Plastic Change along the Intact Crossed Pathway in Acute Phase of Cerebral Ischemia Revealed by Optical Intrinsic Signal Imaging.

Xiaoli Guo,Xin Su,Shanbao Tong,Yao Li,Yongzhi He,Ying Jiang,Hongyang Lu

doi:10.1155/2016/1923160

Abstract

The intact crossed pathway via which the contralesional hemisphere responds to the ipsilesional somatosensory input has shown to be affected by unilateral stroke. The aim of this study was to investigate the plasticity of the intact crossed pathway in response to different intensities of stimulation in a rodent photothrombotic stroke model. Using optical intrinsic signal imaging, an overall increase of the contralesional cortical response was observed in the acute phase (≤48 hours) after stroke. In particular, the contralesional hyperactivation is more prominent under weak stimulations, while a strong stimulation would even elicit a depressed response. The results suggest a distinct stimulation-response pattern along the intact crossed pathway after stroke. We speculate that the contralesional hyperactivation under weak stimulations was due to the reorganization for compensatory response to the weak ipsilateral somatosensory input.

Highlights

The sensory inputs to brain are mainly integrated and processed in the contralateral hemisphere along the crossed pathway via the corpus callosum [1, 2]
Neuroimaging studies by either 18F-fluorodeoxyglucose smallanimal positron emission tomography (FDG micro-PET) or optical intrinsic signal (OIS) on rats did not show metabolic alteration in the contralesional hemisphere [10, 11]. Another three animal studies using functional magnetic resonance imaging, [14C]-2-doexyglucose (2DG) autoradiography, or voltage-sensitive dye imaging found a significant increase of ipsilateral response in the contralesional hemisphere [12,13,14]
Our results showed that the intact crossed pathway was affected by unilateral ischemic stroke

Summary

Introduction

The sensory inputs to brain are mainly integrated and processed in the contralateral hemisphere along the crossed pathway via the corpus callosum [1, 2]. When the brain suffers an ischemic stroke, both afferent and efferent pathways will be injured and lead to malfunction in motor and/or sensory systems In response to such an ischemic lesion, the brain undergoes a battery of changes, referred to as plasticity, in both injured and intact hemispheres to retain the function along both contralateral and ipsilateral connections [4, 5]. Neuroimaging studies by either 18F-fluorodeoxyglucose smallanimal positron emission tomography (FDG micro-PET) or optical intrinsic signal (OIS) on rats did not show metabolic alteration in the contralesional hemisphere [10, 11] Another three animal studies using functional magnetic resonance imaging (fMRI), [14C]-2-doexyglucose (2DG) autoradiography, or voltage-sensitive dye imaging found a significant increase of ipsilateral response in the contralesional hemisphere [12,13,14]. Clinical reports did show that the contralesional uncrossed pathway related to the recovery after stroke [15,16,17,18]

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Conclusion