We describe a new application of cortical unfolding to high-resolution functional magnetic resonance imaging (fMRI) of the human hippocampal region. This procedure includes techniques to segment and unfold the hippocampus, allowing the fusiform, parahippocampal, perirhinal, entorhinal, subicular, and CA fields to be viewed and compared across subjects. Transformation parameters derived from unfolding high-resolution structural images are applied to coplanar, functional images, yielding two-dimensional 'unfolded' activation maps of hippocampi. The application of these unfolding techniques greatly enhances the ability of fMRI to localize and characterize signal changes within the medial temporal lobe. Use of this method on a novelty- encoding paradigm reveals a temporal dissociation between activation along the collateral sulcus and activation in the hippocampus proper. (C) 2000 Academic Press.
Bibliographical noteFunding Information:
This work was supported by NIH National Research Service Award Grant MH12167 from the National Institute of Mental Health, NIH Medical Scientist Training Program Grant GM08042, the Ahmanson Foundation, the Pierson–Lovelace Foundation, the Jennifer–Jones Simon Foundation, and the Tamkin Foundation. Special thanks to Oi Lee Wong for her help in segmentation. We also acknowledge Brian Wandell for the use of his segmentation and unfolding software. Finally, we thank J. Mazziotta, M. Cohen, A. Toga, C. Houser, and three anonymous reviewers for their comments on the manuscript.
- Medial temporal lobe