Distal Bias Research Articles

From expectation to action: an empirical study of the role of confidence

We explore formation of expectations and links between expectations and action among Croatian micro-producers of organic fruits and vegetables. Twenty-nine interviews with entrepreneurs from all Croatian counties and the City of Zagreb were conducted. Thematic analysis reveals four recurring themes linking participants’ expectations and action: positive feedback, coordination devices, proximal vs. distal bias and retrospecting prospects. We relate these themes to the valence of expectations (positive, negative or neutral) and situate our findings within broader theoretical frameworks of Barbalet’s theory of confidence and Emirbayer and Mische’s theory of agency. Enjoying acceptance and recognition as members of community-supported agriculture groups, and having access to specific resources as members of associations of organic producers are identified as key drivers of optimism and confidence among the participants.

Illusory deformation of the finger is more extensive in the distal than the lateral direction.

Previous studies have examined the rubber hand illusion with finger lengthening, but there is limited research on finger widening. This suggests a strong cognitive bias toward the illusory expansion of the finger in a distal direction rather than lateral. To test this, we compared the illusory deformability of the finger in the distal and lateral directions through the generation of illusory finger deformation using a double-touch operation, referred to as the numbness illusion. Our results showed that perceived distal distortion was wholly superior to perceived lateral distortion in terms of sense of ownership ratings. Moreover, the extent of the perceived deformation was greater in the distal than lateral direction, supporting our hypothesis that there is a distal bias. We suggest that this preference may be because the presence of multiple joints is required to create illusory deformation in the target direction.

Tactile localization on stretched skin.

The ability to localize touch on the skin is an important aspect of tactile perception. As our limbs move, the skin stretches flexibly, and research has found that signals specifying stretch affect perception of limb posture. Skin stretch also distorts the relative spatial position of different locations on the skin, posing potential problems for tactile localization. Here, we investigated the effects of skin stretch using an established test of tactile localization on the hand. Twenty participants completed a tactile localization task in no-stretch and stretched conditions, respectively, after giving informed consent. The current study found a clear distal and radial bias in both the no-stretch condition and the stretched condition. Indeed, the distal bias was even larger in the stretched condition than at baseline. Critically, however, this change in distal bias was entirely accounted for by changes in the actual location of stimulus as a result of skin stretch, with no corresponding change in the judged location. Thus, the somatosensory system appears to disregard stretch when calculating the location of tactile stimuli. These results mirror recent findings showing that tactile distance perception also fails to take skin stretch into account. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Conservation and trans-regulation of histone modification in the A and B subgenomes of polyploid wheat during domestication and ploidy transition

BackgroundPolyploidy has played a prominent role in the evolution of plants and many other eukaryotic lineages. However, how polyploid genomes adapt to the abrupt presence of two or more sets of chromosomes via genome regulation remains poorly understood. Here, we analyzed genome-wide histone modification and gene expression profiles in relation to domestication and ploidy transition in the A and B subgenomes of polyploid wheat.ResultsWe found that epigenetic modification patterns by two typical euchromatin histone markers, H3K4me3 and H3K27me3, for the great majority of homoeologous triad genes in A and B subgenomes were highly conserved between wild and domesticated tetraploid wheats and remained stable in the process of ploidy transitions from hexaploid to extracted tetraploid and then back to resynthesized hexaploid. However, a subset of genes was differentially modified during tetraploid and hexaploid wheat domestication and in response to ploidy transitions, and these genes were enriched for particular gene ontology (GO) terms. The extracted tetraploid wheat manifested higher overall histone modification levels than its hexaploid donor, and which were reversible and restored to normal levels in the resynthesized hexaploid. Further, while H3K4me3 marks were distally distributed along each chromosome and significantly correlated with subgenome expression as expected, H3K27me3 marks showed only a weak distal bias and did not show a significant correlation with gene expression.ConclusionsOur results reveal overall high stability of histone modification patterns in the A and B subgenomes of polyploid wheat during domestication and in the process of ploidy transitions. However, modification levels of a subset of functionally relevant genes in the A and B genomes were trans-regulated by the D genome in hexaploid wheat.

Whole-hand perceptual maps of joint location

Hands play a fundamental role in everyday behaviour. Nevertheless, healthy adults show striking misrepresentations of their hands which have been documented by a wide range of studies addressing various aspects of body representation. For example, when asked to indicate the location within the hand of the knuckles, people place them substantially farther forward than they actually are. Previous research, however, has focused exclusively on the knuckles at the base of each finger, not considering the other knuckles in the fingers. This study, therefore, aimed to investigate conceptual knowledge of the structure of the whole hand, by investigating judgements of the location of all 14 knuckle joints in the hand. Participants localised each of the 14 knuckles of their own hand (Experiment 1) or of the experimenter's hand (Experiment 2) on a hand silhouette. We measured whether there are systematic localisation biases. The results showed highly similar pattern of mislocalisation for the knuckles of one's own hand and those of another person's hand, suggesting that people share an abstract conceptual knowledge about the hand structure. In line with previous reports, we showed that the metacarpophalangeal joints at the base of the fingers are judged as substantially father forward in the hand than they actually are. Moreover, for the first time we showed a gradient of this bias, with progressive reduction of distal bias from more proximal to more distal joints. In sum, people think their finger segments are roughly the same, and that their fingers are shorter than they are.

Distal Bias of Meiotic Crossovers in Hexaploid Bread Wheat Reflects Spatio-Temporal Asymmetry of the Meiotic Program.

Meiotic recombination generates genetic variation and provides physical links between homologous chromosomes (crossovers) essential for accurate segregation. In cereals the distribution of crossovers, cytologically evident as chiasmata, is biased toward the distal regions of chromosomes. This creates a bottleneck for plant breeders in the development of varieties with improved agronomic traits, as genes situated in the interstitial and centromere proximal regions of chromosomes rarely recombine. Recent advances in wheat genomics and genome engineering combined with well-developed wheat cytogenetics offer new opportunities to manipulate recombination and unlock genetic variation. As a basis for these investigations we have carried out a detailed analysis of meiotic progression in hexaploid wheat (Triticum aestivum) using immunolocalization of chromosome axis, synaptonemal complex and recombination proteins. 5-Bromo-2′-deoxyuridine (BrdU) labeling was used to determine the chronology of key events in relation to DNA replication. Axis morphogenesis, synapsis and recombination initiation were found to be spatio-temporally coordinated, beginning in the gene-dense distal chromosomal regions and later occurring in the interstitial/proximal regions. Moreover, meiotic progression in the distal regions was coordinated with the conserved chromatin cycles that are a feature of meiosis. This mirroring of the chiasma bias was also evident in the distribution of the gene-associated histone marks, H3K4me3 and H3K27me3; the repeat-associated mark, H3K27me1; and H3K9me3. We believe that this study provides a cytogenetic framework for functional studies and ongoing initiatives to manipulate recombination in the wheat genome.

Degenerative dementia with proximal radial and lower vertical spatial neglect

ABSTRACT A 75 year-old man had a two-year history of progressive memory loss, trouble with finances and getting lost. On examination, he scored 16/30 in MoCA test, noticeably impaired on the attentional tasks. His screening bloodtests werenormal. Brain imaging revealed hippocampal atrophy and bilaterallarge areas of leukoaraiosis below posterior parietal lobes. On vertical line bisection he revealed a large upward bias and on radial bisection, a distal bias. Degeneration of his posterior parietal cortex may have caused both the leukoaraiosis and vertical-radial neglect. Unawareness of portions of space can be a source of disability and cause injury. Therefore, patients with degenerative dementia, especially those with similar patterns of leukoaraiosis or parietal degeneration should be tested for vertical and radial forms of spatial neglect.

Tactile localization biases are modulated by gaze direction.

Identifying the spatial location of touch on the skin surface is a fundamental function of our somatosensory system. Despite the fact that stimulation of even single mechanoreceptive afferent fibres is sufficient to produce clearly localised percepts, tactile localisation can be modulated also by higher level processes such as body posture. This suggests that tactile events are coded using multiple representations using different coordinate systems. Recent reports provide evidence for systematic biases on tactile localisation task, which are thought to result from a supramodal representation of the skin surface. While the influence of non-informative vision of the body and gaze direction on tactile discrimination tasks has been extensively studied, their effects on tactile localisation tasks remain largely unexplored. To address this question, participants performed a tactile localization task on their left hand under different visual conditions by means of a mirror box; in the mirror condition, a single stimulus was delivered on participants' hand, while the reflexion of the right hand was seen through the mirror; in the object condition, participants looked at a box through the mirror, and in the right hand condition, participants looked directly at their right hand. Participants reported the location of the tactile stimuli using a silhouette of a hand. Results showed a shift in the localization of the touches towards the tip of the fingers (distal bias) and the thumb (radial biases) across conditions. Critically, distal biases were reduced when participants looked towards the mirror compared to when they looked at their right hand suggesting that gaze direction reduces the typical proximo-distal biases in tactile localization. Moreover, vision of the hand modulates the internal configuration of points' locations, by elongating it, in the radio-ulnar axis.

Hemispheric asymmetries in perceived depth revealed through a radial line bisection task.

Research suggests that the left cerebral hemisphere is predisposed for processing stimuli in 'near' space, whereas the right hemisphere is specialised for processing stimuli in 'far' space. This hypothesis was tested directly by asking 25 undergraduates to carry out a landmark radial line bisection task. To test the effect of hemispheric differences in processing, the lines were placed to the left, right or centre within the transverse plane. Consistent with predictions, lines in all three conditions were bisected distal to the true centre. More importantly, there was an asymmetry whereby the distal bias was stronger for lines presented in the left hemispace compared to the right hemispace. The results demonstrate that the perception of depth is affected by left/right placement along the lateral axis and highlight the cognitive/neural interplay between the radial and lateral axes.

Visual detail about the body modulates tactile localisation biases.

The localisation of tactile stimuli requires the integration of visual and somatosensory inputs within an internal representation of the body surface and is prone to consistent bias. Joints may play a role in segmenting such internal body representations, and may therefore influence tactile localisation biases, although the nature of this influence remains unclear. Here, we investigate the relationship between conceptual knowledge of joint locations and tactile localisation biases on the hand. In one task, participants localised tactile stimuli applied to the dorsum of their hand. A distal localisation bias was observed in all participants, consistent with previous results. We also manipulated the availability of visual information during this task, to determine whether the absence of this information could account for the distal bias observed here and by Mancini et al. (Neuropsychologia 49:1194-1201, 2011). The observed distal bias increased in magnitude when visual information was restricted, without a corresponding decrease in precision. In a separate task, the same participants indicated, from memory, knuckle locations on a silhouette image of their hand. Analogous distal biases were also seen in the knuckle localisation task. The accuracy of conceptual joint knowledge was not correlated with tactile localisation bias magnitude, although a similarity in observed bias direction suggests that both tasks may rely on a common, higher-order body representation. These results also suggest that distortions of conceptual body representation may be more common in healthy individuals than previously thought.

Quantitative high resolution mapping of HvMLH3 foci in barley pachytene nuclei reveals a strong distal bias and weak interference.

In barley (Hordeum vulgare L.), chiasmata (the physical sites of genetic crossovers) are skewed towards the distal ends of chromosomes, effectively consigning a large proportion of genes to recombination coldspots. This has the effect of limiting potential genetic variability, and of reducing the efficiency of map-based cloning and breeding approaches for this crop. Shifting the sites of recombination to more proximal chromosome regions by forward and reverse genetic means may be profitable in terms of realizing the genetic potential of the species, but is predicated upon a better understanding of the mechanisms governing the sites of these events, and upon the ability to recognize real changes in recombination patterns. The barley MutL Homologue (HvMLH3), a marker for class I interfering crossovers, has been isolated and a specific antibody has been raised. Immunolocalization of HvMLH3 along with the synaptonemal complex transverse filament protein ZYP1, used in conjunction with fluorescence in situ hybridization (FISH) tagging of specific barley chromosomes, has enabled access to the physical recombination landscape of the barley cultivars Morex and Bowman. Consistent distal localization of HvMLH3 foci throughout the genome, and similar patterns of HvMLH3 foci within bivalents 2H and 3H have been observed. A difference in total numbers of HvMLH3 foci between these two cultivars has been quantified, which is interpreted as representing genotypic variation in class I crossover frequency. Discrepancies between the frequencies of HvMLH3 foci and crossover frequencies derived from linkage analysis point to the existence of at least two crossover pathways in barley. It is also shown that interference of HvMLH3 foci is relatively weak compared with other plant species.

Visual Neglect in Horizontal and Radial Space: When Left Goes Right, Proximal Goes Distal

Hemi-spatial neglect can manifest in both the horizontal and radial spatial plane. However, debate exists over how closely the two forms of neglect relate. Here we compared the ability of a neglect patient to bisect stimuli in horizontal versus radial orientation. When oriented horizontally, single lines were mis-bisected to the right, yet when surrounded by visual distracters, the lines were mis-bisected to the left. A leftward bias also emerged when horizontally aligned strings of symbols were bisected. Unexpectedly, an analogous pattern of bias appeared when the stimuli were bisected in radial orientation; stimuli that induced a leftward bias now induced a proximal bias, while stimuli that induced a rightward bias induced a distal bias. Spontaneous reversals in radial bias have not been previously reported, and given that they were coupled with the horizontal reversals, suggest that the spatial boundaries of horizontal and radial neglect are strongly constrained by common stimulus configurations.

Feeling Down: Idiom or Nature?

Different emotions activate different parts of the brain, and different parts of the brain direct actions-intentions as well as attention (AIA) to different portions of space. This pilot study attempted to learn how different emotions elicited by emotional memories altered the voluntary spatial allocation of AIA. Twenty normal participants were asked to mark a large sheet of paper in any place of their choosing following recollection of seven types of emotional memories. The results suggest that different emotional memories-experiences can influence the spatial allocation of AIA with positive emotional memories inducing a distal or superior bias and sad memories inducing a proximal or inferior bias. Although these results support the hypotheses that emotions can influence the spatial direction of AIA, these preliminary results need replication and further exploration.

Effects of spatiotopic factors on bisection of radial lines

Under visual guidance normal subjects usually misbisect radial lines farther than the true midpoint (distal bias). We investigated whether this distal bias is constant across the peripersonal space or it varies by varying the distance of the stimulus from the subject. Subjects were asked to bisect radial lines presented below eye level either in the near or far peripersonal space. The results showed an increase of distal bias in the far-space. This finding suggests that the influence of spatial factors on bisection of radial lines is not constant across the peripersonal space. Distal bias increases as a function of the distance of the stimulus from the subject, according to a spatiotopic processing scheme.

Spatial attentional bias in normal people: Object or viewer-centered

When bisecting radial lines, normal subjects often have a distal bias. To help in explaining this systematic bias, it has been proposed that normal people have an attentional bias to the top of the lines (object centered hypothesis) or toward stimuli falling in the lower portion of the retina (retinotopic hypotheses) or to distal peripersonal space (body centered hypotheses). The primary aim of this study is to test these hypotheses by having normal subjects bisect radial lines, placed in a clockwise distribution in the transverse plane, below eye level. Our results demonstrate that the perception of the midpoint progressively changes as a function of the body centered orientation of the lines, with subjects demonstrating a progressively greater distal bias as they approached the midsagittal plane or radial condition. These findings provide support for the postulate that distal bias on radial lines bisections is body centered.

LATERAL AND VERTICAL ATTENTIONAL BIASES IN NORMAL INDIVIDUALS

Background: When normal people attempt to bisect lines they often make their mark to the left of midline (pseudoneglect) and when attempting to bisect radial lines normal people tend to bisect distal to the actual midline. These biases might be related to asymmetrical activation induced by making spatial computations or attention-intentional preferences. The purpose of this study was to learn if in the absence of spatial computations normal subjects would demonstrate a left and upward bias. Methods: Normal subjects (139) were given 8 pegs and asked to place these pegs anywhere on a 2-foot-square board. Results: Overall, the subjects displaced the pegs to the left and upward. Conclusions: The overall left-distal bias observed in this experiment was not induced by spatial computation or misperceptions, but is consistent with the postulate that the right hemisphere is dominant for attention-intention and has a relatively distal bias.

Radial Character-line Bisection

With conventional solid radially oriented-line bisections (SLB), normal subjects tend to bisect distal to the true midpoint (distal bias). This bias is thought to reflect a distal attentional bias in the radial plane. Whereas the right hemisphere, which mediates distributed-global attention, has a distal bias, the left hemisphere, which mediates focal attention, has a proximal bias. When performing conventional radial-line bisections, participants might primarily use right hemisphere-mediated global-distributed attention and thus develop a distal bias. The character-line bisection (CLB) task consists of strings of target and nontarget characters (letters or symbols) that are linearly aligned, and subjects are required to bisect a character that is closest to the midline. Thus, when performing the CLB subjects must use focal attention and detect symbols and both these activities are mediated by their left hemisphere. This left hemisphere activation might either reduce or reverse the distal bias observed on the SLB. The purpose of this study is to test this hypothesis. Fifteen normal subjects performed CLB (letter-line and symbol-line) and SLB tasks. Overall, the subjects revealed a distal bias in both tasks, but the attempted bisections in the CLB tasks were more proximal than those in the SLB tasks. These result are consistent with the hypothesis that the CLB task, which requires both focal attention and the detection of symbols, activates the left hemisphere that has a greater proximal bias than the right hemisphere, thus reducing the distal bias observed with the SLB task.

Activity of primate magnocellular red nucleus related to hand and finger movements

Single cells were recorded in the magnocellular red nucleus (RNm) of two cynomolgus monkeys using tungsten microelectrodes. The first monkey was trained to press finger switches and to operate a push-pull device. Comparison of responses while operating the two devices demonstrated a strong distal bias. The finger device elicited large modulations in discharge (≥50 impulses/s) in 75% of the sampled neurons. Most cells fired optimally during thumb switch operation, but also fired vigorously in association with other switch operations. The left motor cortex was removed from the second monkey 18 months prior to microelectrode recording. Cells in the cortically denervated RNm discharged vigorously in association with grouped finger movements that opened and closed the affected right hand. These results coupled with our previous findings suggest that the RNm is preferentially linked to distal limb muscles, and the primary role of the forelimb zone may be to control coordinated hand function including grouped movements of the fingers.

Effect of distal endotracheal bias flow on PaCO2 during high frequency oscillatory ventilation.

In order to evaluate the effect of distal endotracheal bias flow during HFOV on PaCO2 we studied adult rabbits with normal lungs and those who had meconium-induced lung dysfunction. Animals were studied while 1.0, 1.4 and 1.8 ml/kg tidal volumes (VT) were delivered by a high frequency oscillator. In animals with normal lungs and a 1.0 liter/min distal bias flow, the PaCO2 decreased significantly (p less than 0.01) with all VT used. In animals with meconium instillation the decrease in PaCO2 was also significant (p less than 0.05) at all combinations of VT and distal bias flow. The higher the distal bias flow the more pronounced was the lowering effect on PaCO2. We conclude that during HFOV it is possible to improve CO2 elimination using small additional bias flow delivered near the tip of the endotracheal tube in animals with normal abnormal lung function. This may allow adequate alveolar ventilation with even smaller VT, thus reducing the risk of barotrauma.

Nematocyte migration in hydra: evidence for contact guidance in vivo.

Nematocytes rapidly emigrate from normal tissue implanted into an epithelial hydra, which lacks its own nematocytes. We observed emigrating nematocytes, both in time-lapse movies and in fixed whole mounts, to learn what controls directionality. The cells migrate at speeds of 10--30 microns/min with a pseudopod forward and the capsule trailing. Migration is aligned parallel to the polyp axis, but cells move both proximally and distally and often shuttle back and forth. Thus, migration is strongly bidirectional, with a slight distal bias since at any time more cells are moving towards the tentacles. Nematocytes freely migrate through tissue of reversed polarity. No evidence was found for a chemotactic stimulus emitted from the tentacles. The bidirectional movement pattern appeared to be imposed by epithelial muscle processes, which form an axial, fibrous mat on which nematocytes migrate. Experimental deformation of the muscle alignment results in a corresponding deformation of nematocyte migration. Thus, nematocyte migration appears to be bidirectionally oriented through contact guidance by epithelial muscle processes.