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Wavefront Engineering Microscopy

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Team leader: Valentina Emiliani

  • Brownian nanoparticles approaching a microelectrode surface
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Introduction

The team Wavefront Engineering microscopy is an interdisciplinary group with complementary knowledge comprising nonlinear optics, multiphoton imaging, spatial light modulator technology, neurophysiology, electrophysiology, and in vivo imaging. The group is dedicated to the development and use of advanced optical methods for the investigation of neuronal circuits. In particular the group has pioneered the use of wave-front engineering in neuroscience and demonstrated a number of new techniques based on computer generated holography, generalized phase contrast and temporal focusing enabling efficient photoactivation of caged compounds and optogenetics molecules.

Presentation

Understanding communication between neurons, who is talking to whom, and how multiple neurons coordinate and integrate multiple signals, is essential for discovering how brain circuits underlie brain function and dysfunction. Neurons can now be genetically manipulated to express proteins that, upon photon absorption, generate transmembrane electrical currents with the potential of reproducing straight away the spatiotemporal pattern of physiological neuronal events.

This new revolutionary field, now called optogenetics, is transforming neuroscience research with the promise of enabling neuroscientists to drive and read neural circuits and determine how they give rise to sensation, perception, and cognitive function.

Over the past several years the wave front engineering microscopy group has been one of the main actors in this revolution by pioneering the use of wave front engineering to pattern and propagate light into neural tissue with the precision necessary to mimic the spatiotemporal distribution of naturally occurring neuronal activity. Precisely, we have developed a number of approaches such as computer generated holography, the generalize phase contrast methods and temporal focusing, enabling to sculpt the excitation volume with a shape perfectly tailored to the selected target.

We were able to demonstrate, for the first time, simultaneous optical control of neuronal firing in defined neuronal sub-populations with single-spike and single-neuron resolution in cortical slices and freely moving mice. We have also recently demonstrated a new approach enabling the illumination of multiple targets at multiple planes within a ~300 x300 x 300 m 3 excitation volume paving the way for reaching optical control of a 3D randomly distributed set of neurons with single-cell resolution.

These approaches have been also used in a large number of national and international collaborative projects with outstanding group of neuroscientists, to investigate the mechanisms regulating the zebrafish swim circuit, to study calcium dynamics in respiratory-related neurons, to investigate the pathophysiology of the visual system and retinal circuits, to optimize the optical detection of neuronal membrane voltage, to investigate neural response dynamics in the amygdala underlying fear learning and expression and to explore in vivo hub neuron function in the adult hippocampus.

Our current research activity focuses on the use of these innovative approaches for the investigation of the mechanisms regulating functional connectivity and signal processing across the main visual pathways (retina, lateral geniculate nucleus, primary visual cortex). This in turn will require further technological advancements including the development of a new optical system for three dimensional (3D) light generation and fast 3D volume imaging, the development of optical microendoscopes for in depth imaging and control of neuronal brain circuits and the development of a theoretical modelling to simulate light and heat spreading during optogenetics experiments and photocurrent temporal dynamics under different illumination conditions.


Research areas

  • Light shaping for two photon optogenetics.

  • Light shaping for functional and volumetric imaging.

  • Microendoscopy.

  • Photothermal imaging&modeling.

  • Optical investigation of visual circuits.

  • Instrumentation.


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