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{1555} | |||||
Recently I've been underwhelmed by the performance of adaptive optics (AO) for imaging head-fixed cranial-window mice. There hasn't been much of an improvement, despite significant optimization effort. This begs the question: where are AO microscopes used? When the purpose of a paper is to explain and qualify an novel AO approach, the improvement is always good, >> 2x. Yet, in the one paper (first below) when the purpose was neuroscience, not optics, the results are less inspiring. Are the results from the optics papers cherry-picked? Thalamus provides layer 4 of primary visual cortex with orientation- and direction-tuned inputs Wenzhi Sun, Zhongchao Tan, Brett D Mensh & Na Ji 2016 https://www.nature.com/articles/nn.4196
Direct wavefront sensing for high-resolution in vivo imaging in scattering tissue Kai Wang, Wenzhi Sun, Christopher T. Richie, Brandon K. Harvey, Eric Betzig & Na Ji, 2015 https://www.nature.com/articles/ncomms8276
Multiplexed aberration measurement for deep tissue imaging in vivo Chen Wang, Rui Liu, Daniel E Milkie, Wenzhi Sun, Zhongchao Tan, Aaron Kerlin, Tsai-Wen Chen, Douglas S Kim & Na Ji 2014 https://www.nature.com/articles/nmeth.3068
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{1523} |
ref: -0
tags: tennenbaum compositional learning character recognition one-shot learning
date: 02-23-2021 18:56 gmt
revision:2
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One-shot learning by inverting a compositional causal process
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{1490} | |||||
PMID-21527931 Two-photon absorption properties of fluorescent proteins
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{1417} |
ref: -0
tags: synaptic plasticity 2-photon imaging inhibition excitation spines dendrites synapses 2p
date: 08-14-2020 01:35 gmt
revision:3
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PMID-22542188 Clustered dynamics of inhibitory synapses and dendritic spines in the adult neocortex.
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{1478} |
ref: -2013
tags: 2p two photon STED super resolution microscope synapse synaptic plasticity
date: 08-14-2020 01:34 gmt
revision:3
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PMID-23442956 Two-Photon Excitation STED Microscopy in Two Colors in Acute Brain Slices
PMID-29932052 Chronic 2P-STED imaging reveals high turnover of spines in the hippocampus in vivo | |||||
{1501} | |||||
A 6-nm ultra-photostable DNA Fluorocube for fluorescence imaging Also including some correspondence with the authors: Me Nice work and nice paper, thanks for sharing .. and not at all what I had expected from Ron's comments! Below are some comments ... would love your opinion. I'd expect that the molar absorption coefficients for the fluorocubes should be ~6x larger than for the free dyes and the single dye cubes (measured?), yet the photon yields for all except Cy3N maybe are around the yield for one dye molecule. So the quantum yield must be decreased by ~6x? This in turn might be from a middling FRET which reduces lifetime, thereby the probability of ISC, photoelectron transfer, and hence photobleaching. I wonder if in the case of ATTO 647N Cy5 and Cy3, the DNA is partly shielding the fluorphores from solvent (ala ethidium bromide), which also helps with stability, just like in fluorescent proteins. ATTO 647N generates a lot of singlet oxygen, who knows what it's doing to DNA. Can you do a log-log autocorrelation of the blinking timeseries of the constructs? This may reveal different rate constants controlling dark/light states (though, for 6 coupled objects, might not be interpretable!) Also, given the effect of DNA shielding, have you compared to free dyes to single-dye cubes other than supp fig 10? The fact that sulfonation made such a huge effect in brightness is suggestive. Again, these are super interesting & exciting results! Author I haven't directly looked at the molar absorption coefficient but judging from the data that I collected for the absorption spectra, there is certainly an increase for the fluorocubes compared to single dyes. I agree that this would be an interesting experiment and I am planning collect data to measure the molar absorption coefficient. I would also expect a ~6 fold increase for the Fluorocubes. Yes, we suspect homo FRET to help reduce photobleaching. So far we only measured lifetimes in bulk but are planning to obtain lifetime data on the single-molecule level soon. We also wondered if the DNA is providing some kind of shield for the fluorophores but could not design an experiment to directly test this hypothesis. If you have a suggestion, that would be wonderful. The log-log autocorrelation of blinking events is indeed difficult to interpret. Already individual intensity traces of fluorocubes are difficult to analyze as many of them get brighter before they bleach. We are also wondering if some fluorocubes are emitting two photons simultaneously. We will hopefully be able to measure this soon. | |||||
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PMID-18204458 High-speed, low-photodamage nonlinear imaging using passive pulse splitters
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{1499} | |||||
PMID-24877017 Optimal lens design and use in laser-scanning microscopy
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{1486} |
ref: -2019
tags: non degenerate two photon excitation fluorophores fluorescence OPO optical parametric oscillator
date: 10-31-2019 20:53 gmt
revision:0
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Efficient non-degenerate two-photon excitation for fluorescence microscopy | |||||
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PMID-26352471 Labelling and optical erasure of synaptic memory traces in the motor cortex
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{1479} | |||||
Can we image biological tissue with entangled photons? How much fluorescence can we expect, based on reasonable concentrations & published ETPA cross sections? Start with beer's law: = absorbance; = sample length, 10 μm, 1e-3 cm; = concentration, 10 μmol; = cross-section, for ETPA assume (this is based on a FMN based fluorophore; actual cross-section may be higher). Including Avogadro's number and , Now, add in quantum efficiency (Rhodamine); collection efficiency ; and an incoming photon pair flux of (which roughly about the limit for quantum behavior; n = 0.1 photons / mode; will add this calculation). This is very low, but within practical imaging limits. As a comparison, incoherent 2p imaging creates ~ 100 photons per pulse, of which 10 make it to the detector; for 512 x 512 pixels at 15fps, the dwell time on each pixel is 20 pulses of a 80 MHz Ti:Sapphire laser, or ~ 200 photons. Note the pair flux is per optical mode; for a typical application, we'll use a Nikon 16x objective with a 600 μm Ø FOV and 0.8 NA. At 800 nm imaging wavelength, the diffraction limit is 0.5 μm. This equates to about addressable modes in the FOV. Then an illumination of photons / sec / mode equates to photons over the whole field; if each photon pair has an energy of , this is equivalent to 300 mW. 100mW is a reasonable limit, hence scale incoming flux to pairs /sec. Hence, the imaging mode is power limited, and not quantum limited (if you could get such a bright entangled source). And right now that's the limit -- for a BBO crystal, circa 1998 experimenters were getting 1e4 photons / sec / mW. So, pairs / sec would require 23 GW. Yikes. More efficient entangled sources have been developed, using periodically-poled potassium titanyl phosphate (PPPTP), which (again assuming linearity) puts the power requirement at 23 MW. This is within the reason of q-switched lasers, but still incredibly inefficient. The down-conversion process is not linear in intensity, which is why Goodson pumps with SHG from a Ti:sapphire to yield ~1e7 photons; but this of induces temporal correlations which increase the frequency of incoherent TPA. Still, combining PPPTP with a Ti:sapphire laser could result in 1e13 photons / sec, which is sufficient for scanned microscopy. Since the laser is pulsed, it will still be subject to incoherent TPA; but that's OK, the point is to reduce the power going into the animal via larger ETPA cross-section. The answer to above is a tentative yes. Upon the development of brighter entangled sources (e.g. arrays of quantum structures), this can move to fully widefield imaging. | |||||
{1474} | |||||
Various papers put out by the Goodson group:
And from a separate group at Northwestern:
Regarding high fluence sources, quantum dots / quantum structures seem promising. | |||||
{1475} |
ref: -2017
tags: two photon holographic imaging Arch optogenetics GCaMP6
date: 09-12-2019 19:24 gmt
revision:1
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PMID-28053310 Simultaneous high-speed imaging and optogenetic inhibition in the intact mouse brain.
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{1473} | |||||
PMID-17179937 Major signal increase in fluorescence microscopy through dark-state relaxation (2007)
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{1469} |
ref: -2016
tags: fluorescent proteins photobleaching quantum yield piston GFP
date: 06-19-2019 14:33 gmt
revision:0
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PMID-27240257 Quantitative assessment of fluorescent proteins.
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{1467} |
ref: -2017
tags: neuromorphic optical computing nanophotonics
date: 06-17-2019 14:46 gmt
revision:5
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Progress in neuromorphic photonics
See also :
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{1418} |
ref: -0
tags: nanophotonics interferometry neural network mach zehnder interferometer optics
date: 06-13-2019 21:55 gmt
revision:3
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Deep Learning with Coherent Nanophotonic Circuits
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PMID-29089483 Three-dimensional scanless holographic optogenetics with temporal focusing (3D-SHOT).
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{305} | |||||
PMID-101388[0] Fine control of operantly conditioned firing patterns of cortical neurons.
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PMID-30635577 Functional imaging of visual cortical layers and subplate in awake mice with optimized three photon microscopy
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{1389} |
ref: -0
tags: photoacoustic tomography mouse imaging q-switched laser
date: 05-11-2017 05:23 gmt
revision:1
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{1390} |
ref: -0
tags: photoacoustic tomography mouse imaging q-switched laser
date: 05-11-2017 05:21 gmt
revision:0
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{1287} |
ref: -0
tags: maleimide azobenzine glutamate photoswitch optogenetics
date: 06-16-2014 21:19 gmt
revision:0
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PMID-16408092 Allosteric control of an ionotropic glutamate receptor with an optical switch
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{1244} |
ref: -0
tags: polyimide electrodes ecog japan photosensitive
date: 06-28-2013 01:50 gmt
revision:0
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PMID-22719725 Photosensitive-polyimide based method for fabricating various neural electrode architectures
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{1184} | |||||
PMID-22308458 Optically monitoring voltage in neurons by photo-induced electron transfer through molecular wires.
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http://www.redshirtimaging.com/redshirt_neuro/neuro_lib_2.htm
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PMID-21880826[0] http://cshprotocols.cshlp.org/content/2011/9/pdb.prot065474.full?rss=1
____References____
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{813} |
ref: work-0
tags: kicadocaml zbuffer comparison picture screenshot
date: 03-03-2010 16:38 gmt
revision:4
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Simple illustration of Kicadocaml with Z buffering enabled: and disabled: I normally use it with Z buffering enabled, but turn it off if, say, I want to clearly see all the track intersections, especially co-linear tracks or zero length tracks. (Probably I should write something to merge and remove these automatically.) Note that in either case, tracks and modules are rendered back-to-front, which effects a Z-sorting of sorts; it is the GPUs Z buffer that is enabled/disabled here. | |||||
{812} | |||||
Aint she pretty? More shots of the completed board (click for full resolution image):
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"One shot of [Lee Freidlander's], from 1969, traps an entire landscape of feeling: a boundless American sky, salted with high clouds, plus Freidlander's wife, Maria, with her slightly smiling face - inside the cab of a single truck, layering what we see through the side window with what is reflected in it. I know of long novels that tell you less " (not the shot above, but just the same - ) some more - http://www.nga.gov.au/SurfaceBeauty/IMAGES/LRG/Fiedlander-1981.954.jpg | |||||
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PMID-17234689[0] Volitional control of neural activity: implications for brain-computer interfaces (part of a symposium)
humm.. this paper came out a month ago, and despite the fact that he is much older and more experienced than i, we have arrived at the same conclusions by looking at the same set of data/papers. so: that's good, i guess. ____References____ | |||||
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How much carbon dioxide (CO2) is released to heat the water for a 5-minute shower?
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Nathan, Misha, and their lives went to Japan for a week to work with the roboticists @ ATR. During the off time, they spent time exploring and photographing Japan. Misha lent me his camera to video record Clementine, and in the process of trying to free up space in the camera's memory, I found these excellent pictures taken by (presumably) Misha. There were other very nice pictures, but they contain Misha, Nathan etc so I excluded them. the photo below is by far the best. | |||||
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http://www.beautifulcrime.com/public/exhibitions/ Need flash to view the site. |