James Bailey

An MRI study of the basal ganglia in autism.

1. High-resolution MRI scans were obtained from 35 relatively high-functioning persons with autism and 36 healthy controls, comparable in age, gender, and IQ. 2. Volumetric measurements were obtained from manual tracing of the bilateral caudate, putamen, and globus pallidus. 3. An increased volume of the caudate nuclei was found in subjects with autism. Caudate enlargement was proportional to increased total brain volume in subjects with autism. 4. Caudate volume was associated with compulsions and rituals, difficulties with minor change, and complex motor mannerisms in autism. 5. Based on evidence of caudate abnormalities, a second MRI study was completed which replicated the finding of caudate enlargement in autism using an independent sample. 6. The caudate may be part of an abnormal distributed neural network in autism and involved in the ritualistic--repetitive behaviors of the disorder.

Regional Brain Enlargement in Autism: A Magnetic Resonance Imaging Study

OBJECTIVE To determine whether increased brain volume in autism, suggested in previous studies, is the result of general or regional brain size differences and to study the effect of gender on brain size and pattern of enlargement. METHOD Total brain volume and cerebral cortical lobe volumes were examined in 35 autistic and 36 comparison subjects using magnetic resonance imaging and an automated method of brain volume measurement. RESULTS After controlling for height and nonverbal IQ, the authors detected a significant diagnosis x gender effect (F = 7.4; p = .009) for total brain volume. A repeated-measures analysis of variance indicated that the pattern of enlargement (brain region x diagnosis) in autistic subjects differed from that in controls (F = 4.88; p = .0004). Subsequent sex-specific analysis revealed significantly increased total brain volume in autistic males but not females. Analysis of lobe sizes showed significant enlargement in autistic subjects in temporal, parietal, and occipital, but not frontal lobes. CONCLUSIONS These results suggest that brain size is increased in autism and that differences are not generalized but appear to be the result of a pattern of enlargement with increases in the size of specific cortical lobes.

An MRI study of autism: The cerebellum revisited

We addressed the controversies surrounding the size of the neocerebellar vermis in autism and examined cerebellar size in light of recent reports of enlarged brain size in this disorder. In this study we use detailed MRI (1.5 mm) to examine the area of cerebellar lobules I through V and VI and VII and the volume of the total cerebellum in 35 autistic subjects and 36 controls. No abnormalities in the size of cerebellar lobules VI and VII in autistic individuals were detected, but the volume of the total cerebellum was significantly increased. We conclude that selective neocerebellar size abnormalities are not present in autistic individuals. Enlarged total cerebellar volume detected in this study is consistent with previous reports of regional brain enlargement in autism and also consistent with theories hypothesizing that the primary defect in autism is the result of abnormal development of a distributed neural network involving a number of regions of the brain.

Human Frontal Cortex: An MRI-Based Parcellation Method

The frontal lobe is not a single anatomical and functional brain region. Several lines of research have demonstrated that particular subregions within the frontal lobe are associated with specific motor and cognitive functions in the human being. Our main purpose is to develop a magnetic resonance image (MRI)-based parcellation method of the frontal lobe that permits us to explore plausible abnormalities in functionally relevant frontal subregions in brain illnesses. We describe a procedure using MRI for subdividing the entire frontal cortex into 11 subregions: supplementary motor area (SMA), rostral anterior cingulate gyrus (r-ACiG), caudal anterior cingulate gyrus (c-ACiG), superior cingulate gyrus (SCiG), medial frontal cortex (MFC), straight gyrus (SG), orbitofrontal cortex (OFC), precentral gyrus (PCG), superior frontal gyrus (SFG), inferior frontal gyrus (IFG), and middle frontal gyrus (MFG). Our method posits to conserve the topographic uniqueness of individual brains and is based on our ability to visualize both the three-dimensional (3D) rendered brain and the three orthogonal planes simultaneously. The reliability study for gray matter volume and surface area of each subregion was performed on a set of 10 MR scans by two raters. The intraclass R coefficients for gray matter volume of each subregion ranged between 0.86 and 0.99. We describe here a reproducible and reliable topography-based parcellation method of the frontal lobe that will allow us to use new approaches to understand the role of particular frontal cortical subregions in schizophrenia and other brain illnesses.

No Difference in Hippocampus Volume Detected on Magnetic Resonance Imaging in Autistic Individuals

Neuropathological and animal studies have implicated the hippocampus as having a potential role in autism. Current imaging methods are well suited to the detailed measurement of the volume of the hippocampus, which has received little attention in previous imaging studies in autism. We report the results of a magnetic resonance imaging (MRI) study of 35 autistic and 36 control subjects. Detailed (1.5 mm) MRI did not reveal differences in the volume of the hippocampus in autistic individuals.