Effects Of Lateral Inhibition Research Articles

Neural correlates of lateral modulation and perceptual filling-in in center-surround radial sinusoidal gratings: an fMRI study

We investigated lateral modulation effects with functional magnetic resonance imaging. We presented radial sinusoidal gratings in random sequence: a scotoma grating with two arc-shaped blank regions (scotomata) in the periphery, one in the left and one in the right visual field, a center grating containing pattern only in the scotoma regions, and a full-field grating where the pattern occupied the whole screen. On each trial, one of the three gratings flickered in counterphase for 10 s, followed by a blank period. Observers were instructed to perform a fixation task and report whether filling-in was experienced during the scotoma condition. The results showed that the blood-oxygen-level-dependent signal was reduced in areas corresponding to the scotoma regions in the full-field compared to the center condition in V1 to V3 areas, indicating a lateral inhibition effect when the surround was added to the center pattern. The univariate analysis results showed no difference between the filling-in and no-filling-in trials. However, multivariate pattern analysis results showed that classifiers trained on activation pattern in V1 to V3 could differentiate between filling-in and no-filling-in trials, suggesting that the neural activation pattern in visual cortex correlated with the subjective percept.

Evolution of the uniformity in the repetitive unipolar nanosecond-pulse dielectric barrier discharge

The time evolution of dielectric barrier discharge driven by nanosecond pulse high-voltage power is investigated by high-speed video analysis, electrical measurements and spectral diagnostics. It is found that the discharge mode generally goes through the evolution process of filamentary discharge → diffuse discharge → filamentary discharge with the increase in discharge cycle. The time-dependent changes in the standard deviation of image gray levels indicate that the discharge uniformity first improves and then deteriorates in this evolution process. The different pre-ionization density and modulated distribution of space charges and surface charges are considered to be the main reasons for the time evolution of discharge uniformity. In addition, the experiments under different frequencies and voltages show that the transition of the discharge mode is more likely to occur at higher frequency and higher voltage. Further measurement and calculation reveal that the discharge at high frequency and high voltage has the same characteristics, that is, high pre-ionization degree, thick filament diameter and short time lag. These characteristics usually lead to higher seed electron density, larger critical avalanche size and weaker lateral inhibition effect, which make the discharge mode transition more likely to occur.

Various patterns in dielectric barrier glow discharges simulated by a dynamic model

In this paper, various patterns of dielectric barrier glow discharge simulated by a phenomenological dynamic model are reported. The model is constructed based on the basic dynamic process of dielectric barrier glow discharge and involves the voltage-transfer characteristic as well as the lateral inhibition effect. In simulations, different driving voltage profiles are applied to achieve one or two pulsed discharges in each half-period and the corresponding pattern evolution is investigated. The final stable patterns driven by a rectangular wave voltage organize simply as stationary striations or hexagonal lattices. The patterns driven by a multi-step wave appear to be much more complicated, with complementary striations, concentric rings and square superlattices observed. The evolutions of these patterns from the initial uniform state are described and it is found that the spreading of the inhibition effect plays a key role in these evolutions. The numerical simulations in the present work are in excellent accordance with previous experiments and fluid modeling. This dynamic model proves to be a convenient and promising approach to reproducing different pattern structures and pattern evolutions in dielectric barrier glow discharge systems.

Application of blurred circular 3D images on the human vision model

This study was developed based on the lateral inhibition effect and the Mach band effect. In the study, various human vision experiments involving blurred circular 3D images of different shapes were conducted under fixed brightness and contrast, and the results of those experiments are described in detail herein, with each type of display and each shape considered and discussed separately. The results show that although the maximum values of the contrast sensitivity function curves of the various displays were different, they showed minimal variations. With changes in spatial frequency, the degree of diminution of the different lines was also minimal. However, since the shape at the intersection of the contour was modified by the Mach band effect, a greater degree of variation was generated. In addition, as the Gaussian blur was increased at the intersection of the contour lines, its Mach band effect tended to decrease as the corresponding contrast sensitivity function curve changed. Summarizing the results of the various experiments on human visual characteristics, a new visual model was developed to match the model tested with the blurred circular 3D images. This model can be used as a reference for the development of artificial vision systems and technological applications in the future.

Postnatal Odor Exposure Increases the Strength of Interglomerular Lateral Inhibition onto Olfactory Bulb Tufted Cells.

Responses of olfactory (OB) bulb mitral cells (MCs) and tufted cells (TCs) are known to depend on prior odor exposure, yet the specific circuit mechanisms underlying these experience-dependent changes are unknown. Here, we show that odor exposure alters one particular circuit element, interglomerular lateral inhibition, which is known to be critical for a variety of OB computations. Early postnatal odor exposure to acetophenone, a ligand of M72 olfactory sensory neurons, increases the strength of M72-mediated lateral inhibition onto TCs, but not MCs, that project to nearby glomeruli. These findings add to a growing list of differences between MCs and TCs suggesting that that these two cell types play distinct roles in odor coding.

Investigating the Effect of Lateral Inhibition in the Retinal Circuitry on Lightness Contrast and Assimilation: A Model Study

Investigating the Effect of Lateral Inhibition in the Retinal Circuitry on Lightness Contrast and Assimilation: A Model Study

Music-induced cortical plasticity and lateral inhibition in the human auditory cortex as foundations for tonal tinnitus treatment

Over the past 15 years, we have studied plasticity in the human auditory cortex by means of magnetoencephalography (MEG). Two main topics nurtured our curiosity: the effects of musical training on plasticity in the auditory system, and the effects of lateral inhibition. One of our plasticity studies found that listening to notched music for 3 h inhibited the neuronal activity in the auditory cortex that corresponded to the center-frequency of the notch, suggesting suppression of neural activity by lateral inhibition. Subsequent research on this topic found that suppression was notably dependent upon the notch width employed, that the lower notch-edge induced stronger attenuation of neural activity than the higher notch-edge, and that auditory focused attention strengthened the inhibitory networks. Crucially, the overall effects of lateral inhibition on human auditory cortical activity were stronger than the habituation effects. Based on these results we developed a novel treatment strategy for tonal tinnitus—tailor-made notched music training (TMNMT). By notching the music energy spectrum around the individual tinnitus frequency, we intended to attract lateral inhibition to auditory neurons involved in tinnitus perception. So far, the training strategy has been evaluated in two studies. The results of the initial long-term controlled study (12 months) supported the validity of the treatment concept: subjective tinnitus loudness and annoyance were significantly reduced after TMNMT but not when notching spared the tinnitus frequencies. Correspondingly, tinnitus-related auditory evoked fields (AEFs) were significantly reduced after training. The subsequent short-term (5 days) training study indicated that training was more effective in the case of tinnitus frequencies ≤ 8 kHz compared to tinnitus frequencies >8 kHz, and that training should be employed over a long-term in order to induce more persistent effects. Further development and evaluation of TMNMT therapy are planned. A goal is to transfer this novel, completely non-invasive and low-cost treatment approach for tonal tinnitus into routine clinical practice.

The vanishing disk; a revealing quirk of the scintillating grid illusion

Take a Hermann grid of gray alleys on a black background and place white disks at the intersections; observers report a striking illusion of transient black spots on the disks (scintillation). There is controversy over whether scintillation is an effect of lateral inhibition or of the cortical processing of repeating patterns. To assess the importance of a repeating pattern, we tested a Hermann grid with a single white disk at one intersection. To our surprise, the disk completely disappeared when distant intersections were fixated. We examined the elements of the grid necessary for this effect to occur and compared them to those that produce scintillation. Subjects fixated on a computer screen; stimulus patterns were then presented randomly above or below fixation. Stimuli, present for 300 ms to preclude changes of fixation, consisted of either a 4 2 or a 2 2 modified scintillating grid pattern that could include a single disk at one intersection. Disks of various luminances were presented with delays of various duration between the onsets of the grid and the disk. Disks significantly darker than the grid alleys were detected with near perfect accuracy. As disk color approached alley color, detectability was reduced for disks relatively distant from fixation, while disks nearer fixation showed scintillation. Increasing the delay improved detection of light disks that otherwise would not be detectable, but did not preclude scintillation. The blanking effect apparently decays rapidly after presentation of the grid. The lack of effect upon dark disks demonstrates that this is not a result of inattention or limited visual capability. Both scintillation and complete cancellation of a light disk at an intersection are possible with minimal repetition of a pattern. In contrast, scintillation does not require simultaneous presentation of the grid and disk, implying a somewhat different mechanism. Brief summary of VSS 2002 poster: Stimuli were presented with various delays between the disk and the squares, as shown below: The blanking effect, like the scintillating grid, is an effect of high contrast squares upon opposite contrast disks Same-contrast disks are somewhat less visible, but the increased threshold may be due to reduced effective contrast Blanking depends upon nearly simultaneous presentation of the disk and squares; asynchrony in either direction diminishes the effect Blanking is stronger more peripherally in the visual field Blanking is more pronounced in the upper visual field than in the lower visual field Blanking can be achieved with a minimally repeating pattern, and is thus not a result of repeating units of cortical architecture A manuscript incorporating these results has been published: A psychoanatomical investigation of the blanking phenomenon. J. Jason McAnany, and Michael W. Levine. (2005). Vision Research. 45; 193-203.. In 2003, we present results of dichoptic presentations that further tease apart the mechanisms of this phenomenon. The 2003 VSS poster is available in its entirety at http://tigger.uic.edu/~mikel/VSS/VSS2003.pdf.

The Application of Lateral Inhibition Model in Image's Contour Enhancement and Design of Its Electro-Model

For overcoming the problem s such as distortion and shift of object ’ s edge, easily losing the object detail information of method s in image edge detection , and satisfying higher demand for object detection in the modern war, a new image edge detection method was designed. LOG edge detection as a typical image processing method was introduced and the disadvantage of this model was analyzed firstly. B ased on lateral inhibition theory, an acyclic lateral inhibition network model (ALINM) based on biology vision information processing mechanism was design ed. The feasibility of object detection by lateral inhibition model was analyzed, i n order to express the advantage such as rapid calculati on easily real time operation of ALINM , the calculation magnitude of circulation difference lateral inhibition model was analyzed. Besides the correctness of ALINM wa s confirmed with two input cells, its transfer function wa s deduced. An algorithm of image edge detection based on this model wa s established finally, lateral inhibition effect also was confirmed by one-dimension and two-dimension circuit model based ALINM . S imulative experiment with different parameters and physics experiment prove that acyclic lateral inhibition network model can be realized easily, it can preserve the farthest detail information of object and has faster calculation speed than LOG operator . ALINM and lateral inhibition theory provide a useful method based on biology vision for object detection under difficult imaging conditions.

The time course of N1m decline caused by exposure to noise with strong spectral contrasts

Stimulating with a noise with strong spectral contrasts resulted in different responsiveness for two types of test stimuli presented after release of the noise. The magnetoencephalographically recorded N1m response to an auditory stimulus, spectrally corresponding to the stop-bands (SB), was decreased more by the noise than a stimulus corresponding to the pass-band (PB) frequencies of the noise. This effect was explained with lateral inhibition in the auditory cortex. The results give important evidence for a decay of the lateral inhibition effect over several seconds.

Signal Preprocessing for Speech Recognition

Consideration was given to the transformations of speech in the frequency domain which precede extraction of the informative attributes of phonemes. A processing of the speech spectrum ensuring stability of recognition in the presence of frequency distortions and additive noise was proposed. It is based on linear bandpass filtering of the logarithmic amplitude spectrum and subsequent nonlinear transformation that models the effect of lateral inhibition in the auditory analyzer.

Ernst Mach and the episode of the monocular depth sensations.

Although Ernst Mach is widely recognized in psychology for his discovery of the effects of lateral inhibition in the retina ("Mach Bands"), his contributions to the theory of depth perception are not as well known. Mach proposed that steady luminance gradients triggered sensations of depth. He also expanded on Ewald Hering's hypothesis of "monocular depth sensations," arguing that they were subject to the same principle of lateral inhibition as light sensations were. Even after Hermann von Helmholtz's attack on Hering in 1866, Mach continued to develop theories involving the monocular depth sensations, proposing an explanation of perspective drawings in which the mutually inhibiting depth sensations scaled to a mean depth. Mach also contemplated a theory of stereopsis in which monocular depth perception played the primary role.

Post-retinal processing of background luminance

It is generally thought that mean luminance and low spatial frequency information in a visual image are sharply attenuated at the retina, due to processes of light adaptation and the spatial filtering effects of lateral inhibition. Our results from interocular luminance masking suggest, however, that cortical masking effects play a primary role in the attenuation of low frequency sensitivity. Results also revealed that interocular luminance masking saturates and that semisaturation occurs where left and right eye luminances are equal, implying that the test luminance limits the effectiveness of the mask through interocular gating.

Antagonism of EGFR and Notch signalling in the reiterative recruitment of Drosophila adult chordotonal sense organ precursors

The selection of Drosophila melanogaster sense organ precursors (SOPs) for sensory bristles is a progressive process: each neural equivalence group is transiently defined by the expression of proneural genes (proneural cluster), and neural fate is refined to single cells by Notch-Delta lateral inhibitory signalling between the cells. Unlike sensory bristles, SOPs of chordotonal (stretch receptor) sense organs are tightly clustered. Here we show that for one large adult chordotonal SOP array, clustering results from the progressive accumulation of a large number of SOPs from a persistent proneural cluster. This is achieved by a novel interplay of inductive epidermal growth factor-receptor (EGFR) and competitive Notch signals. EGFR acts in opposition to Notch signalling in two ways: it promotes continuous SOP recruitment despite lateral inhibition, and it attenuates the effect of lateral inhibition on the proneural cluster equivalence group, thus maintaining the persistent proneural cluster. SOP recruitment is reiterative because the inductive signal comes from previously recruited SOPs.

Modelling spatial contrast sensitivity functions for chromatic and luminance-modulated gratings

We extended our detection model of achromatic spatial vision (Rovamo, J., Mustonen, J., & Näsänen, R. (1994a). Modelling contrast sensitivity as a function of retinal illuminance and grating area. Vision Research, 34, 1301–1314) to colour vision by taking into account the fact that due to the spatio-chromatic opponency of retinal ganglion cells and dorsal lateral geniculate nucleus (dLGN) neurons, equiluminous chromatic gratings are not affected by precortical lateral inhibition. We then tested the extended model by using Mullen’s experimental data (Mullen, K. J. (1985). The contrast sensitivity of human color vision to red–green and blue–yellow chromatic gratings. Journal of Physiology, 359, 381–400). The band-pass shape of the spatial contrast sensitivity function for luminance-modulated green and yellow gratings transformed to a low-pass shape, resembling the chromatic spatial contrast sensitivity function for red–green and blue–yellow equiluminous gratings, when the effect of precortical lateral inhibition on grating contrast was computationally removed by dividing luminance contrast sensitivities by spatial frequency (i.e. by af, where a=1°). After the removal of this direct effect of lateral inhibition, there still remained a residual shape difference between the spatial contrast sensitivity functions for chromatic and luminance gratings. It was due to indirect reduction of grating visibility by quantal noise high-pass filtered by precortical lateral inhibition. When this indirect effect of quantal noise was also removed, contrast sensitivity for luminance gratings was about twice the sensitivity for chromatic gratings at all spatial frequencies. This was evidently due to the fact that the chromatic contrast of the equiluminous grating at the opponent stage (Cole, G. R., Hine, T. & McIihagga, W. (1993). Detection mechanisms in L-, M-, and S-cone contrast space. Journal of the Optical Society of America A, 10, 38–51) was about half of the luminance contrast of either of its chromatic component. Thus, if the contrast of the equiluminous chromatic grating were not expressed as the Michelson contrast of one chromatic component grating against its own background (Mullen, K. J. (1985). The contrast sensitivity of human color vision to red–green and blue–yellow chromatic gratings. Journal of Physiology, 359, 381–400) but as chromatic contrast at the opponent stage, contrast sensitivity would be the same for chromatic and luminance gratings.

A model for timbre discrimination taking the effect of lateral inhibition into consideration.

A model for timbre discrimination taking the effect of lateral inhibition into consideration.

Retinal eccentricity and the detection of targets.

It is known that the detectability of a target depends on its similarity to the individual context elements. This article attempts to show that global properties of the context can also influence detection performance. For example, the detection of an O among several Hs appears to be easier than the detection of an H among several Os, because the context consists of elements that are more angular. However, this angular-context advantage is most apparent when the stimulus projection falls on extrafoveal areas of the retina. The results of two stimulus manipulations suggest that the decreasing ability of the visual system with increasing eccentricity could be responsible for this relationship. Increasing the distance between the single elements, and thus reducing the effect of lateral inhibition, led to a deterioration in performance; and by defocusing the stimulus presentation it was possible to achieve an improvement in performance.

The analogy between stereo depth and brightness.

Apparent depth in stereograms exhibits various simultaneous-contrast and induction effects analogous to those reported in the luminance domain. This behavior suggests that stereo depth, like brightness, is reconstructed, ie recovered from higher-order spatial derivatives or differences of the original signal. The extent to which depth is analogous to brightness is examined. There are similarities in terms of contrast effects but dissimilarities in terms of the lateral inhibition effects traditionally attributed to underlying spatial-differentiation operators.

System analysis of the goldfish olfactory bulb: Spatio-temporal transfer properties of the mitral cell granule cell complex

In this paper the goldfish olfactory bulb is described from a systems theoretical point of view. A chain of nine interacting circuits, each one mitral cell and one granule cell, is modelled. Glomerular synapses are assumed to have variable strengths. The analysis of the model system leads to the following conclusions: 1) The temporal input pattern of a mitral cell—granule cell circuit is either maintained by the circuit or inverted (lateral inhibition effect). This property together with available receptor data allows the theoretical explanation of experimentally recorded mitral cell patterns. 2) The sensitivity of a mitral cell—granule cell circuit is a function of the input signal's frequency. This provides an explanation for mitral cell cluster activity patterns measured in experiments. 3) Given a spatial input pattern to adjacent mitral cell—granule cell circuits, the output pattern depends largely upon the ratio between the feedback parameter p and the similarity β of the inputs to adjacent circuits. For appropriate p and β a local order between the responses of single neighbouring circuits is established. This local order can lead to a globally ordered mapping of odours onto mitral cell activities, thus providing a coding concept for the bulb. Some consequences of this concept coincide well with the spatial activity patterns found in 2-DOG-studies. 4) Glomerular synapses endowed with plasticity could account for long term effects such as degeneration and sensitivity changes with respect to certain odours.

Lateral inhibition between spatially adjacent spatial-frequency channels?

A new lateral inhibitory phenomenon is suggested between spatially neighboring channels that detect similar spatial frequencies. This mechanism tends to enhance the apparent contrast of gratings at their boundaries, and Mach-band-type effects are demonstrated at the edge of a suprathreshold half-field grating. We studied the dependence of this effect on the grating parameters of spatial frequency and contrast. The grating spatial frequency must be above about 4 cycles per degree (cpd) for any effect to be seen. In the range 4–14 cpd, the type of effect seen depends on the contrast of the grating: At high contrasts, the effect is an enhancement of grating contrast near its border, whereas at near threshold contrasts, an opposite effect, edge contrast diminution, is seen. Finally, above about 14 cpd, enhancement is found down to threshold contrasts. The latter very-high-frequency effect may be due to a high-spatial-frequency limit of the visual channels available, with the smallest receptive-field summation area being in the order of 2.2′. The near-threshold edge contrast diminution may derive from illumination lateral inhibition. In the intermediate range, however, the enhancement appears only at high contrast levels and therefore cannot be due to a linear mechanism. This enhancement seems to derive from lateral inhibition between neighboring spatial-frequency channels. A Craik-O’Brien-Cornsweet type of visual illusion is demonstrated in the spatial-frequency grating contrast domain. The effect of lateral inhibition on the selectivity of spatial frequency channels is discussed. Lateral inhibition may cause a shift in the optimal spatial frequency of the channels by about 40% at high contrasts, making such gratings appear to have lower spatial frequencies. This shift may also be responsible for the phenomenon of contrast constancy.