Multiphoton
Multiphoton
Prof Ian Oldenburg
The Oldenburg lab combines optics, multiphoton optogenetics, calcium imaging, and computation to understand the motor system. The overall goal of the Oldenburg Lab is to understand the causal relationship between neural activity and motor actions. We use advanced optical techniques such as multiphoton holographic optogenetics to control neural activity with an incredible degree of precision, writing complex patterns of activity to distributed groups of cells. Only by writing activity into the brain at the scale in which it naturally occurs (individual neurons firing distinct patterns of action potentials) can we test theories of what population activity means. We read out the effects of these precise manipulations locally with calcium imaging, in neighboring brain regions with electrophysiology, and at the 'whole animal level' through changes in behavior. We are looking for curious motivated, and talented people with a wide range of skill sets to join our group at all levels from Technician to Postdoc.
Development of an open-source femtosecond fiber laser system for multiphoton microscopy
This talk will present a low-cost protocol for fabricating an easily constructed femtosecond (fs) fiber laser system suitable for routine multiphoton microscopy (1060–1080 nm, 1 W average power, 70 fs pulse duration, 30–70 MHz repetition rate). Concepts well-known in the laser physics community essential to proper laser operation, but generally obscure to biophysicists and biomedical engineers, will be clarified. The parts list (~$13K US dollars), the equipment list (~$40K+), and the intellectual investment needed to build the laser will be described. A goal of the presentation will be to engage with the audience to discuss trade-offs associated with a custom-built fs fiber laser versus purchasing a commercial system. I will also touch on my research group’s plans to further develop this custom laser system for multiplexed cancer imaging as well as recent developments in the field that promise even higher performance fs fiber lasers for approximately the same cost and ease of construction.
Multiphoton imaging with next-generation indicators
Two-photon (2P) in vivo functional imaging of genetically encoded fluorescent Ca2+indicators (GECIs) for neuronal activity has become a broadly applied standard tool in modern neuroscience, because it allows simultaneous imaging of the activity of many neurons at high spatial resolution within living animals. Unfortunately, the most commonly used light-sources – tunable femtosecond pulsed ti:sapphire lasers – can be prohibitively expensive for many labs and fall short of delivering sufficient powers for some new ultra-fast 2P microscopy modalities. Inexpensive homebuilt or industrial light sources such as Ytterbium fiber lasers (YbFLs) show great promise to overcome these limitations as they are becoming widely available at costs orders of magnitude lower and power outputs of up to many times higher than conventional ti:sapphire lasers. However, these lasers are typically bound to emitting a single wavelength (i.e., not tunable) centered around 1020-1060 nm, which fails to efficiently excite state of the art green GECIs such as jGCaMP7 or 8. To this end, we designed and characterized spectral variants (yellow CaMP = YCaMP) of the ultrasensitive genetically encoded calcium indicator jGCaMP7, that allows for efficient 2P-excitation at wavelengths above 1010nm. In this talk I will give a brief overview over some of the reasons why using a fiber laser for 2P excitation might be right for you. I will talk about the development of jYCaMP and some exciting new experimental avenues that it has opened while touching on the prospect that shifting biosensors yellow could have for the 2P imaging community. Please join me for an interesting and fun discussion on whether “yellow is the new green” after the talk!
Portable and turn-key multimodal multiphoton microscopy for easy-to-access label-free and intravital imaging
FENS Forum 2024