Recalibration Processes Research Articles

Prism adaptation in patients with unilateral lesion of the parietal or cerebellar cortex: A pilot study on two single cases using a concurrent exposure procedure

Neuroimaging studies showed that prism adaptation (PA), a widely used tool for the rehabilitation of neglect, involves a wide network of brain regions including the parietal cortex and the cerebellum. In particular, the parietal cortex has been suggested to mediate the initial stage of PA through conscious compensatory mechanisms as a reaction to the deviation induced by PA. The cerebellum, on the other side, intervenes in sensory errors prediction to update internal models in later stages. It has been suggested that two mechanisms may underlie PA effects: recalibration, a strategic cognitive process occurring in the initial stages of PA, and realignment, a fully automatic reorganization of spatial maps emerging later and more slowly in time. The parietal lobe has been proposed to be involved mainly in the recalibration whereas the realignment would be carried over by the cerebellum. Previous studies have investigated the effects of a lesion involving either the cerebellum or the parietal lobe in PA taking into account both realignment and recalibration processes. Conversely, no studies have compared the performance of a patient with a cerebellar lesion to that of a patient with a parietal lesion. In the present study, we used a recently developed technique for digital PA to test for differences in visuomotor learning after a single session of PA in a patient with parietal and a patient with cerebellar lesions, respectively. The PA procedure, in this case, includes a digital pointing task based on a concurrent exposure technique, which allows patients to fully see their arm during the pointing task. This procedure has been shown to be as effective as the terminal exposure condition in neglect rehabilitation albeit different processes take place during concurrent exposure condition compared to the most used terminal exposure (allowing to see only the final part of the movement). Patients’ performances were compared to that of a control group. A single session of PA was administered to 1) a patient (BC) with left parieto-occipital lesion involving superior parietal lobe (SPL) and inferior parietal lobe (IPL), 2) a patient (TGM) with a stroke in the territory sub-served by the superior cerebellar artery (SCA) , and 3) 14 healthy controls (HC).The task included three conditions: before wearing prismatic goggles (pre-exposure), while wearing prisms (exposure) and after removing the goggles (post-exposure). Mean deviations were calculated for the following phases: pre-exposure, early-exposure, late-exposure, post-exposure. The presence of after-effect was calculated as the difference between pre-exposure and post-exposure conditions. For each of these conditions, patients’ performance was compared to that of the control group by using a modified Crawford t-test. We found that the patient with the parietal lesion had a significantly different performance in the late-exposure and in the post-exposure compared to both HC and the patient with the cerebellar lesion. Conversely, no differences were observed between TGM and HC across all the conditions.Our results show an increase in the magnitude of the adaptation during the late stage of PA in the patient with the parietal lesion whereas no differences in the performance between the cerebellar patient and the controls were found. These results confirm previous studies suggesting that the parietal cortex is an important node of a wider network involved in PA effect. Furthermore, results concerning the cerebellar patient suggest that visuomotor learning is not affected by lesions of the SCA territory when a concurrent exposure is used as, in such case, it less relies on sensory errors prediction to update internal models. Results are discussed considering the novelty of the applied PA technique.

Real-Time Battery Temperature Monitoring Using FBG Sensors: A Data-Driven Calibration Method

Battery storage has an important role to play in integrating large-scale renewable power generations and in transport decarbonization. Real-time monitoring of battery temperature profiles is indispensable for battery safety management. Due to the advantages of small size, resistance to corrosion, immunity to electromagnetic interference, and multiplexing, fiber Bragg-grating (FBG) sensing has received substantial interest in recent years for battery temperature measurement. However, traditional temperature calibration for FBG sensors often requires a high-standard reference and causes the sensors to fail to be consistent during the calibration or recalibration processes. To tackle the challenges, an ensemble data-driven calibration method is developed in this article for FBG sensors. The calibration model consists of a linear part and a nonlinear part. First, the fuzzy <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}$ </tex-math></inline-formula> -means (FCM) algorithm is used to extract the linear relationship between the measured FBG wavelength shift and temperature variation. Then, the empirical mode decomposition (EMD) technique is used to classify the intrinsic mode functions (IMFs) and the remainder of the unmodeled nonlinear information. The unmodeled nonlinear information is further compensated using battery state of charge (SOC) and cycle number information. The experimental results confirm that the proposed temperature calibration method achieves desirable accuracy and reliability, with both the mean absolute error (MAE) and root mean square error (RMSE) being around 0.2 °C, respectively. Compared with the traditional temperature calibration method, the proposed approach can be used online in real-life applications.

"Run to the hills": Specific contributions of anticipated energy expenditure during active spatial learning.

Grounded views of cognition consider that space perception is shaped by the body and its potential for action. These views are substantiated by observations such as the distance-on-hill effect, described as the overestimation of visually perceived uphill distances. An interpretation of this phenomenon is that slanted distances are overestimated because of the integration of energy expenditure cues. The visual perceptual processes involved are, however, usually tackled through explicit estimation tasks in passive situations. The goal of this study was to consider instead more ecological active spatial processing. Using immersive virtual reality and an omnidirectional treadmill, we investigated the effect of anticipated implicit physical locomotion cost by comparing spatial learning for uphill and downhill routes, while maintaining actual physical cost and walking speed constant. In the first experiment, participants learnt city layouts by exploring uphill or downhill routes. They were then tested using a landmark positioning task on a map. In the second experiment, the same protocol was used with participants who wore loaded ankle weights. The results from the first experiment showed that walking uphill routes led to a global underestimation of distances compared with downhill routes. This inverted distance-of-hill effect was not observed in the second experiment, where an additional effort was applied. These results suggest that the underestimation of distances observed in Experiment 1 emerged from recalibration processes whose function was to solve the transgression of proprioceptive predictions linked with uphill energy expenditure. The results are discussed in relation to constructivist approaches on spatial representations and predictive coding theories.

Pathomorphological manifestations of vascular remodeling in the perifocal areas of ischemic cerebral infarction

Abstract. Acute disorders of cerebral circulation remain one of the leading causes of death of patients throughout the world. Tissue recovery after a stroke is directly related to active revascularization, which is intensified in the peri-infarction area. Newly formed vessels contribute to the restoration of cellular metabolism in surviving neurons. The processes of vascular remodeling after stroke have been at the center of many clinical and morphological studies in recent years. The aim of the study. To study the processes of vascular remodeling and neoplasm of vessels in the perifocal areas of ischemic cerebral infarctions. Material and methods. The study researched the brain of 29 deceased patients with hemispheric infarctions with different periods of the disease: up to 3 days (n = 5), 6 days (n = 5), 9-12 (n = 10), 30 (n = 5), 45 days (n = 4). The object of the study was perifocal areas of cerebral infarction, as well as areas outside ischemic lesions. The studies were carried out using histological, morphometric and statistical techniques. Results. Studies have shown that in the perifocal areas of cerebral infarction within 3 days from the onset of the disease, the morpho-functional state of the microvasculature was characterized by circulatory and hemocoagulation disorders. Along with destructive changes in blood vessels, processes are directed to improve blood circulation in ischemic areas of the brain. Collateral blood flow increases, dilation of pial vessels is noted with a decrease in the Kernogan index. On the 6th day, the processes of angiogenesis and vasculogenesis are activated, which intensify in the subsequent stages of the disease. In the long term, the efficiency of collateral blood flow in the pial vessels decreases, reduction in the capillary network, and the lumen of large arteries is recalibrated. Conclusions. In the early stages of cerebral stroke (up to 3 days), increased blood circulation in the ischemic areas of the brain occurs due to increased collateral blood flow. From the 6th day, the processes of angiogenesis in the form of capillary budding and the processes of vasculogenesis intensify. In large arterioles, recalibration processes take place. After 30-45 days in the perifocal areas of cerebral infarction, a significant reduction of the capillary network is recorded, which is regarded as a reaction to a decrease in blood supply to the areas of organized infarction.

The Elucidation of the Molecular Mechanism of the Extrusion Process.

Extrusion is a popular method for producing homogenous population of unilamellar liposomes. The technique relies on forcing a lipid suspension through cylindrical pores in a polycarbonate membrane. The quantification of the extrusion and/or recalibration processes make possible the acquisition of experimental data, which can be correlated with the mechanical properties of the lipid bilayer. In this work, the force needed for the extrusion process was correlated with the mechanical properties of a lipid bilayer derived from other experiments. Measurements were performed using a home-made dedicated device capable of maintaining a stable volumetric flux of a liposome suspension through well-defined pores and to continuously measure the extrusion force. Based on the obtained results, the correlation between the lipid bilayer bending rigidity and extrusion force was derived. Specifically, it was found that the bending rigidity of liposomes formed from well-defined lipid mixtures agrees with data obtained by others using flicker-noise spectroscopy or micromanipulation. The other issue addressed in the presented studies was the identification of molecular mechanisms leading to the formation of unilamellar vesicles in the extrusion process. Finally, it was demonstrated that during the extrusion, lipids are not exchanged between vesicles, i.e., vesicles can divide but no membrane fusion or lipid exchange between bilayers was detected.

The Ventriloquist Illusion as a Tool to Study Multisensory Processing: An Update.

Ventriloquism, the illusion that a voice appears to come from the moving mouth of a puppet rather than from the actual speaker, is one of the classic examples of multisensory processing. In the laboratory, this illusion can be reliably induced by presenting simple meaningless audiovisual stimuli with a spatial discrepancy between the auditory and visual components. Typically, the perceived location of the sound source is biased toward the location of the visual stimulus (the ventriloquism effect). The strength of the visual bias reflects the relative reliability of the visual and auditory inputs as well as prior expectations that the two stimuli originated from the same source. In addition to the ventriloquist illusion, exposure to spatially discrepant audiovisual stimuli results in a subsequent recalibration of unisensory auditory localization (the ventriloquism aftereffect). In the past years, the ventriloquism effect and aftereffect have seen a resurgence as an experimental tool to elucidate basic mechanisms of multisensory integration and learning. For example, recent studies have: (a) revealed top-down influences from the reward and motor systems on cross-modal binding; (b) dissociated recalibration processes operating at different time scales; and (c) identified brain networks involved in the neuronal computations underlying multisensory integration and learning. This mini review article provides a brief overview of established experimental paradigms to measure the ventriloquism effect and aftereffect before summarizing these pathbreaking new advancements. Finally, it is pointed out how the ventriloquism effect and aftereffect could be utilized to address some of the current open questions in the field of multisensory research.

Development of a Methodology for Determining Statewide Recurring and Nonrecurring Freeway Congestion: Virginia Case Study

State transportation agencies working to alleviate congestion need to design appropriate and effective congestion mitigation strategies for each sub-region and corridor, but solutions to solve recurring and nonrecurring congestions problems differ. Past research shows large variations in the proportion of delay attributable to recurring and nonrecurring sources and cannot be readily used by other states to develop practical solutions. An affordable, automated, and sound delay estimation methodology that breaks down congestion cause components could bring some insights to this problem. This paper seeks to use traffic and event data elements that are commonly available to Departments of Transportation to develop a methodology that can be broadly adopted by states to estimate the magnitude of recurring and nonrecurring congestion. The methodology uses data commonly available to public agencies, and does not require additional data-collection efforts or periodic re-calibration processes. A case study with the Virginia Interstate network, covering over 2,200 directional miles, is summarized in this paper. The results show that nonrecurring congestion contributed to around 24% of total delays. The result also clearly shows that recurring congestion contributed to most of the delays in urban districts, whereas nonrecurring congestion contributed to most of the delays in more rural districts. It can, therefore, be concluded that the use of a static statewide congestion profile is not suitable for individual district needs.

Making Sense of Cerebellar Contributions to Perceptual and Motor Adaptation.

The cerebellum is thought to adapt movements to changes in the environment in order to update an implicit understanding of the association between our motor commands and their sensory consequences. This trial-by-trial motor recalibration in response to external perturbations is frequently impaired in people with cerebellar damage. In healthy people, adaptation to motor perturbations is also known to induce a form of sensory perceptual recalibration. For instance, hand-reaching adaptation tasks produce transient changes in the sense of hand position, and walking adaptation tasks can lead to changes in perceived leg speed. Though such motor adaptation tasks are heavily dependent on the cerebellum, it is not yet understood how the cerebellum is associated with these accompanying sensory recalibration processes. Here we asked if the cerebellum is required for the recalibration of leg-speed perception that normally occurs alongside locomotor adaptation, as well as how ataxia severity is related to sensorimotor recalibration deficits in patients with cerebellar damage. Cerebellar patients performed a speed-matching task to assess perception of leg speed before and after walking on a split-belt treadmill, which has two belts driving each leg at a different speed. Healthy participants update their perception of leg speed following split-belt walking such that the "fast" leg during adaptation feels slower afterwards, whereas cerebellar patients have significant deficits in this sensory perceptual recalibration. Furthermore, our analysis demonstrates that ataxia severity is a crucial factor for both the sensory and motor adaptation impairments that affect patients with cerebellar damage.

Reorienting and Recalibrating Inter-organizational Relationships: Strategies for Achieving Optimal Trust

Drawing upon longitudinal, dyadic, comparative case-based research, we analyze the pursuit of optimal trust, i.e. trust that is neither excessive nor insufficient, by introducing the concepts of reorientation and recalibration. First, we show that large deviations from optimal trust are best addressed by reorientation which deals with both too much as well as too little trust. Reorientation processes include substantial efforts to change parties’ attributions of the intentions underlying past behavior, to reestablish social equilibrium among the parties, and to make structural changes via adjustments to goals and incentives. Reorientation is necessary when imbalance occurs in the powerful and opposed forces associated with excessive trust (faith, favoritism, contentment, loyalty) vs insufficient trust (skepticism, impartiality, exigency, opportunism). Second, we demonstrate that there is an effective path to maintaining optimal trust via practices we call recalibration, wherein small deviations are addressed before damage to trust occurs. Recalibration maintains inter-organizational trust near its optimum through processes that proactively balance the opposed forces. Large deviations from optimal trust in either direction can unleash destabilizing dynamics, requiring significant reorientation efforts to offset. Recalibration processes are then essential for preserving the effects of successful reorientation.

An integrated procedure to estimate demand flows of maritime container transport at international scale

The paper proposes an integrated procedure for the estimation of containerised OD flows at international scale. The procedure combines two different systems of models: (1) a meso-aggregated system of models for estimation of OD flows by means of a specification-calibration-validation process and (2) a macro-aggregated system of models for estimation of OD flows by means of a re-calibration process. The procedure has been tested in order to estimate the values of containerised OD flows of a geographical area composed of countries facing the Mediterranean basin at year 2006. The integrated procedure could represent a valid support for market operators and analysts, who need estimates of demand variables in order to mitigate risks of over- or under-investment, and for researchers developing freight models, because it offers the possibility to combine the potentialities of specification-calibration-validation and re-calibration processes in freight demand modelling.

Converging toward a common speech code: imitative and perceptuo-motor recalibration processes in speech production.

Auditory and somatosensory systems play a key role in speech motor control. In the act of speaking, segmental speech movements are programmed to reach phonemic sensory goals, which in turn are used to estimate actual sensory feedback in order to further control production. The adult's tendency to automatically imitate a number of acoustic-phonetic characteristics in another speaker's speech however suggests that speech production not only relies on the intended phonemic sensory goals and actual sensory feedback but also on the processing of external speech inputs. These online adaptive changes in speech production, or phonetic convergence effects, are thought to facilitate conversational exchange by contributing to setting a common perceptuo-motor ground between the speaker and the listener. In line with previous studies on phonetic convergence, we here demonstrate, in a non-interactive situation of communication, online unintentional and voluntary imitative changes in relevant acoustic features of acoustic vowel targets (fundamental and first formant frequencies) during speech production and imitation. In addition, perceptuo-motor recalibration processes, or after-effects, occurred not only after vowel production and imitation but also after auditory categorization of the acoustic vowel targets. Altogether, these findings demonstrate adaptive plasticity of phonemic sensory-motor goals and suggest that, apart from sensory-motor knowledge, speech production continuously draws on perceptual learning from the external speech environment.

Institutional Recalibration and Judicial Delimitation

Throughout American history, a peculiar and recurrent disjunction has often arisen between the substance of transformative reforms and the decidedly less-radical governing arrangements that arise in the aftermath of reform. To account for this disjunction, this article puts forth a theory of postreform “recalibration.” Political processes of recalibration are the means by which vague, indeterminate principles of reform are given operational meaning and translated into new governing arrangements. This article illuminates recalibration processes by examining two case-studies: African American rights in the post-Reconstruction era of the 1870s and 1880s, and labor rights in the post–New Deal era of the late 1930s. Finally, the article also highlights the crucial role of the Supreme Court in recalibration processes and sets forth a theory of judicial behavior as driven by an institutional interest in stability.

Institutional Recalibration and Judicial Delimitation

Throughout American history, a peculiar and recurrent disjunction often arises between the substance of transformative reforms, and the decidedly less-radical governing arrangements that arise in the aftermath of reform. In seeking to account for this disjunction, this article puts forth a theory of post-reform “recalibration.” Political processes of recalibration are the means by which vague, indeterminate principles of reform are given operational meaning, and translated into new governing arrangements. This article illuminates recalibration processes with an examination of two case-studies: African-American rights in the post-Reconstruction era of the 1870s and 1880s, and labor rights in the post-New Deal era of the late 1930s. Finally, the article also highlights the crucial role of the Supreme Court in recalibration processes, and sets forth a theory of judicial behavior as driven by an institutional-interest in stability.

Audiotactile interactions in temporal perception

In the present review, we focus on how commonalities in the ontogenetic development of the auditory and tactile sensory systems may inform the interplay between these signals in the temporal domain. In particular, we describe the results of behavioral studies that have investigated temporal resolution (in temporal order, synchrony/asynchrony, and simultaneity judgment tasks), as well as temporal numerosity perception, and similarities in the perception of frequency across touch and hearing. The evidence reviewed here highlights features of audiotactile temporal perception that are distinctive from those seen for other pairings of sensory modalities. For instance, audiotactile interactions are characterized in certain tasks (e.g., temporal numerosity judgments) by a more balanced reciprocal influence than are other modality pairings. Moreover, relative spatial position plays a different role in the temporal order and temporal recalibration processes for audiotactile stimulus pairings than for other modality pairings. The effect exerted by both the spatial arrangement of stimuli and attention on temporal order judgments is described. Moreover, a number of audiotactile interactions occurring during sensory-motor synchronization are highlighted. We also look at the audiotactile perception of rhythm and how it may be affected by musical training. The differences emerging from this body of research highlight the need for more extensive investigation into audiotactile temporal interactions. We conclude with a brief overview of some of the key issues deserving of further research in this area.

Visual recalibration and selective adaptation in auditory–visual speech perception: Contrasting build-up courses

Exposure to incongruent auditory and visual speech produces both visual recalibration and selective adaptation of auditory speech identification. In an earlier study, exposure to an ambiguous auditory utterance (intermediate between /aba/ and /ada/) dubbed onto the video of a face articulating either /aba/ or /ada/, recalibrated the perceived identity of auditory targets in the direction of the visual component, while exposure to congruent non-ambiguous /aba/ or /ada/ pairs created selective adaptation, i.e. a shift of perceived identity in the opposite direction [Bertelson, P., Vroomen, J., & de Gelder, B. (2003). Visual recalibration of auditory speech identification: a McGurk aftereffect. Psychological Science, 14, 592–597]. Here, we examined the build-up course of the after-effects produced by the same two types of bimodal adapters, over a 1–256 range of presentations. The (negative) after-effects of non-ambiguous congruent adapters increased monotonically across that range, while those of ambiguous incongruent adapters followed a curvilinear course, going up and then down with increasing exposure. This pattern is discussed in terms of an asynchronous interaction between recalibration and selective adaptation processes.

Age and the Elderly Internal Clock: Further Evidence for a Fundamentally Slowed CNS

Earlier studies have found little or no effect for age on the estimation of time. These results may reflect a true independence, or they may be an artifact of a subvocal counting strategy or an automatic and unconscious recalibration process by the elderly that adjusts for a slowed internal clock. These alternatives were examined by requiring subjects to estimate a prescribed time interval either alone or while also engaged in a resource demanding secondary task. The secondary task was assumed to prevent or inhibit the use of a counting strategy and any such recalibration processes from occurring. Thirty-two subjects, consisting of 16 young (mean age = 25 yrs) and 16 old (mean age = 71 yrs) individuals, performed a time estimation task both alone (unfilled interval production, the single-task condition) and while simultaneously counting backwards by threes from a number between 50 and 100 (filled interval production, the dual-task condition). Results indicated that while no age differences existed in interval production during the single-task condition, the older adults significantly overestimated the 10–sec interval during the dual-task condition, compared to the younger subjects. These findings are interpreted in terms of a slowed internal clock in the elderly. Such a slowing of the internal clock may explain a significant portion of the age-related variance in speed of behavior.

Head posture effects in prism adaptation during hallway exposure.

Different groups of subjects walked nearer the left or right side of a hallway while looking through prisms that displaced the visual field in either the left or right direction. As predicted from the head posture required to view the apparently displaced hallway, adaptive pre-post change in felt head position was greater when head turning during exposure was expected to be greater (i.e., when the subject was walking on the prism base side of the hall). This finding supports a postural basis, but not a discordance basis, for change in felt head position. Visual adaptation was not explained either by the head position results or by the eye-in-head posture required to view the apparently displaced hallway, and was attributed to recalibration processes based on discordant input from other sensorimotor systems. Proprioceptive adaptation in the right hand was small and similar to the head position results, except for the group that experienced right-ward displacement and walked near the right wall. The substantial right-hand proprioceptive adaptation in this group was attributed to discordance between visual and proprioceptive systems when subjects visually anticipated an encounter between their arm or shoulder and the wall.