Response inhibition and serotonin in autism: a functional MRI study using acute tryptophan depletion.

It has been suggested that the restricted, stereotyped and repetitive behaviours typically found in autism are underpinned by deficits of inhibitory control. The biological basis of this is unknown but may include differences in the modulatory role of neurotransmitters, such as serotonin, which are implicated in the condition. However, this has never been tested directly.

Serotonin and the neural processing of facial emotions in adults with autism: an fMRI study using acute tryptophan depletion.

Context: People with autism spectrum disorders (ASDs) have lifelong deficits in social behavior and differences in behavioral as well as neural responses to facial expressions of emotion. The biological basis to this is incompletely understood, but it may include differences in the role of neurotransmitters such as serotonin, which modulate facial emotion processing in health. While some individuals with ASD have significant differences in the serotonin system, to our knowledge, no one has investigated its role during facial emotion processing in adults with ASD and control subjects using acute tryptophan depletion (ATD) and functional magnetic resonance imaging.

Anatomy and aging of the amygdala and hippocampus in autism spectrum disorder: an in vivo magnetic resonance imaging study of Asperger syndrome.

It has been proposed that people with autism spectrum disorder (ASD) have abnormal morphometry and development of the amygdala and hippocampus (AH). However, previous reports are inconsistent, perhaps because they included people of different ASD diagnoses, ages, and health. We compared, using magnetic resonance imaging, the in vivo anatomy of the AH in 32 healthy individuals with Asperger syndrome (12-47 years) and 32 healthy controls who did not differ significantly in age or IQ.

In vivo brain anatomy of adult males with Fragile X syndrome: an MRI study.

Fragile X Syndrome (FraX) is caused by the expansion of a single trinucleotide gene sequence (CGG) on the X chromosome, and is a leading cause of learning disability (mental retardation) worldwide. Relatively few studies, however, have examined the neuroanatomical abnormalities associated with FraX. Of those that are available many included mixed gender populations, combined FraX children and adults into one sample, and employed manual tracing techniques which measures bulk volume of particular regions.