A workshop on the application of expansion microscopy (ExM) in connectomics was held in Beijing from Jan 11 to 15. Professor Mojtaba R. Tavakoli, inventor of the LICONN technology, was the lead instructor on the program.

Participants engage in hands-on sessions and discussions during the four-day training session held from Jan 11 to 14, 2025, in Beijing. [Photo/WeChat account: BSC]

The workshop included a four-day training session at the Peking University (PKU) National Biomedical Imaging Center. It brought together 45 participants, including faculty and students from renowned institutions such as Tsinghua University, PKU, China Agricultural University and Fudan University.

The training focused on the assembly of neural circuits in the brain and how modern connectomics, primarily using electron microscopy, reveals the intricate structures of brain tissue.

Among the various hybrid optical-electronic approaches, ExM has recently demonstrated unique capabilities to simultaneously capture circuit structures and analyze information, said Tavakoli.

By expanding brain tissue samples 16-fold and employing pan-protein staining, researchers can achieve electron microscopy-like tissue structure images with nanometer-level resolution by using optical microscopes. Furthermore, by combining this approach with immunofluorescence staining, critical molecular details such as neurotransmitters can also be obtained, he added.

During the four-day event, participants completed the entire process from sample preparation to fluorescent staining. Each attendee performed tissue expansion on mouse brain slices and acquired their own optical microscopy data.

In addition to the hands-on experiences, participants engaged in active discussions and Q&A sessions, which deepened their understanding of the principles behind the experiments.

At the conclusion of the training, participants expressed their gratitude for the opportunity to learn the technical details of ExM and to connect with leading experts and peers. They said they hope the session will not only provide practical skills but also serve as a platform for academic exchange and collaboration, further fueling their scientific ambitions.

Mojtaba R. Tavakoli delivers a lecture on Jan 15, 2025, at PKU. [Photo/WeChat account: BSC]

The workshop also featured a lecture on super-resolution techniques based on optical microscopy at PKU, where Tavakoli explained how this technology enables multi-scale research on the brain, from molecular mechanisms to synapses, neural circuits and behavior.

Participants of the workshop on the application of ExM in connectomics held from Jan 11 to 15, 2025 [Photo/WeChat account: BSC]

During the lecture, Tavakoli introduced the LICONN technology, a light microscopy-based connectomics approach combining hydrogel-based ExM, optical imaging and automated reconstruction algorithm.

He further elaborated on its applications across various species, including humans, rodents and fruit flies, and discussed its current limitations and future potential.