|How is cerebral development disrupted in autism?|
|Autism can begin from the womb|
Even when neurological disorders are not clearly recognizable in childhood, 25% of autistics then develop epilepsy in adolescence or adulthood, and some patients initially declared free of neurological disorders subsequently develop organic pathologies . Finally, the great majority of clinical signs specific to the autism makes it possible to evoke the existence of cerebral dysfunctions. Research in the field of pathological anatomy, electrophysiology and imaging has allowed us to accumulate arguments in favor of a disorder of the development of the brain structures which certainly has repercussions in the processing of information Complex in social interaction, language and learning.
Pathological anatomy has highlighted the existence of structural anomalies and in particular the existence of a weight and a cerebral volume above the average. This data can be found in the cranial perimeter studies (Bailey et al., 1993, 1995, Fombonne, Rogé et al., 1999). It reflects the survival of cells that should have disappeared at an early stage of development.
|Baby brain scans can predict autism|
In the field of electrophysiology, studies using evoked potentials and electroencephalogram show dysfunctions that reflect alterations in the treatment of cortical and cortical information.
Magnetic resonance imaging (MRI) has recently made it possible to make enormous progress in overcoming the mere localization of dysfunctions in order to seek to capture in a dynamic fashion a whole series of processes reflecting brain activity. Early studies were disappointing because they did not identify autism-specific abnormalities. With the development of more sophisticated techniques, a decrease in cerebral blood flow was detected in the two temporal lobes on a population of children with autism (Zilbovicius et al., 2000; Ohnishi et al., 2000). Other works have emphasized the involvement of these brain regions in the perception of elements such as look and facial expressions that are very important in social behaviors. Research into functional imaging in the task execution situation has demonstrated activation deficits in autistic children in the posterior left temporo-occipital region in response to auditory stimulation, which tends to confirm The inadequate treatment of left-hemisphere hearing information in these children. Other work using the same techniques revealed differences in activation varying according to the nature of the tasks proposed. When the subject has to identify mental states, it is at the level of the amygdala that the activation is less. Finally, when the proposed task consists of recognizing a figure in a complex set, the cortical activation is different in autistic people with a lack of involvement of the frontal regions.
Research based on cerebral imagery thus tends to concretize the biological substrate that underlies the anomalies observed in behaviors and in the processing of information. The link between the neurological underlying and its behavioral expression begins to be more directly perceptible.