Application of cortical unfolding techniques to functional MRI of the human hippocampal region

We describe a new application of cortical unfolding to high-resolution func tional magnetic resonance imaging (fMRI) of the human hippocampal region. T his procedure includes techniques to segment and unfold the hippocampus, al lowing the fusiform, parahippocampal, perirhinal, entorhinal, subicular, an d CA fields to be viewed and compared across subjects. Transformation param eters derived from unfolding high-resolution structural images are applied to coplanar, functional images, yielding two-dimensional "unfolded" activat ion maps of hippocampi. The application of these unfolding techniques great ly 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 colla teral sulcus and activation in the hippocampus proper, (C) 2000 Academic Pr ess.