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Query: UMLS:C0004352 (autism)
 32,579 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study presents the first three-dimensional mapping of cortical sulcal patterns in autism, a pervasive developmental disorder, the underlying neurobiology of which remains unknown. High-resolution T(1)-weighted MRI scans were acquired in 21 autistic (age 10.7 +/- 3.1 years) and 20 normal control (age 11.3 +/- 2.9) children and adolescents. Using parametric mesh-based analytic techniques, we created three-dimensional models of the cerebral cortex and detailed maps of 22 major sulci in stereotaxic space. These average maps revealed anatomic shifting of major sulci primarily in frontal and temporal areas. Specifically, we found anterior and superior shifting of the superior frontal sulci bilaterally (P < or = 0.0003), anterior shifting of the right Sylvian fissure (P = 0.0002), the superior temporal sulcus (P = 0.0006 right, P = 0.02 left) and the left inferior frontal sulcus (P < or = 0.002) in the autistic group relative to the normal group. Less significant sulcal shifts occurred in the intraparietal and collateral sulci. These findings may indicate delayed maturation in autistic subjects in these brain regions involved in functions including working memory, emotion processing, language and eye gaze.
Cereb Cortex 2003 Jul
PMID:Cortical sulcal maps in autism. 1281 88

Autism spectrum disorder (ASD) is a neurodevelopmental disorder associated with impaired social and emotional skills, the anatomical substrate of which is still unknown. In this study, we compared a group of 14 high-functioning ASD adults with a group of controls matched for sex, age, intelligence quotient, and handedness. We used an automated technique of analysis that accurately measures the thickness of the cerebral cortex and generates cross-subject statistics in a coordinate system based on cortical anatomy. We found local decreases of gray matter in the ASD group in areas belonging to the mirror neuron system (MNS), argued to be the basis of empathic behavior. Cortical thinning of the MNS was correlated with ASD symptom severity. Cortical thinning was also observed in areas involved in emotion recognition and social cognition. These findings suggest that the social and emotional deficits characteristic of autism may reflect abnormal thinning of the MNS and the broader network of cortical areas subserving social cognition.
Cereb Cortex 2006 Sep
PMID:Anatomical differences in the mirror neuron system and social cognition network in autism. 1630 24

The brain activation of a group of high-functioning autistic participants was measured using functional magnetic resonance imaging during the performance of a Tower of London task, in comparison with a control group matched with respect to intelligent quotient, age, and gender. The 2 groups generally activated the same cortical areas to similar degrees. However, there were 3 indications of underconnectivity in the group with autism. First, the degree of synchronization (i.e., the functional connectivity or the correlation of the time series of the activation) between the frontal and parietal areas of activation was lower for the autistic than the control participants. Second, relevant parts of the corpus callosum, through which many of the bilaterally activated cortical areas communicate, were smaller in cross-sectional area in the autistic participants. Third, within the autism group but not within the control group, the size of the genu of the corpus callosum was correlated with frontal-parietal functional connectivity. These findings suggest that the neural basis of altered cognition in autism entails a lower degree of integration of information across certain cortical areas resulting from reduced intracortical connectivity. The results add support to a new theory of cortical underconnectivity in autism, which posits a deficit in integration of information at the neural and cognitive levels.
Cereb Cortex 2007 Apr
PMID:Functional and anatomical cortical underconnectivity in autism: evidence from an FMRI study of an executive function task and corpus callosum morphometry. 1677 13

The neurotransmitter serotonin (5-HT) plays morphogenetic roles during development, and their alteration could contribute to autism pathogenesis in humans. To further characterize 5-HT's contributions to neocortical development, we assessed the thickness and neuronal cell density of various cerebral cortical areas in serotonin transporter (5-HTT) knockout (ko) mice, characterized by elevated extracellular 5-HT levels. The thickness of layer IV is decreased in 5-HTT ko mice compared with wild-type (wt) mice. The overall effect on cortical thickness, however, depends on the genetic background of the mice. Overall cortical thickness is decreased in many cortical areas of 5-HTT ko mice with a mixed c129-CD1-C57BL/6J background. Instead, 5-HTT ko mice backcrossed into the C57BL/6J background display increases in supragranular and infragranular layers, which compensate entirely for decreased layer IV thickness, resulting in unchanged or even enhanced cortical thickness. Moreover, significant increases in neuronal cell density are found in 5-HTT ko mice with a C57BL/6J background (wt:hz:ko ratio = 1.00:1.04:1.17) but not in the mixed c129-CD1-C57BL/6J 5-HTT ko animals. These results provide evidence of 5-HTT gene effects on neocortical morphology in epistatic interaction with genetic variants at other loci and may model the effect of functional 5-HTT gene variants on neocortical development in autism.
Cereb Cortex 2007 Jun
PMID:Altered neocortical cell density and layer thickness in serotonin transporter knockout mice: a quantitation study. 1690 92

Brain activation and functional connectivity were investigated in high functioning autism using functional magnetic resonance imaging in an n-back working memory task involving photographic face stimuli. The autism group showed reliably lower activation compared with controls in the inferior left prefrontal area (involved in verbal processing and working memory maintenance) and the right posterior temporal area (associated with theory of mind processing). The participants with autism also showed activation in a somewhat different location in the fusiform area than the control participants. These results suggest that the neural circuitry of the brain for face processing in autism may be analyzing the features of the face more as objects and less in terms of their human significance. The functional connectivity results revealed that the abnormal fusiform activation was embedded in a larger context of smaller and less synchronized networks, particularly indicating lower functional connectivity with frontal areas. In contrast to the underconnectivity with frontal areas, the autism group showed no underconnectivity among posterior cortical regions. These results extend previous findings of abnormal face perception in autism by demonstrating that the abnormalities are embedded in an abnormal cortical network that manages to perform the working memory task proficiently, using a visually oriented, asocial processing style that minimizes reliance on prefrontal areas.
Cereb Cortex 2008 Feb
PMID:fMRI investigation of working memory for faces in autism: visual coding and underconnectivity with frontal areas. 1751 80

Through the influence of Goldman-Rakic, much research has been focused on the role of the dorsolateral prefrontal cortex in spatial working memory, decision making, and saccade generation, whereas functions of other parts of the frontal lobe including the ventrolateral prefrontal cortex (VLPFC) are less clear. Previous studies in non-human primates have shown that some VLPFC cells are selectively responsive to faces. Recent findings indicate that adjacent to the region where face- and object-selective cells have been recorded are neurons which respond to complex sounds including human and monkey vocalizations. Furthermore, when neurons in this same region are tested with combined face and voice communication stimuli, it is apparent that some cells in VLPFC are multisensory and respond to audiovisual stimuli. The determination that ventral prefrontal neurons are multisensory and responsive to auditory and visual communication stimuli may help to establish an animal model to assist in the investigation of the circuit and cellular basis of human communication. This will also aid in the understanding of general frontal lobe function and the processes that go awry in disorders including autism and schizophrenia, where disturbances in prefrontal function have been noted.
Cereb Cortex 2007 Sep
PMID:Representation and integration of auditory and visual stimuli in the primate ventral lateral prefrontal cortex. 1763 87

Exposure to valproic acid (VPA) during embryogenesis can cause several teratogenic effects, including developmental delays and in particular autism in humans if exposure occurs during the third week of gestation. We examined the postnatal effects of embryonic exposure to VPA on microcircuit properties of juvenile rat neocortex using in vitro electrophysiology. We found that a single prenatal injection of VPA on embryonic day 11.5 causes a significant enhancement of the local recurrent connectivity formed by neocortical pyramidal neurons. The study of the biophysical properties of these connections revealed weaker excitatory synaptic responses. A marked decrease of the intrinsic excitability of pyramidal neurons was also observed. Furthermore, we demonstrate a diminished number of putative synaptic contacts in connection between layer 5 pyramidal neurons. Local hyperconnectivity may render cortical modules more sensitive to stimulation and once activated, more autonomous, isolated, and more difficult to command. This could underlie some of the core symptoms observed in humans prenatally exposed to valproic acid.
Cereb Cortex 2008 Apr
PMID:Hyperconnectivity of local neocortical microcircuitry induced by prenatal exposure to valproic acid. 1763 26

Human altruistic cooperativeness, one of the most important components of our highly organized society, is along with a greatly enlarged brain relative to body size a spectacular outlier in the animal world. The "social-brain hypothesis" suggests that human brain expansion reflects an increased necessity for information processing to create social reciprocity and cooperation in our complex society. The present study showed that the young adult females (n = 66) showed greater Cooperativeness as well as larger relative global and regional gray matter volumes (GMVs) than the matched males (n = 89), particularly in the social-brain regions including bilateral posterior inferior frontal and left anterior medial prefrontal cortices. Moreover, in females, higher cooperativeness was tightly coupled with the larger relative total GMV and more specifically with the regional GMV in most of the regions revealing larger in female sex-dimorphism. The global and most of regional correlations between GMV and Cooperativeness were significantly specific to female. These results suggest that sexually dimorphic factors may affect the neurodevelopment of these "social-brain" regions, leading to higher cooperativeness in females. The present findings may also have an implication for the pathophysiology of autism; characterized by severe dysfunction in social reciprocity, abnormalities in social-brain, and disproportionately low probability in females.
Cereb Cortex 2008 Oct
PMID:Sex-linked neuroanatomical basis of human altruistic cooperativeness. 1823 82

To investigate frontal lobe white matter in children with autism spectrum disorder (ASD), we performed diffusion tensor imaging (DTI) in 50 ASD children (mean age: 57.5 +/- 29.2 months, 43 males) and 16 typically developing children (mean age: 82.1 +/- 41.4 months, 11 males). The apparent diffusion coefficient (ADC) was significantly higher for whole frontal lobe (P = 0.011), long (P < 0.001) and short range (P = 0.0126) association fibers in ASD group. There was a trend toward statistical significance in the fractional anisotropy (FA) of whole frontal lobe fibers (P = 0.11). FA was significantly lower in ASD group for short range fibers (P = 0.0031) but not for long range fibers (P = not significant [NS]). There was no between-group difference in the number of frontal lobe fibers (short and long) (P = NS). The fiber length distribution was significantly more positively skewed in the normal population than in the ASD group (P < 0.001). The long range association fibers of frontal lobe were significantly longer in ASD group (P = 0.026 for both left and right hemispheres). Abnormal frontal FA and ADC may be due to white matter organization abnormalities in ASD. Lack of evidence for excessive short range connectivity in ASD in this study may need to be re-examined with future advances in DTI technology.
Cereb Cortex 2008 Nov
PMID:Diffusion tensor imaging of frontal lobe in autism spectrum disorder. 1835 80

Unmasking the neural basis of neurodevelopmental disorders, such as autism spectrum disorders (ASD), requires studying functional connectivity during childhood when cognitive skills develop. A functional connectivity magnetic resonance imaging (fcMRI) analysis was performed on data collected during Go/NoGo task performance from 24 children ages 8-12 years (12 with ASD; 12 controls matched on age and intellectual functioning). We investigated the connectivity of the left and right inferior frontal cortex (IFC; BA 47), key regions for response inhibition, with other active regions in frontal, striatal, and parietal cortex. Groups did not differ on behavioral measures or functional connectivity of either IFC region. A trend for reduced connectivity in the right IFC for the ASD group was revealed when controlling for age. In the ASD group, there was a significant negative correlation between age and 2 right IFC correlation pairs: right IFC-bilateral presupplementary motor area (BA 6) and right IFC-right caudate. Compared with typical controls, children with ASD may not have gross differences in IFC functional connectivity during response inhibition, which contrasts with an adult study of ASD that reported reduced functional connectivity. This discrepancy suggests an atypical developmental trajectory in ASD for right IFC connectivity with other neural regions supporting response inhibition.
Cereb Cortex 2009 Aug
PMID:Functional connectivity of the inferior frontal cortex changes with age in children with autism spectrum disorders: a fcMRI study of response inhibition. 1906 86


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