1,721,000 research outputs found
Computer-Generated Holographic Beams for the Investigation of the Molecular and Circuit Function
No full textMethod for generating a lattice of Bessel beams with arbitrarygeometries and optical properties with one single optical element
No full textAn Optical Illusion Pinpoints an Essential Circuit Node for Global Motion Processing
No full textDirection-selective (DS) neurons compute the direction of motion in a visual scene. Brain-wide imaging in larval zebrafish has revealed hundreds of DS neurons scattered throughout the brain. However, the exact population that causally drives motion-dependent behaviors—e.g., compensatory eye and body movements—remains largely unknown. To identify the behaviorally relevant population of DS neurons, here we employ the motion aftereffect (MAE), which causes the well-known “waterfall illusion.” Together with region-specific optogenetic manipulations and cellular-resolution functional imaging, we found that MAE-responsive neurons represent merely a fraction of the entire population of DS cells in larval zebrafish. They are spatially clustered in a nucleus in the ventral lateral pretectal area and are necessary and sufficient to steer the entire cycle of optokinetic eye movements. Thus, our illusion-based behavioral paradigm, combined with optical imaging and optogenetics, identified key circuit elements of global motion processing in the vertebrate brain
Dielectric polarization-insensitive metasurfaces for Bessel beam generation in light sheet microscopy
No full textWe present a method based on wave front engineering for rendering a Bessel Beam (BB) lattice with one single, flat, and lightweight optical element. According to this design, we fabricated and characterized a Silicon Nitride (SiNx) element using Meta-Surface (MS) technology encoding all the operations required to generate the designed BB lattice. Finally, we demonstrated its application in microscopy by integrating it along the excitation path of a light-sheet microscope (LSM) and recording neuronal activity from the zebrafish larva brain
In situ electroporation of mammalian cells through SiO2 thin film capacitive microelectrodes
Full text linkElectroporation is a widely used non-viral technique for the delivery of molecules, including nucleic acids, into cells. Recently, electronic microsystems that miniaturize the electroporation machinery have been developed as a new tool for genetic manipulation of cells in vitro, by integrating metal microelectrodes in the culture substrate and enabling electroporation in-situ. We report that non-faradic SiO2 thin film-insulated microelectrodes can be used for reliable and spatially selective in-situ electroporation of mammalian cells. CHO-K1 and SH-SY5Y cell lines and primary neuronal cultures were electroporated by application of short and low amplitude voltage transients leading to cell electroporation by capacitive currents. We demonstrate reliable delivery of DNA plasmids and exogenous gene expression, accompanied by high spatial selectivity and cell viability, even with differentiated neurons. Finally, we show that SiO2 thin film-insulated microelectrodes support a double and serial transfection of the targeted cells
Feeding State Modulates Behavioral Choice and Processing of Prey Stimuli in the Zebrafish Tectum
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Aberrant patterns of sensory-evoked activity in the olfactory bulb of LRRK2 knockout mice
Full text linkThe LRRK2 gene is the major genetic determinant of familiar Parkinson’s disease (PD). Leucine-rich repeat kinase 2 (LRRK2) is a multidomain protein involved in several intracellular signaling pathways. A wealth of evidence indicates that LRRK2 is enriched at the presynaptic compartment where it regulates vesicle trafficking and neurotransmitter release. However, whether the role of LRRK2 affects neuronal networks dynamic at systems level remains unknown. Addressing this question is critical to unravel the impact of LRRK2 on brain function. Here, combining behavioral tests, electrophysiological recordings, and functional imaging, we investigated neuronal network dynamics, in vivo, in the olfactory bulb of mice carrying a null mutation in LRRK2 gene (LRRK2 knockout, LRRK2 KO, mice). We found that LRRK2 KO mice exhibit olfactory behavioral deficits. At the circuit level, the lack of LRRK2 expression results in altered gamma rhythms and odorant-evoked activity with significant impairments, while the spontaneous activity exhibited limited alterations. Overall, our data in the olfactory bulb suggest that the multifaced role of LRRK2 has a strong impact at system level when the network is engaged in active sensory processing
Targeted in vivo genetic manipulation of the mouse or rat brain by in utero electroporation with a triple-electrode probe
No full textEffects of environmental enrichment on recognition memory in zebrafish larvae
No full textZebrafish (Danio rerio) constitute a useful model for studying memory function and impairment in vertebrates and are now widely used in translational research. On the one hand, the adoption of simple, fast and reliable tests such as novel object recognition (NOR) has increased our knowledge considerable about memory mechanisms in animals. On the other hand, in many model organisms, exposure to environmental enrichment, especially during the early stages of development, affects various cognitive functions. Evidence for the effects of environmental enrichment on zebrafish has been accumulating rapidly, but most of this evidence has been collected in adult subjects. We compared larvae raised in either an enriched or barren environments and measured their memory performance at 14-days post-fertilization. Initially, subjects were allowed to familiarize with two identical novel objects (i.e., pattern of 2D-geometrical figures). After a time interval, larvae faced a two-choice task presenting the same objects paired with a new one. As a measure of recognition memory, we exploit the tendency of individuals to explore a novel object over a familiar one. Our results indicate that larvae from the barren environment spent more time exploring familiar stimuli than novel ones, showing the innate presence of recognition memory capacity in zebrafish larvae. Conversely, subjects bred in a visually enriched environment explore both familiar and novel stimuli almost equally. The increase of exploratory behavior and, consequently, the reduction of avoidance to the novel object may explain the performance shown by larvae exposed to an enrichment environment compared to the larvae bred in a barren environment. Taken together, these results confirm that early-stage zebrafish possess complex visual discrimination capacities and that rearing subjects in a structurally complex environment might hinder memory performance by reducing their neophobic response
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