Temporal contrast enhancement of picosecond pulses based on phase-conjugate wave generation

2012 ◽  
Vol 37 (2) ◽  
pp. 241 ◽  
Author(s):  
S. G. Liang ◽  
H. J. Liu ◽  
N. Huang ◽  
Q. B. Sun ◽  
Y. S. Wang ◽  
...  
Keyword(s):  
Contrast Enhancement ◽  
Wave Generation ◽  
Temporal Contrast ◽  
Phase Conjugate ◽  
Picosecond Pulses

Temporal contrast enhancement and compression of output pulses of ultra-high power lasers

2021 ◽  
Vol 46 (7) ◽  
pp. 1620
Author(s):  
S. Yu. Mironov ◽  
M. V. Starodubtsev ◽  
E. A. Khazanov
Keyword(s):  
Contrast Enhancement ◽  
High Power ◽  
Temporal Contrast ◽  
High Power Lasers

Temporal contrast enhancement of a femtosecond fiber CPA system by filtering of SPM broadened spectra

2018 ◽  
Author(s):  
Joachim Buldt ◽  
Michael Müller ◽  
Robert Klas ◽  
Tino Eidam ◽  
Jens Limpert ◽  
...  
Keyword(s):  
Contrast Enhancement ◽  
Temporal Contrast

Temporal contrast enhancement of ultrashort pulses using a spatiotemporal plasma-lens filter

2020 ◽  
Vol 45 (8) ◽  
pp. 2279
Author(s):  
Ping Zhu ◽  
Arie Zigler ◽  
Xinglong Xie ◽  
Dongjun Zhang ◽  
Qingwei Yang ◽  
...  
Keyword(s):  
Contrast Enhancement ◽  
Ultrashort Pulses ◽  
Temporal Contrast

scholarly journals The effects of flicker adaptation upon temporal contrast enhancement

1983 ◽  
Vol 33 (1) ◽  
pp. 75-78 ◽  
Author(s):  
Frederick L. Kitterle ◽  
Bettina L. Beard
Keyword(s):  
Contrast Enhancement ◽  
Temporal Contrast

Temporal Contrast Enhancement via GABAC Feedback at Bipolar Terminals in the Tiger Salamander Retina

1998 ◽  
Vol 79 (4) ◽  
pp. 2171-2180 ◽  
Author(s):  
Cun-Jian Dong ◽  
Frank S. Werblin
Keyword(s):  
Receptor Antagonist ◽  
Contrast Enhancement ◽  
Ganglion Cells ◽  
Lucifer Yellow ◽  
Light Stimulus ◽  
Ringer Solution ◽  
Bipolar Cells ◽  
Voltage Response ◽  
Tiger Salamander ◽  
Temporal Contrast

Dong, Cun-Jian and Frank S. Werblin. Temporal contrast enhancement via GABAC feedback at bipolar terminals in the tiger salamander retina. J. Neurophysiol. 79: 2171–2180, 1998. Most retinal amacrine (ACs) and ganglion cells (GCs) express temporal contrast by generating action potentials at only the onset and offset of the light stimulus. This study investigated the neural mechanisms that underlie this temporal contrast enhancement. Whole cell patch recordings were made from bipolar cells (BCs), ACs, and GCs in the retinal slice preparation. The cells were identified by the locations of their somas in the inner nuclear layer and ganglion cell layers, their characteristic light responses, and morphology revealed by Lucifer yellow staining. Depolarizing a single BC with a brief voltage pulse elicited a Cl− tail current that was completely abolished when Ca2+ entry to bipolar terminals was prevented, by either removing Ca2+ from the Ringer solution or blocking Ca2+ channels with Co2+. This suggests that the Cl− current is Ca2+-dependent. In those bipolar cells whose axon terminals were cutoff during slicing no Cl− current was observed, indicating that this current is generated at the synaptic terminals. The Cl− current consists of a predominant synaptic component that can be blocked by the non- N-methyl-d-aspartate (NMDA) glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) or by the γ-aminobutyric acid-C (GABAC) receptor antagonist picrotoxin. There also exists a relatively small nonsynaptic component. Thus both glutamatergic and GABAergic transmission were involved in the generation of this Cl− current, suggesting that it is mediated by a recurrent feedback to bipolar cells. Picrotoxin, which blocks both GABAC receptors at BC terminals and GABAA receptors on the dendrites of ACs and GCs, converted the light-elicited voltage response in most on-off ACs and GCs from transient to sustained. Bicuculline, which blocks only the GABAA receptors, did not prolong the transient response in on-off ACs and GCs. This suggests that a negative feedback mediated by the GABAC receptor on the bipolar terminals is responsible for making these responses transient. After the GABAergic feedback was blocked with picrotoxin the light-elicited voltage responses (recorded under current clamp) were more sustained than the current responses (recorded under voltage clamp) to the same light stimuli. This suggests that a voltage-dependent conductance converts the relatively transient current responses to more sustained voltage responses. Our results imply a synaptically driven local GABAergic feedback at bipolar terminals, mediated by GABAC receptors. This feedback appears to be a significant component of the mechanism underlying temporal contrast enhancement in on-off ACs and GCs.

scholarly journals No temporal contrast enhancement of simple decreases in noxious heat

2019 ◽  
Vol 121 (5) ◽  
pp. 1778-1786 ◽  
Author(s):  
Brianna Beck ◽  
Sahana Gnanasampanthan ◽  
Gian Domenico Iannetti ◽  
Patrick Haggard
Keyword(s):  
Contrast Enhancement ◽  
Initial Temperature ◽  
Forced Choice ◽  
Choice Task ◽  
Temporal Contrast ◽  
Contact Heat ◽  
Noxious Heat ◽  
Contrast Mechanism ◽  
Forced Choice Task ◽  
Better Than

Offset analgesia (OA) studies have found that small decreases in the intensity of a tonic noxious heat stimulus yield a disproportionately large amount of pain relief. In the classic OA paradigm, the decrease in stimulus intensity is preceded by an increase of equal size from an initial noxious level. Although the majority of researchers believe this temporal sequence of two changes is important for eliciting OA, it has also been suggested that the temporal contrast mechanism underlying OA may enhance detection of simple, isolated decreases in noxious heat. To test whether decreases in noxious heat intensity, by themselves, are perceived better than increases of comparable sizes, we used an adaptive two-interval alternative forced choice task to find perceptual thresholds for increases and decreases in radiant and contact heat. Decreases in noxious heat were more difficult to perceive than increases of comparable sizes from the same initial temperature of 45°C. In contrast, decreases and increases were perceived equally well within a common range of noxious temperatures (i.e., when increases started from 45°C and decreases started from 47°C). In another task, participants rated the pain intensity of heat stimuli that randomly and unpredictably increased, decreased, or remained constant. Ratings of unpredictable stimulus decreases also showed no evidence of perceptual enhancement. Our results demonstrate that there is no temporal contrast enhancement of simple, isolated decreases in noxious heat intensity. Combined with previous OA findings, they suggest that long-lasting noxious stimuli that follow an increase-decrease pattern may be important for eliciting the OA effect. NEW & NOTEWORTHY Previous research suggested that a small decrease in noxious heat intensity feels surprisingly large because of sensory enhancement of noxious stimulus offsets (a simplified form of “offset analgesia”). Using a two-alternative forced choice task where participants detected simple increases or decreases in noxious heat, we showed that decreases in noxious heat, by themselves, are no better perceived than increases of comparable sizes. This suggests that a decrease alone is not sufficient to elicit offset analgesia.

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