Related Experiment Video
Updated: Jul 5, 2026
12:21
Probing the Brain in Autism Using fMRI and Diffusion Tensor Imaging
Published on: September 12, 2011
Regional callosal morphology in autism and macrocephaly
Shirley Kilian1, Warren S Brown, Bradley J Hallam
1The Travis Research Institute, Fuller Graduate School of Psychology, Jerry L. Pettis Memorial VA Medical Center, Loma Linda, California, USA.
Developmental Neuropsychology
|April 30, 2008
Summary
Autism is linked to corpus callosum (CC) size differences, but head size matters. Macrocephaly in autism correlates with a larger CC, while normocephalic autistic individuals show smaller CC regions.
Area of Science:
- Neuroscience
- Developmental Neuroscience
- Autism Spectrum Disorder Research
Background:
- Previous studies indicate reduced corpus callosum (CC) size in autism spectrum disorder (ASD).
- Regional variations and the influence of head size on CC morphology in autism remain underexplored.
- Understanding these factors is crucial for clarifying interhemispheric connectivity in ASD.
Purpose of the Study:
- To investigate corpus callosum (CC) size and regional distribution in relation to head size in autistic individuals.
- To compare CC morphology across five groups: autistic individuals (normocephalic and with macrocephaly), non-autistic controls (normocephalic and with benign macrocephaly), and a reading disordered (RD) group.
- To determine the impact of macrocephaly on CC size, independent of autism.
Main Methods:
- Corpus callosum (CC) tracing from midsagittal MRI scans.
- Partitioning CC outlines into 99 equidistant width measures.
- Factor analysis to identify 10 contiguous callosal regions for detailed analysis.
Main Results:
- Individuals with macrocephaly (autistic and non-autistic) exhibited larger overall CC size.
- A significantly larger CC midbody was observed in individuals with macrocephaly, irrespective of autism diagnosis.
- Normocephalic autistic individuals displayed smaller CC genu and midbody regions compared to normocephalic controls and the RD group.
Conclusions:
- Head size is a critical factor influencing corpus callosum (CC) morphology in autism studies.
- Autism is associated with specific regional CC abnormalities, particularly in the genu and midbody, when head size is controlled.
- Findings support the hypothesis of impaired interhemispheric connectivity in individuals with autism spectrum disorder.
More Related Videos
Related Concept Videos
01:19Autism Spectrum Disorder
Autism spectrum disorder (ASD) is a neurodevelopmental condition marked by persistent deficits in social communication and interaction alongside restrictive and repetitive behaviors or interests. ASD is sometimes accompanied by intellectual impairment.
These core symptoms manifest differently among individuals, ranging from mild to severe. The disorder's complexity extends beyond its clinical presentation, encompassing a diverse range of biological, cognitive, and sociocultural influences.
These core symptoms manifest differently among individuals, ranging from mild to severe. The disorder's complexity extends beyond its clinical presentation, encompassing a diverse range of biological, cognitive, and sociocultural influences.
01:26Cerebrum: Anatomical Overview I
The main and largest component of the human brain is the cerebrum. The cerebrum consists of two main parts: the cerebral cortex, an outer layer with wrinkles or folds known as gyri and shallow grooves called sulci, and a deeper region beneath it. The cerebrum divides into two distinct hemispheres and contains five different lobes: the frontal, parietal, temporal, occipital, and insula. The central sulcus separates the frontal and parietal lobes and two functionally important gyri — the...
01:11Cerebrum: Anatomical Overview II
Each cerebral hemisphere can be divided into three main regions. The outermost region, the cerebral cortex, is a thin layer (2 to 4 millimeters thick) made up of gray matter, consisting of neuron cell bodies, dendrites, glial cells, and blood vessels. The middle region, or white matter, is primarily composed of myelinated nerve fibers organized into three types of large tracts: association fibers, commissures, and projection fibers. Association fibers connect different areas within the same...
01:21Association Areas of the Cortex
Association areas are regions of the cerebral cortex that do not have a specific sensory or motor function. Instead, they integrate and interpret information from various sources to enable higher cognitive processes such as memory, learning, and decision-making. Some key association areas include the following:
Prefrontal Association Area: This area is located in the frontal lobe and is involved in planning, decision-making, and moderating social behavior. It connects with primary motor areas,...
Prefrontal Association Area: This area is located in the frontal lobe and is involved in planning, decision-making, and moderating social behavior. It connects with primary motor areas,...
01:17Cerebellum: Anatomical Regions
The cerebellum, also known as the "little brain," is located in the posterior cranial fossa, inferior to the tentorium cerebelli and dorsal to the brainstem. It plays a significant role in motor control, coordination, and proprioception.
Cerebellar Structure
Externally, the cerebellum features a highly convoluted surface with numerous folia (narrow ridges) separated by shallow sulci (grooves). The cerebellum is divided into two hemispheres by a thin median structure known as the vermis. The...
Cerebellar Structure
Externally, the cerebellum features a highly convoluted surface with numerous folia (narrow ridges) separated by shallow sulci (grooves). The cerebellum is divided into two hemispheres by a thin median structure known as the vermis. The...