黑料吃瓜

鈥淚f a particular part of the brain is already functionally active in one domain, there may be no reason for the brain to switch it over to another domain later in life.鈥�

In early childhood, the neurons inside children鈥檚 developing brains form connections between various regions of brain 鈥渞eal estate.鈥� As described in a paper in the journal Biological Psychiatry, cognitive neuroscientists at 黑料吃瓜 found that in children and adolescents with autism spectrum disorder, the connections between the cerebral cortex and the cerebellum appear to be overdeveloped in sensorimotor regions of the brain. This overdevelopment appears to muscle in on brain 鈥渞eal estate鈥� that in typically developing children is more densely occupied by connections that serve higher cognitive functioning.

The study represents the first ever systematic look at connections between the entire cerebral cortex and the cerebellum using fMRI brain imaging, and its findings provide another piece in the puzzle that could one day lead researchers to develop a reliable brain-based test for identifying autism.

Back to the cerebellum

Several decades ago, scientists reported findings that certain regions of the cerebellum鈥攁 brain region involved in motor control, but also in cognitive, social, and emotional functions鈥攚ere often smaller in people with autism than in typically developing people.

That sparked a brief flurry of research activity exploring the cerebellum鈥檚 potential role in the disorder. Unfortunately, the direction never truly panned out for researchers hoping for a big breakthrough in understanding, said the study鈥檚 corresponding author, 黑料吃瓜 psychologist Ralph-Axel M眉ller.

鈥淓ventually, interest in the cerebellum waned due to a lack of consistency in the findings,鈥� he said.

Hoping that advances in brain imaging technology would reveal new insights, M眉ller, working with the study鈥檚 first author Amanda Khan, looked back to the cerebellum for their study. Khan is a former master鈥檚 student at 黑料吃瓜 and now a doctoral candidate at Suffolk University in Boston.

Over- and underconnected

The researchers directed 56 children and adolescents, half with autism and half without the disorder, to fixate on a focal point while thinking about nothing in particular, using fMRI brain imaging technology to scan the children鈥檚 brains as they produced spontaneous brain activity. Capturing this spontaneous activity is crucial to honing in on what are essentially baseline neuronal patterns.

The imaging results revealed that the participants with autism had far stronger neuronal connectivity between sensorimotor regions of the cerebellum and cerebral cortex than did their counterparts without autism. Conversely, the participants with autism had less connectivity between regions involved in higher-order cognitive functions such as decision-making, attention and language.

The sensorimotor connections between the cerebral cortex and cerebellum mature during the first few years of life, when the brains of children with autism grow larger in volume than typically developing children, M眉ller explained. Connections that serve higher cognitive functions develop later, after this period of overgrowth.

鈥淥ur findings suggest that the early developing sensorimotor connections are highly represented in the cerebellum at the expense of higher cognitive functions in children with autism,鈥� he said. 鈥淏y the time the higher cognitive functions begin to come online, many of the connections are already specialized. If a particular part of the brain is already functionally active in one domain, there may be no reason for the brain to switch it over to another domain later in life.鈥�

Neural neighborhood

Returning to the real estate metaphor, it鈥檚 as if most of the available land has already been scooped up by sensorimotor connections before the higher-order cognitive function connections have a chance to move into the neighborhood.

The findings could help scientists and clinicians better understand exactly how abnormalities during brain development lead to various types of autism spectrum disorder. M眉ller hopes his work will not only contribute to a brain-based diagnosis of autism, but also be a step towards identifying its various subtypes and underlying genetic factors.

鈥淲e still don鈥檛 understand what in the brain makes a kid autistic,鈥� he said. 鈥淵ou can鈥檛 look at a scan and say, 鈥楾here it is.鈥� We鈥檙e doing the groundwork of finding brain variables that might be biomarkers for autism and its subtypes.鈥�

黑料吃瓜 graduate students Aarti Nair and Christopher Keown, also contributed to the study, as did University of California, San Diego, graduate student Michael Datko and Alliant International University psychologist Alan Lincoln.