Table 1.
Age, IQ, handedness, and gender of the participants.
Figure 1.
Schematic diagram of the two-level exploratory factor analysis procedure.
The first level factor analyses are performed separately for participants 1–13. In these analyses, the activation levels of 135 voxels (marked as red, green, and blue circles for the 3 participants) distributed throughout the brain are expressed via 7 factors (Fa-Fg), and some (but not all) of the voxels are linked to these factors. The second, group-level FA in turn expresses the 13×7 first-level factors in terms of 4 group factors (GF1–GF4). For each of these factors, the originating voxels are spatially clustered. A cluster of such voxels (characterized as a sphere) contains voxels that were initially selected from many (typically all) of the participants. The six largest spheres per factor were treated as the factor-associated brain locations.
Figure 2.
Posterior midline self factor location.
A. Location of the voxels (circled) derived from the factor analysis of the Control Group that defined the posterior cingulate/precuneus sphere of this group’s self factor. Voxels in this cluster (with MNI x-coordinates extending from 0 to −9) are shown projected on the mid-sagittal plane. (The coordinates and radii of all 6 spheres associated with this factor are shown in Table S1 in File S1). B. Mean activation in midline brain structures for the verb hug (averaged over agent and recipient roles) for the two groups, differing in posterior cingulate/precuneus. The verb hug was chosen for illustration here because of the salience of hugging as a social interaction in autism, where enveloping pressure is sometimes desired but without physical contact between oneself with another person, as in Temple Grandin’s squeeze machine [40]. The depiction of the activation in this slice for all of the other verbs was very similar to hug, for both groups.
Figure 3.
Degree of alteration of self-related activation in autism (estimated by its stability in posterior cingulate/precuneus) and its relation to social processing ability measured by the Benton Facial Recognition Test [30].
Both measures were adjusted for participants’ age and full scale IQ. One participant with autism did not have a Benton Test score.
Figure 4.
Social Interactions-Fixation contrasts for the two groups.
The uncorrected p-threshold is 0.001 and the extent threshold is 5 voxels for both groups.