BIOLOGICAL BASIS OF INFANTILE-AUTISM - II - NEUROPATHOLOGICAL, NEUROPHYSIOLOGICAL AND NEUROPSYCHOLOGICAL ASPECTS

In the second part of this review paper on biological basis of infanti le autism we describe the main neuropathological, neurophysiological a nd neuropsychological investigations carried out in this disease. Nume rous neuropathological ''postmorten'' studies as well as neuroanatomic al studies using neuroimaging techniques have demonstrated the existen ce of a broad variety of structural and functional abnormalities in au tistic patients. Although results are not entirely consistent, the mai n changes in autism have been located in limbic system (medial tempora l robe), cerebellum and cerebral cortex, Likewise, it has been propose d that some cases of autism might be provoked by an injury at the time of closure of the neural tube. On the other hand, we examine the main neurophysiological studies in autistic subjects, emphasizing investig ations with evoked potentials. In this context, several authors have s uggested that in autism exists a disordered functioning in brainstem a nd thalamic systems which mediate arousal, attention and information-p rocessing. The third part of this paper focuses on neuropsychological studies realized in autistic patients. It is a well-known fact that th ese subjects exhibit neuropsychological disorders in a wide range of d omains, a fact that suggests that autism probably involves a dysfuncti on of multiple regions rather than of only one brain region. Most stud ies reveal large individual differences in certain neuropsychological domains. Whereas most autistic patients have frontal lobe impairments, great variability exists in the areas of language and memory. This re view concludes with a brief description of several neurofunctional int egrative models of autism (Bachevalier, 1994; Morton and Frith, 1995; Couchesne, Townsend and Chase, 1995, and Waterhouse, Fein and Modahl, 1996).