Autism prodrome 31 of 89
orientation to the eye region (Adolphs et al., 2005) and that children and adolescents
with autism show abnormal functional MRI responses to such tasks (e.g. Dalton et al.,
2005; Wang, Dapretto, Hariri, Sigman, & Bookheimer, 2004; Wang et al., 2005) and
that young children with autism show enlarged amygdale (Sparks et al., 2002).
In their discussion Mosconi et al. (2009) build on earlier accounts by Baron-
Cohen (Baron-Cohen et al., 1999) and Schultz (2006) whereby abnormal amygdala
responses during social processing (including in such activities as eye contact and
joint attention) leads to a cascade of neurodevelopmental outcomes, raising the
possibility that infants and young children with autism find less intrinsic reward in the
typical social affective interactions with caregivers and other adults (see also Dawson
et al., 2004). The precedence of abnormal behavioral responses (not looking to the
eyes) versus abnormal brain structure of function (enlarged and atypically responsive
amygdalae) is not known but such hypotheses establish specific brain systems as
potential neuroanatomical and neurofunctional prodromal markers of ASD, in this
case from at least 2 years of age but possibly from much earlier in development.
This period of abnormal trajectory of brain growth and possibly cortical
connectivity resonates with a number of clinical, neuroanatomical and
neurofunctional findings. With respect to the latter, the interest in an abnormal
head/brain growth trajectories leading to abnormal cortical organization also chimes
with the current interest from functional MRI studies that have found abnormality
connectivity - with reduced connectivity between distal brain circuits and increased
connectivity between proximal brain circuits on a wide number of cognitive tasks
(Just, Cherkassky, Keller, Kana, & Minshew, 2007; Just, Newman, Keller, McEleney,
& Carpenter, 2004; Kana, Keller, Minshew, & Just, 2007; Koshino et al., 2008;
Minshew & Williams, 2007). These observations and experiments, largely conducted