Limits...
Topographical disorientation after ischemic mini infarct in the dorsal hippocampus: whispers in silence.

Faraji J, Soltanpour N, Moeeini R, Roudaki S, Soltanpour N, Abdollahi AA, Metz GA - Front Behav Neurosci (2014)

Bottom Line: Some populations of hippocampal cells are particularly sensitive to ischemic events, however, rendering hippocampal functions especially vulnerable to ischemia-induced deficits.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Canadian Centre for Behavioural Neuroscience (CCBN), University of Lethbridge Lethbridge, AB, Canada ; Faculty of Nursing and Midwifery, Golestan University of Medical Sciences Gorgan, Iran.

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 ischemia-induced 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.

No MeSH data available.


Related in: MedlinePlus

(A) A photograph of a return that can typically occur during the spatial navigation in the ziggurat task. (B, left to right) Path trajectories recorded on Trial seven on the learning day by a control, dHPC, and vHPC rat from starting point (0) to the peripheral goal ziggurat (4). Note the increased number of returns taken by the dHPC rat (middle sub-panel) during the goal-directed navigation in the ZT. (C) A motiongraph of the number of returns taken by the same rats. Light and dark blue squares represent start and goal ziggurats, respectively and red squares indicate the number of returns calculated by the software (SINA motiongraph, V.II, 2011).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4120695&req=5

Figure 2: (A) A photograph of a return that can typically occur during the spatial navigation in the ziggurat task. (B, left to right) Path trajectories recorded on Trial seven on the learning day by a control, dHPC, and vHPC rat from starting point (0) to the peripheral goal ziggurat (4). Note the increased number of returns taken by the dHPC rat (middle sub-panel) during the goal-directed navigation in the ZT. (C) A motiongraph of the number of returns taken by the same rats. Light and dark blue squares represent start and goal ziggurats, respectively and red squares indicate the number of returns calculated by the software (SINA motiongraph, V.II, 2011).

Mentions: In addition to latency (time spent to find either of the peripheral or central goals), path speed (calculated by dividing the path length by the latency), path length, and returns were evaluated. Returns (Figure 2A) were characterized by the different pathways animals chose to return to the goal ziggurat in order to accomplish the task. Returns typically refer to the act of localizing and going back to the goal ziggurat during the goal-directed navigation (Faraji et al., 2008; Figure 2B). The movements of the animals were recorded and analyzed by HVS Image tracking system. Furthermore, returns were analyzed and tracked by a motiongraph software (SINA motiongraph, V.II, 2011, Tabriz, Iran; Figure 2C). A return was characterized by one stop (i.e., speed of 0.0 m/s lasting at least 1 s) followed by creation of a 180° angle towards left or right on the current route.


Topographical disorientation after ischemic mini infarct in the dorsal hippocampus: whispers in silence.

Faraji J, Soltanpour N, Moeeini R, Roudaki S, Soltanpour N, Abdollahi AA, Metz GA - Front Behav Neurosci (2014)

(A) A photograph of a return that can typically occur during the spatial navigation in the ziggurat task. (B, left to right) Path trajectories recorded on Trial seven on the learning day by a control, dHPC, and vHPC rat from starting point (0) to the peripheral goal ziggurat (4). Note the increased number of returns taken by the dHPC rat (middle sub-panel) during the goal-directed navigation in the ZT. (C) A motiongraph of the number of returns taken by the same rats. Light and dark blue squares represent start and goal ziggurats, respectively and red squares indicate the number of returns calculated by the software (SINA motiongraph, V.II, 2011).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4120695&req=5

Figure 2: (A) A photograph of a return that can typically occur during the spatial navigation in the ziggurat task. (B, left to right) Path trajectories recorded on Trial seven on the learning day by a control, dHPC, and vHPC rat from starting point (0) to the peripheral goal ziggurat (4). Note the increased number of returns taken by the dHPC rat (middle sub-panel) during the goal-directed navigation in the ZT. (C) A motiongraph of the number of returns taken by the same rats. Light and dark blue squares represent start and goal ziggurats, respectively and red squares indicate the number of returns calculated by the software (SINA motiongraph, V.II, 2011).
Mentions: In addition to latency (time spent to find either of the peripheral or central goals), path speed (calculated by dividing the path length by the latency), path length, and returns were evaluated. Returns (Figure 2A) were characterized by the different pathways animals chose to return to the goal ziggurat in order to accomplish the task. Returns typically refer to the act of localizing and going back to the goal ziggurat during the goal-directed navigation (Faraji et al., 2008; Figure 2B). The movements of the animals were recorded and analyzed by HVS Image tracking system. Furthermore, returns were analyzed and tracked by a motiongraph software (SINA motiongraph, V.II, 2011, Tabriz, Iran; Figure 2C). A return was characterized by one stop (i.e., speed of 0.0 m/s lasting at least 1 s) followed by creation of a 180° angle towards left or right on the current route.

Bottom Line: Some populations of hippocampal cells are particularly sensitive to ischemic events, however, rendering hippocampal functions especially vulnerable to ischemia-induced deficits.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, Canadian Centre for Behavioural Neuroscience (CCBN), University of Lethbridge Lethbridge, AB, Canada ; Faculty of Nursing and Midwifery, Golestan University of Medical Sciences Gorgan, Iran.

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 ischemia-induced 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.

No MeSH data available.


Related in: MedlinePlus