Modeling chromatic contrast sensitivity across different background colors and luminance

In this research we compare chromatic contrast sensitivity models for two separate datasets and for the pooled dataset. They were obtained from two studies employing a very similar experimental paradigm. The data represent threshold visibilities of chromatic Gabor patterns varying in spatial frequency, background chromaticity, direction of color modulation and luminance, at constant stimulus size. Using the extended data set, we reconfirm our previously reported finding that a model based on coloropponent contrast signals is an improvement over a cone contrast model. However, when linear background scaling in classic cone contrast is replaced by nonlinear background scaling, an improvement of almost similar size is obtained. The results of this study can be of interest for the development of vision models employing the processing of spatio-chromatic information.

Pupillometry in auditory multistability

In multistability, a constant stimulus induces alternating perceptual interpretations. For many forms of visual multistability, the transition from one interpretation to another (“perceptual switch”) is accompanied by a dilation of the pupil. Here we ask whether the same holds for auditory multistability, specifically auditory streaming. Two tones were played in alternation, yielding four distinct interpretations: the tones can be perceived as one integrated percept (single sound source), or as segregated with either tone or both tones in the foreground. We found that the pupil dilates significantly around the time a perceptual switch is reported (“multistable condition”). When participants instead responded to actual stimulus changes that closely mimicked the multistable perceptual experience (“replay condition”), the pupil dilated more around such responses than in multistability. This still held when data were corrected for the pupil response to the stimulus change as such. Hence, active responses to an exogeneous stimulus change trigger a stronger or temporally more confined pupil dilation than responses to an endogenous perceptual switch. In another condition, participants randomly pressed the buttons used for reporting multistability. In Study 1, this “random condition” failed to sufficiently mimic the temporal pattern of multistability. By adapting the instructions, in Study 2 we obtained a response pattern more similar to the multistable condition. In this case, the pupil dilated significantly around the random button presses. Albeit numerically smaller, this pupil response was not significantly different from the multistable condition. While there are several possible explanations–related, e.g., to the decision to respond–this underlines the difficulty to isolate a purely perceptual effect in multistability. Our data extend previous findings from visual to auditory multistability. They highlight methodological challenges in interpreting such data and suggest possible approaches to meet them, including a novel stimulus to simulate the experience of perceptual switches in auditory streaming.

Phototunable self-oscillating system driven by a self-winding fiber actuator

Self-oscillating systems that enable autonomous, continuous motions driven by an unchanging, constant stimulus would have significant applications in intelligent machines, advanced robotics, and biomedical devices. Despite efforts to gain self-oscillations have been made through artificial systems using responsive soft materials of gels or liquid crystal polymers, these systems are plagued with problems that restrict their practical applicability: few available oscillation modes due to limited degrees of freedom, inability to control the evolution between different modes, and failure under loading. Here we create a phototunable self-oscillating system that possesses a broad range of oscillation modes, controllable evolution between diverse modes, and loading capability. This self-oscillating system is driven by a photoactive self-winding fiber actuator designed and prepared through a twistless strategy inspired by the helix formation of plant-tendrils, which endows the system with high degrees of freedom. It enables not only controllable generation of three basic self-oscillations but also production of diverse complex oscillatory motions. Moreover, it can work continuously over 1270000 cycles without obvious fatigue, exhibiting high robustness. We envision that this system with controllable self-oscillations, loading capability, and mechanical robustness will be useful in autonomous, self-sustained machines and devices with the core feature of photo-mechanical transduction.

Cognitive approach to the theory of abbreviation

The formation of abbreviations is explained mainly by the action of two factors: extralinguistic and intralinguistic. Extralinguistic factors include social transformations, scientific and technological progress, and interethnic changes. Being qualitative in nature, they are characterized by dialectical dynamics. Intralinguistic factors should be understood as the effect of internal laws that determine the evolution of language. In language there is a dialectical struggle of opposites, which determines its self-development. These opposites can be called language antinomies, each identity is the key to the stability of the system, the specific resolution of any of these opposites generates new collisions, new contradictions in the language (in principle-of the same order) and, consequently, their final resolution is impossible: they are a constant stimulus for the internal development of the language. The stimulus to abbreviate lies with the speaker, who has full knowledge of information, in the process of communication and unilaterally seeks to reduce multi-component and cumbersome terms represented by long words, complex words and phrases. Language signs are replaced with codes by communicants, and familiar words are shortened.

Chemogenetics Reveal an Anterior Cingulate–Thalamic Pathway for Attending to Task-Relevant Information

In a changing environment, organisms need to decide when to select items that resemble previously rewarded stimuli and when it is best to switch to other stimulus types. Here, we used chemogenetic techniques to provide causal evidence that activity in the rodent anterior cingulate cortex and its efferents to the anterior thalamic nuclei modulate the ability to attend to reliable predictors of important outcomes. Rats completed an attentional set-shifting paradigm that first measures the ability to master serial discriminations involving a constant stimulus dimension that reliably predicts reinforcement (intradimensional-shift), followed by the ability to shift attention to a previously irrelevant class of stimuli when reinforcement contingencies change (extradimensional-shift). Chemogenetic disruption of the anterior cingulate cortex (Experiment 1) as well as selective disruption of anterior cingulate efferents to the anterior thalamic nuclei (Experiment 2) impaired intradimensional learning but facilitated 2 sets of extradimensional-shifts. This pattern of results signals the loss of a corticothalamic system for cognitive control that preferentially processes stimuli resembling those previously associated with reward. Previous studies highlight a separate medial prefrontal system that promotes the converse pattern, that is, switching to hitherto inconsistent predictors of reward when contingencies change. Competition between these 2 systems regulates cognitive flexibility and choice.

Reducción de sodio en salsa de tomate y mayonesa mediante la aplicación de un enfoque de umbral sensorial

El consumo excesivo de sodio es causa importante de enfermedades no transmisibles incluyendo hipertensión. En esta investigación se evaluó una metodología sensorial para reducir el contenido de sodio en salsas de tomate y mayonesas, productos altamente consumidos en Costa Rica. Se caracterizaron, por triplicado, 16 salsas y 7 mayonesas comerciales para determinar los ingredientes más comunes y sus características físicoquímicas. Se comparó el contenido de sodio reportado en la etiqueta contra el valor determinado experimentalmente. Se formularon prototipos de ambos productos y se determinó el umbral de diferencia apenas perceptible (DAP) para el gusto salado utilizando el método de estímulo constante con 40 panelistas no entrenados (d'= 1, significancia de 0,05 y potencia de prueba de 0,95). Se contruyeron las curvas psicofísicas con concentraciones de sal entre 0,67% y 2,5% para salsa de tomate y 0,13% y 4,16% para mayonesa; obteniéndose DAPs de 0,51% y 0,26% respectivamente; equivalentes a 28,3% y 14,4% menos de sal en cada producto. Para la validación del umbral, se aplicó una prueba de discriminación 2-AFC con 40 panelistas comparando la formulación regular con la reducida en sodio. Los panelistas no detectaron diferencias significativas entre mayonesas (P>0,05) pero sí entre salsas (P<0,05), por lo que se aplicó una prueba de agrado con 112 consumidores y se determinó que la salsa reducida en sodio resultó de mayor o igual agrado que la contraparte. Estos resultados guiarían a la industria alimentaria regional hacia el mejoramiento del perfil nutricional de estos productos. The excessive consumption of sodium is an important cause of noncommunicable diseases including hypertension. This research aimed, using a sensorial methodology, to reduce sodium content in tomato sauces and mayonnaise, highly consumed products in Costa Rica. A total of 16 commercial sauces and 7 mayonnaises were characterized to determine their most common ingredients and physicochemical properties. The sodium content reported in the labed was compared against values obtained experimentally. Prototypes for both products were developed and the threshold for the just noticiable difference (JND) for salty flavor was determined using the constant stimulus method with 40 panelists (d'= 1, 0.05 significance and a test power of 0,95). Psychophysical curves were built with salt concentrations between 0.67% and 2.5% for tomato sauce and 0.13% and 4.16% for mayonnaise; obtaining JNDs of 0.51% and 0.26% respectively; equivalent to 28.3% and 14.4% less salt in tomato and mayonnaise. To validate the threshold, a discriminatory 2-AFC test with 40 panelists was performed to compare the regular formulations against those reduced in sodium. Panelists did not detect significant differences among mayonnaises (P>0.05) but they did found differences between sauces (P<0.05). Thus, for tomato sauce a consumer liking test with 112 consumers was performed and it was found that sodium reduced tomato sauce was equally or more liked than its counterpart. These results guide the regional food industry towards the improval of the nutritional profile of both products.

Zinc α-2 Glycoprotein (ZAG) a Novel Biomarker for the Detection of Oral Squamous Cell Carcinoma

Oral cancer, the most challenging and life threatening disease in the field of dentistry, may start as a reactive lesion due to constant stimulus from tobacco consumption, transform into a pre-malignant lesion (dysplastic lesion) and ultimately develop into a cancerous lesion (Invasive carcinoma). There is a fundamental revolution taking place in the analyzing methods; extraction of biological protein from the saliva rather than from tissues or blood. Several of the biomarkers have been studied with pro-carcinogenic effects like Interleukins (ILs), tumor necrosis factor (TNF) and leptin, but only a few have been stated in the literature, which show anti-cancer characteristics like adiponectin and zinc alpha-2 glycoprotein. This review explored the diagnostic and prognostic values of a biomarkers zinc alpha-2 glycoprotein (ZAG) in adults suspected of oral squamous cell carcinoma (OSCC). The PubMed, EMBASE and Google Scholar were searched for scientific studies reported on the potential mechanism of zinc alpha-2 glycoprotein. All the research articles were selected in which ZAG is applied solely or in conjunction with other biomarkers in oral cancer and other cancers. These literatures were carefully assessed to find out and compile the diagnostic and prognostic values and to inquire therapeutic action of ZAG in the process of carcinogenesis.

Chemogenetics reveal an anterior cingulate-thalamic pathway for attending to task-relevant information

In a changing environment, we need to decide when to select items that resemble previously rewarded stimuli and when it is best to switch to other stimulus types. Here, we used chemogenetic techniques to provide causal evidence that activity in the rodent anterior cingulate cortex and its efferents to the anterior thalamic nuclei modulate the ability to attend to reliable predictors of important outcomes. Rats were tested on an attentional set-shifting paradigm that first measures the ability to master serial discriminations involving a constant stimulus dimension that reliably predicts reinforcement (intradimensional-shift), followed by the ability to shift attention to a previously irrelevant class of stimuli when reinforcement contingencies change (extradimensional-shift). Chemogenetic silencing of the anterior cingulate cortex (Experiment 1) as well as selective inactivation of anterior cingulate efferents to the anterior thalamic nuclei (Experiment 2) impaired intradimensional learning but, facilitated two sets of extradimensional-shifts. This pattern of results signals the loss of a cortico-thalamic system for cognitive control that preferentially processes stimuli resembling those previously associated with reward. Previous studies highlight a separate prefrontal system that promotes switching to hitherto inconsistent predictors of reward when contingencies change. Competition between these two systems regulates cognitive flexibility and choice.

A Universal Law of Sensory Adaptation

Sensory adaptation is the gradual decline in response as recorded from sensory neurons to a constant stimulus. Measuring adaptation involves counting the time-varying rate of action potentials generated by the sensory neuron. A typical adaptation curve will involve spontaneous activity prior to the introduction of the stimulus, a peak level of activity soon after the stimulus is presented, and a gradual fall to a new steady-state value. In this study, the steady-state activity is shown to be equal to the geometric mean of the spontaneous and peak activities. This remarkably simple equation holds across different sensory modalities and in different animal species. It is obeyed in both modern measurements of neural adaptation as well as the original recordings of Lord Adrian in his seminal work on the discovery of the all-or-nothing principle of nerves. It is likely a universal relationship governing the peripheral response of sensory neurons.