The objective of this study was to examine the relationship between thalamic volume and brain size in individuals with Asperger's disorder (ASP). Volumetric measurements of the thalamus were performed on MRI scans obtained from 12 individuals with ASP (age range: 10-35 years) and 12 healthy controls (age range: 9-33 years). A positive correlation was found between total brain volume and thalamic size in controls, but not in ASP subjects. This occurred in the absence of differences in mean thalamic volumes between the study groups. Findings from this investigation point to an abnormal relationship between the thalamus and its projection areas in ASP and are consistent with similar studies in autism, supporting that these disorders are qualitatively similar and possibly quantitatively different.
"Previous studies evaluating the volume and volume fraction of the thalamus in autism using magnetic resonance imaging (MRI), no significant differences were determined between the patient groups and the healthy controls.3,4,5 However, the fraction of thalamic volume to total brain volume (TBV) was found to be abnormal both in the high functioning autism (HFA)3,4 and ASP cases.5 "
[Show abstract][Hide abstract] ABSTRACT: Objective
Thalamic abnormalities have been reported in people with pervasive developmental disorders (PDD) including Asperger's Disorder (ASP). The aim of the present study was to compare the volume and volume fraction of the thalamus and the metabolite concentrations in children and adolescents with ASP using the magnetic resonance imaging and proton magnetic resonance spectroscopy. Additionally, the relationships between thalamic abnormalities and clinical features were examined.
Volume and volume fractional and metabolic measurements of bilateral thalamus were collected from 15 boys with ASP with a total IQ over 70 (age range 7-18 years, mean age 11.6±3.79 years), and 15 healthy controls matching age, sex and IQ. The thalamic volumes, hemisphere volumes and total brain volumes (TBV) were estimated using the stereological methods on magnetic resonance images. Chemical metabolites of thalamus were evaluated by 1H spectroscopy.
No differences in thalamic volumes, volume fractions and metabolites were observed between the groups. There were significant correlation between thalamic volume and total brain volume in both groups. The ASP group showed a significant left-minus-right thalamus difference as well as a significantly greater laterality index. In addition, a significant correlation between the laterality index and Autism Behavior Checklist language scores was observed.
Findings from this investigation point to a significant increase in laterality of the thalamus and a relationship with language problems in individuals with ASP. Our findings suggest that thalamic abnormalities may be related to mild language problems observed in ASP.
"The thalamus has also been examined due to its central role in sensory processing. While thalamic volumes have not been found to relate to sensory function, a magnetic resonance spectroscopy study observed indications of a relationship between thalamic brain metabolites (N-acetyl aspartate and glutamate + glutamine) and sensory function (Hardan et al., 2008a,b). Another study reported that GM volume in the brainstem and oral sensitivity measures were associated in high-functioning ASD (Jou et al., 2009). "
[Show abstract][Hide abstract] ABSTRACT: Autism spectrum disorders (ASD) display significant heterogeneity. Although most neuroimaging studies in ASD have been designed to identify commonalities among affected individuals, rather than differences, some studies have explored variation within ASD. There have been two general types of approaches used for this in the neuroimaging literature to date: comparison of subgroups within ASD, and analyses using dimensional measures to link clinical variation to brain differences. This review focuses on structural and functional magnetic resonance imaging studies that have used these approaches to begin to explore heterogeneity between individuals with ASD. Although this type of data is yet sparse, recognition is growing of the limitations of behaviorally defined categorical diagnoses for understanding neurobiology. Study designs that are more informative regarding the sources of heterogeneity in ASD have the potential to improve our understanding of the neurobiological processes underlying ASD.
Frontiers in Human Neuroscience 10/2013; 7:733. DOI:10.3389/fnhum.2013.00733 · 2.99 Impact Factor
"In the literature, theta synchronization relating with recognition of stimuli reflects the activity in thalamus-cortical and hippocampal-cortical circuits . Our findings support the hypothesis that both circuits might contain some functional disorders in participants with AS . Besides, emotion-related theta synchronization is connected with activity of the amygdale . "
[Show abstract][Hide abstract] ABSTRACT: EEG reactions in emotional face recognition were studied in five participants with Asperger syndrome (AS) and seven control subjects. Control subjects showed a spectral power increase following the stimulus onset in two time-frequency intervals-(1) 150-300ms in the 1-16Hz frequency range and (2) 300-650ms in the 1-8Hz range. Also, alpha/beta desynchronization occurred 400-1000ms after the stimulus onset with maximal amplitude in the posterior region. Theta synchronization (4-8Hz) was weaker in the AS group than in the control group, but beta2 desynchronization was stronger in the AS group. The results were interpreted in terms of automatic and voluntary control of perception.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.