| We evaluated the presence of connections between the collateral (CS), rhinal (RS), and occipitotemporal (OTS) sulci in healthy adults and individuals with temporal lobe epilepsy (TLE). These anterior temporobasal (aTB) sulci contribute to the morphology of memory-related structures and are landmarks for neuroimaging analyses. To our knowledge the only direct comparison of aTB sulcal connections in healthy adults and TLE patients (Kim et al., 2008) found dramatic overrepresentation of CS-RS connections in TLE. However, these data are not consistent with the most referenced normative study of sulcal prevalence (Ono et al., 1990) or with another study that reported aTB sulcal connectivity in TLE patients (Novak et al., 2002). This discrepancy may be due to methodological differences.;The following series of studies has four main outcomes: (1) We developed a reliable rating protocol (including training materials and rating forms) for identification of the three aTB sulci and their interconnections. Notably, the final version of the protocol differentiated between "true" and "pseudo" (e.g., shallow, perforated or otherwise ambiguous) connections. (2) We characterized the frequencies of four sulcal pattern types in a sample of 200 healthy undergraduate students. Our results largely replicated Kim et al. (2008) when both true- and pseudo- connections were counted as "connections"; when only true connections were counted, our results were consistent with Ono et al. (1990), suggesting a possible explanation for the discrepancy between these two studies. (3) We characterized the frequency of sulcal pattern types in 79 TLE patients and 70 age-matched controls. We did not find significant group differences consistent with those reported by Kim et al. regardless of whether pseudoconnections were included. However, our findings are consistent with Novak et al. (2002) when pseudoconnections were excluded. (4) We tested the prediction that presence of a CS-RS connection would be associated with worse performance on tests of free recall. Although we did not find an overall effect, we successfully demonstrated that patients with a CS-RS connection in the right hemisphere displayed worse visual memory than patients without this connection. To our knowledge this is the first demonstration of a relationship between aTB sulcal morphology and cognition. |
