Anatomo-functional correspondence in the superior temporal sulcus

The superior temporal sulcus (STS) is an intriguing region both for its complex anatomy and for the multiple functions that it hosts. Unfortunately, most studies explored either the functional organization or the anatomy of the STS only. Here, we link these two aspects by investigating anatomo-functional correspondences between the voice-sensitive cortex (Temporal Voice Areas) and the STS depth. To do so, anatomical and functional scans of 116 subjects were processed such as to generate individual surface maps on which both depth and functional voice activity can be analyzed. Individual depth profiles of manually drawn STS and functional profiles from a voice localizer (voice > non-voice) maps were extracted and compared to assess anatomo-functional correspondences. Three major results were obtained: first, the STS exhibits a highly significant rightward depth asymmetry in its middle part. Second, there is an anatomo-functional correspondence between the location of the voice-sensitive peak and the deepest point inside this asymmetrical region bilaterally. Finally, we showed that this correspondence was independent of the gender and, using a machine learning approach, that it existed at the individual level. These findings offer new perspectives for the understanding of anatomo-functional correspondences in this complex cortical region

Atypical sulcal anatomy in young children with autism spectrum disorder

AbstractAutism spectrum disorder is associated with an altered early brain development. However, the specific cortical structure abnormalities underlying this disorder remain largely unknown. Nonetheless, atypical cortical folding provides lingering evidence of early disruptions in neurodevelopmental processes and identifying changes in the geometry of cortical sulci is of primary interest for characterizing these structural abnormalities in autism and their evolution over the first stages of brain development. Here, we applied state-of-the-art sulcus-based morphometry methods to a large highly-selective cohort of 73 young male children of age spanning from 18 to 108 months. Moreover, such large cohort was selected through extensive behavioral assessments and stringent inclusion criteria for the group of 59 children with autism. After manual labeling of 59 different sulci in each hemisphere, we computed multiple shape descriptors for each single sulcus element, hereby separating the folding measurement into distinct factors such as the length and depth of the sulcus. We demonstrated that the central, intraparietal and frontal medial sulci showed a significant and consistent pattern of abnormalities across our different geometrical indices. We also found that autistic and control children exhibited strikingly different relationships between age and structural changes in brain morphology. Lastly, the different measures of sulcus shapes were correlated with the CARS and ADOS scores that are specific to the autistic pathology and indices of symptom severity. Inherently, these structural abnormalities are confined to regions that are functionally relevant with respect to cognitive disorders in ASD. In contrast to those previously reported in adults, it is very unlikely that these abnormalities originate from general compensatory mechanisms unrelated to the primary pathology. Rather, they most probably reflect an early disruption on developmental trajectory that could be part of the primary pathology

A specific brain structural basis for individual differences in reality monitoring.

Much recent interest has centered on understanding the relationship between brain structure variability and individual differences in cognition, but there has been little progress in identifying specific neuroanatomical bases of such individual differences. One cognitive ability that exhibits considerable variability in the healthy population is reality monitoring; the cognitive processes used to introspectively judge whether a memory came from an internal or external source (e.g., whether an event was imagined or actually occurred). Neuroimaging research has implicated the medial anterior prefrontal cortex (PFC) in reality monitoring, and here we sought to determine whether morphological variability in a specific anteromedial PFC brain structure, the paracingulate sulcus (PCS), might underlie performance. Fifty-three healthy volunteers were selected on the basis of MRI scans and classified into four groups according to presence or absence of the PCS in their left or right hemisphere. The group with absence of the PCS in both hemispheres showed significantly reduced reality monitoring performance and ability to introspect metacognitively about their performance when compared with other participants. Consistent with the prediction that sulcal absence might mean greater volume in the surrounding frontal gyri, voxel-based morphometry revealed a significant negative correlation between anterior PFC gray matter and reality monitoring performance. The findings provide evidence that individual differences in introspective abilities like reality monitoring may be associated with specific structural variability in the PFC

Anatomical characterization of human fetal brain development with diffusion tensor magnetic resonance imaging

Thehumanbrain is extraordinarily complex, and yet its origin is a simple tubular structure. Characterizing its anatomy at different stages of human fetal brain development not only aids in understanding this highly ordered process but also provides clues to detecting abnormalities caused by genetic or environmental factors. During the second trimester of human fetal development, neural structures in the brain undergo significant morphological changes. Diffusion tensor imaging (DTI), a novel method of magnetic resonance imaging, is capable of delineating anatomical components with high contrast and revealing structures at the microscopic level. In this study, high-resolution and high-signal-to-noise-ratio DTI data of fixed tissues of second-trimester human fetal brains were acquired and analyzed. DTI color maps and tractography revealed that important white matter tracts, such as the corpus callosum and uncinate and inferior longitudinal fasciculi, become apparent during this period. Three-dimensional reconstruction shows that major brain fissures appear while most of the cerebral surface remains smooth until the end of the second trimester. A dominant radial organization was identified at 15 gestational weeks, followed by both laminar and radial architectures in the cerebral wall throughout the remainder of the second trimester. Volumetric measurements of different structures indicate that the volumes of basal ganglia and ganglionic eminence increase along with that of the whole brain, while the ventricle size decreases in the later second trimester. The developing fetal brain DTI database presented can be used for education, as an anatomical research reference, and for data registration

Pain-related Somato Sensory Evoked Potentials: A potential new tool to improve the prognostic prediction of coma after cardiac arrest

INTRODUCTION: Early prediction of a good outcome in comatose patients after cardiac arrest still remains an unsolved problem. The main aim of the present study was to examine the accuracy of middle-latency SSEP triggered by a painful electrical stimulation on median nerves to predict a favorable outcome. METHODS: No- and low-flow times, pupillary reflex, Glasgow motor score and biochemical data were evaluated at ICU admission. The following were considered within 72 h of cardiac arrest: highest creatinine value, hyperthermia occurrence, EEG, SSEP at low- (10 mA) and high-intensity (50 mA) stimulation, and blood pressure reactivity to 50 mA. Intensive care treatments were also considered. Data were compared to survival, consciousness recovery and 6-month CPC (Cerebral Performance Category). RESULTS: Pupillary reflex and EEG were statistically significant in predicting survival; the absence of blood pressure reactivity seems to predict brain death within 7 days of cardiac arrest. Middle- and short-latency SSEP were statistically significant in predicting consciousness recovery, and middle-latency SSEP was statistically significant in predicting 6-month CPC outcome. The prognostic capability of 50 mA middle-latency-SSEP was demonstrated to occur earlier than that of EEG reactivity. CONCLUSIONS: Neurophysiological evaluation constitutes the key to early information about the neurological prognostication of postanoxic coma. In particular, the presence of 50 mA middle-latency SSEP seems to be an early and reliable predictor of good neurological outcome, and its absence constitutes a marker of poor prognosis. Moreover, the absence 50 mA blood pressure reactivity seems to identify patients evolving towards the brain death

How to run a brain bank. A report from the Austro-German brain bank

The sophisticated analysis of and growing information on the human brain requires that acquisition, dissection, storage and distribution of rare material are managed in a professional way. In this publication we present the concept and practice of our brain bank. Both brain tissue and information are handled by standardized procedures and flow in parallel from pathology to neuropathology and neurochemistry. Data concerning brain material are updated with clinical information gained by standardized procedures

Local neuronal dynamics in planning during Wisconsin card sorting test in ADHD

Jotta tehokkaiden ja tuotteliaiden päätösten tekeminen on mahdollista, ihmisen tulee suunnitella toimintaansa läpi elämän oleellisen tiedon ylläpitämisen ja päivittämisen avulla. Tällaiset tavoitteelliset tilanteet vaativat joustavaa käyttäytymisen hienosäätöä ja epäoleellisen tiedon vaimentamista. Toiminnanohjauksessa vaadittava kognitiivinen joustavuus, työmuisti ja inhibitio, on liitetty poikkeavaa etuaivokuoren toimintaan. Etuaivokuoren on aiemmin havaittu toimivan taaemmilta alueilta tulevan aistitiedon prosessoijana. Rakenteellisia ja toiminnallisia poikkeavuuksia on löydetty aktiivisuuden ja tarkkaavuuden häiriössä (ADHD) liittyen toiminnanohjauksen aivoalueisiin. Perustana oleva syy toiminnanohjauksen häiriöön ja vaikeuksiin suunnittelussa sekä päätöksenteossa saattaa löytyä yllä mainituista poikkeavuuksista. On silti epäselvää, miten aivojen oskillaatiot muokkaavat erilasia kognitiivisia toimintoja suunnitteluun ja päätöksentekoon liittyen. Tämän tutkimiseksi aivotoimintaa mitattiin MEG-laitteella koehenkilöiden (21 ADHD, 28 kontrolliosallistujaa) suorittaessa Wisconsin korttienlajittelutehtävää (WCST). WCST on nopeatempoinen tehtävä, jossa lajitellaan kortteja muuttuvien sääntöjen mukaan palautetta apuna käyttäen. Tämän tutkimuksen tarkoituksena oli tutkia ADHD-aikuisia ja kontrolliryhmää WCST-suunnitteluvaiheen aikana verraten kokeen suorittamista aiemmin saadun oikean tai väärän palautteen mukaan. ADHD ja kontrolliryhmän välillä odotettiin eroa paikallisessa hermosolutoiminnassa etuaivokuorella ja taaemmilla alueilla. Data-analyysi sekä lähdemallinnus ja - rekonstruktio tehtiin neuronaalisten (MEG) mittausten ja aivojen rakenteellisten (MRI) mittausten perusteella. Tilastolliset analyysit tehtiin selvittäen paikallisten hermosolujen amplitudidynamiikkaa ja visualisoitiin ryhmien sisällä ja välillä. Reaktioajat ja osumatarkkuus eivät osoittaneet merkittäviä eroja ryhmien välillä. Kuitenkin kontrasti suunnittelun aikana verraten oikeita-vääriä vastauksia, ilmensi tehostunutta ja vaimentunutta aivotoimintaa delta-, theta-, alfa- ja beta-oskillaatioissa. Kontrolliryhmä osoitti aktiivisuutta etuaivokuoressa-, parietaalisessa, temporaalisessa ja näköaivoalueilla. Nämä alueet on aiemmin liitetty ns. oletustilan verkostoon sekä somaattis liikkeelliseen verkostoon. Tehostunutta aktiivisuutta havaittiin beta- ja alfa -oskillaatioissa. ADHD -ryhmässä suurin positiivinen aktiivisuus havaittiin etuaivolohkossa ja parietaali- sekä kuuloaivoalueella, jotka on liitetty kahteen huomioverkostoon ja somaattis-liikkeelliseen, mutta myös oletustilan ja näköaivoalueiden verkkoon. Ryhmien välisessä vertailussa havaittiin vaimentunutta delta-, theta- ja alfa -oskillaatioiden aktiivisuutta aivojen lateraalisilla alueilla temporaalilohkolla. Nämä alueet liittyivät ventraalisen huomion ja somaattis-liikkeelliseen verkkoihin. Heikentynyttä aivotoimintaa havaittiin ADHD -ryhmässä vaimentuneissa positiivisesti aktivoituneissa betaoskillaatioissa verrattuna kontrolliryhmään ja kokonaan puuttuvista positiivisesti aktivoituneissa alfa -oskillaatioissa. Tulevien tutkimusten tehtäväksi jää näiden värähtelyiden toiminnan roolien tulkitseminen. Suuntaa-antavia tuloksia ADHD potilaiden aivotoiminnan poikkeavuudesta voitiin löytää aivoalueista ja toiminnasta jotka liittyvät joustavuuden ja työmuistin rooleihin suunnittelussa ja päätöksenteossa. Tulokset viittaavat myös siihen, että WCST:n suunnittelu edellyttää monien kognitiivisten toimintojen ja prosessien joustavaa organisaatiota, joita moduloivat tehostuneet alfa- ja beta -oskillaatiot sekä vaimentuneet delta- ja theta -värähtelyt.To make fast and efficient decisions in changing environments, humans must plan their actions throughout their lives by maintaining and updating relevant information. Such goal-directed situations demand flexible adjustment of behavior and the suppression of task-irrelevant details. Executive dysfunctions in cognitive flexibility, working memory and inhibition have been related to aberrant prefrontal cortex functioning. The prefrontal cortex has previously been found to have an important role in these executive functions as a supervisory modulator and processor of information from posterior sensory brain areas. Structural and functional abnormalities in these brain areas have been found in attention deficit/hyperactivity disorder (ADHD). These impairments may be the underlying reason for problems in decision making and planning for people with ADHD. However how the brain’s oscillatory activity modulates different cognitive functions in areas relating to planning and decision making is still unclear. To investigate thisthe brain’s activity was measured with MEG while participants (21 ADHD patients, 28 controls) performed in Wisconsin card sorting test (WCST). WCST is a fast-paced task, where cards are sorted according to changing rule categories with the direction of feedback. The aim of this study was to investigate planning in adults with ADHD and a control group during WCST planning period and compare trials with previous feedback being correct or incorrect. Difference in the local neuronal activity in prefrontal and posterior areas were expected between the ADHD and control groups. Data-analysis and source modelling and reconstruction were conducted on the neuronal (MEG) data and structural (MRI) data. Statistical analyses were run for local neuronal amplitude dynamics and visualized within and between groups. The behavioral results of reaction times and hit rates did not show significant differences between groups. Clinical questionnaire scores did not correlate with reaction times. However, contrast of planning in correct-incorrect feedback trials within groups showed increased and decreased brain activity in delta, theta, alpha and beta oscillations. The control group showed activity in frontal, parietal, temporal, and occipital regions related to default mode, somatomotor with increased activity in the beta and alpha bands. For the ADHD group greatest positive activity was seen in beta band in frontal and parietal areas, but also in occipital regions. These activation sites were mostly related to dorsal and ventral attention and somatomotor networks but also to default mode and visual networks. Mostly temporal activity of suppressed delta, theta and alpha oscillations in the lateral areas was seen in the between groups comparison. These areas related to ventral attention and somatomotor networks. Impaired neuronal activity in the ADHD group was seen in weaker increased beta than the control group and the missing increased alpha oscillations. It remains for the future studies to interpret the roles of this oscillatory activity but direction towards impairments in cognitive functions like flexibility, working memory and inhibition in planning in ADHD. These data also suggest that planning in the WCST needs the flexible modulation of many cognitive functions and processes that are modulated by increased alpha and beta oscillations and the suppressed delta and theta oscillations

Convergent and divergent fMRI responses in children and adults to increasing language production demands

In adults, patterns of neural activation associated with perhaps the most basic language skill—overt object naming—are extensively modulated by the psycholinguistic and visual complexity of the stimuli. Do children's brains react similarly when confronted with increasing processing demands, or they solve this problem in a different way? Here we scanned 37 children aged 7–13 and 19 young adults who performed a well-normed picture-naming task with 3 levels of difficulty. While neural organization for naming was largely similar in childhood and adulthood, adults had greater activation in all naming conditions over inferior temporal gyri and superior temporal gyri/supramarginal gyri. Manipulating naming complexity affected adults and children quite differently: neural activation, especially over the dorsolateral prefrontal cortex, showed complexity-dependent increases in adults, but complexity-dependent decreases in children. These represent fundamentally different responses to the linguistic and conceptual challenges of a simple naming task that makes no demands on literacy or metalinguistics. We discuss how these neural differences might result from different cognitive strategies used by adults and children during lexical retrieval/production as well as developmental changes in brain structure and functional connectivity