Development of cortical folds in the human brain: An attempt to review biological hypotheses, early neuroimaging investigations and functional correlates

The folding of the human brain mostly takes place in utero, making it challenging to study. After a few pioneer studies looking into it in post-mortem foetal specimen, modern approaches based on neuroimaging have allowed the community to investigate the folding process in vivo, its normal progression, its early disturbances, and its relationship to later functional outcomes. In this review article, we aimed to first give an overview of the current hypotheses on the mechanisms governing cortical folding. After describing the methodological difficulties raised by its study in fetuses, neonates and infants with magnetic resonance imaging (MRI), we reported our current understanding of sulcal pattern emergence in the developing brain. We then highlighted the functional relevance of early sulcal development, through recent insights about hemispheric asymmetries and early factors influencing this dynamic such as prematurity. Finally, we outlined how longitudinal studies have started to relate early folding markers and the child's sensorimotor and cognitive outcome. Through this review, we hope to raise awareness on the potential of studying early sulcal patterns both from a fundamental and clinical perspective, as a window into early neurodevelopment and plasticity in relation to growth in utero and postnatal environment of the child.

Shape variability of the central sulcus in the developing brain: a longitudinal descriptive and predictive study in preterm infants

Despite growing evidence of links between sulcation and function in the adult brain, the folding dynamics, occurring mostly before normal-term-birth, is vastly unknown. Looking into the development of cortical sulci in infants can give us keys to address fundamental questions: what is the sulcal shape variability in the developing brain? When are the shape features encoded? How are these morphological parameters related to further functional development? In this study, we aimed to investigate the shape variability of the developing central sulcus, which is the frontier between the primary somatosensory and motor cortices. We studied a cohort of 71 extremely preterm infants scanned twice using MRI - once around 30 weeks post-menstrual age (w PMA) and once at term-equivalent age, around 40w PMA -, in order to quantify the sulcus's shape variability using manifold learning, regardless of age-group or hemisphere. We then used these shape descriptors to evaluate the sulcus's variability at both ages and to assess hemispheric and age-group specificities. This led us to propose a description of ten shape features capturing the variability in the central sulcus of preterm infants. Our results suggested that most of these features (8/10) are encoded as early as 30w PMA. We unprecedentedly observed hemispheric asymmetries at both ages, and the one captured at term-equivalent age seems to correspond with the asymmetry pattern previously reported in adults. We further trained classifiers in order to explore the predictive value of these shape features on manual performance at 5 years of age (handedness and fine motor outcome). The central sulcus's shape alone showed a limited but relevant predictive capacity in both cases. The study of sulcal shape features during early neurodevelopment may participate to a better comprehension of the complex links between morphological and functional organization of the developing brain.

Percutaneous dilatational tracheostomy for saturating influx of COVID-19 patients: Experience of military ENT physicians deployed in Mulhouse, France

OBJECTIVES

The main objective was to demonstrate the feasibility of percutaneous tracheostomy performed under difficult conditions by military ENT physicians during their deployment in the military intensive care field hospital of the French Military Medical Service in Mulhouse to confront the exceptional COVID-19 pandemic. The secondary objective was to assess reliability and safety for patient and caregivers, with a risk of iatrogenic viral contamination.

MATERIAL AND METHODS

A single-center retrospective study was conducted between March 25 and April 25, 2020, in 47 COVID-19 patients requiring prolonged mechanical ventilation. The inclusion criterion was having undergone percutaneous tracheostomy.

RESULTS

Eighteen consecutively included patients had successfully undergone percutaneous tracheostomy despite unfavorable anatomical conditions (short neck: 83.3%, overweight or obese: 88.9%). Median time to completion was 11 days after intubation, with an average duration of 7minutes. The procedure was technically compliant in 83.3% of cases, and considered easy (on self-assessment) in 72.2%, with 2 minor per-procedural complications. No crossover to surgery was required. There was only 1 major post-procedural complication (late hemorrhage).

CONCLUSION

This study showed the feasibility of percutaneous tracheostomy by an ENT physician under COVID-19 biohazard conditions. The technique was fast, easy and safe and met safety requirements for patient and staff.

[About a case of laryngeal location of SAPHO]

INTRODUCTION

Synovitis, acne, pustulosis, hyperostosis, osteitis (SAPHO) is a syndrome that combines dermatological, articular and osseous inflammatory manifestations. Bilateral laryngeal immobility relative to cricoarytenoid joint origin is very uncommon. This article presents a case of bilateral cricoarytenoid joint ankylosis in a SAPHO syndrome context.

CASE REPORT

A 53-year-old patient presenting with a two year history of intermittent bouts of dyspnea. A SAPHO syndrome was discussed on repeated thoracic CT-scan. The link between dyspnea and SAPHO syndrome had not been made immediately given the absence of any known anteriority. However, having ruled out other etiologies and after having had to perform a tracheotomy due a worsening of the respiratory condition, this diagnosis was considered. Treatment by corticosteroids and infliximab permitted a clinical improvement of the patient.

CONCLUSION

This clinical case report should increase awareness of possible cricoarytenoid joint involvement in SAPHO.

Active and placebo transcranial magnetic stimulation effects on external and internal auditory hallucinations of schizophrenia

OBJECTIVE

Repetitive transcranial magnetic stimulation (rTMS) over the left temporo-parietal region has been proposed as a treatment for resistant auditory verbal hallucinations (AVH), but which patients are more likely to benefit from rTMS is still unclear. This study sought to assess the effects of rTMS on AVH, with a focus on hallucination phenomenology.

METHOD

Twenty-seven patients with schizophrenia and medication-resistant AVH participated to a randomized, double-blind, placebo-controlled, add-on rTMS study. The stimulation targeted a language-perception area individually determined using functional magnetic resonance imaging and a language recognition task. AVH were assessed using the hallucination subscale of the Scale for the Assessment of Positive Symptoms (SAPS). The spatial location of AVH was assessed using the Psychotic Symptom Rating Scales.

RESULTS

A significant improvement in SAPS hallucination subscale score was observed in both actively treated and placebo-treated groups with no difference between both modalities. Patients with external AVH were significantly more improved than patients with internal AVH, with both modalities.

CONCLUSIONS

A marked placebo effect of rTMS was observed in patients with resistant AVH. Patients with prominent external AVH may be more likely to benefit from both active and placebo interventions. Cortical effects related to non-magnetic stimulation of the auditory cortex are suggested.

Longitudinal stability of the folding pattern of the anterior cingulate cortex during development

Prenatal processes are likely critical for the differences in cognitive ability and disease risk that unfold in postnatal life. Prenatally established cortical folding patterns are increasingly studied as an adult proxy for earlier development events - under the as yet untested assumption that an individual's folding pattern is developmentally fixed. Here, we provide the first empirical test of this stability assumption using 263 longitudinally-acquired structural MRI brain scans from 75 typically developing individuals spanning ages 7 to 32 years. We focus on the anterior cingulate cortex (ACC) - an intensely studied cortical region that presents two qualitatively distinct and reliably classifiable sulcal patterns with links to postnatal behavior. We show - without exception-that individual ACC sulcal patterns are fixed from childhood to adulthood, at the same time that quantitative anatomical ACC metrics are undergoing profound developmental change. Our findings buttress use of folding typology as a postnatally-stable marker for linking variations in early brain development to later neurocognitive outcomes in ex utero life.

[Covering of parotid and cervical lymph nodes metastasis of cutaneous squamous cell carcinoma of the head, about 18 cases]

AIM

To describe 18 cases of patients treated for advanced cutaneous squamous cell carcinoma (CSCC) of the head metastasing to cervical lymph nodes and parotid gland. To estimate their survival and the risk factors of metastases.

PATIENTS AND METHODS

18 cases of patients affected by CSCC of the head, metastatic to parotid and cervical lymph nodes were afterward analyzed. Two populations were differentiated: the patients already treated for their CSCC, with secondary appearance of metastases in the Population A, the patients by whom the metastase is concomitantly discovered to the CSCC in the Population B.

RESULTS

The treatment consisted of a parotidectomy and neck dissection, possibly associated with excision of the primary tumour. Adjuvant radiotherapy was systematic. Metastatic progression was on lungs most of the time (57%), in patients of the population B (80%), or of whom primitive CSCC was of bad forecast (group 2) (78%). The mortality was bound to the complications induced by distant metastases (63%), at 5 years it was superior in the population B (100%) than in the population A (77%).

CONCLUSION

CSCC of the head, metastatic to parotid and cervical lymph nodes have a severe prognosis for survival in spite of an optimal curative treatment applied to fragile old patients.

[Sarcoidosis of the thyroid: A case report]

OBJECTIVE

To present a case of thyroid sarcoidosis revealed by a multinodular goiter and cervical and mediastinal adenopathies.

METHODS

We summarize the clinical presentation of a thyroid sarcoidosis. A review of literature regarding this topic is also presented.

RESULTS

A 48-year-old woman presented dysphagia without dyspnea. Clinical and radiological explorations find a multinodular goiter with cervical and mediastinal adenopathies. The symptomatic side of the goiter and the association with adenopathies justify the surgery. Total thyroidectomy and mediastinal lymphadenectomy are processed. Histopathological examination of the thyroid reveal a goiter without malignity, a vesicular nodule, and non necrotizing granulomas consistent with sarcoidosis, as in the adenopathy.

CONCLUSION

The interest here, is the difficulty to make the diagnostic without histopathology, between a thyroid cancer with lymphadenopathies and extrapulmonary sarcoidosis (involving thyroid and adenopathies).

[Multiple intracranial epidermoid cysts: Case report]

Epidermoid cyst is a benign and rare tumor, that evolves slowly. We describe the case of a 55 years-old woman, who came to our consultation for atypical trigeminal neuralgia of left V1 and V2 nerves. Brain MRI found two tumors: T1W hypointense with no appreciable enhancement after gadolinium injection and T2W and diffusion hyperintense. This last feature was in favour of an epidermoid cyst, but the multiplicity of cerebral lesions was definitely not in favor of such a diagnos­tic. They were located behind the right eye and in the left Meckel’s cave (trigeminal cave). The surgical strategy consis­ted in removal the retro orbital tumor witch was the most acces­si­ble of both the diagnostic of epidermoid cyst was retaned thanks to the anatomopathology report. As these lesions had the exact same characteristics, we concluded that they were simi­lar. The second epidermoid cyst was not removed because of surgical risk, its benign nature and low evolutionary potential.

[Role of positron emission tomography and CT with 18F-FDG PET-CT in follow-up of patients treated for head and neck squamous cell carcinoma]

The authors in this article, made from a review of the scientific literature (PubMed search engine), indicate the current position of positron emission tomography with 18F-fluro-2-deoxy-D-glucose coupled computed tomography (PET-CT) in the early and late post-treatment follow up of squamous cell carcinomas of the upper aerodigestive tract. The aim of this follow up is twofold: Early detection of locoregional progressive evolution or metastatic progression and search for a possible second metachronous cancer in patients at risk.

[Diagnosis and treatment of post-traumatic perilymphatic fistula: Report of 16 cases]

INTRODUCTION

When facing cochleovestibular symptoms such as hearing loss, dizziness or unsteadiness, or a tinnitus evolving in the aftermath of a cranial trauma or overpressure in the form of inner ear barotrauma after diving or a from blast, a perilymphatic fistula must be considered.

MATERIALS AND METHODS

We present a homogenous prospective series of 16 cases of perilymphatic fistulae occurring after head trauma or overpressure between 2003 and 2011. Patients suspected of suffering from a perilymphatic fistula and presenting with the following criteria were included: the occurrence after a variable delay of cochleovestibular symptoms (vertigo, tinnitus, and hearing loss) in the aftermath of a head trauma or overpressure. All patients received medical treatment with intravenous corticosteroids. Failure of the initial treatment and in the presence of clinical data suggesting a perilymphatic fistula, an exploration of the middle ear was performed.

RESULTS

13 patients (81.2% underwent surgical exploration with early and stable subtotal recovery of hearing in 90%, a rapid disappearance of vertigo in 89.9%, a loss of tinnitus in 45% and in 27% improvement.

CONCLUSION

The diagnosis must be supported by various diagnostic tests. If evidence in favor of a perilymphatic fistula is credible, surgery has always achieved an excellent functional outcome.

Robust clustering of massive tractography datasets

This paper presents a clustering method that detects the fiber bundles embedded in any MR-diffusion based tractography dataset. Our method can be seen as a compressing operation, capturing the most meaningful information enclosed in the fiber dataset. For the sake of efficiency, part of the analysis is based on clustering the white matter (WM) voxels rather than the fibers. The resulting regions of interest are used to define subset of fibers that are subdivided further into consistent bundles using a clustering of the fiber extremities. The dataset is reduced from more than one million fiber tracts to about two thousand fiber bundles. Validations are provided using simulated data and a physical phantom. We see our approach as a crucial preprocessing step before further analysis of huge fiber datasets. An important application will be the inference of detailed models of the subdivisions of white matter pathways and the mapping of the main U-fiber bundles.

Model-driven parameterization of the cortical surface for localization and inter-subject matching

In this paper we present a generic and organized model of cortical folding, and a way to implement this model on any given cortical surface. This results in a model-driven parameterization, providing an anatomically meaningful coordinate system for cortical localization, and implicitly defining inter-subject surface matching without any deformation of surfaces. We present our cortical folding model and show how it naturally defines a parameterization of the cortex. The mapping of the model to any given cortical surface is detailed, leading to an anatomically invariant coordinate system. The process is evaluated on real data in terms of both anatomical and functional localization, and shows improved performance compared to a traditional volume-based normalization. It is fully automatic and available with the BrainVISA software platform.

Nitric oxide production by the alveolar compartment of the lungs in cirrhotic patients

In cirrhotic patients, alveolar nitric oxide (NO) concentration is increased. This may be secondary to increased output of NO produced by the alveoli (V'(A,NO)) and/or to decreased lung transfer factor of NO. In advanced liver cirrhosis, NO produced by the alveoli may play a role in abnormalities of pulmonary haemodynamics and gas exchanges. In cirrhotic patients, we aimed to measure V'(A,NO) and to compare V'(A,NO) with pulmonary haemodynamics and gas exchange parameters. Measurements were performed in 22 healthy controls and in 29 cirrhotic patients, of whom eight had hepatopulmonary syndrome. Exhaled NO concentrations were measured at multiple expiratory flow rates to derive alveolar NO concentration. V'(A,NO) was the product of alveolar NO concentration by single breath lung transfer factor for NO. V'(A,NO) was increased in patients (median (range) 260 (177-341) nL x min(-1)) compared with controls (79 (60-90), p<0.0001). Alveolar-arterial oxygen tension difference failed to correlate with V'(A,NO). However, cardiac index correlated positively and systemic vascular resistance correlated negatively with V'(A,NO) (r = 0.56, p = 0.001 and r = -0.52, p = 0.004, respectively). In cirrhotic patients, NO was produced in excess by the alveolar compartment of the lungs. Alveolar NO production was associated with hyperdynamic circulatory syndrome but not with arterial oxygenation impairment.

Automatic inference of sulcus patterns using 3D moment invariants

The goal of this work is the automatic inference of frequent patterns of the cortical sulci, namely patterns that can be observed only for a subset of the population. The sulci are detected and identified using brainVISA open software. Then, each sulcus is represented by a set of shape descriptors called the 3D moment invariants. Unsupervised agglomerative clustering is performed to define the patterns. A ratio between compactness and contrast among clusters is used to select the best patterns. A pattern is considered significant when this ratio is statistically better than the ratios obtained for clouds of points following a Gaussian distribution. The patterns inferred for the left cingulate sulcus are consistent with the patterns described in the atlas of Ono.

MR diffusion-based inference of a fiber bundle model from a population of subjects

This paper proposes a method to infer a high level model of the white matter organization from a population of subjects using MR diffusion imaging. This method takes as input for each subject a set of trajectories stemming from any tracking algorithm. Then the inference results from two nested clustering stages. The first clustering converts each individual set of trajectories into a set of bundles supposed to represent large white matter pathways. The second clustering matches these bundles across subjects in order to provide a list of candidates for the bundle model. The method is applied on a population of eleven subjects and leads to the inference of 17 such candidates.

Anatomically constrained surface parameterization for cortical localization

We present here a method that aims at defining a surface-based coordinate system on the cortical surface. Such a system is needed for both cortical localization and intersubject matching in the framework of neuroimaging. We propose an automatic parameterization based on the spherical topology of the grey/white matter interface of each hemisphere and on the use of naturally organized and reproducible anatomical features. From those markers used as initial constraints, the coordinate system is propagated via a PDE solved on the cortical surface.

Modulation of language areas with functional MR image-guided magnetic stimulation

Repetitive transcranial magnetic stimulation (rTMS) can interfere with linguistic performance when delivered over language areas. At low frequency (1 Hz), rTMS is assumed to decrease cortical excitability; however, the degree of TMS effect on cortical language areas may depend on the localization of the stimulation coil with respect to the inter-individual anatomo-functional variations. Hence, we aimed at investigating individual brain areas involved in semantic and phonological auditory processes. We hypothesized that active rTMS targeted over Wernicke's area might modify the performance during a language-fragment-detection task. Sentences in native or foreign languages were presented to 12 right-handed male healthy volunteers during functional magnetic resonance imaging (fMRI). 3D-functional maps localized the posterior temporal activation (Wernicke) in each subject and MRI anatomical cortical landmarks were used to define Broca's pars opercularis (F3Op). A frameless stereotaxy system was used to guide the TMS coil position over Wernicke's and F3Op areas in each subject. Active and placebo randomized rTMS sessions were applied at 1 Hz, 110% of motor threshold, during the same language-fragment-detection task. Accuracy and response time (RT) were recorded. RT was significantly decreased by active rTMS compared to placebo over Wernicke's area, and was more decreased for native than for foreign languages. No significant RT change was observed for F3Op area. rTMS conditions did not impair participants' accuracy. Thus, low-frequency rTMS over Wernicke's area can speed-up the response to a task tapping on native language perception in healthy volunteers. This individually-guided stimulation study confirms that facilitatory effects are not confined to high-frequency rTMS.

Effects of brisk walking on static and dynamic balance, locomotion, body composition, and aerobic capacity in ageing healthy active men

This work analyses the short-term physiological and neurophysiological effects of a brisk walking programme in ageing, healthy, active men. Twenty-one men 63 to 72 years of age were recruited and separated into 2 groups. One group performed a walking programme (WP) (n = 11) and another served as control (C) group (n = 10). The walking programme lasted for twelve weeks and included five sessions per week. Several parameters were assessed before and after the programme for the WP group. The same tests were performed (separated by twelve weeks) in group C. During each assessment, the subjects were put through static and dynamic balance tests, spatio-temporal gait analysis, body composition measurements and determination of aerobic capacity and bone mineral density. The statistic analysis showed a significant improvement in dynamic balance performance, especially in lateral sway when the subjects kept their eyes open, an increase of VO(2) max and loss of fat mass in the WP group. However, no alterations appeared in spatiotemporal gait characteristics, static balance performance, lean mass or bone mineral density (total body and hip). According to these results, this walking programme may have positive effects on preventing ageing subjects from falling.

Fiber tracking in q-ball fields using regularized particle trajectories

Most of the approaches dedicated to fiber tracking from diffusion-weighted MR data rely on a tensor model. However, the tensor model can only resolve a single fiber orientation within each imaging voxel. New emerging approaches have been proposed to obtain a better representation of the diffusion process occurring in fiber crossing. In this paper, we adapt a tracking algorithm to the q-ball representation, which results from a spherical Radon transform of high angular resolution data. This algorithm is based on a Monte-Carlo strategy, using regularized particle trajectories to sample the white matter geometry. The method is validated using a phantom of bundle crossing made up of haemodialysis fibers. The method is also applied to the detection of the auditory tract in three human subjects.

Brain morphometry using 3D moment invariants

This paper advocates the use of shape descriptors based on moments of 3D coordinates for morphometry of the cortical sulci. These descriptors, which have been introduced more than a decade ago, are invariant relatively to rotations, translations and scale and can be computed for any topology. A rapid insight into the derivation of these invariants is proposed first. Then, their potential to characterize shapes is shown from a principal component analysis of the 12 first invariants computed for 12 different deep brain structures manually drawn for 7 different brains. Finally, these invariants are used to find some correlates of handedness and sex among the shapes of 116 different cortical sulci automatically identified in each of 142 brains of the ICBM database.

Object-based morphometry of the cerebral cortex

Most of the approaches dedicated to automatic morphometry rely on a point-by-point strategy based on warping each brain toward a reference coordinate system. In this paper, we describe an alternative object-based strategy dedicated to the cortex. This strategy relies on an artificial neuroanatomist performing automatic recognition of the main cortical sulci and parcellation of the cortical surface into gyral patches. A set of shape descriptors, which can be compared across subjects, is then attached to the sulcus and gyrus related objects segmented by this process. The framework is used to perform a study of 142 brains of the International Consortium for Brain Mapping (ICBM) database. This study reveals some correlates of handedness on the size of the sulci located in motor areas, which was not detected previously using standard voxel based morphometry.

Coordinate-based versus structural approaches to brain image analysis

A basic issue in neurosciences is to look for possible relationships between brain architecture and cognitive models. The lack of architectural information in magnetic resonance images, however, has led the neuroimaging community to develop brain mapping strategies based on various coordinate systems without accurate architectural content. Therefore, the relationships between architectural and functional brain organizations are difficult to study when analyzing neuroimaging experiments. This paper advocates that the design of new brain image analysis methods inspired by the structural strategies often used in computer vision may provide better ways to address these relationships. The key point underlying this new framework is the conversion of the raw images into structural representations before analysis. These representations are made up of data-driven elementary features like activated clusters, cortical folds or fiber bundles. Two classes of methods are introduced. Inference of structural models via matching across a set of individuals is described first. This inference problem is illustrated by the group analysis of functional statistical parametric maps (SPMs). Then, the matching of new individual data with a priori known structural models is described, using the recognition of the cortical sulci as a prototypical example.

A generic framework for the parcellation of the cortical surface into gyri using geodesic Voronoï diagrams

In this paper we propose a generic automatic approach for the parcellation of the cortical surface into labeled gyri. These gyri are defined from a set of pairs of sulci selected by the user. The selected sulci are first automatically identified in the data, then projected onto the cortical surface. The parcellation stems from two nested Voronoï diagrams computed geodesically to the cortical surface. The first diagram provides the zones of influence of the sulci. The boundary between the two zones of influence of each selected pair of sulci stands for a gyrus seed. A second diagram yields the gyrus parcellation. The distance underlying the Voronoï diagram allows the method to interpolate the gyrus boundaries where the limiting sulci are interrupted. The method is illustrated with 12 different hemispheres.

A framework to study the cortical folding patterns

This paper describes a decade-long research program focused on the variability of the cortical folding patterns. The program has developed a framework of using artificial neuroanatomists that are trained to identify sulci from a database. The framework relies on a renormalization of the brain warping problem, which consists in matching the cortices at the scale of the folds. Another component of the program is the search for the alphabet of the folding patterns, namely, a list of indivisible elementary sulci. The search relies on the study of the cortical folding process using antenatal imaging and on backward simulations of morphogenesis aimed at revealing traces of the embryologic dimples in the mature cortical surface. The importance of sulcal-based morphometry is illustrated by a simple study of the correlates of handedness on asymmetry indices. The study shows for instance that the central sulcus is larger in the dominant hemisphere.

[Sport and atopy]

INTRODUCTION

The atopic diseases, asthma, allergic rhinitis and atopic dermatitis, are common in children, adolescents and young adults. They may have important consequences on physical exercise, especially asthma.

STATE OF ART

Elite athletes have been observed to have a high prevalence of asthma (and perhaps also rhinitis). The reasons for this observation are still debated, but different mechanisms linked to the intensity of physical activity in athletes are probably involved. Exercise-induced symptoms should be confirmed not only from the clinical history but also by objective measurements of lung function. In elite athletes confirmation of exercise-induced asthma might be difficult and may require special diagnostic tests such as bronchial provocation by eucapnic voluntary hyperventilation. Several drugs are effective in exercise-induced prevention of nasal and bronchial symptoms. Therapeutic approaches for atopic diseases in international guidelines (GINA and ARIA) are generally compatible with anti-doping laws but require compliance with specific prescription rules.

PERSPECTIVES

A better understanding of mechanisms and risk factors involved in the increase of asthma prevalence in elite athletes may permit prevention by modifying training conditions during exercise.

CONCLUSIONS

Atopic diseases are common in athletes. They require special therapeutic considerations. The increasing prevalence of respiratory asthma-like symptoms in elite athlete is opening new paths for research into airway physiology in extreme conditions.

Aerobic training improves exercise-induced lipolysis in SCAT and lipid utilization in overweight men

The aim of this study was to investigate whether endurance training improves lipid mobilization and oxidation in overweight subjects. Eleven young men (25.6 +/- 1.4 yr and body mass index 27.7 +/- 0.2) performed a 4-mo training program consisting of practicing aerobic exercise 5 days/wk. Before and after the training period, lipid oxidation was explored during a 60-min exercise at 50% of peak O2 consumption by use of indirect calorimetry. Lipid mobilization and antilipolytic alpha2-adrenoceptor effect were also studied using the microdialysis method in abdominal subcutaneous adipose tissue (SCAT). After training, plasma nonesterified fatty acid (NEFA) levels, at rest and during exercise, were significantly lower than before (P < 0.001). Lipolysis in SCAT was significantly higher after than before training. An antilipolytic alpha2-adrenoceptor effect in SCAT was underlined during exercise before training and disappeared after. The respiratory exchange ratio was lower after training, i.e., the percentage of lipid oxidation was higher only at rest. The amount of lipid oxidized was higher after training, at rest, and during exercise. Although exercise power was higher after training, the relative intensity was equivalent, as suggested by a similar increase in plasma catecholamine concentrations before and after training. In conclusion, 4-mo training in overweight men improved lipid mobilization through a decrease of antilipolytic alpha2-adrenoceptor effect in SCAT and lipid oxidation during moderate exercise. Training induced a decrease of blood NEFA, predicting better prevention of obesity.

Object-based strategy for morphometry of the cerebral cortex

Most of the approaches dedicated to automatic morphometry rely on a point-by-point strategy based on warping each brain towards a reference coordinate system. In this paper, we describe an alternative object-based strategy dedicated to the cortex. This strategy relies on an artificial neuroanatomist performing automatic recognition of the main cortical sulci and parcellation of the cortical surface into gyral patches. A set of shape descriptors, which can be compared across subjects, is then attached to the sulcus and gyrus related objects segmented by this process. The framework is used to perform a study of 142 brains of the ICBM database. This study reveals some correlates of handedness on the size of the sulci located in motor areas, which seem to be beyond the scope of the standard voxel based morphometry.

A primal sketch of the cortex mean curvature: a morphogenesis based approach to study the variability of the folding patterns

In this paper, we propose a new representation of the cortical surface that may be used to study the cortex folding process and to recover some putative stable anatomical landmarks called sulcal roots usually buried in the depth of adult brains. This representation is a primal sketch derived from a scale space computed for the mean curvature of the cortical surface. This scale-space stems from a diffusion equation geodesic to the cortical surface. The primal sketch is made up of objects defined from mean curvature minima and saddle points. The resulting sketch aims first at highlighting significant elementary cortical folds, second at representing the fold merging process during brain growth. The relevance of the framework is illustrated by the study of central sulcus sulcal roots from antenatal to adult age. Some results are proposed for ten different brains. Some preliminary results are also provided for superior temporal sulcus.