Neuroimaging in the Developmental Disorders: The State of the Science

Abstract

The developmental disorders of childhood autistic, developmental language, reading (dyslexia), and attention deficit-hyperactivity disorders-manifest with deficits in the traditional behavioral domains of cognition, language, visual-spatial function, attention, and socialization. However, none of these disorders has been associated with characteristic discrete focal lesions or recognized encephaloclastic processes. Developmental cognitive neuroscientists must therefore begin with the spectrum of sometimes divergent behaviors occurring within these disorders and work backward in an attempt to identify the responsible anomalous neural systems. Since the advent of "brain imaging" two decades ago, much effort has focused on identifying brain-behavior correlates in these disorders. The results of these neuropathologic, structural, and functional neuroimaging studies are presented and the reasons for the often divergent findings are discussed. As we approach the end of the Decade of the Brain, current neuroimaging techniques give us the technology for the first time to apply a fundamental cognitive approach to brain-behavior relationships in the developmental disorders, to eliminate the conglomeration of "apples and camels" phenomenon. Researchers are working together to create comparable protocols and to adhere to methods that can be replicated across sites. The future prospects for a greater understanding of the developmental disorders are now much brighter with neuroimaging technology.

A combined clinical, neuropsychological, and neuroanatomical study of adults with high functioning autism

“…The predominantly negative findings on tests of the PFC hypothesis are consistent with other research showing only subtle anatomical differences between the frontal lobes of individuals with autism compared with controls (Filipek, 1999); and also with research indicating that some but by no means all executive functions are impaired, at least in people with HFA (Hughes, 2001). The neuropsychological origins of the impaired creativity/behavioural flexibility, which is diagnostic of autism, and the neuropathology underlying the critical neuropsychological deficits, therefore remain elusive (but see below).…”

“…Furthermore, functional neuroimaging suggests that PFC abnormalities occur in people with autism during tasks involving theory of mind (Baron-Cohen et al, 1999;Happe  et al, 1996;Ohnishi et al, 2000). Until recently, however, there was little if any secure evidence of structural abnormalities of PFC in autism (Filipek, 1999). This situation is currently changing, with recent reports of abnormalities at the cellular level affecting both the structure and the physiology (Chugani et al, 1997;Murphy et al, 2002) of frontal lobe neurons.…”

Neuropsychological Differences Among Children With Asperger Syndrome, Nonverbal Learning Disabilities, Attention Deficit Disorder, and Controls

“…Similarly, Rourke (1995) suggested that difficulty was present in the right-hemispheric white matter in NLD. Differences have also been found in the smaller volume of the corpus callosum for children with AS despite control for white matter volume (Chung, Dalton, Alexander, & Davidson, 2004), higher volumes of white matter (Filipek, 1999), and increased volume in the caudate regions (Sears et al, 1999). While the emerging MRI research in AS suggests white matter involvement in the disorder, the findings are not conclusive.…”

Maturation processes in automatic change detection as revealed by event-related brain potentials and dipole source localization: Significance for adult AD/HD

“…Castellanos et al (2002) also noted not only reduced white matter in childhood AD/ HD, but reduced cerebral grey matter in frontal and temporal cortices that was correlated with the severity of psychopathology. Filipek (1999) noted that the involvement of right frontal regions in particular seemed to depend on comorbid problems. Indeed, a recent MRI study of adolescents with conduct disorder (independent of substance-abuse) showed volumetric reductions in the right hemisphere, reminiscent of AD/HD studies (Kruesi et al, 2004).…”