New patterns of intracortical projections after focal cortical stroke.
Cortical strokes alter functional maps but associated changes in connections have not been documented. The neuroanatomical tracer biotinylated dextran amine (BDA) was injected into cortex bordering infarcts 3 weeks after focal strokes in rat whisker barrel (somatosensory) cortex. The mirror locus in the opposite hemisphere was injected as a control. After 1 week of survival, brains were processed for cytochrome oxidase (CO)-, Nissl-, and BDA-labeled neurons. Cortex bordering the infarct (peri-infarct cortex) had abnormal CO and Nissl structure. BDA-labeled neurons were plotted and projections were analyzed quantitatively. Animals with small strokes had intracortical projections, arising from peri-infarct cortex, not seen in normal hemispheres: the overall orientation was statistically significantly different from and rotated 157 degrees relative to the controls. Compared to the controls, significantly fewer cells were labeled in the thalamus. Thus, after focal cortical stroke, the peri-infarct cortex is structurally abnormal, loses thalamic connections, and develops new horizontal cortical connections by axonal sprouting.
Carmichael
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Department of Neurology and Neurological Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA. scarmichael@mednet.ucla.edu
Wei
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Rovainen
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Woolsey
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D000200:Action Potentials; D000818:Animals; D001370:Axonal Transport; D001369:Axons / Q000648:ultrastructure; D001710:Biotin / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D003911:Dextrans / Q000493:pharmacokinetics; D003576:Electron Transport Complex IV / Q000032:analysis; D005260:Female; D005456:Fluorescent Dyes / Q000493:pharmacokinetics; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology*; D008297:Male; D009416:Nerve Regeneration; D009419:Nerve Tissue Proteins / Q000032:analysis; D009434:Neural Pathways / Q000648:ultrastructure*; D009473:Neuronal Plasticity; D009474:Neurons / Q000737:chemistry / Q000648:ultrastructure; D009562:Nissl Bodies / Q000737:chemistry / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000473:pathology*; D013238:Stereotaxic Techniques; D013788:Thalamus / Q000737:chemistry; D014738:Vibrissae / Q000294:innervation
D003911:Dextrans; D005456:Fluorescent Dyes; D009419:Nerve Tissue Proteins; C076397:biotinylated dextran amine; D001710:Biotin; D003576:Electron Transport Complex IV