scholarly journals Time-Resolved Integrative Optical Imaging of Diffusion during Spreading Depression

2019 ◽  
Author(s):  
J. Hrabe ◽  
S. Hrabetova
Keyword(s):  
Optical Imaging ◽  
Time Resolution ◽  
Spreading Depression ◽  
Hippocampal Slices ◽  
Effective Diffusion ◽  
Time Dependent ◽  
Imaging Method ◽  
Diffusion Measurement ◽  
Time Resolved ◽  
Depression Wave

ABSTRACTAn improved version of Integrative Optical Imaging method has been developed which substantially increases the time resolution of diffusion measurements. We present a theory for Time-Resolved Integrative Optical Imaging (TR-IOI) that incorporates time-dependent effective diffusion coefficient in homogeneous anisotropic media and time-dependent nonspecific linear clearance. The method was applied to measure the very fast changes in extracellular diffusion that occur during spreading depression in rat hippocampal slices. We were able to achieve time resolution of approximately one second, an improvement of at least ten times compared to the standard methods for extracellular diffusion measurement. We have found that diffusion of a small fluorescent extracellular marker (MW 3000) completely stopped during the maximum DC shift associated with the spreading depression wave, then gradually resumed over several minutes afterward. The effect of spreading depression on extracellular space is much larger than previously estimated by other methods with lower time resolution.

Pump-Probe Measurements Using Silicon Nanocrystal Waveguides

2003 ◽  
Vol 770 ◽  
Author(s):  
Nathanael Smith ◽  
Max J. Lederer ◽  
Marek Samoc ◽  
Barry Luther-Davies ◽  
Robert G. Elliman
Keyword(s):  
Probe Beam ◽  
Time Resolution ◽  
Pump Beam ◽  
Silicon Nanocrystals ◽  
Continuous Wave ◽  
Optical Gain ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Probe Measurements

AbstractOptical pump-probe measurements were performed on planar slab waveguides containing silicon nanocrystals in an attempt to measure optical gain from photo-excited silicon nanocrystals. Two experiments were performed, one with a continuous-wave probe beam and a pulsed pump beam, giving a time resolution of approximately 25 ns, and the other with a pulsed pump and probe beam, giving a time resolution of approximately 10 ps. In both cases the intensity of the probe beam was found to be attenuated by the pump beam, with the attenuation increasing monotonically with increasing pump power. Time-resolved measurements using the first experimental arrangement showed that the probe signal recovered its initial intensity on a time scale of 45-70 μs, a value comparable to the exciton lifetime in Si nanocrystals. These data are shown to be consistent with an induced absorption process such as confined carrier absorption. No evidence for optical gain was observed.

scholarly journals Ground- and excited-state characteristics in photovoltaic polymer N2200

RSC Advances ◽  
2021 ◽  
Author(s):  
Guanzhao Wen ◽  
Xianshao Zou ◽  
Rong Hu ◽  
Jun Peng ◽  
Zhifeng Chen ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Steady State ◽  
Excited States ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Time Dependent ◽  
Functional Theory ◽  
Time Resolved ◽  
Dependent Density

Ground- and excited-states properties of N2200 have been studied by steady-state and time-resolved spectroscopies as well as time-dependent density functional theory calculations.

Mitochondrial Inhibition Prior to Oxygen-Withdrawal Facilitates the Occurrence of Hypoxia-Induced Spreading Depression in Rat Hippocampal Slices

2006 ◽  
Vol 96 (1) ◽  
pp. 492-504 ◽  
Author(s):  
Florian J. Gerich ◽  
Sebastian Hepp ◽  
Irmelin Probst ◽  
Michael Müller
Keyword(s):  
Mitochondrial Respiration ◽  
Spreading Depression ◽  
Hippocampal Slices ◽  
Atp Synthesis ◽  
Atp Depletion ◽  
Mitochondrial Uncoupling ◽  
Ca1 Neurons ◽  
Optical Signals ◽  
Nitropropionic Acid ◽  
Carbonyl Cyanide

Oxygen withdrawal blocks mitochondrial respiration. In rat hippocampal slices, this triggers a massive depolarization of CA1 neurons and a negative shift of the extracellular DC potential, the characteristic sign of hypoxia-induced spreading depression (HSD). To unveil the contribution of mitochondria to the sensing of hypoxia and the ignition of HSD, we modified mitochondrial function. Mitochondrial uncoupling by carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP, 1 μM) prior to hypoxia hastened the onset and shortened the duration of HSD. Blocking mitochondrial ATP synthesis by oligomycin (10 μg/ml) was without effect. Inhibition of mitochondrial respiration by rotenone (20 μM), diphenyleneiodonium (25 μM), or antimycin A (20 μM) also hastened HSD onset and shortened HSD duration. 3-nitropropionic acid (1 mM) increased HSD duration. Cyanide (100 μM) hastened HSD onset and increased HSD duration. At higher concentrations, cyanide (1 mM), azide (2 mM), and FCCP (10 μM) triggered SD episodes on their own. Compared with control HSD, the spatial extent of the intrinsic optical signals of cyanide- and azide-induced SDs was more pronounced. Monitoring NADH (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) autofluorescence and mitochondrial membrane potential verified the mitochondrial targeting by the drugs used. Except 1 mM cyanide, no treatment reduced cellular ATP levels severely and no correlation was found between ATP, NADH, or FAD levels and the time to HSD onset. Therefore ATP depletion or a cytosolic reducing shift due to NADH/FADH2 accumulation cannot serve as a general explanation for the hastening of HSD onset on mitochondrial inhibition. Additional redox couples (glutathione) or events downstream of the mitochondrial depolarization need to be considered.

Time-Resolved Optical Imaging of an AC Magnetron Discharge

2008 ◽  
Vol 36 (4) ◽  
pp. 1372-1373
Author(s):  
G.C.B. Clarke ◽  
P.J. Kelly ◽  
J.W. Bradley
Keyword(s):  
Optical Imaging ◽  
Magnetron Discharge ◽  
Time Resolved
Sign in / Sign up

Export Citation Format

Share Document