Meeting Abstract

P1.104  Monday, Jan. 4  Consistencies and Variations in Sulcal and Gyral Patterns in Human Insular Cortex. JOHNSON, J/I*; BUCHANAN, K/J; MORRIS, J/A; FOBBS JR., A/J ; Michigan State Univ., East Lansing; Michigan State Univ., East Lansing; Allen Institute for Brain Science, Seattle WA; National Museum of Health and Medicine, AFIP, Washington DC johnij@aol.com

To elucidate the degree of cortical folding in different regions of the insula, we measured the amount of cortical folding in a stratified sample of stained horizontal sections through each of 10 adult human insulas. The most folded region is about midway between the superior and inferior limits, and the flattest, least folded, region is in the inferiormost third of the insula. This sequence was consistent in all of the insulas sampled. A basic pattern, 6 early-formed insular sulci outlining 5 insular gyri, was reported by Afif et al., 2007; they did not detect structural variations in sulcation in any of their fetal specimens. To record the inter-specimen variation in patterns of gyral folding in adult human insulas, we photographed the exposed surfaces of 33 insulas. Only 10 of these 33 insulas showed the complete basic pattern. The remaining 23 had a wide variety of alternative folds. We were unable to identify any individual intra-insular sulcus in the horizontal sections we measured; there was no consistent difference in the depths or positions of individual sulci. The divergence of the adult patterns from the initial basic pattern may be evidence of individual plasticity in the growth and development of insular cortex. Regional consistency of the overall degree of folding, regardless of very different patterns of folds, may indicate limits on the range of possible differential growth of insular regions.