Inhibition of—But Not between—Orientation Detectors: A Theoretical Note on Illusions of Direction

1980 ◽  
Vol 50 (1) ◽  
pp. 255-262 ◽  
Author(s):  
Willard L. Brigner
Keyword(s):  
Lateral Inhibition ◽  
Single Stimulus ◽  
Single Line ◽  
Collective Effects ◽  
Collective Effect ◽  
Stimulus Line ◽  
Model Based ◽  
Multiple Stimulus

In accounting for illusions of direction, many current models assume lateral inhibition among orientation detectors; however, that assumption is unnecessary. Rather, the illusions can be predicted by a model based on the pattern of inhibition and excitation across orientation detectors as caused by a single stimulus line. From the collective effects of multiple stimulus lines, a pattern of excitation and inhibition results which is perceived as an illusion of direction. This collective effect is predicted by convoluting a function representing physical orientation of stimulus lines with a function representing the pattern of inhibition and excitation elicited by a single line. Both perceived angle-expansion (repulsion) and perceived angle-contraction (attraction) are generated by the model.

Collective Effects on the Transition Bremsstrahlung Spectrum due to the Polarization Interaction in Nonideal Plasmas

2009 ◽  
Vol 64 (1-2) ◽  
pp. 49-53
Author(s):  
Hwa-Min Kim ◽  
Young-Dae Jung
Keyword(s):  
Cross Section ◽  
Impact Parameter ◽  
Photon Energy ◽  
Parameter Analysis ◽  
Collective Effects ◽  
Bremsstrahlung Spectrum ◽  
Collective Effect ◽  
Bremsstrahlung Radiation ◽  
Polarization Interaction ◽  
Nonideal Plasmas

The collective effects on the transition bremsstrahlung spectrum due to the polarization interaction between the electron and Debye shielding cloud of an ion are investigated in nonideal plasmas. The impact parameter analysis with the effective pseudopotential model taking into account the nonideal collective and plasma screening effects is applied to obtain the bremsstrahlung radiation cross-section as a function of the nonideality plasma parameter, Debye length, photon energy, and projectile energy. It is shown that the collective effects enhance the bremsstrahlung radiation cross-section and decrease with increasing impact parameter. It is also shown that the collective effect is the most significant near the maximum position of the bremsstrahlung cross-section. In addition, it is shown that the collective effect decreases with an increase of the radiation photon energy

Circuit Properties Generating Gamma Oscillations in a Network Model of the Olfactory Bulb

2006 ◽  
Vol 95 (4) ◽  
pp. 2678-2691 ◽  
Author(s):  
Brice Bathellier ◽  
Samuel Lagier ◽  
Philippe Faure ◽  
Pierre-Marie Lledo
Keyword(s):  
Olfactory Bulb ◽  
Firing Rate ◽  
Lateral Inhibition ◽  
Temporal Structure ◽  
Gamma Oscillations ◽  
Synaptic Organization ◽  
Neural Basis ◽  
Sensory Inputs ◽  
Model Based

The study of the neural basis of olfaction is important both for understanding the sense of smell and for understanding the mechanisms of neural computation. In the olfactory bulb (OB), the spatial patterning of both sensory inputs and synaptic interactions is crucial for processing odor information, although this patterning alone is not sufficient. Recent studies have suggested that representations of odor may already be distributed and dynamic in the first olfactory relay. The growing evidence demonstrating a functional role for the temporal structure of bulbar neuronal activity supports this assumption. However, the detailed mechanisms underlying this temporal structure have never been thoroughly studied. Our study focused on gamma (40–100 Hz) network oscillations in the mammalian OB, which is a form of temporal patterning in bulbar activity elicited by olfactory stimuli. We used computational modeling combined with electrophysiological recordings to investigate the basic synaptic organization necessary and sufficient to generate sustained gamma rhythms. We found that features of gamma oscillations obtained in vitro were identical to those of a model based on lateral inhibition as the coupling modality (i.e., low irregular firing rate and high oscillation stability). In contrast, they differed substantially from those of a model based on lateral excitatory coupling (i.e., high regular firing rate and instable oscillations). Therefore we could precisely tune the oscillation frequency by changing the kinetics of inhibitory events supporting the lateral inhibition. Moreover, gradually decreasing GABAergic synaptic transmission decreased the degree of relay neuron synchronization in response to sensory inputs, both theoretically and experimentally. Thus we have shown that lateral inhibition provides a mechanism by which the dynamic processing of odor information might be finely tuned within the OB circuit.

Single stimulus and multiple stimulus threshold

1972 ◽  
Vol 12 (9) ◽  
pp. 1533-1543 ◽  
Author(s):  
E.L. Greve
Keyword(s):  
Single Stimulus ◽  
Multiple Stimulus

Discrepancies between single stimulus and multiple stimulus visual field examinations with the Peritest semi-automated perimeter in glaucoma patients

1992 ◽  
Vol 82 (1-2) ◽  
pp. 135-140
Author(s):  
C. T. Langerhorst ◽  
D. Bakker ◽  
J. Felius ◽  
T. J. T. P. Van Den Berg
Keyword(s):  
Visual Field ◽  
Single Stimulus ◽  
Multiple Stimulus

scholarly journals Nonideal effects on inelastic Compton scattering in a nonideal plasma

2002 ◽  
Vol 67 (2-3) ◽  
pp. 175-182 ◽  
Author(s):  
YOUNG-DAE JUNG
Keyword(s):  
Compton Scattering ◽  
Cross Section ◽  
Debye Length ◽  
Transition Matrix Element ◽  
Collective Effects ◽  
Nonideal Plasma ◽  
Collective Effect ◽  
Photon Process ◽  
The Cross ◽  
Hydrogenic Ions

Inelastic Compton scattering of photons by hydrogenic ions in a classical nonideal plasma is investigated. An effective pseudopotential model taking into account plasma screening and collective effects is applied to describe the interaction potential in a nonideal plasma. The screened atomic wave functions and energy eigenvalues for the ground and excited states of the hydrogenic ion in a classical nonideal plasma obtained by the Ritz variational and perturbational methods. The expression for the lowest-order transition matrix element is obtained by a two-photon process associated with terms quadratic in the vector potential A. The inelastic Compton scattering cross-section horn the 1s ground state to the 2p excited state is obtained as a function of the incident photon energy, Debye length, and the non-ideality plasma parameter. It is found that the collective effect reduces the cross-section. The collective effect on the cross-section is decreased with increasing Debye length.

Discrete event model-based simulation for train movement on a single-line railway

2014 ◽  
Vol 23 (8) ◽  
pp. 080205 ◽  
Author(s):  
Xiao-Ming Xu ◽  
Ke-Ping Li ◽  
Li-Xing Yang
Keyword(s):  
Discrete Event ◽  
Single Line ◽  
Model Based ◽  
Event Model ◽  
Discrete Event Model

Advantages and Caveats When Recording Steady-State Responses to Multiple Simultaneous Stimuli

2002 ◽  
Vol 13 (05) ◽  
pp. 246-259 ◽  
Author(s):  
M. Sasha John ◽  
David W. Purcell ◽  
Andrew Dimitrijevic ◽  
Terence W. Picton
Keyword(s):  
Steady State ◽  
Evoked Potential ◽  
Low Frequency ◽  
Single Stimulus ◽  
Multiple Response ◽  
Signal To Noise ◽  
Multiple Stimulus ◽  
Steady State Responses ◽  
Time Required ◽  
State Responses

This article considers the efficiency of evoked potential audiometry using steady-state responses evoked by multiple simultaneous stimuli with carrier frequencies at 500, 1000, 2000, and 4000 Hz. The general principles of signal-to-noise enhancement through averaging provide a basis for determining the time required to estimate thresholds. The advantage of the multiple-stimulus technique over a single-stimulus approach is less than the ratio of the number of stimuli presented. When testing two ears simultaneously, the advantage is typically that the multiple-stimulus technique is two to three times faster. One factor that increases the time of the multiple-response recording is the relatively small size of responses at 500 and 4000 Hz. Increasing the intensities of the 500- and 4000-Hz stimuli by 10 or 20 dB can enhance their responses without significantly changing the other responses. Using multiple simultaneous stimuli causes small changes in the responses compared with when the responses are evoked by single stimuli. The clearest of these interactions is the attenuation of the responses to low-frequency stimuli in the presence of higher-frequency stimuli. Although these interactions are interesting physiologically, their small size means that they do not lessen the advantages of the multiple-stimulus approach.

Facilitatory Interactions between Flashed Lines

Perception ◽  
1986 ◽  
Vol 15 (4) ◽  
pp. 443-460 ◽  
Author(s):  
Robert A Smith ◽  
Peter Cass
Keyword(s):  
Lateral Inhibition ◽  
Motion Detection ◽  
Detection System ◽  
Quantitative Model ◽  
Joint Function ◽  
Temporal Separation ◽  
Probability Summation ◽  
Model Based ◽  
Nonlinear Transient ◽  
Motion Detection System

The detectability of pairs of flashed lines was investigated as a joint function of their separation in both space and time. In contrast to previous studies of contrast interactions as a function of either spatial or temporal separation alone, the predominant interaction is not lateral inhibition, but a delayed facilitation. A quantitative model based on probability summation between lateral-inhibitory detectors does not appear able to account for these results. Two related explanations are suggested: either a motion detection system or the nonlinear ‘transient’ subsystem is being tapped.

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