title: Functional connectivity of the left and right hippocampi: Evidence for functional lateralization along the long-axis using meta-analytic approaches and ultra-high field functional neuroimaging.
abstract: Theories regarding the functional specialization of the hippocampus date back to over a century ago. Two main theories have dominated the field. First, evidence has supported the notion of hemispheric specialization, which appears to be preserved across species. Second, an emergent and mounting set of data has suggested an anterior-posterior neurofunctional gradient. However, no study has examined these theories, and their potential interaction, using objective, robust methodological approaches. Here, we employed an established meta-analytic technique and use ultra-high field, high-resolution functional and structural neuroimaging to examine hippocampal lateralization with consideration for a long-axis differentiation. Data revealed strong support for an evolutionarily preserved hemispheric specialization. Specifically, we found intra- and interhemispheric differences with regard to anterior and posterior functional and structural connectivity, between the right and left hippocampi. For task-independent functional connectivity, we found the right anterior hippocampus to have functional connectivity with a large, distributed network, whereas the left anterior hippocampus demonstrated primarily fronto-limbic connectivity. These patterns were reversed for the posterior segmentations. Not surprisingly, for task-dependent connectivity, we found interhemispheric differences within key ipsilateral structures (i.e., parahippocampal gyrus) for both anterior and posterior segmentations. Furthermore, we identified pivotal neural hubs that share connectivity across behavioral domains, and are supported by structural connectivity (i.e., posterior cingulate cortex). Thus, our data provide evidence for a hemisphere-specific, anterior-posterior specialization of the hippocampal formation.
authors.affiliation: Auburn University, Department of Psychology, 226 Thach Hall, Auburn, AL 36849, USA; Auburn University, Auburn University Magnetic Resonance Imaging Research Center, Department of Electrical and Computer Engineering, 560 Devall Drive, Auburn, AL 36849, USA; Auburn University, Department of Kinesiology, 226 Thach Hall, Auburn, AL 36849, USA; Alabama Advanced Imaging Consortium, Auburn University, AL, USA. Electronic address: jrobinson@auburn.edu.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Robinson
authors.affiliation: Auburn University, Auburn University Magnetic Resonance Imaging Research Center, Department of Electrical and Computer Engineering, 560 Devall Drive, Auburn, AL 36849, USA; Siemens Healthcare, MR Research & Development, 51 Valley Stream Parkway, Malvern, PA 19355, USA.
authors.forename: Nouha
authors.initials: N
authors.lastname: Salibi
authors.affiliation: Auburn University, Department of Psychology, 226 Thach Hall, Auburn, AL 36849, USA; Auburn University, Auburn University Magnetic Resonance Imaging Research Center, Department of Electrical and Computer Engineering, 560 Devall Drive, Auburn, AL 36849, USA; Alabama Advanced Imaging Consortium, Auburn University, AL, USA.
authors.forename: Gopikrishna
authors.initials: G
authors.lastname: Deshpande
mesh_terms: D001931:Brain Mapping / Q000379:methods; D003198:Computer Simulation; D063132:Connectome / Q000379:methods*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006624:Hippocampus / Q000033:anatomy & histology* / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008959:Models, Neurological; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology; D059906:Neuroimaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: 7T; BrainMap; DTI; Long-axis; MACM; fMRI