scholarly journals The trade-off between pulse duration and power in optical excitation of midbrain dopamine neurons approximates Bloch’s law

2021 ◽  
Author(s):  
Vasilios Pallikaras ◽  
Francis Carter ◽  
David Natanael Velázquez Martínez ◽  
Andreas Arvanitogiannis ◽  
Peter Shizgal
Keyword(s):  
Pulse Duration ◽  
Optical Power ◽  
Human Vision ◽  
Dopamine Neurons ◽  
List Type ◽  
Energy Principle ◽  
Trade Off ◽  
Neuronal Excitation ◽  
Equal Energy ◽  
Reward Seeking

AbstractBackgroundOptogenetic experiments reveal functional roles of specific neurons. However, such inferences have been restricted by widespread adoption of a fixed set of stimulation parameters. Broader exploration of the parameter space can deepen insight into the mapping between selective neural activity and behavior. In this way, characteristics of the activated neurons, such as temporal integration, can be inferred.ObjectiveTo determine whether an equal-energy principle accounts for the interaction of pulse duration and optical power in optogenetic excitation.MethodsSix male TH::Cre rats worked for optogenetic (ChannelRhodopsin-2) stimulation of Ventral Tegmental Area dopamine neurons. We used a within-subject design to describe the trade-off between pulse duration and optical power in determining reward seeking. Parameters were customized for each subject on the basis of behavioral effectiveness.ResultsWithin a useful range of powers (~12.6-31.6 mW) the product of optical power and pulse duration required to produce a given level of reward seeking was roughly constant. Such reciprocity is consistent with Bloch’s law, which posits an equal-energy principle of temporal summation over short durations in human vision. The trade-off between pulse duration and power broke down at higher powers.ConclusionsOptical power can be substituted for pulse duration to scale the region of neuronal excitation in behavioral optogenetic experiments. Power and duration can be adjusted reciprocally for brief durations and lower powers. The findings demonstrate the utility of within-subject and trade-off designs in optogenetics and of parameter adjustment based on functional endpoints instead of physical properties of the stimulation.HighlightsWe provide behaviorally derived intensity-duration curves for ChannelRhodopsin-2.Duration trades off almost perfectly with power within useful ranges.This trade-off breaks down at high optical powers.Pulse duration and optical power scale the area of neuronal excitation equivalently.Behaviorally derived trade-offs can reveal optogenetic excitation mechanisms.

scholarly journals The trade-off between pulse duration and power in optical excitation of midbrain dopamine neurons approximates Bloch’s law

2022 ◽  
Vol 419 ◽  
pp. 113702
Author(s):  
Vasilios Pallikaras ◽  
Francis Carter ◽  
David Natanael Velazquez-Martinez ◽  
Andreas Arvanitogiannis ◽  
Peter Shizgal
Keyword(s):  
Pulse Duration ◽  
Optical Excitation ◽  
Dopamine Neurons ◽  
Trade Off ◽  
Midbrain Dopamine ◽  
Midbrain Dopamine Neurons

scholarly journals A trade-off between classical and quantum circuit size for an attack against CSIDH

2020 ◽  
Vol 15 (1) ◽  
pp. 4-17
Author(s):  
Jean-François Biasse ◽  
Xavier Bonnetain ◽  
Benjamin Pring ◽  
André Schrottenloher ◽  
William Youmans
Keyword(s):  
Endomorphism Ring ◽  
State Of The Art ◽  
Quantum Circuit ◽  
List Type ◽  
Hard Problem ◽  
Trade Off ◽  
Classical State ◽  
Security Parameter ◽  
The Cost ◽  
Quadratic Order

AbstractWe propose a heuristic algorithm to solve the underlying hard problem of the CSIDH cryptosystem (and other isogeny-based cryptosystems using elliptic curves with endomorphism ring isomorphic to an imaginary quadratic order 𝒪). Let Δ = Disc(𝒪) (in CSIDH, Δ = −4p for p the security parameter). Let 0 < α < 1/2, our algorithm requires:A classical circuit of size $2^{\tilde{O}\left(\log(|\Delta|)^{1-\alpha}\right)}.$A quantum circuit of size $2^{\tilde{O}\left(\log(|\Delta|)^{\alpha}\right)}.$Polynomial classical and quantum memory.Essentially, we propose to reduce the size of the quantum circuit below the state-of-the-art complexity $2^{\tilde{O}\left(\log(|\Delta|)^{1/2}\right)}$ at the cost of increasing the classical circuit-size required. The required classical circuit remains subexponential, which is a superpolynomial improvement over the classical state-of-the-art exponential solutions to these problems. Our method requires polynomial memory, both classical and quantum.

Platinum(ii) acetylide complexes with star- and V-shaped configurations possessing good trade-off between optical transparency and optical power limiting performance

2017 ◽  
Vol 5 (45) ◽  
pp. 11672-11682 ◽  
Author(s):  
C. Yao ◽  
Z. Tian ◽  
D. Jin ◽  
F. Zhao ◽  
Y. Sun ◽  
...  
Keyword(s):  
Optical Power ◽  
Optical Transparency ◽  
Trade Off ◽  
Good Trade ◽  
Optical Power Limiting

Two series of Pt(ii) acetylide complexes containing dimesitylborane and phenyl terminal groups with star- and V-shaped configurations were synthesized.

scholarly journals Transient dopamine neuron activity precedes and encodes the vigor of contralateral movements

2021 ◽  
Author(s):  
Marcelo D Mendonça ◽  
Joaquim Alves da Silva ◽  
Ledia F. Hernandez ◽  
Ivan Castela ◽  
José Obeso ◽  
...  
Keyword(s):  
Substantia Nigra ◽  
Dopamine Neurons ◽  
Substantia Nigra Pars Compacta ◽  
Neuron Activity ◽  
Similar Proportion ◽  
List Type ◽  
Dopamine Depletion ◽  
Movement Initiation ◽  
Transient Activity ◽  
Forelimb Movement

SummaryDopamine neurons (DANs) in the substantia nigra pars compacta (SNc) have been related to movement vigor, and loss of these neurons leads to bradykinesia in Parkinson’s disease. However, it remains unclear whether DANs encode a general motivation signal or modulate movement kinematics. We imaged activity of SNc DANs in mice trained in a novel operant task which relies on individual forelimb movement sequences. We uncovered that a similar proportion of SNc DANs increased their activity before ipsi- vs. contralateral forelimb movements. However, the magnitude of this activity was higher for contralateral actions, and was related to contralateral but not ipsilateral action vigor. In contrast, the activity of reward-related DANs, largely distinct from those modulated by movement, was not lateralized. Finally, unilateral dopamine depletion impaired contralateral, but not ipsilateral, movement vigor. These results indicate that movement-initiation DANs encode more than a general motivation signal, and invigorate kinematic aspects of contralateral movements.HighlightsDeveloped a freely-moving task where mice learn rapid individual forelimb sequences.Movement-related DANs encode contralateral but not ipsilateral action vigor.The activity of reward-related DANs is not lateralized.Unilateral dopamine depletion impaired contralateral, but not ipsilateral, movement vigor.eTOC summary: Mendonça et al. show that transient activity in movement-related dopamine neurons in substantia nigra pars compacta encodes contralateral, but not ipsilateral action vigor. Consistently, unilateral dopamine depletion impaired contralateral, but not ipsilateral, movement vigor.

scholarly journals Mesolimbic dopamine projections mediate cue-motivated reward seeking but not reward retrieval in rats

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Briac Halbout ◽  
Andrew T Marshall ◽  
Ali Azimi ◽  
Mimi Liljeholm ◽  
Stephen V Mahler ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Nucleus Accumbens ◽  
Suppressive Effect ◽  
Maladaptive Behavior ◽  
Dopamine Neurons ◽  
Action Sequence ◽  
Reward Seeking ◽  
Fixed Action ◽  
Dopamine Circuits ◽  
Goal Directed Behavior

Efficient foraging requires an ability to coordinate discrete reward-seeking and reward-retrieval behaviors. We used pathway-specific chemogenetic inhibition to investigate how rats’ mesolimbic and mesocortical dopamine circuits contribute to the expression and modulation of reward seeking and retrieval. Inhibiting ventral tegmental area dopamine neurons disrupted the tendency for reward-paired cues to motivate reward seeking, but spared their ability to increase attempts to retrieve reward. Similar effects were produced by inhibiting dopamine inputs to nucleus accumbens, but not medial prefrontal cortex. Inhibiting dopamine neurons spared the suppressive effect of reward devaluation on reward seeking, an assay of goal-directed behavior. Attempts to retrieve reward persisted after devaluation, indicating they were habitually performed as part of a fixed action sequence. Our findings show that complete bouts of reward seeking and retrieval are behaviorally and neurally dissociable from bouts of reward seeking without retrieval. This dichotomy may prove useful for uncovering mechanisms of maladaptive behavior.

scholarly journals High peak optical power of 1ns pulse duration from laser diodes – low voltage thyristor vertical stack

2019 ◽  
Vol 27 (22) ◽  
pp. 31446 ◽  
Author(s):  
S. O. Slipchenko ◽  
A. A. Podoskin ◽  
V. S. Golovin ◽  
D. N. Romanovich ◽  
V. V. Shamakhov ◽  
...  
Keyword(s):  
Pulse Duration ◽  
Low Voltage ◽  
Laser Diodes ◽  
Optical Power ◽  
High Peak

New heterobimetallic Au(i)–Pt(ii) polyynes achieving a good trade-off between transparency and optical power limiting performance

2018 ◽  
Vol 6 (42) ◽  
pp. 11416-11426 ◽  
Author(s):  
Zhuanzhuan Tian ◽  
Xiaolong Yang ◽  
Boao Liu ◽  
Daokun Zhong ◽  
Guijiang Zhou ◽  
...  
Keyword(s):  
Optical Power ◽  
Trade Off ◽  
Good Trade ◽  
Optical Power Limiting

Two series of heterobimetallic Au(i)–Pt(ii) polyynes achieve consistency between enhanced transparency and high optical power limiting performances.

Zooming Diamonds: A New Illusion, and a Warning on the Biological Relevance of Parallel Projection

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 119-119
Author(s):  
R Cowie
Keyword(s):  
Vision Research ◽  
Biological Systems ◽  
Human Vision ◽  
Motion Path ◽  
Parallel Projection ◽  
Shape Discrimination ◽  
Elevation Change ◽  
Size Change ◽  
Trade Off ◽  
Fixed Distance

A new illusion is described. Observers watch parallel projections of ‘diamonds’ (rhombi) tumbling in 3-D. The displays are generated by moving a viewpoint round a fixed rhombus on a trajectory with two components—a circle parallel to the plane of the diamond, and a superimposed change in elevation which varies sinusoidally. To a greater or lesser extent, depending on the phase of the sinusoid, elevation change is misinterpreted as ‘zooming’ in and out—though in fact the projection always corresponds to an object at a fixed distance. The illusion was devised to underline the questions surrounding the treatment of parallel projection in biological systems. The standard formulations considered in computational vision preclude the kind of size - distance trade-off that the illusion demonstrates, but they do imply that observers should be able to register the shape of an object from this kind of display. A less familiar formulation, ‘paraperspective projection’, allows size - distance trade-off as in perspective projection, but it suggests the shape of a lamina should be impossible to recover from motion. Stimuli which promote ‘zooming’ do weaken shape discrimination, but the trade-off is incomplete. A possible solution is that human vision picks out size change in a way that is appropriate when either object or motion path is ‘friendly’, but that misleads when awkward combinations occur. Certainly vision research should avoid assuming that the attractively simple consequences associated with standard parallel projection govern the way biological systems operate.

scholarly journals A touchy subject: advancing the modulated visual pathways account of altered vision near the hand

2015 ◽  
Vol 6 (1) ◽  
pp. 1-7 ◽  
Author(s):  
J. Eric T. Taylor ◽  
Davood G. Gozli ◽  
David Chan ◽  
Greg Huffman ◽  
Jay Pratt
Keyword(s):  
Visual Pathway ◽  
Visual Pathways ◽  
Human Vision ◽  
Hand Position ◽  
Alternative Account ◽  
Trade Off ◽  
Parvocellular Pathway ◽  
Growing Body ◽  
New Research ◽  
Magnocellular Visual Pathway

AbstractA growing body of evidence demonstrates that human vision operates differently in the space near and on the hands; for example, early findings in this literature reported that rapid onsets are detected faster near the hands, and that objects are searched more thoroughly. These and many other effects were attributed to enhanced attention via the recruitment of bimodal visual-tactile neurons representing the hand and near-hand space. However, recent research supports an alternative account: stimuli near the hands are preferentially processed by the action-oriented magnocellular visual pathway at the expense of processing in the parvocellular pathway. This Modulated Visual Pathways (MVP) account of altered vision near the hands describes a hand position-dependent trade-off between the two main retinal-cortical visual pathways between the eye and brain. The MVP account explains past findings and makes new predictions regarding near-hand vision supported by new research.

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