Visuospatial Integration Research Articles

Cognitive archaeology, and the psychological assessment of extinct minds.

Evolutionary anthropology relies on both neontological and paleontological information. In the latter case, fields such as paleoneurology, neuroarchaeology, and cognitive archaeology are supplying new perspectives in prehistory and neuroscience. Cognitive archaeology, in particular, investigates the behaviors associated with extinct species or cultures according to specific psychological models. For example, changes in working memory, attention, or visuospatial integration can be postulated when related behavioral changes are described in the archaeological record. However, cognition is a process based on different and partially independent functional elements, and extinct species could hence have evolved distinct combinations of cognitive abilities or features, based on both quantitative and qualitative differences. Accordingly, differences in working memory can lead to more conceptual or more holistic mindsets, with important changes in the perception and management of the mental experience. The parietal cortex is particularly interesting, in this sense, being involved in functions associated with body-tool integration, attention, and visual imaging. In some cases, evolutionary mismatches among these elements can induce drawbacks that, despite their positive effects on natural selection, can introduce important constraints in our own mental skills. Beyond the theoretical background, some hypotheses can be tested following methods in experimental psychology. In any case, theories in cognitive evolution must acknowledge that, beyond the brain and its biology, the human mind is also deeply rooted in body perception, in social networks, and in technological extension.

The Moderating Role of Emotional Regulation on the Relationship between School Results and Personal Characteristics of Pupils with Attention Deficit/Hyperactivity Disorder

This study aimed to explore the possible moderating role of emotional regulation in the relationship between problem-solving ability, visuomotor precision and visuospatial integration on the one hand and school results on the other in pupils with ADHD. A total of 241 pupils with ADHD (study group) and 207 children without ADHD (control group) were included in our research. Specific tests for the evaluation of the problem-solving ability, visuomotor precision, visuospatial integration, and emotional regulation were applied. The results showed that emotional regulation is a significant moderator of the relationship between school results and problem-solving ability, visuomotor precision, visuospatial integration, and working memory. There are statistically significant differences depending on emotional regulation, visuomotor precision, visuospatial integration, problem-solving ability and working memory in terms of school results of students with ADHD compared to children without this diagnosis. These results can be used in the development of intervention programs.

ACL Research Retreat IX Summary Statement: The Pediatric Athlete, March 17-19, 2022; High Point, North Carolina.

ACL Research Retreat IX Summary Statement: The Pediatric Athlete, March 17-19, 2022; High Point, North Carolina.

A-31 Distinguishing Neuro-Markers of Math Learning Disability Using EEG Coherence

Abstract Objective The current study evaluated brain connectivity in math learning disability (MLD) by examining intra- and interhemispheric electroencephalography (EEG) coherence in three groups of children with differing math profiles. Differential patterns of connectivity were evaluated during “at-rest” conditions and statistically evaluated across three groups. Method Testing occurred in a university laboratory setting. Participants were recruited through media and local agencies serving children with disabilities. The Woodcock Johnson cognitive and achievement tests were used to determine general intelligence and skills across all math achievement subtests. Additionally, 3-minute eye-closed EEG resting data was collected. Groups used in the current study were: neurotypical controls (NC) (n = 30), math learning disability (MLD) (n = 15), and lower achievement (LA) (n = 15). Participants’ mean age was 9.58 (SD = 1.38) with 53.3% being male. Results Intrahemispheric comparisons suggest MLD children demonstrated reduced left hemispheric coherence to NC’s (p = 0.006), not seen in LA children. Additionally, NC’s had greater beta coherence (p = 0.002). Interhemispheric analyses revealed the MLD group had reduced alpha occipital coherence compared to the LA group (p = 0.031). Conclusion The current study provides supporting evidence for implicating brain connectivity as an underlying cause of MLD. Specifically, left hemispheric differences in delta coherence were found in children with MLD not observed in children with LA profiles. Weaknesses in areas of visuo-spatial integration in the MLD group were also observed. Results suggest atypical patterns of brain connectivity in the default-mode network (DMN) in delta wavelengths may serve as a useful biomarker of MLD.

Anatomy and White Matter Connections of the Superior Parietal Lobule.

The superior parietal lobule (SPL) is involved in somatosensory and visuospatial integration with additional roles in attention, written language, and working memory. A detailed understanding of the exact location and nature of associated white matter tracts could improve surgical decisions and subsequent postoperative morbidity related to surgery in and around this gyrus. To characterize the fiber tracts of the SPL based on relationships to other well-known neuroanatomic structures through diffusion spectrum imaging (DSI)-based fiber tracking validated by gross anatomical dissection as ground truth. Neuroimaging data of 10 healthy, adult control subjects was obtained from a publicly accessible database published in Human Connectome Project for subsequent tractographic analyses. White matter tracts were mapped between both cerebral hemispheres, and a lateralization index was calculated based on resultant tract volumes. Post-mortem dissections of 10 cadavers identified the location of major tracts and validated our tractography results based on qualitative visual agreement. We identified 9 major connections of the SPL: U-fiber, superior longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, middle longitudinal fasciculus, extreme capsule, vertical occipital fasciculus, cingulum, and corpus callosum. There was no significant fiber lateralization detected. The SPL is an important region implicated in a variety of tasks involving visuomotor and visuospatial integration. Improved understanding of the fiber bundle anatomy elucidated in this study can provide invaluable information for surgical treatment decisions related to this region.

Evolving Human Brains: Paleoneurology and the Fate of Middle Pleistocene

In the evolutionary radiation of the human genus, we have observed changes in both brain size and proportions. Some of these morphological differences are thought to be associated with functional variations, in physiological or cognitive aspects, while some others are the secondary results of cortical or cranial structural constraints. Most archaic human species, like Homo erectus and H. heidelbergensis, display larger brains when compared with earlier hominids, but specializations in their cortical proportions, if there are any, are difficult to recognize. In contrast, after or during Middle Pleistocene, more derived species like H. sapiens and H. neanderthalensis show changes in overall brain size but also in specific cerebral regions. Functions associated with body cognition, visuospatial integration, tool use, language, and social structure may be involved in these paleoneurological changes. Nonetheless, a proper evaluation of cognitive differences must take into account not only the cerebral components, but also the associated mechanisms underlying technological extension. Brain-body prosthetic capacity can have represented, indeed, a crucial adaptation to become obligatory tool users. These processes involve both genetic and environmental effects, and they are probably influent at phylogenetic (species) and historical (populations) level, bridging biological and cultural factors through epigenetic feedbacks that are still poorly known and scarcely investigated.

Functional representation of the symbol digit modalities test in relapsing remitting multiple sclerosis

BackgroundThe Symbol Digit Modalities Test (SDMT) is essential in the screening of cognitive impairments in multiple sclerosis (MS). Methodological adaptions of the SDMT on functional MRI exist, but without specific investigation of more cognitive components of information processing speed (IPS). Additionally, there is only limited data on functional differences between MS-patients and healthy controls (HC). Methods20 MS-patients and 20 HC were investigated executing the original version of the SDMT on fMRI. We analyzed (1) neural networks as indicated in the methodological adaptions (i.e. frontal (Brodman area BA6, BA9), parietal (BA7), occipital (BA17) and cerebellar), (2) functional activations of cognitive components of IPS and (3) functional differences between MS and HC during SDMT. ResultsMS patients performed worse during the SDMT. Both groups demonstrated activation on each region of interest. Cognitive component of IPS was driven by superior parietal and posterior cerebellar activation. MS-patients showed decreased cingulate activation during SDMT as compared to HC. ConclusionThe original SDMT task revealed comparable fMRI-activation sites as reported for previous adaptions. Cognitive components of IPS depend on superior parietal and medial posterior cerebellar regions known to process visuo-spatial integration and anticipation. Attention related areas in the cingulate cortex were decreased in MS-patients.

Specific cognitive correlates of the quality of life of extremely preterm school-aged children without major neurodevelopmental disability.

We examined how specific cognitive behavioral impairments impacted quality of life (QoL) within a large multicenter cohort of 7-10 year olds surviving extremely preterm (EPT) without major neurodevelopmental disability. Between 7 and 10 years of age, two generic, self-proxy, and parental evaluations were obtained. QoL measurement questionnaires (Kidscreen-10/VSPA (Vécu et Santé Perçue de l'Enfant et de l'Adolescent)) were used and compared to a reference population. The general and specific cognitive functions, such as executive functions, behavior and anxiety, and clinical neurologic examination, were also assessed. We analyzed 211 school-aged EPT children. The mean gestational age was 26.2 (±0.8) weeks, birth weight was 879 g (±181) and the mean age was 8.4 years (±0.87). Children with a Full-Scale Index Quotient ≥89, who were considered as normal, had a lower QoL. Specific cognitive impairments: comprehensive language delay, visuo-spatial integration defect, and dysexecutive disorders) were the QoL correlates in the domains of school performance and body image. School and health care professionals need to increase their focus on EPT children's lower so as to recognize the preterm behavioral/cognitive phenotype and their potential need for supportive measures. Research on preventive interventions is warranted to investigate if these long-term effects of an EPT birth can be attenuated in neonatal period and after.

Clinical and neuropsychological outcome of pediatric non-midline central nervous system germinoma treated with chemotherapy and reduced dose/volume irradiation: The Children's Hospital Los Angeles experience.

Germ cell tumors (GCT) arising from non-midline structures (basal ganglia, thalamus, and posterior fossa) are rare. Although patients with midline (pineal and suprasellar) germinoma have excellent survival with chemotherapy and whole ventricular irradiation (WVI), germinoma in non-midline locations have traditionally been treated with craniospinal irradiation (CSI) or whole brain irradiation (WBI) to achieve similar outcomes. However, CSI and WBI are associated with significant long-term neuropsychological sequelae. We describe the clinical and neuropsychological outcomes of patients with non-midline germinoma treated at the Children's Hospital Los Angeles between 1990 and 2015. Nine patients had basal ganglia/thalamic germinoma and one patient had a cerebellar primary. Eight patients received chemotherapy followed by reduced dose/volume irradiation, whereas two patients received chemotherapy alone as upfront therapy. One patient in the chemotherapy alone group relapsed after 4.3years and was salvaged with CSI plus boost. The overall survival for the entire cohort was 100% at a median follow-up of 8.5years. Neuropsychological data were available for six patients at a median of five months (baseline) and 4.2years (follow-up) post-diagnosis. At four-year follow-up, data available revealed intact overall cognitive ability, verbal memory, and executive functioning, but persistent deficits in fine motor function. Comparison of baseline to follow-up suggests a downward trend in working memory, planning/problem-solving, verbal memory, and visuospatial integration. Chemotherapy followed by reduced dose/volume of irradiation is an effective strategy resulting in long-term survival in patients with non-midline germinoma. Neuropsychological data suggest relatively minimal morbidity over time.

Neurocognitive profile in children with arachnoid cysts before and after surgical intervention.

Treatment indications for arachnoid cysts are not clear. Some surgeons take improvement in neurocognitive function into account as a surgical indication for arachnoid cysts. However, only a few studies have evaluated the relationship between arachnoid cysts and neurocognitive function. Furthermore, studies that analyze neurocognitive function as an effect of arachnoid cyst surgery are even rarer. The purpose of this study was to analyze the neurocognitive function scores of children with arachnoid cysts before and after surgery and to examine whether surgical treatment led to improved neurocognitive function. From June 2009 to August 2012, data for 24 children diagnosed with arachnoid cysts who underwent surgery at Seoul National University Children's Hospital were analyzed. Pre-operative and post-operative cyst volume was assessed and neurocognitive function was tested using the Korean version of the Wechsler Intelligence Scale for Children-Revised (WISC-R) and the Bender-Gestalt Test (BGT). Comparison of pre- and post-operative profiles by laterality of the arachnoid cyst was performed. Patients had age-appropriate full-scale intelligent quotients (FSIQ), verbal IQ (VIQ), and performance IQ (PIQ) pre-operatively, which were maintained after surgery. Of the subtests, Block Design showed significant improvement post-operatively (p = 0.021). This means that visuo-spatial integration and mental construction abilities were improved after surgery. Patients with left or right arachnoid cysts did not show statistically significant changes in FSIQ, VIQ, or PIQ after surgery (110.21 versus 113.95, p = 0.307; 108.92 versus 111.54, p = 0.368; 107.88 versus 111.04, p = 0.152, respectively). Subanalysis showed that the pre- and post-operation VIQ mean scores of the patients with right arachnoid cysts were significantly higher (p < 0.054) than those of the patients with left arachnoid cysts, and there was no significant change after the surgery. There was no significant association among cyst volume reduction, laterality, and clinical neurocognitive function improvement. The present findings indicate a limited role for surgical intervention in improving the intellectual abilities of children with arachnoid cysts.

Visuospatial and Sensory Integration Tasks in Patients With Schizophrenia or Schizoaffective Disorder: Relationship to Body Mass Index and Smoking.

Neurological soft signs (NSSs) are highly prevalent among patients with schizophrenia, but their pathophysiological significance remains unclear. The present study employed perceptual-motor and visuospatial processing tests that have not yet been attempted in this patient population. Patients with schizophrenia or schizoaffective disorder (n = 42) and mentally healthy subjects (n = 10) were administered Copy Figure Test, Detection and Recognition of an Object Test and Road Map Test. As compared to controls, schizophrenic and schizoaffective patients displayed significantly poorer ability to copy three-dimensional figures (namely, Necker- and hidden line elimination cubes) and to orient in space on a road-map test; group differences in copying two-dimensional figures and on objects' recognition against a background noise were not apparent. In the schizophrenia/schizoaffective group, more mistakes on the hidden line elimination cube was associated with greater body mass index and greater severity of nicotine dependence measured via the Fagerstrom Test of Nicotine Dependence. The above findings replicate those of prior reports and extend them to the tasks that do not involve motivational and attentional confounds. Furthermore, the present data support the hypothesis that subtle cerebral cortical abnormalities detected with specific NSSs tests may be related to some aspects of metabolic and motivational function in patients with schizophrenia/schizoaffective disorder.

A Network Approach to Link Visibility and Urban Activity Location

Performance of a range of urban amenities is influenced by their accessibility to pedestrians. Success in attracting pedestrians to a particular location depends on how they project visuospatial information. In this paper, we propose an original method for analysing the visuospatial integration of particular locations within a street network. As a case study we analyse the distribution of one type of urban amenities - food and drink public facilities. We represent them in a form of visibility graph as objects of navigational decisions within the street network. To explore how urban facilities, streets and pedestrian visual cognition are interrelated, we create and compare three cases: a street network visibility graph and two visibility graphs of amenities. The first graph is based on the existing, “natural” distribution, while the second is an “artificial”, fabricated version of the environment, where urban locations are redistributed evenly across the case study. We study the graphs’ global network properties by the use of small-world, and scale-free models. Our results demonstrate that views available for an urban traveller in the existing, “natural” setting had a particular structure. It is built of numerous weakly connected locations coexisting with a small number of hubs with an exceptionally large number of visual connections. Such organisation of urban visibility shows that visuospatial network shares morphological similarities with other natural networks, suggesting that common organizational principles underlie network structure.

Developmental trends in susceptibility to perceptual illusions: Not all illusions are created equal.

This study examined the development of the utilization of contextual information in visuospatial integration during childhood. We examined four contextual size illusions in children and adults asking whether young children's sensitivity to context is reduced or varies with the perceptual mechanisms or the levels of integration involved. We tested susceptibility to contextual illusions in four-year-olds, seven-year-olds, and adults, employing two psychophysical paradigms, perceptual estimation and a 2AFC discrimination task. We tested susceptibility to Ebbinghaus and Ponzo illusions to estimate the effect of the interaction of object size with its contextual background on the rescaling of its perceived size; we also tested susceptibility to the rectangle and 3D-cube illusions to estimate the effect of the interaction of two dimensions of the target object on the rescaling of its perceived size. While four-year-olds were affected by the Ebbinghaus and Ponzo illusions, they showed no susceptibility to the rectangle or 3D-cube illusion. The results show that, overall, sensitivity to context is not reduced in early childhood; rather, it varies with the perceptual mechanisms or the levels of integration involved. In particular, development is protracted for size illusions in which contextual effects entail the extraction of the relations of dimensions within an object.

Frontoparietal Tracts Linked to Lateralized Hand Preference and Manual Specialization.

Humans show a preference for using the right hand over the left for tasks and activities of everyday life. While experimental work in non-human primates has identified the neural systems responsible for reaching and grasping, the neural basis of lateralized motor behavior in humans remains elusive. The advent of diffusion imaging tractography for studying connectional anatomy in the living human brain provides the possibility of understanding the relationship between hemispheric asymmetry, hand preference, and manual specialization. In this study, diffusion tractography was used to demonstrate an interaction between hand preference and the asymmetry of frontoparietal tracts, specifically the dorsal branch of the superior longitudinal fasciculus, responsible for visuospatial integration and motor planning. This is in contrast to the corticospinal tract and the superior cerebellar peduncle, for which asymmetry was not related to hand preference. Asymmetry of the dorsal frontoparietal tract was also highly correlated with the degree of lateralization in tasks requiring visuospatial integration and fine motor control. These results suggest a common anatomical substrate for hand preference and lateralized manual specialization in frontoparietal tracts important for visuomotor processing.

Cognitive archeology, body cognition, and hand-tool interaction.

Body cognition and lateralization can be investigated in fossils by integrating anatomical and functional aspects. Paleoneurology cannot provide strong evidence in this sense, because hemispheric asymmetries are shared in all extinct human species, and motor cortical areas are difficult to delineate in endocranial casts. However, paleoneurological analyses also suggest that modern humans and Neanderthals underwent an expansion of parietal regions crucial for visuospatial integration and eye-hand-tool management. Because of our technological specialization, haptic cognition can be particularly targeted by evolutionary processes. Hand-tool relationships can be investigated through physical and physiological correlates. In terms of metrics, size is the main factor of hand morphological variation among adult humans, followed by the ratio between thumb length and palmar size. In modern humans, emotional changes during hand-tool contact can be measured by electrodermal activity. During tool manipulation, electrodermal response, which is a physiological correlate of emotional engagement, shows differences between males and females, and it is different for distinct Paleolithic technologies. Emotional engagement, hand management, and haptic cognition are part of a specialized prosthetic technological capacity of modern humans and can provide indirect evidence of cognitive discontinuities in the archeological record.

Midsagittal Brain Variation among Non-Human Primates: Insights into Evolutionary Expansion of the Human Precuneus

The precuneus is a major element of the superior parietal lobule, positioned on the medial side of the hemisphere and reaching the dorsal surface of the brain. It is a crucial functional region for visuospatial integration, visual imagery, and body coordination. Previously, we argued that the precuneus expanded in recent human evolution, based on a combination of paleontological, comparative, and intraspecific evidence from fossil and modern human endocasts as well as from human and chimpanzee brains. The longitudinal proportions of this region are a major source of anatomical variation among adult humans and, being much larger in Homo sapiens, is the main characteristic differentiating human midsagittal brain morphology from that of our closest living primate relative, the chimpanzee. In the current shape analysis, we examine precuneus variation in non-human primates through landmark-based models, to evaluate the general pattern of variability in non-human primates, and to test whether precuneus proportions are influenced by allometric effects of brain size. Results show that precuneus proportions do not covary with brain size, and that the main difference between monkeys and apes involves a vertical expansion of the frontal and occipital regions in apes. Such differences might reflect differences in brain proportions or differences in cranial architecture. In this sample, precuneus variation is apparently not influenced by phylogenetic or allometric factors, but does vary consistently within species, at least in chimpanzees and macaques. This result further supports the hypothesis that precuneus expansion in modern humans is not merely a consequence of increasing brain size or of allometric scaling, but rather represents a species-specific morphological change in our lineage.

Abstract: Altered Brain Functional Connectivity Varies By Form of Craniosynostosis

INTRODUCTION: Recent studies have begun to elucidate the long-term neurocognitive and behavioral sequelae of nonsyndromic craniosynostosis (NSC).1,2 With advances in functional MRI (fMRI) techniques with improved statistical rigor, this study seeks to determine if there is neurologic evidence of altered brain connectivity in NSC, and to investigate if these aberrations vary by form of synostosis. METHODS. Twenty participants (average age 11.6 ± 2.27 years, 15 males) with surgically-treated NSC (10 sagittal (SSO), 5 right unilateral coronal (UCS), 5 metopic (MSO)) were individually matched to controls by age, gender, and handedness. Resting-state fMRI was acquired in a 3T Siemens TIM Trio scanner (Erlangen, Germany). Data was motion-corrected with SPM (University College London) and underwent CSF and WM signal regression. BioImage Suite (Yale School of Medicine) was then used to analyze whole-brain intrinsic connectivity as well as seed-based connectivity for Brodmann Areas (BA) 7, 39 and 40, which are areas of language and visuospatial integration that have been previously implicated.3 Resulting group-level t-maps were cluster-corrected using nonparametric permutation tests with 5000 permutations in FSL (FMRIB, Oxford, UK).4 RESULTS: SSO demonstrated decreased whole-brain intrinsic connectivity compared to controls in left BA-39 and bilateral BA-7’s (p=0.071), which are the superior parietal lobules and the angular gyrus. UCS had significantly decreased intrinsic connectivity throughout the prefrontal cortex (PFC, p=0.031). On seed-based analysis, UCS had significantly increased connectivity between left BA-40 and bilateral BA-6, BA-8, and BA-9, and left BA-32 (p=0.050), between left BA-7 and the anterior PFC (p=0.065), and between left BA-7 and right BA-7 and BA-9 (p=0.077). MSO demonstrated increased connectivity between the left BA-7 seed and the right inferior frontal gyrus and right insula (p=0.090). CONCLUSION: NSC is associated with altered brain connectivity that varies by type of synostosis. SSO had decreased connectivity in regions of the parietal cortex associated with spatial cognition, visuomotor integration, and attention. UCS demonstrated significantly decreased intrinsic connectivity in the PFC, which plays a crucial role in executive function, as well as increased connectivity between the PFC and the right parietal cortex. Finally, MSO was the only group to demonstrate aberrations in the right insula and right inferior frontal gyrus. This study provides neurologic evidence of long-term sequelae of NSC that varies by suture type, which may underlie different phenotypes of neuropsychiatric impairment. Reference Citations: 1. Hashim PW, Patel A, Yang JF, et al. The effects of whole-vault cranioplasty versus strip craniectomy on long-term neuropsychological outcomes in sagittal craniosynostosis. Plast Reconstr Surg. 2014;134(3):491–501. 2. Kapp-Simon KA, Wallace E, Collett BR, Cradock MM, Crerand CE, Speltz ML. Language, learning, and memory in children with and without single-suture craniosynostosis. J Neurosurg Pediatr. 2016;17(5):578–588. 3. Beckett JS, Brooks ED, Lacadie C, et al. Altered brain connectivity in sagittal craniosynostosis. J Neurosurg Pediatr. 2014;13(6):690–698. 4. Eklund A, Nichols TE, Knutsson H. Cluster failure: Why fMRI inferences for spatial extent have inflated false-positive rates. Proc Natl Acad Sci U S A. 2016;113(28):7900–7905.

Perceptual similarity and the neural correlates of geometrical illusions in human brain structure

Geometrical visual illusions are an intriguing phenomenon, in which subjective perception consistently misjudges the objective, physical properties of the visual stimulus. Prominent theoretical proposals have been advanced attempting to find common mechanisms across illusions. But empirically testing the similarity between illusions has been notoriously difficult because illusions have very different visual appearances. Here we overcome this difficulty by capitalizing on the variability of the illusory magnitude across participants. Fifty-nine healthy volunteers participated in the study that included measurement of individual illusion magnitude and structural MRI scanning. We tested the Muller-Lyer, Ebbinghaus, Ponzo, and vertical-horizontal geometrical illusions as well as a non-geometrical, contrast illusion. We found some degree of similarity in behavioral judgments of all tested geometrical illusions, but not between geometrical illusions and non-geometrical, contrast illusion. The highest similarity was found between Ebbinghaus and Muller-Lyer geometrical illusions. Furthermore, the magnitude of all geometrical illusions, and particularly the Ebbinghaus and Muller-Lyer illusions, correlated with local gray matter density in the parahippocampal cortex, but not in other brain areas. Our findings suggest that visuospatial integration and scene construction processes might partly mediate individual differences in geometric illusory perception. Overall, these findings contribute to a better understanding of the mechanisms behind geometrical illusions.

Sulcal pattern, extension, and morphology of the precuneus in adult humans

The precuneus represents a relevant cortical component of the parietal lobes. It is involved in visuospatial integration, imagery and simulation, self-awareness, and it is a main node of the Default Mode Network. Its morphology is extremely variable among adult humans, and it has been hypothesized to have undergone major morphological changes in the evolution of Homo sapiens. Recent studies have evidenced a marked variation also associated with its sulcal patterns. The present survey contributes to add further information on this topic, investigating the extension of its main folds, their geometrical influence on the lateral parietal areas, and the relationships with the sulcal schemes. The subparietal sulcus, on average, extends 14mm in its anterior and middle regions and 11mm in its posterior area. The precuneal area extends 36mm above this sulcus. The subparietal sulcus is generally wider on the right hemisphere. Males have larger values than females, but differences are not significant. Sulcal pattern is not correlated with the size of the subparietal sulcus extension. There is a lack of consistent correspondence between hemispheres in the sulcal patterns, pointing further towards a notable individual variability and random asymmetries. The vertical extension of the precuneus influences the height and proportions of the upper parietal profile, but the lateral parietal outline is not sensitive to precuneal variation. There is no correlation between external cortical shape and the size of the subparietal sulcus. Morphological analyses of the precuneus must be integrated with studies on histological factors involved in its variability and, ultimately, with analyses on possible relationships with functional factors.

Tract-specific white matter microstructure and gait in humans

Gait is a complex sequence of movements, requiring cooperation of many brain areas, such as the motor cortex, somatosensory cortex, and cerebellum. However, it is unclear which connecting white matter tracts are essential for communication across brain areas to facilitate proper gait. Using diffusion tensor imaging, we investigated associations of microstructural organization in 14 brain white matter tracts with gait, among 2330 dementia- and stroke-free community-dwelling individuals. Gait was assessed by electronic walkway and summarized into Global Gait, and 7 gait domains. Higher white matter microstructure associated with higher Global Gait, Phases, Variability, Pace, and Turning. Microstructure in thalamic radiations, followed by association tracts and the forceps major, associated most strongly with gait. Hence, in community-dwelling individuals, higher white matter microstructure associated with better gait, including larger strides, more single support, less stride-to-stride variability, and less turning steps. Our findings suggest that intact thalamocortical communication, cortex-to-cortex communication, and interhemispheric visuospatial integration are most essential in human gait.