The intersubject and intrasubject reproducibility of FMRI activation during three encoding tasks: implications for clinical applications

Abstract

The goal of the present study was to evaluate the inter- and intrasubject reproducibility of FMRI activation for three memory encoding tasks previously used in the context of presurgical functional mapping. The primary region of interest (ROI) was the medial temporal lobe (MTL). Comparative ROIs included the inferior frontal and fusiform gyri which are less affected by susceptibility-induced signal losses than the MTL regions. Eighteen subjects were scanned using three memory encoding paradigms: word-pair, pattern, and scene encoding. Nine subjects underwent repeat scanning. Intersubject reproducibility of FMRI activation was evaluated by examining the percent of subjects who showed activation within a given ROI and the range to which individual laterality indices (LIs) varied from the mean. Intrasubject test-retest reproducibility was evaluated by examining the LI test-retest correlation, the average difference between LIs from two separate imaging sessions, and concordance ratios of activation volumes (R(volume) and R(overlap)). For scene encoding the reproducibility of activation volume and LIs within the MTL were as good as or better than the reproducibility within the fusiform and inferior frontal ROIs. For pattern encoding and word-pair encoding, the reproducibility of activation volume and LIs within the MTL tended to be worse compared to the fusiform and inferior frontal ROIs. The differences in FMRI reproducibility appeared more dependent on the task than the susceptibility effects. The results of this study suggest that FMRI-based assessment of the neural substrates of memory using a scene encoding task may be a useful clinical tool.

The first taste is always with the eyes: A meta-analysis on the neural correlates of processing visual food cues

“…The cluster that we found in the LOC may reflect this attention effect. The high concurrence in this area is also in line with multiple studies (e.g., Harrington et al, 2006;Peelen and Downing, 2005) that showed a relatively high (compared to other brain regions) within-and between-subjects reproducibility of activation in the fusiform gyrus and other visual areas.…”

Memory Assessment in the Clinical Context Using Functional Magnetic Resonance Imaging

“…Those that rely on encoding of complex novel visual information, such as scenes, in comparison with baseline repeated images are strong activators of MTL, including posterior regions such as the parahippocampal gyrus. [16][17][18] Tasks that involve relational processing (eg, pairs of elements such as word-word or word-face; item-context associations) typically engage this region to a greater extent than those focusing on single elements, at both encoding and retrieval. [19][20][21][22][23][24] Finally, very robust activation of the MTL bilaterally is typically observed when individuals retrieve memories of events from their own personal past (ie, details of autobiographical memories) in comparison with other forms of semantic retrieval (typically word meaning but also facts about one's life).…”

Reproducibility of functional MRI localization within the human somatosensory cortex

“…Reproducibility was determined in terms of the 95% confidence interval (CI) on location, or distance, as proposed by Bland and Altman (14) (Eqs. [3] and [4]). For digit location, the results of digit 2 and digit 4 were combined.…”

“…This is particularly important when using fMRI in multisession longitudinal studies or multi-site protocols; approaches that are becoming increasingly popular for both basic and clinical research, for example when monitoring cortical recovery following an event such as a stroke (2). Studies using presurgical paradigms (3,4) have been used to explore the level of reproducibility of fMRI localization; however, findings were often constrained by the paradigm design or the use of patients. Studies in healthy subjects have determined reproducibility within visual (5), motor (6), and somatosensory (7) cortices and have explored aspects such as voxel size and spatial smoothing (7) and thresholding (6).…”