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Updated: Mar 12, 2026
Circumscribed Capsular Infarct Modeling Using a Photothrombotic Technique
Published on: June 2, 2016
Capsular stroke modeling based on somatotopic mapping of motor fibers
Hanlim Song1, Wonbin Jung1, Eulgi Lee1
11 Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea.
Abstract:
Recently, several capsular stroke models have been reported with different targets of destruction. This study was performed to establish an accurate internal capsule (IC) target for capsular stroke modeling in rats. We injected adeno-associated virus serotype 5 (AAV)-CaMKII-EYFP into forelimb motor cortex and AAV-CaMKII-mCherry into hindlimb motor cortex (n = 9) to anterogradely trace the pyramidal fibers and map their somatotopic distribution in the IC. On the basis of the neural tracing results, we created photothrombotic infarct lesions in rat forelimb and hindlimb motor fiber (FMF and HMF) areas of the IC (n = 29) and assessed motor behavior using a forelimb-use asymmetry test, a foot-fault test, and a single-pellet reaching test. We found that the FMFs and HMFs were primarily distributed in the inferior portion of the posterior limb of the IC, with the FMFs located largely ventral to the HMFs but with an area of partial overlap. Photothrombotic lesions in the FMF area resulted in persistent motor deficits. In contrast, lesions in the HMF area did not result in persistent motor deficits. These results indicate that identification of the somatotopic distribution of pyramidal fibers is critical for accurate targeting in animal capsular stroke models: only infarcts in the FMF area resulted in long-lasting motor deficits.
Insights
Accurate targeting in rat capsular stroke models is crucial. Lesions in the forelimb motor fiber area of the internal capsule caused persistent motor deficits, unlike hindlimb motor fiber lesions.
Area of Science:
- Neuroscience
- Stroke Research
- Animal Models
Background:
- Capsular stroke models are vital for understanding stroke mechanisms.
- Previous models lacked precise targeting within the internal capsule.
- Accurate somatotopic mapping is needed for reliable stroke modeling.
Purpose of the Study:
- To establish an accurate internal capsule target for capsular stroke modeling in rats.
- To map the somatotopic distribution of pyramidal fibers in the rat internal capsule.
- To correlate lesion location with motor deficits in a rat stroke model.
Main Methods:
- Anterograde tracing using adeno-associated virus serotype 5 (AAV)-CaMKII-EYFP and AAV-CaMKII-mCherry to map pyramidal fibers.
- Photothrombotic infarct lesion creation in identified forelimb and hindlimb motor fiber areas of the internal capsule.
- Assessment of motor behavior using forelimb-use asymmetry, foot-fault, and single-pellet reaching tests.
Main Results:
- Forelimb and hindlimb motor fibers are located in the inferior posterior limb of the internal capsule, with forelimb fibers ventral to hindlimb fibers.
- Photothrombotic lesions in the forelimb motor fiber area induced persistent motor deficits.
- Lesions in the hindlimb motor fiber area did not result in persistent motor deficits.
Conclusions:
- Somatotopic organization of pyramidal fibers in the internal capsule is critical for accurate stroke modeling.
- Precise targeting of the forelimb motor fiber area is necessary to induce long-lasting motor deficits in rat capsular stroke models.
- This study refines capsular stroke modeling for better research outcomes.
