Chronic intravital two-photon microscopy for studying the neuronal and glial dynamics in the central nervous system of behaving mice

Yu-Wei Wu^1,2,3*, Han-Yuan Yeh^1,2, Srimayee Bhattacharjee^1,2,4, Poulomi Adhikari^1,2,4, Tzu-Hsien Liu^1,2,3, Rui-Ni Wu^1,2, Ping-Yen Wu^1,2, Cheng-Han Lee⁵

¹Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
²Neuroscience Program in Academia Sinica (NPAS), Academia Sinica, Taipei, Taiwan
³Department of Life Science, College of Life Science, National Taiwan University, Taipei, Taiwan
⁴Taiwan International Graduate Program in Molecular Biology (TIGP-MCB), National Defense and Medical Center and Academia Sinica, Taipei, Taiwan
⁵Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan

* Presenter:Yu-Wei Wu, email:wuyuwei@gate.sinica.edu.tw

To understand how the brain works, it is crucial to monitor the brain's activity in behaving animals. Our lab focuses on understanding the principle of neural network re-organized underlying motor control and learning. This re-organization includes changes in neuronal synaptic connections and biochemical and electrophysiological activities of neurons and glial cells. We combined in vivo two-photon imaging with different behavioral tasks to monitor the synaptic structural plasticity and Ca2+ activity of the neurons and glial cells associated with learning through a chronic cranial window. A similar approach is used to monitor neural activity in the spinal cord and the dorsal root ganglia upon different sensory stimuli. We also combined gradient-index (GRIN) lens with two-photon imaging to study the role of the striatal neurons in the deeper brain regions, i.e. basal ganglia, which is essential for motor control. In addition, we study the role of Ca²⁺ signaling in a type of glial cell, astrocytes, which compose a large population of brain cells. We employed volumetric imaging of individual astrocytes and revealed a very complex repertoire of intracellular Ca²⁺ transients. The distributions of the spreading volume and duration of the Ca²⁺ transients follow a power law, a signature of self-organized criticality. In summary, our chronic intravital two-photon imaging approaches provide a window for linking the subcellular and cellular activity with animal behaviors as a crucial step toward understanding how our brain works.

Keywords: Intravital imaging, two-photon microscopy, neuroscience, neuron, calcium imaging