Mapping the major connections of the amygdala in chimpanzees and humans using diffusion tensor imaging (DTI) and probabilistic tractography 公开

Jacquez, Nadine Juwita (2014)

Permanent URL: https://etd.library.emory.edu/concern/etds/vh53ww248?locale=zh
Published

Abstract

The amygdala plays a key role in emotional processing and social behaviors in humans, nonhuman primates, and other mammals. Although it is well established that the mammalian amygdala can be divided into three anatomically and functionally distinct subregions - basolateral, centromedial, and cortical - the internal organization of these divisions and the absolute and relative sizes of their connections vary substantially across species. Despite this, studies of connectivity of the amygdala have heretofore been concentrated in a relatively few experimental species - mainly rodents and macaque monkeys. The development of the noninvasive diffusion tensor imaging (DTI) technology has made it possible to extend studies of connectivity to humans, and in this study, to chimpanzees, our closest relatives. It gives us an opportunity to compare humans to chimpanzees (and to macaques, based on the literature), and gain insight into how the organization of the amygdala changed during human evolution. In this study, DTI and probabilistic tractography were used in a study of the distribution of the major connections of the amygdala in chimpanzees and humans. From this, we expected to identify the three major subregions in both species and compared their size and distribution in humans to interrogate possible differences in amygdalar organization between species. My hypothesis was that the basolateral subdivision tracts would be proportionately larger and stronger in humans as compared to chimpanzees, because of its strong connections to sensory and association areas, and the dramatic increase in the amount of association cortex in human evolution. Furthermore, I hypothesized that the centromedial and the cortical division tracts in humans would be proportionately smaller because of their strong connections to brainstem regions, and primary olfactory cortex, respectively.

Table of Contents

Table of Contents

1. Introduction......................................................1

2. Methods...........................................................5

2.1. Subjects........................................................5

2.2. MRI acquisition................................................5

2.3. Data preprocessing..........................................6

2.4. Voxelwise analysis using probability tractography..7

2.5. Find-the-biggest...............................................7

2.6. Mask drawings.................................................8

2.6.1. Amygdala.....................................................9

2.6.2. Periaqueductal Gray .....................................12

2.6.3. Olfactory Cortex...........................................13

2.6.4. Orbitofrontal Cortex......................................15

2.6.5. Temporal Lobe.............................................16

2.6.6. Hippocampus...............................................19

2.7. Quantitative Methods........................................19

3. Results.............................................................20

3.1. Qualitative results............................................20

3.2. Quantitative results..........................................29

4. Discussion.........................................................33

5. References........................................................40

About this Honors Thesis

Rights statement
  • Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.
School
Department
Degree
Submission
Language
  • English
Research field
关键词
Committee Chair / Thesis Advisor
Committee Members
最新修改

Primary PDF

Supplemental Files