Lobule X PC Density is Associated with Direct Gaze.

<p>Lobule X PC density in the autism group negatively correlated with ADI-R question 50, which assessed the social and communicative use of eye contact (R² = −0.75±0.04, p = 0.012). Higher scores on the ADI-R correspond with increased symptom severity. One case from the autism group was lacking sufficient ADI-R data to be included in this analysis.</p

Overall PC Density Decreases with Age.

<p>Overall PC density obtained from the anterior, posterior, and flocculonodular lobes negatively correlates with age (R² = −0.39±0.14, p = 0.030). Some cases were missing data from an individual region (as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081255#s2" target="_blank">Methods</a>) and were not included: one female and one male case from the autism and control groups were not included.</p

Linear Mixed Models.^a

a<p>Cells in the table that have bold data presented designate the target results for each variable and interaction, whereas cells with italicized data designate results that are more adequately assessed by a different test presented in the table: Test 1 was designed to investigate the overall effect of gender and autism diagnosis on PC density. It incorporated cerebellar regional volume as a WLS weight to adjust the test's significance relative to the regional volume for each PC density measurement. Test 3 was designed to test the regional differences in PC density as an effect of gender and diagnosis. Tests 2 and 4 are designed to investigate the contribution of fresh brain weight (grams), as a correlate of tissue volume <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081255#pone.0081255-Witelson1" target="_blank">[39]</a>, to Tests 1 and 3, respectively.</p>b<p>One control male case was missing brain weight information.</p

Models of PC Arrangement.

<p>These figures represent the importance of estimating PC density in 3-dimensional space rather than along a 1-dimensional line (PC/mm³ rather than PC/mm). 7a and 7b display two views of a 3-dimensional model of a cerebellar folium, in which PCs (black) are arranged in a monolayer apposed to the granule cell layer (blue) that surrounds a central white matter tract (white). 7b displays two slices, one perfectly parallel to a plane of PCs, and the other, more realistically, transverse to this plane. 7c and 7d are cartoons demonstrating the PC arrangement within the parallel and transverse slice, respectively. Notice in 7d the PC layer is thicker, the degree to which depends on the slice position. Also notice that the selection of which PCs lie perfectly along a line is ambiguous (a few examples have been circled in red). This ambiguity introduces human error when performing an estimate of PC/mm that is eliminated in 3-dimensional estimates of PC/mm³ as are utilized in this study.</p

Photomicrograph of Transverse Section.

<p>This photomicrograph is an illustrative example of the arrangement of PCs on a transverse section. The PCs (purple) go out of focus to the left as the PC layer curves through the depth of the tissue section. The granule cell layer (blue) is visible below the PC layer, the molecular layer surrounds the PC layer (seen here as sparsely stained space), and the white matter tract is out of view to the right. Nissl-stained section from the celloidin collection used in this study, reference bar = 100 µm.</p

Clinical Characteristics.

a<p>Fresh brain weight (in grams) was measured prior to tissue processing.</p>b<p>Postmortem interval.</p>c<p>Mental Retardation.</p>d<p>Left brain hemisphere was investigated. (All other cases were investigated from the right brain hemisphere).</p