Journal of neurotrauma
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Journal of neurotrauma · Jun 1996
Working memory deficits following traumatic brain injury in the rat.
This study was designed to examine working memory following fluid-percussion traumatic brain injury (TBI) using the Morris water maze (MWM). Rats were injured (n = 9) at a moderate level of central fluid percussion injury (2.1 atm) or were prepared for injury but did not receive a fluid pulse (sham injury) (n = 10). On days 11-15 postinjury, working memory was assessed using the MWM. ⋯ Analyses of the latency to reach the goal platform indicated that sham-injured animals performed significantly better on the second trial than on the first trial of each pair. However, injured animals did not significantly differ between first and second trial goal latencies on any day. These results indicate that injured animals have a profound and enduring deficit in spatial working memory function on days 11-15 after TBI.
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Journal of neurotrauma · Mar 1996
Diminished microtubule-associated protein 2 (MAP2) immunoreactivity following cortical impact brain injury.
This study employed Western blotting and qualitative immunohistochemistry to analyze the effects of cortical impact traumatic brain injury (TBI) on acute changes in MAP2 immunoreactivity in the rat cortex. We employed a lateral cortical impact injury device to induce severe TBI, which is associated with focal cortical contusion and neuronal death at the impact site. Three hours following TBI, Western blotting detected substantial MAP2 loss only in the cortex ipsilateral to the site of injury. ⋯ Alterations in MAP2 immunofluorescence were found both within and beyond areas of focal contusion and necrosis in the ipsilateral cortex. Thus, traumatic brain injury in rats can produce rapid and significant dendritic pathology within sites of contusion. However, immunohistochemical changes in MAP2 labeling outside of contused regions suggests that TBI-induced dendritic damage may not be exclusively associated with acute cell death.
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Journal of neurotrauma · Mar 1996
Laser-Doppler flowmetry measurements of subcortical blood flow changes after fluid percussion brain injury in rats.
Laser-Doppler flowmetry (LDF) was used to record subcortical cerebral blood flow in hippocampus and striatum immediately following parasaggital fluid percussion brain injuries of mild to moderate severity (2.58 +/- 0.09 atm, 10-11 msec duration) in spontaneously breathing anesthetized rats. At 5 min postinjury, mean blood flow decreased bilaterally by 20-30% in both brain structures, and remained significantly reduced during the remainder of the 60 min postinjury recording interval. Blood flow did not change in the sham-injured rats. ⋯ The microsphere measurements revealed that the preinjury baseline and postinjury right hippocampal blood flow changes were not significantly altered by the intrahippocampal presence of an LDF probe, verifying that the LDF probe was not by itself an unacceptably disruptive influence on local cerebrovascular reactivity. Moreover, when right hippocampal blood flow was simultaneously evaluated in injured rats by both techniques, the relative blood flow changes were significantly correlated. These results indicate that laser-Doppler flowmetry provides a potentially useful means to appreciate acute regional cerebrovascular changes relative to other measures of outcome after brain trauma.
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Journal of neurotrauma · Feb 1996
Lesion volume, injury severity, and thalamic integrity following head injury.
Magnetic resonance (MR) scans of 63 traumatic brain injury (TBI) patients were analyzed to examine the relationship between injury severity, lesion volume (nonthalamic cortical/subcortical lesions), ventricle-to-brain ratio (VBR), and thalamic volume. For comparison, 33 normal control subjects were used. Patients with visible nonthalamic structural lesions showed significantly smaller thalamic volumes than patients without visible lesions or control subjects. ⋯ Patients with moderate-severe injuries had significantly smaller thalamic volumes and greater VBRs than patients with mild-moderate injuries. Although several variables related to thalamic volume, the presence of nonthalamic lesions was sufficient to result in smaller thalamic volume. Decreased thalamic volume following head injury suggests that subcortical brain structures may be susceptible to transneuronal degeneration following cortical lesions, and that this can be detected by in vivo MR-based volumetric analysis.
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Journal of neurotrauma · Feb 1996
The effect of lesion volume on cerebral vasomotor tone after focal brain injury and shock.
We have previously shown that the volume of a focal brain injury influences cerebral blood flow. We hypothesized that the cerebral vasomotor tone after traumatic brain injury and shock is related to lesion volume and that the size of the lesion would affect vasomotor reactivity. Swine were randomized to receive either a large or small cryogenic injury followed by shock, and were studied for 5 h postresuscitation. ⋯ A large brain injury and shock resulted in a significant decrease in the pial arteriolar diameter in the injured hemisphere. We also noted significant differences between and within groups in interhemispheric pial arteriolar diameter and pial arteriolar reactivity to acetylcholine and hypocarbia. These data suggest that the volume of injured tissue influences cerebral blood flow by a vascular mechanism, which may be due in part to an alteration in cerebral endothelial cell function.