The present work provides a comprehensive set of guidelines for manually tracing the medial temporal lobe (MTL) structures. This protocol can be applied to research involving structural and/or combined structural-functional magnetic resonance imaging (MRI) investigations of the MTL, in both healthy and clinical groups.
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Method Article
A Comprehensive Protocol for Manual Segmentation of the Medial Temporal Lobe Structures
* These authors contributed equally
In This Article
Erratum Notice
Important: There has been an erratum issued for this article. View Erratum Notice
Summary
Abstract
The present paper describes a comprehensive protocol for manual tracing of the set of brain regions comprising the medial temporal lobe (MTL): amygdala, hippocampus, and the associated parahippocampal regions (perirhinal, entorhinal, and parahippocampal proper). Unlike most other tracing protocols available, typically focusing on certain MTL areas (e.g., amygdala and/or hippocampus), the integrative perspective adopted by the present tracing guidelines allows for clear localization of all MTL subregions. By integrating information from a variety of sources, including extant tracing protocols separately targeting various MTL structures, histological reports, and brain atlases, and with the complement of illustrative visual materials, the present protocol provides an accurate, intuitive, and convenient guide for understanding the MTL anatomy. The need for such tracing guidelines is also emphasized by illustrating possible differences between automatic and manual segmentation protocols. This knowledge can be applied toward research involving not only structural MRI investigations but also structural-functional colocalization and fMRI signal extraction from anatomically defined ROIs, in healthy and clinical groups alike.
Introduction
The medial temporal lobe (MTL), a putative area of the highest level of integration of sensory information1, has been a frequent subject of targeted analyses. For example, the hippocampus and the associated parahippocampal areas have been extensively studied in memory research2-5. Also, the role of the amygdala has been frequently emphasized in research examining emotion processing and emotion-cognition interactions6-11. Recently, various MTL regions have also received attention in the emerging field of personality neuroscience, which links the structure and function of these and other brain regions to individual variation in personali....
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Protocol
1. Amygdala
- Anterior Slices of the AMY
- Identify the first slice of the AMY in which the limen insula initially appears, where the white matter connection between the frontal and temporal lobes is continuous and visible30. In the coronal view, use the angular bundle as the inferolateral border of the AMY.
- Locate the optic chiasm as a landmark for the appearance of the AMY. Use the axial and sagittal views to distinguish the AMY in its early slices from the surrounding uncus. Follow the white matter tract around the AMY in the axial view to exclude the entorhinal area32.
- Moving posteriorly, identify the....
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Results
Illustration of Possible Differences between Manual and Automatic Segmentation
A 3D model of the manual segmentation for the AMY, HC, PRC, ERC, and PHC is shown in Figure 1, and a sagittal section of the segmentation is shown in Figure 2. For the purpose of illustrating extreme possible differences between manual and automatic tracings, slices of the AMY from a representative subject with erroneous automated segmentation were juxtaposed with m.......
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Discussion
Traditionally, manual segmentation has been considered the gold standard by many researchers. Nevertheless, a precise delineation of the individual structures has been complicated by the highly variable morphology of the MTL structures, and by the usually weak MRI contrasts of these structures against the surrounding neural tissue and non-neural areas. Historically, there have been conflicting descriptions in the literature for some MTL structures. In some cases of segmenting the PRC, for example, the collateral sulcus h.......
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Disclosures
The authors have no conflicts of interest to declare.
Acknowledgements
This research was supported by funds to FD. MM was supported by an IGERT Fellowship under National Science Foundation Grant No. 0903622. The authors wish to thank the Dolcos Lab members for assistance with data collection and preparation.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| ITK-SNAP | ITK-SNAP Team at University of Pennsylvania and University of Utah | ITK-SNAP v2.2 | |
| FSL | Functional Magnetic Resonance Imaging of the Brain (FMRIB) Analysis Group | FSL v4.1 | |
| Siemens Magnetom Trio 3T MR Scanner | Siemens | Magnetom Trio 3T |
References
- Amaral, D. G. Introduction: what is where in the medial temporal lobe. Hippocampus. 9, 1-6 (1999).
- Squire, L. R., Zola-Morgan, S. The medial temporal lobe memory system. Science. 253 (5026), 1380-1386 (1991).
- Eichenbaum, H., Otto, T., Cohen, N. J.
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Reprints and Permissions
Erratum
Formal Correction: Erratum: A Comprehensive Protocol for Manual Segmentation of the Medial Temporal Lobe Structures
Posted by JoVE Editors on 9/01/2014. Citeable Link.
A correction was made to A Comprehensive Protocol for Manual Segmentation of the Medial Temporal Lobe Structures. Table 1 and its legend were updated. References 10 and 14 were also updated.
The references were updated from:
- Wager, T. D. & Smith, E. E. Neuroimaging studies of working memory: a meta-analysis. Cognitive, Affective & Behavioral Neuroscience. 3(4), 255-274 (2003).
- Scheltens, Ph, et al. Atrophyofmedialtemporallobeson MRIin 'probable' Alzheimer's disease and normal ageing: diagnostic value and neuropsychological correlates. Journal of Neurology, Neurosurgery, and Psychiatry. 55(10), 967-972, (1992).
to:
- Wager, T. D., Phan, K. L., Liberzon, I., & Taylor, S. F. Valence, gender, and lateralization of functional brain anatomy in emotion: a meta-analysis of findings from neuroimaging. Neuroimage. 19 (3), 513-31, doi:10.1016/S1053-8119(03)00078-8 (2003).
- de Leon, M. J. et al. Imaging and CSF studies in the preclinical diagnosis of Alzheimer's disease. Annals of the New York Academy of Sciences. 1097, 114-145, doi:10.1196/annals.1379.012 (2007).
Table 1 had its legend updated from:
Table 1. Representative volumetric results of the bilateral AMY and the HC of a single subject, from manual tracing using the present protocol and automatic segmentation. Automatic segmentation has underestimated the volume of each of the four structures compared. Corrected volume was calculated as the ratio between Voxel volume and Intracranial volume (ICV). For this subject, ICV = 1446616.73 mm3.
to:
Table 1. Representative volumetric results of the bilateral AMY and the HC of a single subject, from manual tracing using the present protocol and automatic segmentation. Automatic segmentation has misestimated the volume of each of the four structures compared. Corrected volume was calculated as the ratio between Voxel volume and ICV. For this subject, ICV = 1599482.11 mm3. Please click here to view a larger version of this figure.
