Top-down Processes Research Articles

Bottom-Up Synthesized Glucan Materials: Opportunities from Applied Biocatalysis.

Linear d-glucans are natural polysaccharides of simple chemical structure. They are comprised of d-glucosyl units linked by a single type of glycosidic bond. Noncovalent interactions within, and between, the d-glucan chains give rise to a broad variety of macromolecular nanostructures that can assemble into crystalline-organized materials of tunable morphology. Structure design and functionalization of d-glucans for diverse material applications largely relies on top-down processing and chemical derivatization of naturally derived starting materials. The top-down approach encounters critical limitations in efficiency, selectivity, and flexibility. Bottom-up approaches of d-glucan synthesis offer different, and often more precise, ways of polymer structure control and provide means of functional diversification widely inaccessible to top-down routes of polysaccharide material processing. Here the natural and engineered enzymes (glycosyltransferases, glycoside hydrolases and phosphorylases, glycosynthases) for d-glucan polymerization are described and the use of applied biocatalysis for the bottom-up assembly of specific d-glucan structures is shown. Advanced material applications of the resulting polymeric products are further shown and their important role in the development of sustainable macromolecular materials in a bio-based circular economy is discussed.

Making meaning of one's own life story in words and images: A narrative case report of personal recovery from personality disorder through the interventions "An Empowering Story" and art therapy.

Understanding and processing life experiences are essential in the treatment of personality disorders to promote personal recovery and psychological wellbeing. In this qualitative case report, drafted in co-creation between the client, clinical psychologist, and art therapist, individual treatment consisted of two psychotherapeutic interventions, "An Empowering Story" and life-story-focused art therapy, in 12 parallel sessions for 24 weeks. Hilda, 68 years of age, had been diagnosed with an unspecified personality disorder and various traits of borderline personality disorder. She experienced emotional exhaustion following long-term mental health problems rooted in a traumatic early childhood. This affected her ability to manage her emotions and social relations, resulting in the sense that her life had no meaning. Hilda was invited to reconstruct her life experiences, divided into the past, turning point, and present/future, in a written and a painted life story. This allowed for the integration of traumatic as well as positive memories, enhanced self-compassion, and meaning making. She developed self-reflection and integration of internal conflicts leading to a better emotional balance and self-understanding. Art therapy emphasizes bottom-up regulatory processes, while narrative psychology supports top-down regulatory processes. The combined approach effectively integrated bottom-up, experiential, sensory experiences with top-down, cognitive emotion-regulation processes. The results suggest that psychotherapeutic interventions involving a multi-pronged, complementary, and thus more holistic approach can support personal recovery in personality disorders.

How to See It Both Ways

When you see something, how do you figure out what it is? It might seem like you “just know”, but your brain uses two methods to help you know what you are seeing. One method is called bottom-up processing. In this method, the brain uses the shapes and colors seen by your eyes to figure out what something is. The other method is called top-down processing, which uses experiences, memories, or expectations to figure out what you are seeing. These processes happen at the same time in different parts of the brain. This article will explain how the brain’s top-down and bottom-up expectations can change what you see, and we include special pictures so you can experience it yourself.

Visual perception of facial expressions of emotions and alexithymia among people suffering from schizophrenia

Aim of the studyThe aim of the study is to find out whether there is a relationship between the severity of alexithymia and the visual perception of facial expressions of emotions among people suffering from schizophrenia.Subject or material and methods41 people suffering from schizophrenia and 41 healthy people participated in the study. In the first stage, the subjects completed the Toronto Alexithymia Scale (TAS-20) questionnaire. The second stage was based on eye-tracking measurements made during a computer experiment of recognising facial expressions.ResultsPeople with schizophrenia showed significantly higher intensity of alexithymia than healthy people. In the group of patients with schizophrenia, a negative correlation between alexithymia and the length of saccades on the nose was found.DiscussionIn the group of people with schizophrenia, alexithymia is associated with less intensive exploration of the nasal area. A wrinkled nose is an important area, first of all, in the manifestation of negative emotions, in recognition of which the sick people make the most mistakes.ConclusionsProblems with recognising emotions in people suffering from schizophrenia are associated with neuronal dysfunction and abnormalities in the eye movement. These factors disrupt the early stages of sensory processing. The relationship of alexithymia with the visual perception of patients with schizophrenia suggests that top-down processes may also contribute to the development of these deficits.

Visuospatial cueing differences as a function of autistic traits.

Atypical orienting of visuospatial attention in autistic individuals or individuals with a high level of autistic-like traits (ALTs) has been well documented and viewed as a core feature underlying the development of autism. However, there has been limited testing of three alternative theoretical positions advanced to explain atypical orienting - difficulty in disengagement, cue indifference, and delay in orienting. Moreover, research commonly has not separated facilitation (reaction time difference between neutral and valid cues) and cost effects (reaction time difference between invalid and neutral cues) in orienting tasks. We addressed these limitations in two experiments that compared groups selected for Low- and High-ALT levels on exogenous and endogenous versions of the Posner cueing paradigm. Experiment 1 showed that High-ALT participants exhibited a significantly reduced cost effect compared to Low-ALT participants in the endogenous cueing task, although the overall orienting effect remained small. In Experiment 2, we increased task difficulty of the endogenous task to augment cueing effects. Results were comparable to Experiment 1 regarding the finding of a reduced cost effect for High-ALT participants on the endogenous cueing task and additionally demonstrated a reduced facilitation effect in High-ALT participants on the same task. No ALT group differences were observed on an exogenous cueing task included in Experiment 2. These findings suggest atypical orienting in High-ALT individuals may be attributable to general cue indifference, which implicates differences in top-down attentional processes between Low- and High-ALT individuals. We discuss how indifference to endogenous cues may contribute to social cognitive differences in autism.

Effect of Cognitive Processing Style on Attentional Blink during Analogue Trauma

Background: This study attempted to examine the impact of each cognitive processing style (bottom-up, top-down) on attention patterns following a traumatic experience by measuring attentional blink (AB).Methods: Participants were 37 university students with no direct experience of traffic accidents. They were randomly assigned to either a single-task (bottom-up processing) group or a dual-task (top-down processing) group, who performed the Rapid Serial Visual Presentation (RSVP) after watching an analogue trauma video. The correct response rate to target stimuli was then compared between groups based on stimulus type and stimulus presentation interval.Results: In the dual-task group, no significant differences were found. However, in the single-task group, a trend towards a decrease in the correct response rate to the target stimulus was observed 200 ms after the presentation of the traumatic stimulus (i.e., AB).Conclusions: This tendency can be explained by the phenomenon of automatic attentional capture by traumatic stimuli, suggesting a relationship between bottom-up processing and attentional bias.

The Relationship Between Executive Functions, Self-Reflection, and Insight Across Adulthood

ABSTRACT Objective Research suggests that executive functions and metacognitive abilities, including self-reflection and insight, may share underlying mechanisms since both rely on top-down cognitive processes and require self-regulation. However, these relationships have not been thoroughly examined by empirical research. The current study investigated the relationship between insight, self-reflection, and executive functions cross-sectionally across different stages of aging. Methods Participants were 1284 (655 men and 629 women) cognitively healthy community dwellers with an age range of 18–89 years (M = 47.91, SD = 19.83). The sample was divided into three groups based on age, e.g., the young adults (18–34 years-old), the middle-aged adults (35–59 years-old), and older adults (60 years and older). Participants completed multiple executive function tasks (including trail making, verbal fluency, Stroop, digit span) and a self-report insight and self-reflection measure individually in face-to-face sessions. Results The results show that education, age, digit span forward, which is a measure of short-term memory and phonemic fluency were significant predictors of self-reported insight. Furthermore, insight, but not self-reflection, had significant positive correlations with short-term memory and phonemic fluency across three age groups. Conclusions Overall, the results indicate that performance on executive function measures and self-reported self-reflection and insight are relatively independent cognitive abilities.

Enhanced amygdala-anterior cingulate white matter structural connectivity in Sahaja Yoga Meditators.

To study the white matter connections between anterior cingulate cortex, anterior insula and amygdala as key regions of the frontal-limbic network that have been related to meditation. Twenty experienced practitioners of Sahaja Yoga Meditation and twenty nonmeditators matched on age, gender and education level, were scanned using Diffusion Weighted Imaging, using a 3T scanner, and their white matter connectivity was compared using diffusion tensor imaging analyses. There were five white matter fiber paths in which meditators showed a larger number of tracts, two of them connecting the same area in both hemispheres: the left and right amygdalae and the left and right anterior insula; and the other three connecting left anterior cingulate with the right anterior insula, the right amygdala and the left amygdala. On the other hand, non-meditators showed larger number of tracts in two paths connecting the left anterior insula with the left amygdala, and the left anterior insula with the left anterior cingulate. The study shows that long-term practice of Sahaja Yoga Meditation is associated with larger white matter tracts strengthening interhemispheric connections between limbic regions and connections between cingulo-amygdalar and cingulo-insular brain regions related to top-down attentional and emotional processes as well as between top-down control functions that could potentially be related to the witness state perceived through the state of mental silence promoted with this meditation. On the other hand, reduced connectivity strength in left anterior insula in the meditation group could be associated to reduced emotional processing affecting top-down processes.

Engineering Precise Interconnected Porosity in β-Tricalcium Phosphate (β-TCP) Matrices by Means of Top-Down Digital Light Processing.

This study evaluated the biocompatibility and accuracy of 3D-printed β-tricalcium phosphate (β-TCP) pure ceramic scaffolds. A specific shaping process associating a digital light processing (DLP) 3D printer and a heat treatment was developed to produce pure β-TCP scaffolds leaving no polymer binder residue. The β-TCP was characterised using X-ray diffraction, infrared spectroscopy and the detection of pollutants. The open porosity of produced matrices and their resorption were studied by hydrostatic weighing and calcium release measures. The biocompatibility of the printed matrices was evaluated by mean of osteoblast cultures. Finally, macroporous cubic matrices were produced. They were scanned using a micro-Computed Tomography scanner (micro-CT scan) and compared to their numeric models. The results demonstrated that DLP 3D printing with heat treatment produces pure β-TCP matrices with enhanced biocompatibility. They also demonstrated the printing accuracy of our technique, associating top-down DLP with the sintering of green parts. Thus, this production process is promising and will enable us to explore complex phosphocalcic matrices with a special focus on the development of a functional vascular network.

Breathing Right… or Left! The Effects of Unilateral Nostril Breathing on Psychological and Cognitive Wellbeing: A Pilot Study.

The impact of controlled breathing on cognitive and affective processing has been recognized since ancient times, giving rise to multiple practices aimed at achieving different psychophysical states, mostly related to mental clarity and focus, stress reduction, and relaxation. Previous scientific research explored the effects of forced unilateral nostril breathing (UNB) on brain activity and emotional and cognitive functions. Some evidence concluded that it had a contralateral effect, while other studies presented controversial results, making it difficult to come to an unambiguous interpretation. Also, a few studies specifically addressed wellbeing. In the present study, we invited a pilot sample of 20 participants to take part in an 8-day training program for breathing, and each person was assigned to either a unilateral right nostril (URNB) or left nostril breathing condition (ULNB). Then, each day, we assessed the participants' wellbeing indices using their moods and mind wandering scales. The results revealed that, after the daily practice, both groups reported improved wellbeing perception. However, the effect was specifically related to the nostril involved. URNB produced more benefits in terms of stress reduction and relaxation, while ULNB significantly and increasingly reduced mind-wandering occurrences over time. Our results suggest that UNB can be effectively used to increase wellbeing in the general population. Additionally, they support the idea that understanding the effects of unilateral breathing on wellbeing and cognition requires a complex interpretive model with multiple brain networks to address bottom-up and top-down processes.

Catalyzing Organizational Change for Equity in Graduate Education: A Case Study of Adopting Collective Impact in a College of Engineering

Graduate education in engineering is an extremely challenging, complex entity that is difficult to change. The purpose of this exploratory research paper was to investigate the applicability of the Collective Impact framework, which has been used within community organizing contexts, to organize the change efforts of a center focused on advancing equitable graduate education within engineering. We sought to understand how the conditions of Collective Impact (i.e., common agenda, backbone organization, mutually reinforcing activities, shared measurement system, and continuous communication) could facilitate the organization of equity-focused change efforts across a college of engineering at a single institution. To achieve this, we took an action research approach. We found the Collective Impact framework to be a useful tool for organizing cross-sectional partnerships to facilitate equity-focused change in graduate education; we also found the five conditions of Collective Impact to be applicable to the higher education context, with some intentional considerations and modifications. Through coordinated efforts, the Collective Impact framework can support the goal of reorienting existing decentralized structures, resource flows, and decision processes to foster bottom-up and top-down change processes to advance equitable support for graduate students.

Spectrotemporal cues and attention jointly modulate fMRI network topology for sentence and melody perception

Speech and music are two fundamental modes of human communication. Lateralisation of key processes underlying their perception has been related both to the distinct sensitivity to low-level spectrotemporal acoustic features and to top-down attention. However, the interplay between bottom-up and top-down processes needs to be clarified. In the present study, we investigated the contribution of acoustics and attention to melodies or sentences to lateralisation in fMRI functional network topology. We used sung speech stimuli selectively filtered in temporal or spectral modulation domains with crossed and balanced verbal and melodic content. Perception of speech decreased with degradation of temporal information, whereas perception of melodies decreased with spectral degradation. Applying graph theoretical metrics on fMRI connectivity matrices, we found that local clustering, reflecting functional specialisation, linearly increased when spectral or temporal cues crucial for the task goal were incrementally degraded. These effects occurred in a bilateral fronto-temporo-parietal network for processing temporally degraded sentences and in right auditory regions for processing spectrally degraded melodies. In contrast, global topology remained stable across conditions. These findings suggest that lateralisation for speech and music partially depends on an interplay of acoustic cues and task goals under increased attentional demands.

Anthropogenic bottom-up and top-down impacts on boreal breeding waterbirds.

Wetland habitats are changing under multiple anthropogenic pressures. Nutrient leakage and pollution modify physico-chemical state of wetlands and affect the ecosystem through bottom-up processes, while alien predators affect the ecosystems in a top-down manner. Boreal wetlands are important breeding areas for several waterbird species, the abundances of which potentially reflect both bottom-up and top-down ecosystem processes. Here, we use long-term national monitoring data gathered from c. 130 waterbird breeding sites in Finland from the 1980s to the 2020s. We hypothesised that the physico-chemical state of the waters and increasing alien predator abundance both play a role in steering the waterbird population trends. We set out to test this hypothesis by relating population changes of 17 waterbird species to changes in water chemistry and to regional alien predator indices while allowing species-specific effects to vary with foraging niche (dabblers, invertivore divers, piscivorous divers, herbivores), nesting site, female mass and habitat (oligotrophic, eutrophic). We found niche and nesting site-specific, habitat-dependent changes in waterbird numbers. While the associations with higher phosphorus levels and browning water were in overall positive at the oligotrophic lakes, the numbers of invertivore and piscivore diving ducks were most strongly negatively associated with higher phosphorus levels and browning water at the eutrophic lakes. Furthermore, increased pH levels benefitted piscivores. Invertivore diving duck species nesting on the wetlands had declined most on sites with high alien predator indices. Large herbivorous species and species preferring oligotrophic lakes seem to be successful. We conclude that the large-scale breeding waterbird decline in Finland is closely connected to both bottom-up and top-down processes, where negative associations are emphasised especially at eutrophic lakes. Niche-, nest site- and habitat-specific management actions are required to conserve declining waterbird populations. Managing wetlands on catchments level together with alien predator control may provide important approaches to future wetland management.

Bottom-up rather than top-down mechanisms determine mesocarnivore interactions in Norway.

Interactions among coexisting mesocarnivores can be influenced by different factors such as the presence of large carnivores, land-use, environmental productivity, or human disturbance. Disentangling the relative importance of bottom-up and top-down processes can be challenging, but it is important for biodiversity conservation and wildlife management. The aim of this study was to assess how the interactions among mesocarnivores (red fox Vulpes vulpes, badger Meles meles, and pine marten Martes martes) were affected by large carnivores (Eurasian lynx Lynx lynx and wolf Canis lupus), land cover variables (proportion of agricultural land and primary productivity), and human disturbance, as well as how these top-down and bottom-up mechanisms were influenced by season. We analyzed 3 years (2018-2020) of camera trapping observations from Norway and used structural equation models to assess hypothesized networks of causal relationships. Our results showed that land cover variables were more strongly associated with mesocarnivore detection rates than large carnivores in Norway. This might be caused by a combination of low density of large carnivores in an unproductive ecosystem with strong seasonality. Additionally, detection rates of all mesocarnivores showed positive associations among each other, which were stronger in winter. The prevalence of positive interactions among predators might indicate a tendency to use the same areas and resources combined with weak interference competition. Alternatively, it might indicate some kind of facilitative relationship among species. Human disturbance had contrasting effects for different species, benefiting the larger mesocarnivores (red fox and badger) probably through food subsidization, but negatively affecting apex predators (wolf and lynx) and smaller mesocarnivores (pine marten). In a human-dominated world, this highlights the importance of including anthropogenic influences in the study of species interactions.

Speech perception difficulty modulates theta-band encoding of articulatory synergies.

The human brain tracks available speech acoustics and extrapolates missing information such as the speaker's articulatory patterns. However, the extent to which articulatory reconstruction supports speech perception remains unclear. This study explores the relationship between articulatory reconstruction and task difficulty. Participants listened to sentences and performed a speech-rhyming task. Real kinematic data of the speaker's vocal tract were recorded via electromagnetic articulography (EMA) and aligned to corresponding acoustic outputs. We extracted articulatory synergies from the EMA data with principal component analysis (PCA) and employed partial information decomposition (PID) to separate the electroencephalographic (EEG) encoding of acoustic and articulatory features into unique, redundant, and synergistic atoms of information. We median-split sentences into easy (ES) and hard (HS) based on participants' performance and found that greater task difficulty involved greater encoding of unique articulatory information in the theta band. We conclude that fine-grained articulatory reconstruction plays a complementary role in the encoding of speech acoustics, lending further support to the claim that motor processes support speech perception.NEW & NOTEWORTHY Top-down processes originating from the motor system contribute to speech perception through the reconstruction of the speaker's articulatory movement. This study investigates the role of such articulatory simulation under variable task difficulty. We show that more challenging listening tasks lead to increased encoding of articulatory kinematics in the theta band and suggest that, in such situations, fine-grained articulatory reconstruction complements acoustic encoding.

3D orientation field transform

Vascular structure enhancement is very useful in image processing and computer vision. The enhancement of the presence of the structures like tubular networks in given images can improve image-dependent diagnostics and can also facilitate tasks like segmentation. The two-dimensional (2D) orientation field transform has been proved to be effective at enhancing 2D contours and curves in images by means of top-down processing. It, however, has no counterpart in 3D images due to the extremely complicated orientation in 3D against 2D. Given the rising demand and interest in handling 3D images, we experiment with modularising the concept and generalise the algorithm to 3D curves. In this work, we propose a 3D orientation field transform. It is a vascular structure enhancement algorithm that can cleanly enhance images having very low signal-to-noise ratio, and push the limits of 3D image quality that can be enhanced computationally. This work also utilises the benefits of modularity and offers several combinative options that each yield moderately better enhancement results in different scenarios. In principle, the proposed 3D orientation field transform can naturally tackle any number of dimensions. As a special case, it is also ideal for 2D images, owning a simpler methodology compared to the previous 2D orientation field transform. The concise structure of the proposed 3D orientation field transform also allows it to be mixed with other enhancement algorithms, and as a preliminary filter to other tasks like segmentation and detection. The effectiveness of the proposed method is demonstrated with synthetic 3D images and real-world transmission electron microscopy tomograms ranging from 2D curve enhancement to, the more important and interesting, 3D ones. Extensive experiments and comparisons with existing related methods also demonstrate the excellent performance of the proposed 3D orientation field transform.

Divergent mechanisms of perceptual reversals in spinning and wobbling structure-from-motion stimuli.

This study explores the visual phenomenon of random dot structure-from-motion (SFM), where the brain perceives 3D shapes from the coordinated 2D motion of dots. Observing SFM may lead to ambiguous depth relations that reverse back and forth during prolonged viewing. I demonstrate that different processes are involved in triggering perceived reversals for identical SFM shapes involved in spinning and wobbling motion. Durations of stable percepts were measured while human participants viewed the two SFM stimuli, and also a static Necker figure, and a wobbling Necker figure for two sets of 2.5 minutes each. The results showed that wobbling SFM resulted in much longer stable durations compared to the other stimuli. The durations for the wobbling SFM stimuli was not correlated with the spinning SFM, or the two Necker stimuli. Yet, such correlations were obtained between the other stimuli. It is known that reversals obtained while viewing spinning SFM stimuli involves bottom-up driven adaptation and recovery cycles between neural populations. This result suggests that wobbling SFM efficiently deactivates this process and targets other contributions to the reversals, such as top-down processes. In addition, biases observed in the first set disappeared in the second set implying influences of learning between the sets. Imagery vividness, which measures intrinsic top-down processes, was also scored but no correlation between scores in visual imagery and reversal rates were obtained. This research provides insight into the complex interplay between bottom-up driven adaptation-recovery cycles, and top-down processes in ambiguous perception.

The Gaze of Schizophrenia Patients Captured by Bottom-up Saliency

Schizophrenia (SCHZ) notably impacts various human perceptual modalities, including vision. Prior research has identified marked abnormalities in perceptual organization in SCHZ, predominantly attributed to deficits in bottom-up processing. Our study introduces a novel paradigm to differentiate the roles of top-down and bottom-up processes in visual perception in SCHZ. We analysed eye-tracking fixation ground truth maps from 28 SCHZ patients and 25 healthy controls (HC), comparing these with two mathematical models of visual saliency: one bottom-up, based on the physical attributes of images, and the other top-down, incorporating machine learning. While the bottom-up (GBVS) model revealed no significant overall differences between groups (beta = 0.01, p = 0.281, with a marginal increase in SCHZ patients), it did show enhanced performance by SCHZ patients with highly salient images. Conversely, the top-down (EML-Net) model indicated no general group difference (beta = −0.03, p = 0.206, lower in SCHZ patients) but highlighted significantly reduced performance in SCHZ patients for images depicting social interactions (beta = −0.06, p < 0.001). Over time, the disparity between the groups diminished for both models. The previously reported bottom-up bias in SCHZ patients was apparent only during the initial stages of visual exploration and corresponded with progressively shorter fixation durations in this group. Our research proposes an innovative approach to understanding early visual information processing in SCHZ patients, shedding light on the interplay between bottom-up perception and top-down cognition.

Behavioral and Cortical Activation Changes in Children Following Auditory Training for Dichotic Deficits.

We report changes following auditory rehabilitation for interaural asymmetry (ARIA) training in behavioral test performance and cortical activation in children identified with dichotic listening deficits. In a one group pretest-posttest design, measures of dichotic listening, speech perception in noise, and frequency pattern identification were assessed before and 3 to 4.5 months after completing an auditory training protocol designed to improve binaural processing of verbal material. Functional MRI scans were also acquired before and after treatment while participants passively listened in silence or to diotic or dichotic digits. Significant improvements occurred after ARIA training for dichotic listening and speech-in-noise tests. Post-ARIA, fMRI activation increased during diotic tasks in anterior cingulate and medial prefrontal regions and during dichotic tasks, decreased in the left precentral gyrus, right-hemisphere pars triangularis, and right dorsolateral and ventral prefrontal cortices, regions known to be engaged in phonologic processing and working memory. The results suggest that children with dichotic deficits may benefit from the ARIA program because of reorganization of cortical capacity required for listening and a reduced need for higher-order, top-down processing skills when listening to dichotic presentations.

Educators of deaf and hearing interpreting students as agents of change: challenging the curriculum

ABSTRACT Educational systems change in top-down and bottom-up processes. One example is when authorities introduce a new curriculum, but it can also be changed by agents active in the system. In education, agents of change include educators, students and institutions. In this article, we explore the narratives of educators (n = 4) in the bachelor’s programme for signed language interpreter education (both deaf and hearing students) at Humak University of Applied Sciences in Helsinki, Finland. Data were collected through interviews conducted in 2016. We used content analysis and the theory of agency as a framework for analysis. Here, agency is understood as threefold building on the past, present and future. We explore the different dimensions of becoming an agent of change, being an agent of change and being an agent in a changing field. We find that within the context of this sign language interpreting programme, educators’ previous experiences, intercultural competence and ideas about the future contribute to changes in the curriculum and possibly to social change.