New Patterns of Intracortical Projections after Focal Cortical Stroke

• Main Authors: S. Thomas Carmichael, Ling Wei, Carl M. Rovainen, Thomas A. Woolsey
• Format: Article
• Language: English
• Published: Elsevier 2001-10-01
• Series: Neurobiology of Disease
• Subjects: neuronal plasticity; functional reorganization; cerebral ischemia; focal; repair; axonal sprouting
• Online Access: http://www.sciencedirect.com/science/article/pii/S0969996101904255

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° 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.