| Abstract No.: | B-C2089 |
| Country: | Canada |
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| Title: | IN VIVO CALCIUM IMAGING REVEALS FUNCTIONAL REWIRING OF SINGLE SOMATOSENSORY NEURONS AFTER STROKE |
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| Authors/Affiliations: | 2 Ian Winship*; 1 Timothy Murphy;
1 thmurphy@interchange.ubc.ca; 2 University of Alberta, Edmonton, AB, Canada
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| Content: | Objectives: Functional mapping and microstimulation studies suggest that recovery after stroke damage can be attributed to surviving brain regions taking on the functional roles of lost tissues. Although this model is well-supported by data, it is not clear how activity in single neurons is altered in relation to cortical functional maps. It is conceivable that individual surviving neurons could adopt new roles at the expense of their usual function. Alternatively, neurons that contribute to recovery may take on multiple functions and exhibit a wider repertoire of neuronal processing. In this project, we investigated plasticity in the somatosensory cortex following focal stroke using regional and single cell in vivo imaging.
Materials and Methods: Adult mice were imaged over 2-8 weeks following targeted photothrombosis of the forelimb somatosensory cortex. Regional maps of the reorganized forelimb and hindlimb somatosensory functional maps were made by imaging the sensory-evoked intrinsic optical signal. In vivo two-photon calcium imaging was then performed within these reorganized functional maps to determine how the response properties of resident neurons and glia are altered during recovery from ischemic damage during long-term recovery.
Results: Single cell imaging reveals that the limb-selectivity of individual neurons was altered by ischemia, such that neurons normally selective for a single contralateral limb processed information from multiple limbs. Altered limb-selectivity was most prominent in border regions between stroke-altered forelimb and hindlimb macroscopic representations, and peaked one month after the targeted insult. Two months after stroke, individual neurons near the center of reorganized functional areas became more selective for a preferred limb.
Conclusion: These previously unreported forms of plasticity indicate that in adult animals seemingly hardwired cortical neurons first adopt wider functional roles as they develop strategies to compensate for loss of specific sensory modalities following forms of brain damage such as stroke.
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