions especially vulnerable to ischemiainduced
deficits. The present study investigated whether an otherwise silent ischemic
mini infarct in the hippocampus (HPC) can produce impairments in spatial performance in
rats. Spatial performance was assessed in the ziggurat task (ZT) using a 10-trial spatial
learning protocol for 4 days prior to undergoing hippocampal ischemic lesion or sham
surgery. Hippocampal silent ischemia was induced by infusion of endothelin-1 (ET-1), a
potent vasoconstrictor, into either the dorsal or the ventral hippocampus (dHPC and vHPC).
When tested postoperatively in the ZT using a standard testing protocol for 8 days, rats
with hippocampal lesions exhibited no spatial deficit. Although spatial learning and memory
in the ZT were not affected by the ET-1-induced silent ischemia, rats with dHPC stroke
showed more returns when navigating the ZT as opposed to the vHPC rats. Comparison of
region-specific HPC lesions in the present study indicated that dorsal hippocampal function
is critically required for topographic orientation in a complex environment. Topographic
disorientation as reflected by enhanced return behaviors may represent one of the earliest
predictors of cognitive decline after silent ischemic insult that may be potentially traced
with sensitive clinical examination in humans.
Description
Open access journal
Keywords
Silent stroke , Endotelin-1 , Hippocampus , Ziggurat task , Return behavior , Spatial navigation , Topographical disorientation , Early cognitive decline
Citation
Faraji, J., Soltanpour, N., Moeeini, R., Roudaki, S., Soltanpour, N., Abdollahi, A., & Metz, G. A. S. (2014). Topographical disorientation after ischemic mini infarct in the dorsal hippocampus: whispers in silence. Frontiers in Behavioral Neuroscience, 8, 261. doi:10.3389/fnbeh.2014.00261