Visual memory scores are associated with lateralization of tau in the medial temporal lobe

Abstract

AbstractBackgroundAggie Figures Learning Test (AFLT) is a visual memory test that was conceived as an analogue of the widespread Rey Auditory Verbal Learning Test (RAVLT), which tests verbal memory. Previous research has indicated that performance may rely on the left medial temporal lobe (lMTL) for RAVLT and on the right medial temporal lobe (rMTL) for AFLT, although evidence is inconclusive. The present study looks into the association between delayed recall (DR) scores in both tests and tau binding in the brain.MethodTau PET ([18F]‐MK6240) was acquired for 130 individuals for analysis involving AFLT, and 139 for analysis involving RAVLT. Demographic data is shown on Tables 1 and 2. MRI were segmented into probabilistic grey (GM) and white (WM) maps, non‐linearly registered to the ADNI template using Dartel and smoothed with an 8mm FWHM gaussian kernel. Voxel‐wise linear regression models were applied, using VoxelStats, with either DR AFLT or DR RAVLT as dependent variables and tau as a predictor. We corrected for age, diagnosis, and amyloid load. All other variables that were tested did not significantly contribute to predict DR scores.ResultsWe found negative associations between tau binding and DR RAVLT in the MTL bilaterally. Interestingly, we found a negative correlation between tau binding and DR AFLT scores that is remarkable in the rMTL and barely reaches significance in the lMTL.ConclusionOur findings provide evidence in support of the lateralization of memory in the brain based on the learning modality. This dissociation is in line with previous findings; namely, that the rMTL is responsible for visual memory. However, these findings are not entirely in line with previous research since associations with RAVLT are found bilaterally. Of note, most of the previous research has been made in the context of epilepsy and/or patients with anterior MTL lesions. Here, however, we are investigating a totally different population and we are looking at a parameter that is specific to this population.