Establishing a Visual Guideline for the Locus of Auditory Cortex in Humans Item Type text; Electronic Dissertation Authors Whiteley, Aaron Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction, presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 01/10/2021 09:32:42 Link to Item http://hdl.handle.net/10150/641405 1 ESTABLISHING A VISUAL GUIDELINE FOR THE LOCUS OF AUDITORY CORTEX IN HUMANS by Aaron Whiteley _________________________________ Copyright © Aaron Whiteley 2020 Audiology Doctoral Project Submitted to the Faculty of the DEPARTMENT OF SPEECH, LANGUAGE, AND HEARING SCIENCES In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF AUDIOLOGY In the Graduate College THE UNIVERSITY OF ARIZONA 2020 ESTABLISHING A VISUAL GUIDELINE FOR THE LOCUS OF AUDITORY CORTEX IN HUMANS 2 ESTABLISHING A VISUAL GUIDELINE FOR THE LOCUS OF AUDITORY CORTEX IN HUMANS 3 Table of Contents List of Figures ................................................................................................................................. 4 List of Tables .................................................................................................................................. 5 Abstract ........................................................................................................................................... 6 Introduction ..................................................................................................................................... 7 Historical Perspective ................................................................................................................ 7 Function of Heschl’s Gyrus ....................................................................................................... 8 Gross Morphology of Heschl’s Gyrus ....................................................................................... 9 Cytoarchitecture of Heschl’s Gyrus ........................................................................................... 9 Motivation for Study ................................................................................................................ 10 Methods......................................................................................................................................... 11 Boundaries of Anatomical Landmarks .................................................................................... 13 Superior Temporal Plane .................................................................................................... 13 Heschl's Gyrus .................................................................................................................... 15 Planum Temporale ............................................................................................................. 16 Definitions of Additional Categorical Terms .......................................................................... 18 Heschl’s Gyrus Type/Number ............................................................................................ 18 Heschl’s Gyrus Angle Type ................................................................................................ 19 Ascending Ramus Type ...................................................................................................... 20 A Note on Normalization .................................................................................................... 21 Statistical Analysis ........................................................................................................................ 22 Results ........................................................................................................................................... 22 Medial Vector Measurements .................................................................................................. 22 Superior Temporal Plane .................................................................................................... 22 Distance to Anterior Edge of Heschl’s Gyrus..................................................................... 22 Distance to Posterior Edge of Heschl’s Gyrus .................................................................... 23 Lateral Vector Measurements .................................................................................................. 23 Superior Temporal Plane .................................................................................................... 23 Distance to Anterior Edge of Heschl’s Gyrus..................................................................... 24 Distance to Posterior Edge of Heschl’s Gyrus .................................................................... 24 Mid-Way Vector Measurements .............................................................................................. 25 Superior Temporal Plane .................................................................................................... 25 Distance to Anterior Edge of Heschl’s Gyrus..................................................................... 25 Distance to Posterior Edge of Heschl’s Gyrus .................................................................... 26 Gender Differences - Mid-Way Vector ................................................................................... 26 Superior Temporal Plane .................................................................................................... 26 Distance to Anterior Edge of Heschl’s Gyrus..................................................................... 27 Distance to Posterior Edge of Heschl’s Gyrus .................................................................... 27 Percent of Superior Temporal Plane Length vs. Heschl’s Gyrus Number .............................. 28 Percent of Superior Temporal Plane Length vs. Heschl’s Gyrus Angle Type ........................ 29 Angle of Heschl’s Gyrus vs. Angle Type ................................................................................ 29 Percent of Superior Temporal Plane Length vs. Ascending Ramus Type ............................... 30 Discussion ..................................................................................................................................... 31 Study Limitations and Future Goals ........................................................................................ 34 Conclusion .................................................................................................................................... 35 References ..................................................................................................................................... 36 ESTABLISHING A VISUAL GUIDELINE FOR THE LOCUS OF AUDITORY CORTEX IN HUMANS 4 List of Figures Figure 1 ......................................................................................................................................... 13 Figure 2 ......................................................................................................................................... 14 Figure 3 ......................................................................................................................................... 17 Figure 4 ......................................................................................................................................... 18 Figure 5 ......................................................................................................................................... 19 Figure 6 ......................................................................................................................................... 20 Figure 7 ......................................................................................................................................... 28 Figure 8 ......................................................................................................................................... 29 Figure 9 ......................................................................................................................................... 30 Figure 10 ....................................................................................................................................... 31 ESTABLISHING A VISUAL GUIDELINE FOR THE LOCUS OF AUDITORY CORTEX IN HUMANS 5 List of Tables Table 1 .......................................................................................................................................... 26 ESTABLISHING A VISUAL GUIDELINE FOR THE LOCUS OF AUDITORY CORTEX IN HUMANS 6 Abstract Given the variability of human brain anatomy, there is a need to develop a guideline for visually identifying important auditory structures. Traditionally, visual guidelines have been taught in order to help clinicians quickly and reliably identify central auditory structures in the brain. However, the reliability of some of these guidelines have been accepted at face value but not necessarily studied extensively. This study examines the location of Heschl’s gyrus along the superior temporal plane and the consistency of the “two-thirds rule” – which states that Heschl’s gyrus appears in the most posterior third of the superior temporal plane. Heschl’s gyrus and intra-hemispheric measures along the superior temporal plane are examined,