A team of researchers has been able to correlate data from eye tracking, a technique for monitoring and analyzing eye movement, with specific brain characteristics identified by MRI in people with autism. This result could make it easier to identify different patient profiles and, in time, to find new therapeutic avenues...
In people with autism spectrum disorders (ASD) the cerebellum – a brain structure that is involved in numerous cognitive processes - presents morphological abnormalities. These could contribute in particular to the difficulties that people with autism have in focusing their gaze on the faces of others they are speaking to and recognizing their emotions. Recently, a team of researchers* has for the first time described how these brain abnormalities, which are identifiable on MRI, can be correlated with results from gaze analysis, obtained by eye tracking.
In order to achieve this, the team followed three steps:
- The first step was to compare the MRI scans of people with ASD to those of control subjects. After an arduous process of identifying sub-regions of the cerebellum, made easier by using automated software, the researchers showed that while its overall size remained the same, certain areas of the cerebellum were smaller in people with ASD.
- Secondly, the researchers carried out the eye-tracking analysis in order to study how long participants fixed their gaze on faces shown to them with expressions typical of fear, happiness or anger.
- Based on these two series of experiments, the researchers were able to show that the length of time that the gaze was fixed, measured using eye tracking, was correlated to the cerebellum morphology in patients with ASD.
A simple method to diagnose or evaluate treatments
Autism spectrum disorders are extremely varied. Some people have an intellectual disability or poorly developed language skills, while others present greater-than-usual intelligence. In spite of this, there is one common feature: difficulties with social interaction, which manifest in particular by abnormalities of the gaze. “The clinical variation in presentations of the disease makes research more complex,” explains Charles Laidi* who led this project. Up until now, the majority of studies into this condition have been conducted in children and adolescents. When working with young patients, “it is even more arduous since these subjects can follow quite separate trajectories of development, from the onset of the main symptoms to the time when they worsen. Conducting this study in adults meant that we could overcome this variability,” he continues. “By linking a simple clinical gaze test with the brain morphology of patients, we can contemplate ways of understanding the mechanisms of autism, developing new and reliable tools for diagnosis or even, ultimately, opening new therapeutic avenues by attempting to stimulate the altered areas.”
In this work, the researchers focused on the cerebellum, a structure located below the cerebral hemispheres that is involved in both fine motor coordination and posture, as well as a large number of cognitive processes. At the same time, the same team looked at another region of the brain: the superior temporal sulcus, which is connected to the cerebellum and involved in cognition and interpreting emotions in social interactions. In the same way, the researchers showed a correlation between the eye-tracking results and abnormalities of this structure observed on MRI imaging. For Laidi, “the cerebellum – superior temporal sulcus pathway could ultimately constitute a therapeutic target in autism spectrum disorders”, for example, by using non-invasive methods of brain stimulation.
* Inserm unit 955/Université Paris Est Créteil Val de Marne, Mondor Institute of Biomedical Research, Créteil Translational Psychiatry team of the Fondation FondaMental, in collaboration with the Roche Institute for Research and Translational Medicine
**Hotier S et al. Social cognition in autism is associated with the neurodevelopment of the posterior superior temporal sulcus. J. Sci Rep. 2017 Nov;136(5):517-525. doi: 10.1111/acps.12814. Epub 2017 Sep 22.
Laidi C et al. Cerebellar anatomical alterations and attention to eyes in autism. Sci Rep. 2017 Sep 20;7(1):12008. doi: 10.1038/s41598-017-11883-w.
Hotier S et al. Social cognition in autism is associated with the neurodevelopment of the posterior superior temporal sulcus. Acta Psy Scan. 2017 Nov;136(5):517-525. doi: 10.1111/acps.12814. Epub 2017 Sep 22.