Neural correlates underlying local and global processing during visual search across adulthood.

Visual processing relies on the identification of both local and global features of visual stimuli. While well investigated at the behavioral level, the underlying brain mechanisms are less clear, especially in the context of aging. Using fMRI, we aimed to investigate the neural correlates underlying local and global processing in early and late adulthood. We recruited 77 healthy adults aged 19-77 who completed a visual search task based on 2-level hierarchical stimuli made of squares and/or circles. Participants were instructed to detect a target (a square) at either a local (small) or global (large) level of a hierarchical geometrical form, in the presence or absence of other hierarchical geometrical forms (distractors). At the behavioral level, we revealed high accuracy for all participants, but older participants were slower to detect local targets, specifically in presence of distractors. At the brain level, while both local and global processing were associated with occipital activation, local processing also recruited the anterior insula and dorsal anterior cingulate cortex, that are core regions of the salience network. However, while the presence of distractors in the local condition elicited specifically stronger activation within the right anterior insula for the young group, it was not observed for older participants. In addition, older participants showed less activation than younger participants in the occipital cortex, especially for the most complex conditions. Our findings suggest that the brain correlates underlying local and global processing change with aging, especially for complex visual patterns. These results are discussed in terms of top-down reduction effects from the salience network on primary visual areas, that may lead to specific difficulties to process local visual details in older adults.

Effects of general anaesthesia in early childhood on local and global visual processing: a post hoc analysis of the APEX cohort study.

BACKGROUND: Preclinical studies suggest that early exposure to anaesthesia alters the visual system in mice and non-human primates. We investigated whether exposure to general anaesthesia leads to visual attention processing changes in children, which could potentially impact essential life skills, including learning. METHODS: This was a post hoc analysis of data from the APprentissages EXécutifs et cerveau chez les enfants d'âge scolaire (APEX) cohort study. A total of 24 healthy 9-10-yr-old children who were or were not exposed to general anaesthesia (for surgery) by a mean age of 3.8 (2.6) yr performed a visual attention task to evaluate ability to process either local details or general global visual information. Whether children were distracted by visual interference during global and local information processing was also assessed. RESULTS: Participants included in the analyses (n=12 participants exposed to general anaesthesia and n=12 controls) successfully completed (>90% of correct answers) the trial tasks. Children from both groups were equally distracted by visual interference. However, children who had been exposed to general anaesthesia were more attracted to global visual information than were control children (P=0.03). CONCLUSIONS: These findings suggest lasting effects of early-life exposure to general anaesthesia on visuospatial abilities. Further investigations of the mechanisms by which general anaesthesia could have delayed effects on how children perceive their visual environment are needed.

Lateralization of the cerebral network of inhibition in children before and after cognitive training.

Inhibitory control (IC) plays a critical role in cognitive and socio-emotional development. IC relies on a lateralized cortico-subcortical brain network including the inferior frontal cortex, anterior parts of insula, anterior cingulate cortex, caudate nucleus and putamen. Brain asymmetries play a critical role for IC efficiency. In parallel to age-related changes, IC can be improved following training. The aim of this study was to (1) assess the lateralization of IC network in children (N = 60, 9-10 y.o.) and (2) examine possible changes in neural asymmetry of this network from anatomical (structural MRI) and functional (resting-state fMRI) levels after 5-week computerized IC vs. active control (AC) training. We observed that IC training, but not AC training, led to a leftward lateralization of the putamen anatomy, similarly to what is observed in adults, supporting that training could accelerate the maturation of this structure.

Impaired Global Precedence Effect in Severe Alcohol Use Disorder and Korsakoff's Syndrome: A Pilot Exploration through a Global/Local Visual Paradigm.

In healthy populations, visual abilities are characterized by a faster and more efficient processing of global features in a stimulus compared to local ones. This phenomenon is known as the global precedence effect (GPE), which is demonstrated by (1) a global advantage, resulting in faster response times for global features than local features and (2) interference from global distractors during the identification of local targets, but not vice versa. This GPE is essential for adapting visual processing in everyday life (e.g., extracting useful information from complex scenes). We investigated how the GPE is affected in patients with Korsakoff's syndrome (KS) compared to patients with severe alcohol use disorder (sAUD). Three groups (including healthy controls, patients with KS and patients with sAUD) completed a global/local visual task in which predefined targets appeared at the global or local level during either congruent or incongruent (i.e., interference) situations. The results showed that healthy controls (N = 41) presented a classical GPE, while patients with sAUD (N = 16) presented neither a global advantage nor global interference effects. Patients with KS (N = 7) presented no global advantage and an inversion of the interference effect, characterized by strong interference from local information during global processing. The absence of the GPE in sAUD and the interference from local information in KS have implications in daily-life situations, providing preliminary data for a better understanding of how these patients perceive their visual world.

Consequences of General Anesthesia in Infancy on Behavior and Brain Structure.

BACKGROUND: One in 7 children will need general anesthesia (GA) before the age of 3. Brain toxicity of anesthetics is controversial. Our objective was to clarify whether exposure of GA to the developing brain could lead to lasting behavioral and structural brain changes. METHODS: A first study was performed in mice. The behaviors (fear conditioning, Y-maze, and actimetry) and brain anatomy (high-resolution magnetic resonance imaging) of 6- to 8-week-old Swiss mice exposed or not exposed to GA from 4 to 10 days old were evaluated. A second study was a complementary analysis from the preexisting APprentissages EXécutifs et cerveau chez les enfants d'âge scolaire (APEX) cohort to assess the replicability of our data in humans. The behaviors (behavior rating inventory of executive function, emotional control, and working memory score, Backward Digit Span, and Raven 36) and brain anatomy (high-resolution magnetic resonance imaging) were compared in 102 children 9 to 10 years of age exposed or not exposed to a single GA (surgery) during infancy. RESULTS: The animal study revealed chronic exacerbated fear behavior in the adult mice (95% confidence interval [CI], 4-80; P = .03) exposed to postnatal GA; this was associated with an 11% (95% CI, 7.5-14.5) reduction of the periaqueductal gray matter (P = .046). The study in humans suggested lower emotional control (95% CI, 0.33-9.10; P = .06) and a 6.1% (95% CI, 4.3-7.8) reduction in the posterior part of the right inferior frontal gyrus (P = .019) in the children who had been exposed to a single GA procedure. CONCLUSIONS: The preclinical and clinical findings of these independent studies suggest lasting effects of early life exposure to anesthetics on later emotional control behaviors and brain structures.

Approach in green, avoid in red? Examining interindividual variabilities and personal color preferences through continuous measures of specific meaning associations.

Empirically based literature suggests that avoidance/approach motivation arising from color-meaning associations assume a key mediational role in the color effect during psychological functioning. Even if several studies investigated color-meaning associations through different methodological approaches, no study investigated specific color-meaning associations (1) through continuous measures (2) for both positive and negative meanings. In addition, color effects are not unequivocal, and interindividual variability issues are still underexplored. The present study is based on the application of visual analog scales to assess continuous measures of specific color-meaning associations related to both negative and positive meanings that could rely on avoidance/approach motivation. The data analyses compared the distribution of the color-meaning association scores rated by participants (N = 152) on visual analog scales. The results showed strong associations between red color and items that could be related to avoidance motivation. Conversely, green color association scores showed distinct and specific associations that could be related to approach motivation. The results also revealed that blue color could exhibit a similar pattern for some meaning association scores compared with green color, as well as orange compared with red association scores. In addition, the results suggest that color preferences may influence color effects, especially regarding color-related approach motivation. The present study provides new insights about the color effect on psychological functioning and a novel approach to investigate the mediational processes such as avoidance/approach motivation that considers interindividual differences along a continuum.

Link between fluid/crystallized intelligence and global/local visual abilities across adulthood.

Human visual processing involves the extraction of both global and local information from a visual stimulus. Such processing may be related to cognitive abilities, which is likely going to change over time as we age. We aimed to investigate the impact of healthy aging on the association between visual global vs local processing and intelligence. In this context, we collected behavioral data during a visual search task in 103 adults (50 younger/53 older). We extracted three metrics reflecting global advantage (faster global than local processing), and visual interference in detecting either local or global features (based on interfering visual distractors). We found that older, but not younger, adults with higher levels of fluid and crystallized intelligence showed stronger signs of global advantage and interference effects during local processing, respectively. The present findings also provide promising clues regarding how participants consider and process their visual world in healthy aging.

The forest, the trees, and the leaves across adulthood: Age-related changes on a visual search task containing three-level hierarchical stimuli.

Selecting relevant visual information in complex scenes by processing either global information or local parts helps us act efficiently within our environment and achieve goals. A global advantage (faster global than local processing) and global interference (global processing interferes with local processing) comprise an evidentiary global precedence phenomenon in early adulthood. However, the impact of healthy aging on this phenomenon remains unclear. As such, we collected behavioral data during a visual search task, including three-levels hierarchical stimuli (i.e., global, intermediate, and local levels) with several hierarchical distractors, in 50 healthy adults (26 younger (mean age: 26 years) and 24 older (mean age: 62 years)). Results revealed that processing information presented at the global and intermediate levels was independent of age. Conversely, older adults were slower for local processing compared to the younger adults, suggesting lower efficiency to deal with visual distractors during detail-oriented visual search. Although healthy older adults continued exhibiting a global precedence phenomenon, they were disproportionately less efficient during local aspects of information processing, especially when multiple visual information was displayed. Our results could have important implications for many life situations by suggesting that visual information processing is impacted by healthy aging, even with similar visual stimuli objectively presented.

Framing the area: An efficient approach for avoiding visual interference and optimising visual search in adolescents.

Attentional resources are limited, and resistance to interference plays a critical role during cognitive tasks and learning. Previous studies have shown that participants find it difficult to avoid being distracted by global visual information when processing local details. In this study, we investigated an innovative approach for enhancing the processing of local visual details by middle-school adolescents. Two groups completed a classic global/local visual search task in which a predefined target could appear at the global or local level, either with or without a frame. The results from the no-frame display group provided a direct replication in adolescents of previous findings in adults, with increasing number of interferent stimuli presented in the display adversely affecting detection of local targets. In addition, by varying the numbers of distractors inside and outside the frame, we showed that distractors only interfered with the processing of local information inside the frame, while the deleterious impact of increases in distracting information was prevented when the distractors were outside the frame. These findings suggest that when a frame delimits an attentional area, the influence of an increasing number of distractors present outside the frame is eliminated. We assume that application of a frame allows for efficient delimitation of attention deployment to a restricted topographical visual area in adolescents. These results evidence that processing of local details can be improved without modifying the structure of the stimuli, and provide promising clues for optimising attentional resources during time-absorbing visual searches. Applicable implications in the educational field are discussed.

Preventing the Long-term Effects of General Anesthesia on the Developing Brain: How Translational Research can Contribute.

In 2017, the Food and Drug Administration published a safety recommendation to limit the exposure to general anesthesia as much as possible below the age of three. Indeed, several preclinical and clinical studies have questioned the possible toxicity of general anesthesia on the developing brain. Since then, recent clinical studies tried to mitigate this alarming issue. What is true, what is false? Contrary to some perceptions, the debate is not over yet. Only stronger translational research will allow scientists to provide concrete answers to this public health issue. In this review, we will provide and discuss the more recent data in this field, including the point of view of preclinical researchers, neuropsychologists and pediatric anesthesiologists. Through translational research, preclinical researchers have more than ever a role to play to better understand and identify long-term effects of general anesthesia for pediatric surgery on brain development in order to minimize it.

The forest, the trees, and the leaves in preterm children: the impact of prematurity on a visual search task containing three-level hierarchical stimuli.

Very preterm (VPT; < 33 gestational weeks) children are at risk of developing visuospatial deficits, including local/global attention deficits. They are also more likely to develop poorer inhibitory control. Here, we investigated, using the same stimuli, the potential local/global attention and inhibitory control deficits of VPT children using three levels compound stimuli (global, intermediate, and local levels), more ecological than the ones used in a classic global/local task (Navon task). We compared the results from 22 VPT children to those of a control group of 21 children to investigate (1) how VPT children processed compound stimuli with three-level information and (2) how inhibitory control in a visual task differs between VPT and control children. The results revealed that VPT children had no difficulty processing information presented at the local level. By contrast, VPT children were impaired when considering the intermediate and global levels of processing in comparison to control children. Finally, a reduced efficiency in VPT children in inhibiting visual distractors was evidenced for the conditions with a larger number of distractors. These results are discussed in terms of neurodevelopmental disorders of both dorsal stream (global visual processing) and prefrontal regions (inhibitory control) in VPT children. Given the central role of visuospatial and inhibitory control in day-to-day situations, the present results provide important clues for pedagogical implications regarding the organization of visual information presented to VPT children.

Cortical Thickness and Natural Scene Recognition in the Child's Brain.

Visual scenes are processed in terms of spatial frequencies. Low spatial frequencies (LSF) carry coarse information, whereas high spatial frequencies (HSF) subsequently carry information about fine details. The present magnetic resonance imaging study investigated how cortical thickness covaried with LSF/HSF processing abilities in ten-year-old children and adults. Participants indicated whether natural scenes that were filtered in either LSF or HSF represented outdoor or indoor scenes, while reaction times (RTs) and accuracy measures were recorded. In adults, faster RTs for LSF and HSF images were consistently associated with a thicker cortex (parahippocampal cortex, middle frontal gyrus, and precentral and insula regions for LSF; parahippocampal cortex and fronto-marginal and supramarginal gyri for HSF). On the other hand, in children, faster RTs for HSF were associated with a thicker cortex (posterior cingulate, supramarginal and calcarine cortical regions), whereas faster RTs for LSF were associated with a thinner cortex (subcallosal and insula regions). Increased cortical thickness in adults and children could correspond to an expansion mechanism linked to visual scene processing efficiency. In contrast, lower cortical thickness associated with LSF efficiency in children could correspond to a pruning mechanism reflecting an ongoing maturational process, in agreement with the view that LSF efficiency continues to be refined during childhood. This differing pattern between children and adults appeared to be particularly significant in anterior regions of the brain, in line with the proposed existence of a postero-anterior gradient of brain development. Taken together, our results highlight the dynamic brain processes that allow children and adults to perceive a visual natural scene in a coherent way.

Anatomical Connectivity of the Visuospatial Attentional Network in Schizophrenia: A Diffusion Tensor Imaging Tractography Study.

OBJECTIVE: In healthy individuals, the visuospatial attentional network consists of frontoparietal bundles; however, the anatomical organization of this network in persons with schizophrenia remains largely unknown. Using diffusion tensor imaging-based tractography, the authors investigated the white matter integrity and volume of frontoparietal and frontotemporo-occipital bundles in the right and left hemispheres and studied their structural asymmetry in persons with schizophrenia and in healthy individuals. METHODS: This study included 34 participants with schizophrenia and 69 healthy individuals. Integrity parameters and volume were calculated in the three branches of the superior longitudinal fasciculus (SLF I, II, and III), the inferior longitudinal fasciculus, and the inferior fronto-occipital fasciculus in both hemispheres. RESULTS: In the SLF II and SLF III of the right hemisphere, healthy individuals showed greater integrity, compared with participants with schizophrenia. Both groups presented increased integrity in the SLF III of the right hemisphere, compared with the SLF III of the left hemisphere, but only healthy individuals had this pattern regarding the SLF II. Bundle volumes did not differ between groups. CONCLUSIONS: This study is the first to describe the structural hemispheric lateralization and organization of the visuospatial attentional network in persons with schizophrenia. The main findings indicate loss of integrity in the SLF II, associated with loss of asymmetry in participants with schizophrenia, compared with healthy individuals, suggesting a potential substrate of attentional deficits.

Complex and subtle structural changes in prefrontal cortex induced by inhibitory control training from childhood to adolescence.

A number of training interventions have been designed to improve executive functions and inhibitory control (IC) across the lifespan. Surprisingly, no study has investigated the structural neuroplasticity induced by IC training from childhood to late adolescence, a developmental period characterized by IC efficiency improvement and protracted maturation of prefrontal cortex (PFC) subregions involved in IC. The aim of the present study was to investigate the behavioral and structural changes induced by a 5-week computerized and adaptive IC training in school-aged children (10-year-olds) and in adolescents (16-year-olds). Sixty-four children and 59 adolescents were randomly assigned to an IC (i.e. Color-Word Stroop and Stop-Signal tasks) or an active control (AC) (knowledge- and vocabulary-based tasks) training group. In the pre- and posttraining sessions, participants performed the Color-Word Stroop and Stop-signal tasks, and an anatomical resonance imaging (MRI) was acquired for each of them. Children's IC efficiency improved from the pre- to the posttraining session in boys but not in girls. In adolescents, IC efficiency did not improve after IC training. Similar to the neuroplastic mechanisms observed during brain maturation, we observed IC training-related changes in cortical thickness and cortical surface area in several PFC subregions (e.g. the pars opercularis, triangularis, and orbitalis of the inferior frontal gyri) that were age- and gender-specific. Because no correction for multiple comparisons was applied, the results of our study provide only preliminary evidence of the complex structural neuroplastic mechanisms at the root of behavioral changes in IC efficiency from pre- to posttraining in school-aged children and adolescents.

Who's got the global advantage? Visual field differences in processing of global and local shape.

Much evidence suggests that we first perceive the overall layout of a scene or object followed later by the details. This coarse-to-fine temporal dynamic in visual processing is also found in Navon's classical paradigm where information at the global level of compound stimuli is processed faster than information at the local level (global precedence effect), and where information at the global level has larger effects on local level responses than local level information has on global level responses (asymmetric interference effects). Traditionally, global shape primacy in Navon's paradigm has been linked with a right hemisphere preference (left visual field advantage) for global shape processing, and a left hemisphere preference (right visual field advantage) for local shape processing. This link, however, has been based on measures which confound global precedence and interference effects. Indeed, when these measures are de-confounded, we find no evidence for larger global precedence effects in the left compared with the right visual field in a large sample of participants (N = 337). In comparison, global-to-local interference effects are found to be stronger in the left than in the right visual field. We argue that these findings can be accounted for by assuming that the right hemisphere plays a special role in integrating shape information across spatial scales, that is, without assuming the existence of a right hemisphere preference for global shape processing per se.

Developmental frontal brain activation differences in overcoming heuristic bias.

Since reasoning is often biased by intuitive heuristics, the development of sound reasoning has long been postulated to depend on successful bias monitoring and inhibition. The present fMRI study aimed to identify neural correlates of developmental changes in these processes. A group of adults and young adolescents were presented with ratio-bias problems in which an intuitively cued heuristic response could be incongruent (conflict item) or congruent (no-conflict item) with the correct response. Results showed that successfully avoiding biased responding on conflict items across both age groups was associated with increased activation in Anterior Cingulate Cortex (ACC) and the right Lateral Prefrontal Cortex (LPFC) regions of interest. Critically, the right LPFC activation decreased with age. Biased responding did not result in right LPFC or ACC modulation and failed to show any developmental activation changes. We discuss implications for ongoing debates on the nature of heuristic bias and its development.

Children inhibit global information when the forest is dense and local information when the forest is sparse.

Visual environments are composed of global shapes and local details that compete for attentional resources. In adults, the global level is processed more rapidly than the local level, and global information must be inhibited in order to process local information when the local information and global information are in conflict. Compared with adults, children present less of a bias toward global visual information and appear to be more sensitive to the density of local elements that constitute the global level. The current study aimed, for the first time, to investigate the key role of inhibition during global/local processing in children. By including two different conditions of global saliency during a negative priming procedure, the results showed that when the global level was salient (dense hierarchical figures), 7-year-old children and adults needed to inhibit the global level to process the local information. However, when the global level was less salient (sparse hierarchical figures), only children needed to inhibit the local level to process the global information. These results confirm a weaker global bias and the greater impact of saliency in children than in adults. Moreover, the results indicate that, regardless of age, inhibition of the most salient hierarchical level is systematically required to select the less salient but more relevant level. These findings have important implications for future research in this area.

Sulcal Polymorphisms of the IFC and ACC Contribute to Inhibitory Control Variability in Children and Adults.

Inhibitory control (IC) is a core executive function that enables humans to resist habits, temptations, or distractions. IC efficiency in childhood is a strong predictor of academic and professional success later in life. Based on analysis of the sulcal pattern, a qualitative feature of cortex anatomy determined during fetal life and stable during development, we searched for evidence that interindividual differences in IC partly trace back to prenatal processes. Using anatomical magnetic resonance imaging (MRI), we analyzed the sulcal pattern of two key regions of the IC neural network, the dorsal anterior cingulate cortex (ACC) and the inferior frontal cortex (IFC), which limits the inferior frontal gyrus. We found that the sulcal pattern asymmetry of both the ACC and IFC contributes to IC (Stroop score) in children and adults: participants with asymmetrical ACC or IFC sulcal patterns had better IC efficiency than participants with symmetrical ACC or IFC sulcal patterns. Such additive effects of IFC and ACC sulcal patterns on IC efficiency suggest that distinct early neurodevelopmental mechanisms targeting different brain regions likely contribute to IC efficiency. This view shares some analogies with the "common variant-small effect" model in genetics, which states that frequent genetic polymorphisms have small effects but collectively account for a large portion of the variance. Similarly, each sulcal polymorphism has a small but additive effect: IFC and ACC sulcal patterns, respectively, explained 3% and 14% of the variance of the Stroop interference scores.

Neural basis of functional fixedness during creative idea generation: An EEG study.

Decades of problem solving and creativity research have converged to show that the ability to generate new and useful ideas can be blocked or impeded by intuitive biases leading to mental fixations. The present study aimed at investigating the neural bases of the processes involved in overcoming fixation effects during creative idea generation. Using the AU task adapted for EEG recording, we examined whether participant's ability to provide original ideas was related to alpha power changes in both the frontal and temporo-parietal regions. Critically, for half of the presented objects, the classical use of the object was primed orally, and a picture of the classical use was presented visually to increase functional fixedness (Fixation Priming condition). For the other half, only the name of the object and a picture of the object was provided to the participants (control condition). As expected, priming the classical use of an object before the generation of creative alternative uses of the object impeded participants' performances in terms of remoteness. In the control condition, while the frontal alpha synchronization was maintained across all successive time windows in participants with high remoteness scores, the frontal alpha synchronization decreased in participants with low remoteness scores. In the Fixation Priming condition, in which functional fixedness was maximal, both participants with high and low remoteness scores maintained frontal alpha synchronization throughout the period preceding their answer. Whereas participants with high remoteness scores maintained alpha synchronization in the temporo-parietal regions throughout the creative idea generation period, participants with low remoteness scores displayed alpha desynchronization in the same regions during this period. We speculate that individuals with high remoteness scores might generate more creative ideas than individuals with low remoteness scores because they rely more on internal semantic association and selection processes.

Navon's classical paradigm concerning local and global processing relates systematically to visual object classification performance.

Forty years ago David Navon tried to tackle a central problem in psychology concerning the time course of perceptual processing: Do we first see the details (local level) followed by the overall outlay (global level) or is it rather the other way around? He did this by developing a now classical paradigm involving the presentation of compound stimuli; large letters composed of smaller letters. Despite the usefulness of this paradigm it remains uncertain whether effects found with compound stimuli relate directly to visual object recognition. It does so because compound stimuli are not actual objects but rather formations of elements and because the elements that form the global shape of compound stimuli are not features of the global shape but rather objects in their own right. To examine the relationship between performance on Navon's paradigm and visual object processing we derived two indexes from Navon's paradigm that reflect different aspects of the relationship between global and local processing. We find that individual differences on these indexes can explain a considerable amount of variance in two standard object classification paradigms; object decision and superordinate categorization, suggesting that Navon's paradigm does relate to visual object processing.