Colloquium- “Photoemission electron microscopy for connectomics” with Prof. Kevin Boergens (UIC Physics)
Colloquium
April 9, 2025
3:00 PM - 4:00 PM
Location
238 2SES
Calendar
Download iCal FileKevin Boergens
Research Assistant Professor
Department of Physics
University of Illinois Chicago
Connectomics—the effort to map all synaptic connections within a brain—requires imaging technologies capable of capturing nanometer-scale structure across brain-wide volumes. While scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have provided foundational insights into local circuit architecture, both face fundamental limitations when scaled to larger systems. SEM is restricted by its single-pixel acquisition and beam current constraints due to space charging and sample heating, while TEM, despite its throughput advantages, depends on fragile, electron-transparent substrates that are impractical for imaging entire mammalian brains.
To address these limitations, we have been developing a widefield, substrate-based imaging approach using Photoemission Electron Microscopy (PEEM). PEEM enables parallel acquisition across large fields of view and circumvents the need for ultrathin, transparent sections, making it well-suited for large-volume biological imaging. By integrating femtosecond laser excitation, we have demonstrated that PEEM can produce high-contrast images from poorly conductive brain tissue, achieving reliable imaging with as few as one billion pulses.
In parallel, we have investigated the underlying physical constraints—particularly space charging and thermal effects—that limit throughput in electron microscopy. These studies have informed ongoing efforts to improve instrumentation, including the utilization of higher-efficiency scintillators and more robust detectors to enhance sensitivity and dynamic range in PEEM systems.
Together, these advances offer a scalable path toward synaptic-resolution reconstructions of brain connectivity, bridging the gap between high-resolution imaging and whole-brain mapping in model organisms.
Date posted
Jan 24, 2025
Date updated
Apr 4, 2025