THE COMPANYFemtonics is one of the most dynamically expanding manufacturers of two-photon laser scanning microscopy. We make unique, custom designed 2D systems and as a pioneer we have introduced real-time 3D imaging technology to the market. By our modularity, each Femtonics microscope fits the researcher’s own needs and it can suit a wide variety of biological applications. Our other advantage is our multidisciplinary team which continually enhance and confirm the scientific applicability of our new developments.
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Understanding neural computation requires methods that can simultaneously read out activity on both somatic and dendritic scales. As shown by Katona el al. AO point scanning can effectively record fluorescent signal from up to 1000 points from in vitro preparation or from anesthetized animal. But the maximal scanning rate is limited by the switching time of the AO deflectors. In this article presents a novel technology, 3D DRIFT AO scanning, which can extend each scanning point to small 3D lines, surfaces, or volume elements for flexible and fast imaging of complex structures simultaneously in multiple locations around our ROIs. The scanning abilities were demonstrated by fast 3D recording of over 150 dendritic spines with 3D lines, over 100 somata with squares and cubes, or multiple spiny dendritic segments with surface and volume elements. Also, when measuring from awake, behaving animals relatively big motion artifacts can occur caused by vessel pulsing, respiration or locomotion. Extending the ROIs by with maintained temporal resolution allows of line motion compensation and the elimination of most of the motion artifacts. All two-photon experiments were performed with Femto3D-AcoustoOpctic microscope.
A precisely controlled model of brain injury induced by cerebral ischaemia was develpoed combined with fast in vivo two-photon calcium imaging and selective microglial manipulation revealing the influence of microglia on neuronal activity and survival in the injured brain. According to the model, selective elimination of microglia leads to a striking, 60% increase in infarct size, which is reversed by microglial repopulation. Microglia-mediated protection includes reduction of excitotoxic injury, since an absence of microglia leads to dysregulated neuronal calcium responses, calcium overload and increased neuronal death. Furthermore, the incidence of spreading depolarization (SD) is markedly reduced in the absence of microglia. Thus, microglia are involved in changes in neuronal network activity and SD after brain injury in vivo that could have important implications for common brain diseases. All two-photon experiments were performed on a Femto2D-Dual microscope.
This paper published in Nature Methods demonstrates the capabilities of the Femto3D-AO microscope developed by Gergely Katona et al. The acousto-optic two photon microscope is equipped with an electrically tunable lens focusing the excitation point very fast to any locations in 3D under the objective without mechanical restrictions. Scanning can be done in a near-cubic-millimeter range with high spatial and sub-millisecond temporal resolution. The paper describes two scanning strategies implemented on the system: continuous 3D trajectory scanning allows to precisely follow neural processes over several hundred micrometers to image the propagation of action potentials or dendritic spikes. Random access scanning mode supports imaging evoked or spontaneous calcium-activity in hundreds of neurons simultaneously in vivo.