Wide-field calcium imaging reveals widespread changes in cortical functional connectivity following mild traumatic brain injury in the mouse

Samuel W. Cramer, Samuel P. Haley, Laurentiu S. Popa, Russell E. Carter, Earl Scott, Evelyn B. Flaherty, Judith Dominguez, Justin D. Aronson, Luke Sabal, Daniel Surinach, Clark C. Chen, Suhasa B. Kodandaramaiah, Timothy J. Ebner

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

>2.5 million individuals in the United States suffer mild traumatic brain injuries (mTBI) annually. Mild TBI is characterized by a brief period of altered consciousness, without objective findings of anatomic injury on clinical imaging or physical deficit on examination. Nevertheless, a subset of mTBI patients experience persistent subjective symptoms and repeated mTBI can lead to quantifiable neurological deficits, suggesting that each mTBI alters neurophysiology in a deleterious manner not detected using current clinical methods. To better understand these effects, we performed mesoscopic Ca2+ imaging in mice to evaluate how mTBI alters patterns of neuronal interactions across the dorsal cerebral cortex. Spatial Independent Component Analysis (sICA) and Localized semi-Nonnegative Matrix Factorization (LocaNMF) were used to quantify changes in cerebral functional connectivity (FC). Repetitive, mild, controlled cortical impacts induce temporary neuroinflammatory responses, characterized by increased density of microglia exhibiting de-ramified morphology. These temporary neuro-inflammatory changes were not associated with compromised cognitive performance in the Barnes maze or motor function as assessed by rotarod. However, long-term alterations in functional connectivity (FC) were observed. Widespread, bilateral changes in FC occurred immediately following impact and persisted for up to 7 weeks, the duration of the experiment. Network alterations include decreases in global efficiency, clustering coefficient, and nodal strength, thereby disrupting functional interactions and information flow throughout the dorsal cerebral cortex. A subnetwork analysis shows the largest disruptions in FC were concentrated near the impact site. Therefore, mTBI induces a transient neuroinflammation, without alterations in cognitive or motor behavior, and a reorganized cortical network evidenced by the widespread, chronic alterations in cortical FC.

Original languageEnglish (US)
Article number105943
JournalNeurobiology of Disease
Volume176
DOIs
StatePublished - Jan 2023

Bibliographical note

Funding Information:
We would like to thank Lijuan Zhuo for assistance with animal surgeries. We thank Alexander Cramer at the University of Minnesota University Imaging Center (SCR_20997) for assistance in generating graphics and 3D printing, and the Mouse Behavior Core for behavioral testing. The work was supported in part by NIH R61/R33 NS115089, Minnesota SCI-TBI fund (Grant Contracts: 143722 and 191546), and University of Minnesota's MnDRIVE (Minnesota's Discovery, Research, and Innovation Economy) initiative.

Funding Information:
We would like to thank Lijuan Zhuo for assistance with animal surgeries. We thank Alexander Cramer at the University of Minnesota University Imaging Center (SCR_20997) for assistance in generating graphics and 3D printing, and the Mouse Behavior Core for behavioral testing. The work was supported in part by NIH R61/R33 NS115089 , Minnesota SCI-TBI fund (Grant Contracts: 143722 and 191546 ), and University of Minnesota's MnDRIVE (Minnesota's Discovery, Research, and Innovation Economy) initiative.

Publisher Copyright:
© 2022

Keywords

  • Calcium imaging
  • Functional connectivity
  • In vivo optical imaging
  • Network dynamics
  • Spatial independent component analysis
  • Traumatic brain injury

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

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