Stimulus Area Research Articles

Glossiness perception and its pupillary response

Recent studies have revealed that pupillary response changes depend on perceptual factors such as subjective brightness caused by optical illusions and luminance. However, the manner in which the perceptual factor that is derived from the glossiness perception of object surfaces affects the pupillary response remains unclear. We investigated the relationship between the glossiness perception and pupillary response through a glossiness rating experiment that included recording the pupil diameter. We prepared general object images (original) and randomized images (shuffled) that comprised the same images with randomized small square regions as stimuli. The image features were controlled by matching the luminance histogram. The observers were asked to rate the perceived glossiness of the stimuli presented for 3,000 ms and the changes in their pupil diameters were recorded. Images with higher glossiness ratings constricted the pupil size more than those with lower glossiness ratings at the peak constriction of the pupillary responses during the stimulus duration. The linear mixed-effects model demonstrated that the glossiness rating, image category (original/shuffled), variance of the luminance histogram, and stimulus area were most effective in predicting the pupillary responses. These results suggest that the illusory brightness obtained by the image regions of high-glossiness objects, such as specular highlights, induce pupil constriction.

CastleCSF - A contrast sensitivity function of color, area, spatiotemporal frequency, luminance and eccentricity.

The contrast sensitivity function (CSF) is a fundamental visual model explaining our ability to detect small contrast patterns. CSFs found many applications in engineering, where they can be used to optimize a design for perceptual limits. To serve such a purpose, CSFs must explain possibly a complete set of stimulus parameters, such as spatial and temporal frequency, luminance, and others. Although numerous contrast sensitivity measurements can be found in the literature, none fully explains the complete space of stimulus parameters. Therefore, in this work, we first collect and consolidate contrast sensitivity measurements from 18 studies, which explain the sensitivity variation across the parameters of interest. Then, we build an analytical contrast sensitivity model that explains the data from all those studies. The proposed castleCSF model explains the sensitivity as the function of spatial and temporal frequencies, an arbitrary contrast modulation direction in the color space, mean luminance, and chromaticity of the background, eccentricity, and stimulus area. The proposed model uses the same set of parameters to explain the data from 18 studies with an error of 3.59dB. The consolidated contrast sensitivity data and the code for the model are publicly available at https://github.com/gfxdisp/castleCSF/.

«Hierarchical» and «Modular» Models of Psychopathological Syndromes and Mental Functions

The aim was to compare «hierarchical» and «modular» models of the mental functions and psychopathological syndromes.Material and method: a historical analysis is undertaken in the narrative review the works of thinkers of different times who put forward the concepts of mental deviations from the norm. Discussion and conclusion: hierarchical models go back to the concepts of the ancient Greek philosopher Plato, modular models – to the concepts of the German doctor F. Gall. The most famous hierarchical model of «circles» of positive and negative general psychopathological syndromes in Russian psychiatry by A.V. Snezhnevsky was preceded by the hierarchical model of M.O. Gurevich – M.Ya. Sereisky, in turn, based on the model of «levels» of the psyche of the English neurologist J.H. Jackson and E. Kraepelin’s «organ registers» model. In German psychiatry also K. Jaspers cited the «onion» model in the first edition of General Psychopathology, substantiating the complication of psychopathological symptoms depending on the nosology of mental disorders. Later, the American psycholinguist and philosopher J. Fodor proposed a «modular» model of the psyche, according to which the human psyche consists of relatively independent «modules» («encapsulated») that are specific to a certain area of stimuli, are genetically determined, correlate with certain neural structures and are «computationally autonomous». The concept of modular construction of the psyche was further developed in the works of psychologists and psychiatrists of the «evolutionary» direction (models of «massive modularity», which denied the «encapsulation» of modules according to J. Fodor), based, among other premises, on the modular construction of the brain of many animal species. Diversity turns out to be inherent not only in modular models of the psyche, but also in hierarchical ones, for example, the sequence of general psychopathological positive syndromes in A.V. Snezhnevsky’s model of «circles» differs from the correlation of psychopathological syndromes in the model of «registers» by E. Kraepelin, who at the final stage of his scientific activity postulated the principles of «comparative psychiatry», in many respects similar to the principles of the subsequent direction of «evolutionary» psychiatry.

Effect of eccentric fixation on the steady-state pattern electroretinogram

PurposeThe steady-state pattern electroretinogram (ssPERG) is used to assess retinal ganglion cell function in a variety of research contexts and diagnostic applications. In certain groups of patients or study participants, stable central fixation of the stimulus is not guaranteed. The present study aimed at assessing the effects of misfixation on the ssPERG response to checkerboard reversal stimuli.MethodsUsing two check sizes (0.8° and 15°), we compared ssPERG responses for several amounts of fixation deviation, ranging from 0° to 19° horizontally and from 0° to 14° diagonally. The stimulus area extended to 15° eccentricity, stimulus reversal rate was 15/s.ResultsUp to around 7° eccentricity, there was no sizable effect of fixation deviation under most conditions. Effects were somewhat larger for nasal than for temporal deviation, in particular for small checks. Diagonal deviation was associated with a response to luminance onset/offset at 7.5 Hz (subharmonic of the reversal rate), most prominently when the interior of a large check was fixated.ConclusionGenerally, moderate inaccuracies of fixation do not have a sizable effect on ssPERG amplitude. However, with large checks, the luminance response has to be considered.

An integrated electronic skin with biaxial sensitivity from a layered biphasic liquid metal/polymer film.

Research on electronic skin (e-skin) is dedicated to simulating natural skin for the perception of external mechanical stimuli. Currently, e-skin is ineffective in analyzing a single stimulus from different directions. This work successfully fabricates an integrated electronic skin (IES) with biaxial sensing capability through the combination of a biphasic liquid metal and porous foam. Remarkably different from traditional e-skin, the IES can analyze the type, strength, and area of an external mechanical stimulus from vertical and horizontal dimensions with a dual response (capacitive and resistive change, respectively). As a multifunctional sensor, the IES simultaneously responds to compression via capacitive change and tension via resistive change. Furthermore, 1000 cyclic compressions were conducted to confirm the electrical stability of the IES. Very subtle stimuli (e.g. thawing ice and touch) can be detected by the IES via biaxial detection. This work provides a new protocol for the development of future intelligent flexible electronics.

A sub-region combination scheme for spatial coding in a high-frequency SSVEP-based BCI

Objective. In studying the spatial coding mechanism of visual evoked potentials, it is significant to construct a model that shows the relationship between steady-state visual evoked potential (SSVEP) responses to the local and global visual field stimulation. In order to investigate whether SSVEPs produced by sub-region stimulation can predict that produced by joint region stimulation, a sub-region combination scheme for spatial coding in a high-frequency SSVEP-based brain-computer interface (BCI) is developed innovatively. Approach. An annular visual field is divided equally into eight sub-regions. The 60 Hz visual stimuli in different sub-regions and joint regions are presented separately to participants. The SSVEP produced by the sub-region stimulation is superimposed to simulate the SSVEP produced by the joint region stimulation with different spatial combinations. A four-class spatially-coded BCI paradigm is used to evaluate the simulated classification performance, and the performance ranking of all simulated SSVEPs is obtained. Six representative stimulus patterns from two performance levels and three stimulus areas are applied to the online BCI system for each participant. Main results. The experimental result shows that the proposed scheme can implement a spatially-coded visual BCI system and realize satisfactory performance with imperceptible flicker. Offline analysis indicates that the classification accuracy and information transfer rate (ITR) are 89.69 ± 8.75% and 24.35 ± 7.09 bits min−1 with 3 s data length under the 3/8 stimulus area. The online BCI system reaches an average classification accuracy of 87.50 ± 9.13% with 3 s data length, resulting in an ITR of 22.48 ± 6.71 bits min−1 under the 3/8 stimulus area. Significance. This study proves the feasibility of using the sub-region’s response to predict the joint region’s response. It has the potential to extend to other frequency bands and lays a foundation for future research on more complex spatial coding methods.

Layout Furniture in Supporting the Visually Impaired People at the Dining Area of PSBN Wyata Guna

The dining room at PSBN Wyata Guna is used for visually impaired people when it's time to eat in the dining room. This room has high potential complexity and level of activity. Because of the activities that occur, the movement of visually impaired persons is essential in this dining room. But the lack of treatment in the dining room causes frequent collisions and difficulties for the visually impaired person in finding directions. Therefore, we need a stimulus that can support the movement of the visually impaired person in circulation. Through previous research, stimuli that play a high role are sound and layout. This study uses an experimental method to determine how significant the layout and sound stimuli are for visual impaired person in circulation. And it has been concluded that distance is not significant to determine the time of movement in circulation in the dining room, the most important thing for people with visual impaired person is the instructions located in the area of circulation and sound stimuli which are located at critical points. The instructions referred to can be in the form of furniture or other objects if they do not inhibit circulating movements and have a consistent distance, while sound is needed to convince persons with disabilities that their direction is correct. Furthermore, this research can be a recommendation for further research, both academics and related institutions as well as input for interior designers and architects in designing dining rooms for persons with disabilities on a small scale.

Investigating the linkage between mesopic spatial summation and variations in retinal ganglion cell density across the central visual field.

The relationship between perimetric stimulus area and Ricco's area (RA) determines measured thresholds and the sensitivity of perimetry to retinal disease. The nature of this relationship, in addition to effect of retinal ganglion cell (RGC) number on this, is currently unknown for the adaptation conditions of mesopic microperimetry. In this study, achromatic mesopic spatial summation was measured across the central visual field to estimate RA with the number of RGCs underlying RA also being established. Achromatic luminance thresholds were measured for six incremental spot stimuli (0.009-2.07 deg2 ) and 190.4 ms duration, at four locations, each at 2.5°, 5° and 10° eccentricity in five healthy observers (mean age 61.4 years) under mesopic conditions (background 1.58 cd/m2 ). RA was estimated using two-phase regression analysis with the number of RGCs underlying RA being calculated using normative histological RGC counts. Ricco's area exhibited a small but statistically insignificant increase between 2.5° and 10° eccentricity. Compared with photopic conditions, RA was larger, with the difference between RA and the Goldmann III stimulus (0.43°) being minimised. RGC number underlying RA was also higher than reported for photopic conditions (median 70 cells, IQR 36-93), with no significant difference being observed across test locations. Ricco's area and the number of RGCs underlying RA do not vary significantly across the central visual field in mesopic conditions. However, RA is larger and more similar to the standard perimetric Goldmann III stimulus under mesopic compared with photopic adaptation conditions. Further work is required to determine if compensatory enlargements in RA occur in age-related macular degeneration, to establish the optimal stimulus parameters for AMD-specific microperimetry.

Mechanoregulatory role of TRPV4 in prenatal skeletal development.

Biophysical cues are essential for guiding skeletal development, but the mechanisms underlying the mechanical regulation of cartilage and bone formation are unknown. TRPV4 is a mechanically sensitive ion channel involved in cartilage and bone cell mechanosensing, mutations of which lead to skeletal developmental pathologies. We tested the hypothesis that loading-driven prenatal skeletal development is dependent on TRPV4 activity. We first establish that mechanically stimulating mouse embryo hindlimbs cultured ex vivo stimulates knee cartilage growth, morphogenesis, and expression of TRPV4, which localizes to areas of high biophysical stimuli. We then demonstrate that loading-driven joint cartilage growth and shape are dependent on TRPV4 activity, mediated via control of cell proliferation and matrix biosynthesis, indicating a mechanism by which mechanical loading could direct growth and morphogenesis during joint formation. We conclude that mechanoregulatory pathways initiated by TRPV4 guide skeletal development; therefore, TRPV4 is a valuable target for the development of skeletal regenerative and repair strategies.

Cortical mechanisms of visual brightness.

SUMMARYThe primary visual cortex signals the onset of light and dark stimuli with ON and OFF cortical pathways. Here, we demonstrate that both pathways generate similar response increments to large homogeneous surfaces and their response average increases with surface brightness. We show that, in cat visual cortex, response dominance from ON or OFF pathways is bimodally distributed when stimuli are smaller than one receptive field center but unimodally distributed when they are larger. Moreover, whereas small bright stimuli drive opposite responses from ON and OFF pathways (increased versus suppressed activity), large bright surfaces drive similar response increments. We show that this size-brightness relation emerges because strong illumination increases the size of light surfaces in nature and both ON and OFF cortical neurons receive input from ON thalamic pathways. We conclude that visual scenes are perceived as brighter when the average response increments from ON and OFF cortical pathways become stronger.

Experimental methods to investigate time-course of chromatic adaptation

Two different experimental methods, method of adjustment and yellow/blue forced choice, were tested to investigate the time-course of chromatic adaptation. Inside the lighting booth, 2cmx2cm square color stimulus was displayed on the LCD display and the surface of the display was covered with gray paper except for the stimulus area. The lighting of the booth was controlled to have 3,000 K or 6,500 K with 800 lux at the bottom of the booth. During the adjustment method experiment, the observers adjusted the stimulus to preserve an achromatic appearance. In the forced-choice experiment, observers are asked to identify whether the stimuli are yellow or blue. In all experiments, evaluations were performed once every 5 seconds to track color appearance over time. CCT of the booth lighting was changed from 6,500 K to 3,000K or 3,000K to 6,500K every two minutes. The results showed that the observers had difficulties tracking the neutral colors using the adjustment method while the forced-choice experiment showed the more consistent results.

Effect of central and peripheral cone- and rod-specific stimulation on the pupillary light reflex

PurposeTo assess the effect of central and peripheral stimulation on the pupillary light reflex. The aim was to detect possible differences between cone- and rod-driven reactions.MethodsRelative maximal pupil constriction amplitude (relMCA) and latency to constriction onset (latency) to cone- and rod-specific stimuli of 30 healthy participants (24 ± 5 years (standard deviation)) were measured using chromatic pupil campimetry. Cone- and rod-specific stimuli had different intensities and wavelengths according to the Standards in Pupillography. Five filled circles with radii of 3°, 5°, 10°, 20° and 40° and four rings with a constant outer radius of 40° and inner radii of 3°, 5°, 10° and 20° were used as stimuli.ResultsFor cone-and rod-specific stimuli, relMCA increased with the stimulus area for both, circles and rings. However, increasing the area of a cone-specific ring by minimizing its inner radius with constant outer radius increased relMCA significantly stronger than the same did for a rod-specific ring. For cones and rods, a circle stimulus with a radius of 40° created a lower relMCA than the summation of the relMCAs to the corresponding ring and circle stimuli which combined create a 40° circle-stimulus. Latency was longer for rods than for cones. It decreased with increasing stimulus area for circle stimuli while it stayed nearly constant with increasing ring stimulus area for cone- and rod-specific stimuli.ConclusionThe effect of central stimulation on relMCA is more dominant for cone-specific stimuli than for rod-specific stimuli while latency dynamics are similar for both conditions.

The intervention of mechanical tactile stimulation modulates somatosensory evoked magnetic fields and cortical oscillations

The different cortical activity evoked by a mechanical tactile stimulus depends on tactile stimulus patterns, which demonstrates that simple stimuli (i.e., global synchronous stimulation the stimulus area) activate the primary somatosensory cortex alone, whereas complex stimuli (i.e., stimulation while moving in the stimulus area) activate not only the primary somatosensory cortex but also the primary motor area. Here, we investigated whether the effects of a repetitive mechanical tactile stimulation (MS) on somatosensory evoked magnetic fields (SEFs) and cortical oscillations depend on MS patterns. This single-blinded study included 15 healthy participants. Two types interventions of MS lasting 20min were used: a repetitive global tactile stimulation (RGS) was used to stimulate the finger by using 24 pins installed on a finger pad, whereas a sequential stepwise displacement tactile stimulation (SSDS) was used to stimulate the finger by moving a row of six pins between the left and right sides on the finger pad. Each parameter was measured pre- and post-intervention. The P50m amplitude of the SEF was increased by RGS and decreased by SSDS. The modulation of P50m was correlated with its amplitude before RGS and with the modulation of beta band oscillation at the resting state after SSDS. This study showed that the effects of a 20-min MS on SEFs and cortical oscillations depend on mechanical tactile stimulus patterns. Moreover, our results offer potential for the modulation of tactile functions and selection of stimulation patterns according to cortical states.

Asymmetric Brightness Effects With Dark Versus Light Glare-Like Stimuli.

The glare effect is a brightness illusion that has captured the attention of the vision community since its discovery. However, its photometrical reversal, which we refer to here as photometrical reversed glare (PRG) stimuli, remained relatively unexplored. We presented three experiments that sought to examine the perceived brightness of a target area surrounded by luminance gradients in PRG stimuli and compare them with conventional glare effect configurations. Experiment 1 measured the brightness of the central target area of PRG stimuli through an adjustment task; the results showed that the target appeared brighter than similar, comparative areas not surrounded by luminance gradients. This finding was unexpected given the recent report that PRG stimuli cause pupil dilation. Meanwhile, Experiments 2 and 3 implemented a rating task to further test the findings in Experiment 1. Again, the study found a robust brightening illusion in the target area of PRG stimuli in a wide range of target and background luminance. The results are discussed in comparison with the brightness enhancement of the glare effect.

Can Placement of Governmental Sector Jobs Spur Private Sector Employment and Performance?

We analyse the impact of establishment of governmental sector jobs on private sector employment based on Norwegian population-wide administrative-register data. Based on precise geographical information on the location of jobs, differential treatment intensities yield identification of causal effects. The results suggest that governmental employment has positive effects on private sector employment in the close proximity of the stimulus area. In the same area, we also observe positive short-term effects on wage growth and on firms' sales. Over time, only employment effects prevail. Two different types of placebo tests give support to the causal interpretation of the main results.

Threshold vision under full-field stimulation: Revisiting the minimum number of quanta necessary to evoke a visual sensation

At the absolute threshold of vision, Hecht, Shlaer and Pirenne estimate that 5–14 photons are absorbed within a retinal area containing ~500 rods. Other estimates of scotopic threshold vision based on stimuli with different durations and focal areas range up to ~100,000 photons. Given that rod density varies with retinal eccentricity and the magnitude of the intrinsic noise increases with increasing stimulus area and duration, here we determine whether the scotopic threshold estimates with focal stimuli can be extended to full-field stimulation and whether summation explains inter-study differences. We show that full-field threshold vision (~1018 mm2, 10 ms duration) is more sensitive than at absolute threshold, requiring the absorption of ~1000 photons across ~91.96 million rods. A summation model is presented integrating our and published data and using a nominal exposure duration, criterion frequency of seeing, rod density, and retinal area that largely explains the inter-study differences and allows estimation of rods per photon ratio for any stimulus size and duration. The highest signal to noise ratio is defined by a peak rod convergence estimated at 53:4:1:2 (rods:rod bipolar cells:AII amacrine cells:retinal ganglion cells), in line with macaque anatomical estimates that show AII amacrine cells form the bottleneck in the rod pathway to set the scotopic visual limit. Our model estimations that the rods per photon ratio under full-field stimulation is ~3000X higher than at absolute threshold are in accordance with visual summation effects and provide an alternative approach for understanding the limits of scotopic vision.

Changes in Pigeons’ Responses to Numerical Stimuli Depending on Total Element Area Differences between Stimuli

This experiment investigated whether pigeons’ response to numerical stimuli in a numerosity discrimination task differed by degree of difference in total element area ratio between numerical stimuli. After the pigeons learned to respond to a smaller numerical stimulus containing fewer elements, Tests 1 and 2 were conducted. In Test 1, the study compared smaller numerical stimulus choice ratios under several conditions, wherein the ratios of the total element area between smaller and larger numerical stimuli were manipulated. Test 2 presented a test pair with the same number of pairs, but whose areas differed, and examined whether discrimination based on total element area was established through different reinforcements within the numerosity discrimination task. In Test 1, birds responded to smaller numerical stimuli under the conditions that the total area of the smaller numerical stimuli was less than or equal to that of the larger numerical stimuli. On the other hand, under the condition that the total area of the smaller numerical stimuli was larger than that of the larger numerical stimuli, the frequency of responses to the smaller numerical stimuli decreased with the increase in differences in the area ratio between stimuli. Test 2 demonstrated that the birds consistently chose the smaller area of stimuli when the numerical stimulus pairs differed only in area size. These results suggested that either stimulus control by numerosity or by nonnumerical visual cues is dominant, depending on the degree of the total element area ratio between the numerical stimuli.

Triboelectric nanogenerator sensors for soft robotics aiming at digital twin applications

Designing efficient sensors for soft robotics aiming at human machine interaction remains a challenge. Here, we report a smart soft-robotic gripper system based on triboelectric nanogenerator sensors to capture the continuous motion and tactile information for soft gripper. With the special distributed electrodes, the tactile sensor can perceive the contact position and area of external stimuli. The gear-based length sensor with a stretchable strip allows the continuous detection of elongation via the sequential contact of each tooth. The triboelectric sensory information collected during the operation of soft gripper is further trained by support vector machine algorithm to identify diverse objects with an accuracy of 98.1%. Demonstration of digital twin applications, which show the object identification and duplicate robotic manipulation in virtual environment according to the real-time operation of the soft-robotic gripper system, is successfully created for virtual assembly lines and unmanned warehouse applications.

Modulación de la percepción biestable: un estudio basado en estimulación multimodal y registros de actividad oculomotora

Las imágenes biestables tienen la posibilidad de ser interpretadas de dos maneras diferentes. La interpretación que haga el observador se puede relacionar tanto con el área del estímulo visual que el observador está mirando, como con información exógena provista de manera simultánea a la exposición de la imagen ambigua. Cuando se hace una determinada configuración perceptual de un estímulo visual de esta naturaleza, factores moduladores asociados a las fijaciones oculares del observador juegan un rol, lo mismo que la modulación que puede ejercer la carga semántica proveniente de otro estímulo de diferente modalidad sensorial presentado junto con la imagen. Emerge, en consecuencia, el problema de si, ante la presencia de una estimulación multimodal audiovisual en la que el audio tiene carga semántica asociada a los perceptos de una imagen biestable, se produce efectivamente una modulación semántica y si, adicionalmente, es posible reconocer una asociación entre las fijaciones oculares hechas sobre la imagen biestable y el percepto que de ella se reconoce. Para resolver esta cuestión, se diseñó una tarea experimental en la que treinta y cinco (35) participantes observaron en un dispositivo fijo de registro de actividad oculomotora de 120 Hz. la imagen biestable My girlfriend or my mother-in-law mientras escuchaban tonos de voz, uno de una mujer joven, otro de una mujer anciana, para observar el efecto modulador de dichas tonalidades vocales. Se encontraron diferencias significativas entre las duraciones de las interpretaciones congruentes y no congruentes con el audio. También se encontró evidencia de la relación entre las fijaciones oculares manifestadas en las áreas de análisis y los perceptos visuales reportados. Adicionalmente, el entendimiento de los audios moduladores no se constituyó en un factor que repercutiera en las percepciones visuales congruentes con el modulador acústico. Se concluye que tanto las fijaciones oculares como la carga semántica auditiva guardan relación con la percepción de la image biestable.

Presynaptic Calcium Channel Open Probability and Changes in Calcium Influx Throughout the Action Potential Determined Using AP-Waveforms.

Action potentials arriving at a nerve terminal activate voltage-gated calcium channels and set the electrical driving force for calcium entry which affects the amount and duration of neurotransmitter release. During propagation, the duration, amplitude, and shape of action potentials often changes. This affects calcium entry, and can cause large changes in neurotransmitter release. Here, we have used a series of amplitude and area matched stimuli to examine how the shape and amplitude of a stimulus affect calcium influx at a presynaptic nerve terminal in the mammalian brain. We identify fundamental differences in calcium entry following calcium channel activation by a standard voltage jump vs. an action potential-like stimulation. We also tested a series of action potential-like stimuli with the same amplitude, duration, and stimulus area, but differing in their rise and decay times. We find that a stimulus that matches the rise and decay times of a physiological action potential produces a calcium channel response that is optimized over a range of peak amplitudes. Next, we determined the relative number of calcium channels that are active at different times during an action potential, which is important in the context of how local calcium domains trigger neurotransmitter release. We find the depolarizing phase of an AP-like stimulus only opens ~20% of the maximum number of calcium channels that can be activated. Channels continue to activate during the falling phase of the action potential, with peak calcium channel activation occurring near 0 mV. Although less than 25% of calcium channels are active at the end of the action potential, these calcium channels will generate a larger local calcium concentration that will increase the release probability for nearby vesicles. Determining the change in open probability of presynaptic calcium channels, and taking into account how local calcium concentration also changes throughout the action potential are both necessary to fully understand how the action potential triggers neurotransmitter release.