A Comparison of Single- and Multi-Echo Processing of Functional MRI Data During Overt Autobiographical Recall

Recent years have seen an increase in the use of multi-echo fMRI designs by cognitive neuroscientists. Acquiring multiple echoes allows one to increase contrast-to-noise; reduce signal dropout and thermal noise; and identify nuisance signal components in BOLD data. At the same time, multi-echo acquisitions increase data processing complexity and may incur a cost to the temporal and spatial resolution of the acquired data. Here, we re-examine a multi-echo dataset previously analyzed using multi-echo independent components analysis (ME-ICA) and focused on hippocampal activity during the overtly spoken recall of recent and remote autobiographical memories. The goal of the present series of analyses was to determine if ME-ICA's theoretical denoising benefits might lead to a practical difference in the overall conclusions reached. Compared to single-echo (SE) data, ME-ICA led to qualitatively different findings regarding hippocampal contributions to autobiographical recall: whereas the SE analysis largely failed to reveal hippocampal activity relative to an active baseline, ME-ICA results supported predictions of the Standard Model of Consolidation and a time limited hippocampal involvement. These data provide a practical example of the benefits multi-echo denoising in a naturalistic memory paradigm and demonstrate how they can be used to address long-standing theoretical questions.

Automated summary

In recent years, there has been an increasing use of multi-echo fMRI designs in cognitive neuroscience. Acquiring multiple echoes provides various benefits such as increased contrast-to-noise ratio, reduced signal dropout and thermal noise, as well as the identification of nuisance signal components in BOLD data. However, the use of multi-echo acquisitions also comes with increased data processing complexity and potential trade-offs in temporal and spatial resolution. This study reexamines a multi-echo dataset and demonstrates the practical benefits of multi-echo denoising in a naturalistic memory paradigm, specifically in understanding hippocampal activity during autobiographical recall.