Representation Of Orientation Research Articles

A gradual transition toward categorical representations along the visual hierarchy during working memory, but not perception.

The ability to stably maintain visual information over brief delays is central to healthy cognitive functioning, as is the ability to differentiate such internal representations from external inputs. One possible way to achieve both is via multiple concurrent mnemonic representations along the visual hierarchy that differ systematically from the representations of perceptual inputs. To test this possibility, we examine orientation representations along the visual hierarchy during perception and working memory. Human participants directly viewed, or held in mind, oriented grating patterns, and the similarity between fMRI activation patterns for different orientations was calculated throughout retinotopic cortex. During direct viewing of grating stimuli, similarity was relatively evenly distributed amongst all orientations, while during working memory the similarity was higher around oblique orientations. We modeled these differences in representational geometry based on the known distribution of orientation information in the natural world: The "veridical" model uses an efficient coding framework to capture hypothesized representations during visual perception. The "categorical" model assumes that different "psychological distances" between orientations result in orientation categorization relative to cardinal axes. During direct perception, the veridical model explained the data well. During working memory, the categorical model gradually gained explanatory power over the veridical model for increasingly anterior retinotopic regions. Thus, directly viewed images are represented veridically, but once visual information is no longer tethered to the sensory world there is a gradual progression to more categorical mnemonic formats along the visual hierarchy.

Recurrent inhibition refines mental templates to optimize perceptual decisions.

Translating sensory inputs to perceptual decisions relies on building internal representations of features critical for solving complex tasks. Yet, we still lack a mechanistic account of how the brain forms these mental templates of task-relevant features to optimize decision-making. Here, we provide evidence for recurrent inhibition: an experience-dependent plasticity mechanism that refines mental templates by enhancing γ-aminobutyric acid (GABA)-mediated (GABAergic) inhibition and recurrent processing in superficial visual cortex layers. We combine ultrahigh-field (7 T) functional magnetic resonance imaging at submillimeter resolution with magnetic resonance spectroscopy to investigate the fine-scale functional and neurochemical plasticity mechanisms for optimized perceptual decisions. We demonstrate that GABAergic inhibition increases following training on a visual (i.e., fine orientation) discrimination task, enhancing the discriminability of orientation representations in superficial visual cortex layers that are known to support recurrent processing. Modeling functional and neurochemical plasticity interactions reveals that recurrent inhibitory processing optimizes brain computations for perpetual decisions and adaptive behavior.

Hue and orientation pinwheels in macaque area V4.

Area V4 is an intermediate-level area of the macaque visual cortical hierarchy that serves key functions in visual processing by integrating inputs from lower areas such as V1 and V2 and providing feedforward inputs to many higher cortical areas. Previous V4 imaging studies have focused on differential responses to color, orientation, disparity, and motion stimuli, but many details of the spatial organization of significant hue and orientation tuning have not been fully described. We used support vector machine (SVM) decoding of intrinsic cortical single-condition responses to generate high-resolution maps of hue and orientation tuning and to describe the organization of hue and orientation pinwheels in V4. Like V1 and V2, V4 contains maps of orientation that are organized as pinwheels. V4 also contains maps of hue that are organized as pinwheels, whose circular organization more closely represents the perception of hue than is observed in antecedent cortical areas. Unlike V1, where orientation is continuously mapped across the surface, V4 hue and orientation pinwheels are organized in limited numbers of pinwheel sequences. The organization of these sequences and the distance between pinwheels may provide insight into the functional organization of V4. Regions significantly tuned for hue occupy roughly four times that of the orientation, are largely separated from each other, and overlap by roughly 5%. This spatial organization is largely consistent with segregated inputs arising from V2 thin and interstripes. This modular organization of V4 suggests that further integration of color and shape might occur in higher areas in inferotemporal cortical.NEW & NOTEWORTHY The representation of hue and orientation in macaque monkey area V4 was determined by intrinsic cortical imaging of responses to isoluminant hues and achromatic grating stimuli. Vector summation of support vector machine (SVM) decoded single-condition responses was used to generate hue and orientation maps that, like V1 orientation maps, were both characterized by distinct pinwheel patterns. These data suggest that pinwheels are an important structure to represent different stimulus features across multiple visual cortical areas.

Orientation and mental representations in the decision-making process: a comparison between junior and senior professional

In the workplace, professionals have an orientation to individual or group decision-making based on ideal or real representation of the group situation. However, no previous studies investigated these dimensions in professionals of different ages. A total of 216 professionals were enrolled in this study based on their work experience and seniority. Specifically, senior professionals were from different Italian consulting companies, while juniors had not yet approached the world of work, but were completing their professional education. Participants were asked to read a realistic decision-making scenario and rate their individual or group decision-making orientation, thinking of an ideal and real group situation. A stronger group decision-making orientation was found in both groups of professionals, independent of age. However, professionals appear less group-oriented when they mentally self-represent their real compared to their ideal group. Additionally, in senior professionals, a positive correlation between individual and group orientation was found in the ideal group situation. Indeed, in junior professionals, a positive correlation between individual and group orientation was found in the real situation. Therefore, it might be that becoming older and increasing professionalism level correlate with awareness of the difference between real and ideal group representations.

Redundant non-serial compound manipulator kinematics and dynamics

Redundant non-serial compound manipulators with closed kinematic and actuator loops that enhance precision control and load carrying capacity are treated. Generalized coordinates and associated holonomic constraints that account for kinematic and actuator closed loops and singularity free representation of orientation of spatial manipulator bodies augment input and output coordinates in the kinematic formulation. Disjoint assembly components and path connected singularity free assembly components of manipulator configuration space are defined, in which manipulator kinematics and dynamics can be reliably carried out. A set-valued inverse kinematic configuration mapping is derived, with which compound redundant manipulators are shown to be locally cyclic. A new system of manipulator operational coordinates comprised of output and self-motion coordinates are defined and shown to be equivalent to input coordinates in representation of manipulator kinematics and dynamics. Well-posed ordinary differential equations of manipulator dynamics in both input and operational coordinates are presented that require no ad-hoc derivation. Five model manipulators illustrate applications involved and theoretical methods presented.

Self-organization of modular activity in immature cortical networks

During development, cortical activity is organized into distributed modular patterns that are a precursor of the mature columnar functional architecture. Theoretically, such structured neural activity can emerge dynamically from local synaptic interactions through a recurrent network with effective local excitation with lateral inhibition (LE/LI) connectivity. Utilizing simultaneous widefield calcium imaging and optogenetics in juvenile ferret cortex prior to eye opening, we directly test several critical predictions of an LE/LI mechanism. We show that cortical networks transform uniform stimulations into diverse modular patterns exhibiting a characteristic spatial wavelength. Moreover, patterned optogenetic stimulation matching this wavelength selectively biases evoked activity patterns, while stimulation with varying wavelengths transforms activity towards this characteristic wavelength, revealing a dynamic compromise between input drive and the network’s intrinsic tendency to organize activity. Furthermore, the structure of early spontaneous cortical activity – which is reflected in the developing representations of visual orientation – strongly overlaps that of uniform opto-evoked activity, suggesting a common underlying mechanism as a basis for the formation of orderly columnar maps underlying sensory representations in the brain.

Reinforcement learning for path planning of free-floating space robotic manipulator with collision avoidance and observation noise

This study introduces a novel approach for the path planning of a 6-degree-of-freedom free-floating space robotic manipulator, focusing on collision and obstacle avoidance through reinforcement learning. It addresses the challenges of dynamic coupling between the spacecraft and the robotic manipulator, which significantly affects control and precision in the space environment. An innovative reward function is introduced in the reinforcement learning framework to ensure accurate alignment of the manipulator’s end effector with its target, despite disturbances from the spacecraft and the need for obstacle and collision avoidance. A key feature of this study is the use of quaternions for orientation representation to avoid the singularities associated with conventional Euler angles and enhance the training process’ efficiency. Furthermore, the reward function incorporates joint velocity constraints to refine the path planning for the manipulator joints, enabling efficient obstacle and collision avoidance. Another key feature of this study is the inclusion of observation noise in the training process to enhance the robustness of the agent. Results demonstrate that the proposed reward function enables effective exploration of the action space, leading to high precision in achieving the desired objectives. The study provides a solid theoretical foundation for the application of reinforcement learning in complex free-floating space robotic operations and offers insights for future space missions.

Functional neuroanatomy of the vestibular cortex and vestibular stimulation methods for neuroimaging studies

The vestibular cortex is a distributed network of multisensory areas that plays a crucial role in balance, posture, and spatial orientation. The core region of the vestibular cortex is the parietoinsular vestibular cortex (PIVC), which is located at the junction between the posterior insula, parietal operculum, and retroinsular region. The PIVC is connected to other vestibular areas, the primary and secondary somatosensory cortices, and the premotor and posterior parietal cortices. It also sends projections to the vestibular nuclei in the brainstem. The PIVC is a multisensory region that integrates vestibular, visual, and somatosensory information to create a representation of head-in-space motion, which is used to control eye movements, posture, and balance. Other regions of the vestibular cortex include the primary somatosensory, posterior parietal, and frontal cortices. The primary somatosensory cortex is involved in processing information about touch and body position. The posterior parietal cortex is involved in integrating vestibular, visual, and somatosensory information to create a representation of spatial orientation. The frontal cortex is involved in controlling posture, and eye movements. The various methods used to stimulate the vestibular receptors in neuroimaging studies include caloric vestibular stimulation (CVS), galvanic vestibular stimulation (GVS), and auditory vestibular stimulation (AVS). CVS uses warm or cold water or air to stimulate the semicircular canals, GVS uses a weak electrical current to stimulate the vestibular nerve, and AVS uses high-intensity clicks or short tone bursts to stimulate the otolithic receptors.

A novel self-supervised contrastive learning based sentence-level attribute induction method for online satisfaction evaluation

Satisfaction evaluation provides valuable support for procurement decisions and product improvement on e-commerce platforms. As an important task of satisfaction evaluation, attribute induction is essential to identify relevant aspects and demands of user-generated evaluations. However, previous methods have often directly predicted typical attributes using individual words, neglecting valuable sentence-level information that could significantly enhance effectiveness. To alleviate this issue, this article introduces the concept of representations of potential attributes (PARs) to explicitly capture sentence-level information regarding product attributes in customer reviews. It further develops a novel self-supervised contrastive learning based sentence-level attribute induction method (SSCL-SAI) to train these PARs. Recognizing that sentences are the basic units of human expression, this approach mitigates information loss. Then, an aspect-category sentiment analysis model is used to transform the unstructured online textual reviews into linguistic 2-tuple for obtaining final satisfaction evaluation result. These 2-tuples provide a representation of sentiment orientations on a continuous numerical scale, enabling precise linguistic operations. Afterwards, an illustrative example conducted on real-world laptop product satisfaction analysis testify the validity of the approach. Finally, the comparative analysis shows the effectiveness of the proposed SSCL-SAI, and experiments on the impact of hyperparameter settings demonstrate that SSCL-SAI can be applied in various scenarios.

The Challenge of Identity Politics in The 2024 Election

Identity and representation are two significant things in human life. While religion and ethnicity are two things that become the identity and representation of humans. The democratic process in Indonesia is inseparable from the political orientation of identity and representation. This research is qualitative in nature, focusing on the case of the 2018-2022 DKI Regional Election in the second round. The case will be analyzed using the theory of identity politics and political representation. The results show that identity politics orientation and political representation affect the democratic process. Democratization that upholds freedom is the basis for every individual to actualize themselves, including in political matters. The individual freedom guaranteed by the constitution in Indonesia reflects the high popularity of this democratic system. However, this freedom has ultimately made the divide between identities (religion, ethnicity, language, gender, etc.) in Indonesia clearer, especially in relation to the nation's political issues. The issue of religion and nationalism are two identities that are currently being debated in Indonesia. The polemics of identity politics are increasingly tapering until the emergence of truth claims that one interest group is better than other interest groups, this interest affair then begins to divide the nation that previously upheld differences.

(320) Erectile Dysfunction and Men’s Health Websites: How diverse is our Racial, Ethnic, and Sexual Orientation Representation?

Abstract Introduction Images featured in patient educational materials can enhance comprehension of medical conditions, particularly those associated with sensitive issues like erectile dysfunction (ED). Past research indicates that minority men are often underrepresented in online urological content and thus may not relate to the material. Objective The present study aims to evaluate the representation of racial, ethnic, and sexual orientation diversity in ED and men’s health content on reputable urology program websites. Methods Websites of the top urology departments from U.S. News & World Reports 2022 rankings were reviewed as sources of high quality content. All subpages were reviewed to identify ED and men’s health sites with extraction of photo and video imagery depicting human subjects. A three-person review team interpreted race, ethnicity, and sexual orientation categorically. Race was also interpreted using a numeric scale, Fitzpatrick skin rating, and median ratings classified as white (1-3) or non-white (4-6). Consensus ratings were summarized descriptively. Spearman’s rank correlation was used to measure inter-rater reliability of Fitzpatrick ratings and MedCalc’s z-test used to compare diversity proportions to national rates from census data. Results The top 50 ranked urology program websites were reviewed. Seven programs did not have any patient-facing ED or men’s health web pages. Nearly half of programs with sites did not contain any human images (n=19/43, 44%). A total of 113 images were collected and reviewed. Race in the 102 (90.3%) interpretable images included 6 (5.9%) Asian, 16 (15.7%) black, 75 (73.5%) white, and 5 (4.9%) other men. Latino men were represented in 3/70 (4.3%) images. Utilizing Fitzpatrick ratings, 94 (83.2%) subjects were classified as white and 19 (16.8%) non-white. Most images [67 (59.3%)] demonstrated a man without a partner which precluded sexual orientation evaluation. Of those pictured with a partner, 25 (92.6%) were interpreted as heterosexual and 2 (7.4%) as same sex. Between reviewer correlation coefficients for Fitzpatrick ratings ranged from 0.66-0.69. Table 1 compares interpreted image data to population benchmarks from United States census data. Conclusions Limited imagery on academic urology ED websites continues to underrepresent some groups, namely Latinos. Although men in same sex relationships were depicted, the absolute number of such images was low. Conscious effort to improve diversity in online men’s health, and namely ED, content is needed. Disclosure No.

Investigating the Roles of the Visual and Parietal Cortex in Representing Content versus Context in Visual Working Memory.

Content-to-context binding is crucial for working memory performance. Using a dual-serial retrocueing (DSR) task on oriented gratings, Yu et al. (2020) found that content (orientation) of both prioritized and unprioritized memory items (PMI; UMI) was represented simultaneously in visual cortex, while their context (location) was represented in intraparietal sulcus (IPS), with a priority-based remapping of the representation of content and context of the UMI in each region, respectively. This registered report acquired fMRI of 24 healthy adults while they performed a DSR task with location as the to-be-reported content and orientation as the task-relevant context. We contrasted three accounts: domain-dependent, the engagement of visual and parietal regions depends on the feature domain (orientation vs location); functional, the engagement of these regions depends on their function (content vs context); and hybrid-a combination of the domain-dependent account and the additional stipulation that IPS encodes context regardless of domain. Delay-period activity in early visual cortex conformed most closely with functional predictions: robust priority-sensitive representation of stimulus location (content), but no evidence for the active representation of stimulus orientation (context). Delay-period activity in IPS, in contrast, conformed most closely to predictions of the hybrid account: active representation of content (location) and of prioritized context (orientation). Exploratory analyses further supported the hybrid account of IPS, revealing univariate sensitivity to variation in both content and context load, the latter in a manner that predicted individual differences in behavior. The representation of visual information in working memory is highly dependent on behavioral context.

Prejudice but no pride: The Portuguese Universal Decimal Classification’s labelling of sexual orientation

Critical cataloguing aims to study cases of social injustice, misrepresentation, negative biases, offensive terminologies, and hegemonic and oppressive hierarchical structures in the representation of communities and identities in knowledge organization systems. The aim of this study is to provide a critical analysis of the representation of sexual orientation in the Portuguese Universal Decimal Classification, grounded in a qualitative content analysis method. The results show that the principle of exhaustiveness does not manifest itself in the representation of sexual orientation. The absence of the term ‘heterosexuality’ mirrors the heteronormative hegemony, while the minoritization of ‘lesbianism’, but not of ‘male homosexuality’, reflects the patriarchal hegemony. The representation of sexual orientation carries the historical pathologization of sexual orientations other than heterosexuality. The Portuguese Universal Decimal Classification conveys negative biases and misrepresents sexual orientation in a way that is irreconcilable with present-day reality. Critical thinking must be encouraged within the library community and the Universal Decimal Classification should be promptly revised and updated.

Decoding time-resolved neural representations of orientation ensemble perception.

The visual system can compute summary statistics of several visual elements at a glance. Numerous studies have shown that an ensemble of different visual features can be perceived over 50-200 ms; however, the time point at which the visual system forms an accurate ensemble representation associated with an individual's perception remains unclear. This is mainly because most previous studies have not fully addressed time-resolved neural representations that occur during ensemble perception, particularly lacking quantification of the representational strength of ensembles and their correlation with behavior. Here, we conducted orientation ensemble discrimination tasks and electroencephalogram (EEG) recordings to decode orientation representations over time while human observers discriminated an average of multiple orientations. We modeled EEG signals as a linear sum of hypothetical orientation channel responses and inverted this model to quantify the representational strength of orientation ensemble. Our analysis using this inverted encoding model revealed stronger representations of the average orientation over 400-700 ms. We also correlated the orientation representation estimated from EEG signals with the perceived average orientation reported in the ensemble discrimination task with adjustment methods. We found that the estimated orientation at approximately 600-700 ms significantly correlated with the individual differences in perceived average orientation. These results suggest that although ensembles can be quickly and roughly computed, the visual system may gradually compute an orientation ensemble over several hundred milliseconds to achieve a more accurate ensemble representation.

LANGUAGE REPRESENTATIVES OF VALUE ORIENTATIONS OF UKRAINIANS AND IRISH: A TRANSLATION ASPECT (BASED ON THE MATERIALS OF CONTEMPORARY FICTION AND MEDIA TEXTS)

The article defines the leading features of the linguistic representation of the value orientations of Ukrainians and Irish people in the translation studies aspect. It is emphasized that the works of modern Ukrainian and Irish literature combine spatial and temporal definiteness, i.e., closeness to the “real plot”, and the expressiveness of the reflection of a person – an actor, endowed with features and values that attach him to history. The tendency of the development of the value component in modern Ukrainian and Irish literature consists in the strengthening of the psychological load of images, in the desire to outline with the help of linguistic means not only the functional, but also the deep-emotional aspect of the national values of the Ukrainian and Irish people.

Reference Motion Quality and Design Choices for Bipedal Walking with PPO

This paper investigates the influence of reference motion quality and other design choices on the performance of deep reinforcement learning for bipedal walking with Proximate Policy Optimization (PPO). We use parametrized Cartesian quintic splines to generate reference actions for an omnidirectional walk policy. By using parameter sets with different qualities, we show that the performance of the trained policy correlates to the quality of the reference motion. We also show that a policy in Cartesian space performs superior to a joint-space-based one if an advantageous representation of orientation is chosen. Additionally, we show that using an initial bias for the policy speeds up the training and leads to higher performances for policies using position control. We also show that we can achieve a stable omnidirectional walk on a wide variety of simulated humanoid robots.

Orientation representation in human visual cortices: contributions of non-visual information and action-related process.

Orientation processing in the human brain plays a crucial role in guiding grasping actions toward an object. Remarkably, despite the absence of visual input, the human visual cortex can still process orientation information. Instead of visual input, non-visual information, including tactile and proprioceptive sensory input from the hand and arm, as well as feedback from action-related processes, may contribute to orientation processing. However, the precise mechanisms by which the visual cortices process orientation information in the context of non-visual sensory input and action-related processes remain to be elucidated. Thus, our study examined the orientation representation within the visual cortices by analyzing the blood-oxygenation-level-dependent (BOLD) signals under four action conditions: direct grasp (DG), air grasp (AG), non-grasp (NG), and uninformed grasp (UG). The images of the cylindrical object were shown at +45° or - 45° orientations, corresponding to those of the real object to be grasped with the whole-hand gesture. Participants judged their orientation under all conditions. Grasping was performed without online visual feedback of the hand and object. The purpose of this design was to investigate the visual areas under conditions involving tactile feedback, proprioception, and action-related processes. To address this, a multivariate pattern analysis was used to examine the differences among the cortical patterns of the four action conditions in orientation representation by classification. Overall, significant decoding accuracy over chance level was discovered for the DG; however, during AG, only the early visual areas showed significant accuracy, suggesting that the object's tactile feedback influences the orientation process in higher visual areas. The NG showed no statistical significance in any area, indicating that without the grasping action, visual input does not contribute to cortical pattern representation. Interestingly, only the dorsal and ventral divisions of the third visual area (V3d and V3v) showed significant decoding accuracy during the UG despite the absence of visual instructions, suggesting that the orientation representation was derived from action-related processes in V3d and visual recognition of object visualization in V3v. The processing of orientation information during non-visually guided grasping of objects relies on other non-visual sources and is specifically divided by the purpose of action or recognition.

Category Learning Selectively Enhances Representations of Boundary-Adjacent Exemplars in Early Visual Cortex.

Category learning and visual perception are fundamentally interactive processes, such that successful categorization often depends on the ability to make fine visual discriminations between stimuli that vary on continuously valued dimensions. Research suggests that category learning can improve perceptual discrimination along the stimulus dimensions that predict category membership and that these perceptual enhancements are a byproduct of functional plasticity in the visual system. However, the precise mechanisms underlying learning-dependent sensory modulation in categorization are not well understood. We hypothesized that category learning leads to a representational sharpening of underlying sensory populations tuned to values at or near the category boundary. Furthermore, such sharpening should occur largely during active learning of new categories. These hypotheses were tested using fMRI and a theoretically constrained model of vision to quantify changes in the shape of orientation representations while human adult subjects learned to categorize physically identical stimuli based on either an orientation rule (N = 12) or an orthogonal spatial frequency rule (N = 13). Consistent with our predictions, modeling results revealed relatively enhanced reconstructed representations of stimulus orientation in visual cortex (V1-V3) only for orientation rule learners. Moreover, these reconstructed representations varied as a function of distance from the category boundary, such that representations for challenging stimuli near the boundary were significantly sharper than those for stimuli at the category centers. These results support an efficient model of plasticity wherein only the sensory populations tuned to the most behaviorally relevant regions of feature space are enhanced during category learning.

The Suite for the Assessment of Low-Level cues on Orientation (SALLO): The psychophysics of spatial orientation in virtual reality

Spatial orientation is a complex ability that emerges from the interaction of several systems in a way that is still unclear. One of the reasons limiting the research on the topic is the lack of methodologies aimed at studying multimodal psychophysics in an ecological manner and with affordable settings. Virtual reality can provide a workaround to this impasse by using virtual stimuli rather than real ones. However, the available virtual reality development platforms are not meant for psychophysical testing; therefore, using them as such can be very difficult for newcomers, especially the ones new to coding. For this reason, we developed SALLO, the Suite for the Assessment of Low-Level cues on Orientation, which is a suite of utilities that simplifies assessing the psychophysics of multimodal spatial orientation in virtual reality. The tools in it cover all the fundamental steps to design a psychophysical experiment. Plus, dedicated tracks guide the users in extending the suite components to simplify developing new experiments. An experimental use-case used SALLO and virtual reality to show that the head posture affects both the egocentric and the allocentric mental representations of spatial orientation. Such a use-case demonstrated how SALLO and virtual reality can be used to accelerate hypothesis testing concerning the psychophysics of spatial orientation and, more broadly, how the community of researchers in the field may benefit from such a tool to carry out their investigations.

Roles of Political Orientation and Social Representations of Social Order on Socio-Representational Construction Towards Universal Basic Income in France

Abstract As an object which is new, complex and potentially challenging some of the foundations of the Social Order (SO), we sought to study the influence of the Political Orientation (PO) and Social Representations (SR) of the Social Order (Staerklé et al., 2007). Qui a droit à quoi ? Représentations et légitimation de l’ordre social. PUG) on the socio-representational construction of the Universal Basic Income (UBI) and stances towards this measure (attitude and estimated fair amount). Data were collected via Facebook from 264 French general population participants (Mage = 37.8; SD = 12.7; 174 women). Our Structural Equation Model revealed that the PO would be associated with the stances towards the UBI, mediated by the different ways of representing it and the representations of the SO. Results show two differents socio-representational logics in relation to being right-wing and one in relation to being left-wing. This leads to contrasting stances towards the UBI and seems to reflect different desires to maintain or change the SO.