Radial distance determination in the rat vibrissal system and the effects of Weber's law

Rats rhythmically tap and brush their vibrissae (whiskers) against objects to tactually explore the environment. To extract a complex feature such as the contour of an object, the rat must at least implicitly estimate radial object distance, that is, the distance from the base of the vibrissa to the point of object contact. Radial object distance cannot be directly measured, however, because there are no mechanoreceptors along the vibrissa. Instead, the mechanical signals generated by the vibrissa's interaction with the environment must be transmitted to mechanoreceptors near the vibrissa base. The first part of this paper surveys the different mechanical methods by which the rat could determine radial object distance. Two novel methods are highlighted: one based on measurement of bending moment and axial force at the vibrissa base, and a second based on measurement of how far the vibrissa rotates beyond initial contact. The second part of the paper discusses the application of Weber's law to two methods for radial distance determination. In both cases, Weber's law predicts that the rat will have greatest sensing resolution close to the vibrissa tip. These predictions could be tested with behavioural experiments that measure the perceptual acuity of the rat.     

The effect of the functional attributes of objects within the caged environment on interaction time in laboratory rats

Determining rat preferences for, and behaviour towards, environmental enrichment objects allows us to provide evidence-based information about how the caged environment may be enriched. In recent years there have been many studies investigating the preferences of laboratory rodents for a wide variety of environmental enrichment objects and materials. While these have provided important information regarding the animals’ perception of the items, very few studies have attempted to systematically investigate the precise attributes that constitute a preferred object and the behaviour that these objects afford. We have designed a research program to systematically study rats’ motivation to interact with enrichment objects. Here we present the results from two experiments which examined the time rats spent with objects that only differed in size. This showed that rats spent longer with large objects rather than small ones, even though objects were presented individually. We also investigated the rats’ behaviour with the objects in an open field and found that rats spent longer climbing on top of the large object. This behaviour continued when the large objects were laid on their sides instead of placed upright in the arena, suggesting that the rats were not simply climbing on the objects to investigate the top of the arena and thus an escape route, but instead were genuinely motivated to climb. This suggests that rat welfare could be enhanced by the addition to their cages of objects that permit climbing.     

Fish can encode order in their spatial map

Animals must often orient through areas that are larger than their perceptual range. The blind Mexican cave fish, Astyanax fasciatus, depends on detecting self-induced near-field wave perturbations by objects via the use of its lateral line organ. Its perceptual range (less than or equal to 0.05 m) is greatly exceeded by its ecological ranging requirements (ca. 30 m). Although known to possess a spatial map of its environment, it is not known how this fish links places (or the area over which the perceptual range extends) together. Using the blind cave fish's propensity to accelerate when faced with objects or environments that are recognizably different, I used a behavioural assay to test whether fishes can learn and remember the order of a landmark sequence. I show, to my knowledge for the first time, that blind Mexican cave fish can encode order in their spatial map. The ability to represent the order in which a series of places are spatially linked is a powerful tool for animals that must orient beyond the limit of their perceptual range. The resulting spatial map would be analogous to a jigsaw puzzle, where each piece represents a place whose size is constrained by the animal's perceptual range.     

Object-oriented echo perception and cortical representation in echolocating bats

Echolocating bats can identify three-dimensional objects exclusively through the analysis of acoustic echoes of their ultrasonic emissions. However, objects of the same structure can differ in size, and the auditory system must achieve a size-invariant, normalized object representation for reliable object recognition. This study describes both the behavioral classification and the cortical neural representation of echoes of complex virtual objects that vary in object size. In a phantom-target playback experiment, it is shown that the bat Phyllostomus discolor spontaneously classifies most scaled versions of objects according to trained standards. This psychophysical performance is reflected in the electrophysiological responses of a population of cortical units that showed an object-size invariant response (14/109 units, 13%). These units respond preferentially to echoes from objects in which echo duration (encoding object depth) and echo amplitude (encoding object surface area) co-varies in a meaningful manner. These results indicate that at the level of the bat's auditory cortex, an object-oriented rather than a stimulus-parameter-oriented representation of echoes is achieved.     

Active touch, exploratory movements, and sensory prediction

The relation between somatosensory input and motor output is asymmetric. Somatosensation is associated with every movement an animal makes, but movement is not required for somatosensation. This symposium paper proposes a classification scheme for movement, in which movements are placed along a continuum that describes the role that somatosensory information plays during the movement. Fine sensorimotor control-manipulation and exploration-are found to fall to one extreme of the spectrum, and exploratory movements in particular are shown to possess characteristics that clearly distinguish them from other varieties of movement. Specifically, the exploratory process must permit animals to extract an object's features independently of the sequence of movements executed to explore the object. Based in part on our work on the rat vibrissal system, we suggest that exploration of objects may consist of two complementary levels of sensorimotor prediction operating in parallel. At the cognitive level, the animal might move so as to perform hypothesis testing about the identity or nature of the object. The particular hypothesis tests chosen by the animal might be implemented through sequences of control-level predictions that could be generated at the level of the brainstem and cerebellum.     

A simple strategy for detecting moving objects during locomotion revealed by animal-robot interactions

An important role of visual systems is to detect nearby predators, prey, and potential mates, which may be distinguished in part by their motion. When an animal is at rest, an object moving in any direction may easily be detected by motion-sensitive visual circuits. During locomotion, however, this strategy is compromised because the observer must detect a moving object within the pattern of optic flow created by its own motion through the stationary background. However, objects that move creating back-to-front (regressive) motion may be unambiguously distinguished from stationary objects because forward locomotion creates only front-to-back (progressive) optic flow. Thus, moving animals should exhibit an enhanced sensitivity to regressively moving objects. We explicitly tested this hypothesis by constructing a simple fly-sized robot that was programmed to interact with a real fly. Our measurements indicate that whereas walking female flies freeze in response to a regressively moving object, they ignore a progressively moving one. Regressive motion salience also explains observations of behaviors exhibited by pairs of walking flies. Because the assumptions underlying the regressive motion salience hypothesis are general, we suspect that the behavior we have observed in Drosophila may be widespread among eyed, motile organisms.     

The Materiality of Relational Transformations: Propositions for Renewed Analyses of Life-Cycle Rituals in Melanesia and Australia

ABSTRACT

This paper introduces this special issue and analyses Papua New Guinea and Australian initiation and death rituals as moments of relational transformations. Although the general argument is not completely new, it has often remained an undemonstrated statement. The paper hence focuses on the specific ways people make these changes effective and express them in their rituals. It is suggested that an invariant modus operandi is in play in which, for a relation to be transformed, its previous state must first be ritually enacted. Towards the end of the ritual, the new state of the relationship is itself publicly enacted through a manifestation of the form the relation takes after the ritual. The paper suggests that a relationship cannot be transformed in the absence of the persons concerned. The relational components need to be either directly present, such as in initiations, or mediated through objects, such as in death rituals.     

Multifocal attention filters targets from distracters within and beyond primate MT neurons' receptive field boundaries

Visual attention has been classically described as a spotlight that enhances the processing of a behaviorally relevant object. However, in many situations, humans and animals must simultaneously attend to several relevant objects separated by distracters. To account for this ability, various models of attention have been proposed including splitting of the attentional spotlight into multiple foci, zooming of the spotlight over a region of space, and switching of the spotlight among objects. We investigated this controversial issue by recording neuronal activity in visual area MT of two macaques while they attended to two translating objects that circumvented a third distracter object located inside the neurons' receptive field. We found that when the attended objects passed through or nearby the receptive field, neuronal responses to the distracter were either decreased or remained unaltered. These results demonstrate that attention can split into multiple spotlights corresponding to relevant objects while filtering out interspersed distracters.     

Flexible representations of dynamics are used in object manipulation

To manipulate an object skillfully, the brain must learn its dynamics, specifying the mapping between applied force and motion. A fundamental issue in sensorimotor control is whether such dynamics are represented in an extrinsic frame of reference tied to the object or an intrinsic frame of reference linked to the arm. Although previous studies have suggested that objects are represented in arm-centered coordinates [1-6], all of these studies have used objects with unusual and complex dynamics. Thus, it is not known how objects with natural dynamics are represented. Here we show that objects with simple (or familiar) dynamics and those with complex (or unfamiliar) dynamics are represented in object- and arm-centered coordinates, respectively. We also show that objects with simple dynamics are represented with an intermediate coordinate frame when vision of the object is removed. These results indicate that object dynamics can be flexibly represented in different coordinate frames by the brain. We suggest that with experience, the representation of the dynamics of a manipulated object may shift from a coordinate frame tied to the arm toward one that is linked to the object. The additional complexity required to represent dynamics in object-centered coordinates would be economical for familiar objects because such a representation allows object use regardless of the orientation of the object in hand.     

Computer modeling of spatial-time distribution of metabolite concentrations in phantoms of biological objects by example of rat brain pial

A method for quantitative assessment of the metabolite concentrations in digital phantoms of the biological objects has been proposed. The objects under consideration are expected to have a complex geometry of diffusive sources. We present an algorithm for calculation of non-steady state gradients of the diffusing compounds under their constant border concentration. The algorithm is based on the analytical solutions for a centrally symmetric spherical source. Spatial-time distribution of metabolites is considered by the example of glucose diffusion around blood vessels in the rat brain pial. It was shown that glucose level in the tissue was increased after glycine treatment and under condition of other biological system parameters to be unchanged.     

“When we got divorced,I left all my things behind.”: How the lifespan of household goods is linked to the biographical trajectory of their owners

Social science research suggests that in our current affluent societies, individuals are accustomed to frequently replacing their household goods. However, some still try to keep their objects for a long time. How do they come to be concerned about products’ lifespan? This paper draws on a powerful method already explored in the literature on consumption: the diachronic approach through individual life trajectories. Analyzing interviews conducted with 60 individuals seeking to make their objects last, this biographical approach allows identifying some factors that explain people's propensity to make objects last. This paper shows that the tendency to keep objects for a long time can come from the familial milieu, just as it can happen later, in connection with personal events—advancement in the life cycle, bifurcations in the personal course, or interactions with public discourses and objects’ breakdowns. Finally, it demonstrates that biographical events can also have a one-time influence on products’ careers in the households, without changing the individual's relationship to objects’ lifespan—these can be personal or more historical and exceptional events, such as lockdown during the COVID-19 crisis.     

Manikin‐Ship: Value‐added relatedness in Vietnamese museums, 1996–2005

Objects are telling of identity and difference, through possession, exchange, and display, but this dynamic must be historicised and socially situated. In this article, I focus on the signification of ethnicity in Vietnamese museums, particularly on an apparent distinction between historically ‘hot’ and ‘cold’ matter. The earliest displays responded to the previous hegemony of French colonial significations. Subsequent national exhibits consistently enable Vietnam through assemblies of objects and images, but suggest—when examined over time—fundamentally different configurations of the nation, ethnicity, gender, and historicity. Object assemblies, where a centrepiece signifies the surrounding objects, indicate repeated prospecting for new social assemblages, most recently situating Vietnam in post‐Cold War networks through the Southeast Asian kinship implied in the nation’s ethnic diversity.     

Object motion: a world view

Moving objects are detected by virtue of their shifting image on the retina. But to know how objects are moving in the world, we must take into account the rotation of our eyes, as well as the rotation of our head. A recent paper describes neurons that carry out this computation.     

Introducing an inquiry-based experiment-integrated science game for elementary students: the shadow races game

Abstract

This article introduces a science game which can be used for innovative teaching and as an assessment tool. The Shadow Races Game is designed for first and second grade students to learn the phenomenon of shadow through inquiry-based activities and questions that require the children to apply inferences from those activities. In this amusing board game, students will discover the relationship between light, objects and shadows using familiar objects.     

Complex echo classification by echo-locating bats: a review

Echo-locating bats constantly emit ultrasonic pulses and analyze the returning echoes to detect, localize, and classify objects in their surroundings. Echo classification is essential for bats’ everyday life; for instance, it enables bats to use acoustical landmarks for navigation and to recognize food sources from other objects. Most of the research of echo based object classification in echo-locating bats was done in the context of simple artificial objects. These objects might represent prey, flower, or fruit and are characterized by simple echoes with a single up to several reflectors. Bats, however, must also be able to use echoes that return from complex structures such as plants or other types of background. Such echoes are characterized by superpositions of many reflections that can only be described using a stochastic statistical approach. Scientists have only lately started to address the issue of complex echo classification by echo-locating bats. Some behavioral evidence showing that bats can classify complex echoes has been accumulated and several hypotheses have been suggested as to how they do so. Here, we present a first review of this data. We raise some hypotheses regarding possible interpretations of the data and point out necessary future directions that should be pursued.     

Neural Androgen Receptor Deletion Impairs the Temporal Processing of Objects and Hippocampal CA1-Dependent Mechanisms

We studied the role of testosterone, mediated by the androgen receptor (AR), in modulating temporal order memory for visual objects. For this purpose, we used male mice lacking AR specifically in the nervous system. Control and mutant males were gonadectomized at adulthood and supplemented with equivalent amounts of testosterone in order to normalize their hormonal levels. We found that neural AR deletion selectively impaired the processing of temporal information for visual objects, without affecting classical object recognition or anxiety-like behavior and circulating corticosterone levels, which remained similar to those in control males. Thus, mutant males were unable to discriminate between the most recently seen object and previously seen objects, whereas their control littermates showed more interest in exploring previously seen objects. Because the hippocampal CA1 area has been associated with temporal memory for visual objects, we investigated whether neural AR deletion altered the functionality of this region. Electrophysiological analysis showed that neural AR deletion affected basal glutamate synaptic transmission and decreased the magnitude of N-methyl-D-aspartate receptor (NMDAR) activation and high-frequency stimulation-induced long-term potentiation. The impairment of NMDAR function was not due to changes in protein levels of receptor. These results provide the first evidence for the modulation of temporal processing of information for visual objects by androgens, via AR activation, possibly through regulation of NMDAR signaling in the CA1 area in male mice.     

The Establishment and Defeat of Hierarchy: Inalienable Possessions and the History of Collective Prestige Structures in the Pueblo Southwest

The role of social valuables in establishing and defeating hierarchies in prestate societies is explored through the use of Annette Weiner's concept of "inalienable possessions." Inalienable possessions are objects made to be kept (not exchanged), have symbolic and economic power that cannot be transferred, and are often used to authenticate the ritual authority of corporate groups. Ethnographic examples from Zuni are used to understand the range of individually and collectively owned inalienable objects in Pueblo societies. I then use three classes of these objects from archaeological contexts to gain insight into the history of collective prestige structures in the Southwest. I argue that inalienable goods are more useful than shape prestige goods for understanding the role of social valuables in many nonstate societies, especially those in which inequalities are based on ritual knowledge.     

Studies on the mechanism of natural killer cell-mediated cytotoxicity. V. Lack of NK specificity at the level of induction of natural killer cytotoxic factors in cultures of human, murine, or rat effector cells stimulated with mycoplasma-free cell lines

We have proposed that lysis of target cells by NK cells is mediated by NK cytotoxic factors (NKCF). According to our model, for a target cell to be NK-sensitive, it must be recognized by the NK cell, it must stimulate the release of NKCF, and it must be sensitive to lysis by these factors. This report examines whether the ability to stimulate release of NKCF is a characteristic restricted to NK-sensitive tumor cells or whether it is also a property of NK-resistant target cells. Many different types of cell lines were tested for their ability to stimulate release of NKCF in the human, rat, and murine systems. It was found that mycoplasma-free NK-sensitive cell lines, resistant cell lines, and Con A could stimulate the release of NKCF. Many different types of cell lines grown in suspension or in monolayers were found to be effective stimulators, including T or B lymphoid, myeloid, and those of histiocytic origin. Cells cultured in the absence of serum stimulated NKCF release, thus ruling out the possible involvement of serum components in stimulation. NKCF was also produced by xenogeneic combinations of effector and stimulator cells, demonstrating lack of species specificity in NKCF production. Factors stimulated by NK-resistant cell lines or by Con A exhibited the same NK target specificity as supernatants stimulated by NK-sensitive tumor cells. The finding that many different NK-resistant cell lines can stimulate the release of NKCF indicates that there is no apparent NK specificity at the level of induction of NKCF release from human, rat, or murine effector cells. Therefore, the NK specificity of a target cell is determined ultimately by its sensitivity to lysis by NKCF.     

The rejection of noncellular artifacts in Papanicolaou-stained slide specimens by an automated high-resolution system. Identification of important cytometric features

The important cytodiagnostic features that permit discrimination of typical cell types by high-resolution image analysis and pattern recognition techniques have been previously studied in detail. An automated system for the diagnosis of Papanicolaou-stained specimens must also deal, however, with the "real world" of extraneous noncellular artifacts and debris found on every slide. Features that are ideal for the separation of typical normal and abnormal cells may not be adequate by themselves to reject these objects. A new set of discriminatory features must be found. In order to identify those features, a large set of images acquired using the TICAS high-resolution television rapid-scanning system was analyzed and studied. These images, from a variety of slide types, included normal cells, abnormal cells and noncellular artifacts identified by low-resolution preprocessing logic as suspicious enough to warrant high-resolution study. The results indicate that the more important features for such discrimination are not those traditionally important in distinguishing abnormal from normal cells but include color relations, shape measures, boundary properties and texture features.