Détails de la réservation
- Le : 6 September 2019
- De : 11 h 30
- à : 12 h 30
- Salle : Amphi Broca Nouvelle - Aquitaine
Détails de l'évènement
Institut de Biologie de l’école normale supérieure – Paris
"Fast 3D imaging of neuronal activity in visual cortex across multiple layers in awake mice "
2-photon microscopy allows recordings structural and functional information deep in scattering biological tissues with cellular resolution. However, standard light steering techniques are slow, providing frame rates of a few tens of Hz, and are limited to a plane of interest. We recently developed a new type of 2-photon microscope able to sample neuronal activity from 3D cortical networks in head-fixed animals at kilohertz rate. The microscope operates in a non-imaging mode, where individual laser pulses are spatially modulated with tilt and defocus to random-address individual cell bodies within a 400x400x400 µm3 volume. Single pulse modulation is achieved by a large aperture, two-axis acousto-optic deflectors (AODs) synchronized to a 40 kHz regenerative laser amplifier. Individual pulses are further modulated in phase and amplitude to pattern the beam into a square array of up to 25 focal spots targeting the bodies of individual cells, interleaved with a pattern of 10 spots targeting the neuropil. This spatial patterning helped (1) to raise the single pulse photon yield; (2) to dampen the occurrence of artefacts induced by locomotion and (3) to suppress contamination of somatic signal by surrounding neuropil activity. We validated the microscope by recording single unit activity from neurons in primary visual cortex of layer 2/3 and 5A while the animal was free to move on a treadmill. In agreement with published data we find a significantly higher level of spontaneous activity of layer 5 cells, including a higher incidence of large amplitude burst discharge, while layer 2/3 cells were more sensitive to the orientation of a moving contrast grating presented as a visual stimulus. Finally, the layered organization of the evoked activity could be revealed directly by the analysis of neuron pairwise correlations.
Invité par Bordeaux Neurocampus et la NBA
- Nom : Rodriguez Arnaud