scholarly journals Correction of z ‐motion artefacts to allow population imaging of synaptic activity in behaving mice

2020 ◽  
Vol 598 (10) ◽  
pp. 1809-1827 ◽  
Author(s):  
Thomas Michael Ryan ◽  
Antonio Jesus Hinojosa ◽  
Rozan Vroman ◽  
Christoforos Papasavvas ◽  
Leon Lagnado
Keyword(s):  
Synaptic Activity ◽  
Motion Artefacts ◽  
Population Imaging

scholarly journals Correction of z-motion artefacts to allow population imaging of synaptic activity in awake behaving mice

2019 ◽  
Author(s):  
Thomas Ryan ◽  
Antonio Hinojosa ◽  
Rozan Vroman ◽  
Christoforos Papasavvas ◽  
Leon Lagnado
Keyword(s):  
Blood Vessels ◽  
Point Spread Function ◽  
Synaptic Activity ◽  
List Type ◽  
Motion Artefacts ◽  
Single Plane ◽  
Substantial Impact ◽  
Point Spread ◽  
Spread Function ◽  
Population Imaging

AbstractFunctional imaging of head-fixed, awake, behaving mice using two-photon imaging of fluorescent activity reporters has become a powerful tool in the studying the function of the brain. Motion artefacts are an inevitable problem during such experiments and are routinely corrected for in x and y dimensions. However, axial (z) shifts of several microns can also occur, leading to intensity fluctuations in structures such as synapses that are small compared to the axial point-spread function of the microscope. Here we present a simple strategy to correct z-motion artefacts arising over the course of a time-series experiment in a single optical plane. Displacement in z was calculated using dye-filled blood vessels as an anatomical marker, providing high contrast images and accuracy to within ∼0.1 µm. The axial profiles of ROIs corresponding to synapses were described using a Moffat function and this “ROI-spread function” used to correct activity traces on an ROI-by-ROI basis. We demonstrate the accuracy and utility of the procedures in simulation experiments using fluorescent beads and then apply them to correcting measurements of synaptic activity in populations of vasoactive-intestinal peptide (VIP) interneurons expressing the synaptic reporter SyGCaMP6f. Correction of z-motion artefacts had a substantial impact on the apparent correlation between synaptic activity and running speed, demonstrating the importance of correcting for these artefacts for the interpretation of in vivo imaging experiments in awake mice.Summary of Key PointsMotion artefacts associated with motor behaviour are an inevitable problem of multiphoton imaging in awake behaving animals, particularly imaging synapses.Correction of axial motion usually requires volumetric imaging resulting in slower rates of acquisition.We describe a method that is easy to implement to correct z-motion artefacts that allows population imaging of synaptic activity while scanning a single plane in a standard multiphoton microscope.The method uses a reference volume acquired in two colour channels – an activity reporter and an anatomical marker of blood vessels. The procedure estimates the z-displacement in every frame and applies an intensity correction in which the z point-spread function for each synapse is modelled as a Moffat function.We demonstrate that the method allows synaptic calcium activity signals to be collected from populations of synaptic boutons in mouse primary visual cortex during locomotion.

Ischemic preconditioning protects the hippocampal CA1 neurons by inhibiting synaptic activity in rat

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S300-S300
Author(s):  
Thomas J Sick ◽  
Ami P Raval ◽  
Isabel Saul ◽  
Kunjan R Dave ◽  
Raul Busto ◽  
...  
Keyword(s):  
Ischemic Preconditioning ◽  
Synaptic Activity ◽  
Ca1 Neurons ◽  
Hippocampal Ca1 Neurons ◽  
Hippocampal Ca1

scholarly journals NIR Laser Photobiomodulation Induces Neuroprotection in an In Vitro Model of Cerebral Hypoxia/Ischemia

2021 ◽  
Author(s):  
Elisabetta Gerace ◽  
Francesca Cialdai ◽  
Elettra Sereni ◽  
Daniele Lana ◽  
Daniele Nosi ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Cerebral Ischemia ◽  
Molecular Mechanisms ◽  
Hippocampal Slices ◽  
Treatment Protocol ◽  
Synaptic Activity ◽  
Laser Source ◽  
Therapeutic Window ◽  
Hypoxia Ischemia ◽  
Nir Laser

AbstractBrain photobiomodulation (PBM) is an innovative treatment for a variety of neurological conditions, including cerebral ischemia. However, the capability of PBM for ischemic stroke needs to be further explored and its mechanisms of action remain currently unclear. The aim of the present research was to identify a treatment protocol capable of inducing neuroprotection and to investigate the molecular mechanisms activated by a dual-wavelength near infrared (NIR) laser source in an organotypic hippocampal slice model of hypoxia/ischemia. Hippocampal slices were exposed to oxygen and glucose deprivation (OGD) for 30 min followed by NIR laser light (fluence 3.71, 7.42, or 14.84 J/cm2; wavelengths 808 nm and 905 nm) delivered immediately or 30 min or 60 min after OGD, in order to establish a therapeutic window. Neuronal injury was assessed by propidium iodide fluorescence 24 h later. Our results show that NIR laser irradiation attenuates OGD neurotoxicity once applied immediately or 30 min after OGD. Western blot analysis of proteins involved in neuroinflammation (iNOS, COX-2, NFkB subunit p65, and Bcl-2) and in glutamatergic-mediated synaptic activity (vGluT1, EAAT2, GluN1, and PSD95) showed that the protein modifications induced by OGD were reverted by NIR laser application. Moreover, CA1 confocal microscopy revealed that the profound morphological changes induced by OGD were reverted by NIR laser radiation. In conclusion, NIR laser radiation attenuates OGD neurotoxicity in organotypic hippocampal slices through attenuation of inflammatory mechanisms. These findings shed light on molecular definition of NIR neuroprotective mechanisms, thus underlining the potential benefit of this technique for the treatment of cerebral ischemia.

scholarly journals Neuro-Inspired Signal Processing in Ferromagnetic Nanofibers

Biomimetics ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 32
Author(s):  
Tomasz Blachowicz ◽  
Jacek Grzybowski ◽  
Pawel Steblinski ◽  
Andrea Ehrmann
Keyword(s):  
Data Processing ◽  
Data Storage ◽  
Domain Walls ◽  
Data Transfer ◽  
Synaptic Activity ◽  
Neuromorphic Computing ◽  
Rotating Magnetic Fields ◽  
Micromagnetic Simulations ◽  
Energy Consuming ◽  
Stochastic Data

Computers nowadays have different components for data storage and data processing, making data transfer between these units a bottleneck for computing speed. Therefore, so-called cognitive (or neuromorphic) computing approaches try combining both these tasks, as is done in the human brain, to make computing faster and less energy-consuming. One possible method to prepare new hardware solutions for neuromorphic computing is given by nanofiber networks as they can be prepared by diverse methods, from lithography to electrospinning. Here, we show results of micromagnetic simulations of three coupled semicircle fibers in which domain walls are excited by rotating magnetic fields (inputs), leading to different output signals that can be used for stochastic data processing, mimicking biological synaptic activity and thus being suitable as artificial synapses in artificial neural networks.

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