Browse

Functional characterization of memory-encoding networks after medial temporal lobe resection

DC Field Value Language
dc.contributor.advisor정천기-
dc.contributor.author정우림-
dc.date.accessioned2017-10-27T17:15:22Z-
dc.date.available2018-10-25-
dc.date.issued2017-08-
dc.identifier.other000000144953-
dc.identifier.urihttps://hdl.handle.net/10371/137182-
dc.description학위논문 (박사)-- 서울대학교 대학원 자연과학대학 협동과정 뇌과학전공, 2017. 8. 정천기.-
dc.description.abstractConsidering the central position of the hippocampus as a densely interconnected hub in brain networks and its role in episodic memory, medial temporal lobe resection, including the hippocampus, should modify recruitment and strength of connectivity of functional memory network. However, functional memory encoding network in patients with medial temporal lobe resection has not been well characterized, which could provide a clue for new therapeutic targets for people with memory impairment. The aim of present study is to understand how brain supports normal episodic memory function without unilateral medial temporal lobe structures in a new perspective of functional interactions of brain network. Thirty-seven patients who underwent unilateral medial temporal lobe resection for the treatment of medically intractable temporal lobe epilepsy (17 left, 20 right-
dc.description.abstractmedian age 34 years) and 24 healthy controls (median age 32 years) were studied. To understand stable and an effective memory network, patients who underwent resective surgery at least 1 year before fMRI scanning and who have normal range of postoperative memory capacity were recruited. All subjects performed functional MRI memory encoding paradigm of words and figures. Hippocampal regions of interest analysis revealed that greater activation of hippocampus contralateral to the resection was related to higher memory scores in both patient groups. Whole-brain functional activation analysis revealed that well-known task-negative areas including the medial prefrontal cortex were less deactivated in patient groups than healthy controls. Task-based functional connectivity analysis revealed that the right medial prefrontal cortex showed stronger interactions with widespread brain areas including hippocampus contralateral to the resection during successful word encoding in left surgery group and during successful figure encoding in right surgery group. Furthermore, the strengths of right medial prefrontal cortex functional connectivity predict individual memory capacity of patients. The results of present study suggest that hyper-connectivity of medial prefrontal cortex may play a pivotal role in episodic memory function with the absence of functional connections of medial temporal lobe. These results, therefore, further implicated in the studies of brain stimulation toward enhancing memory for people who suffer from medial temporal lobe-dysfunction-related memory disturbances by providing possible new target area of medial prefrontal cortex.-
dc.description.tableofcontentsSECTION I. INTRODUCTION 1
CHAPTER 1: Memory and Medial Temporal Lobe 1
1.1. Human Memory System 1
1.2. Structures and Connections of the MTL 3
1.3. MTL-dysfunction-related Memory Deficits 4
1.3.1. MTL Lesion Studies 4
1.3.2. Memory Deficits in Neurological Disorders 5
CHAPTER 2: Epilepsy and Epilepsy Surgery 8
2.1. Definition of Epilepsy 8
2.2. Temporal lobe Epilepsy 9
2.3. Epilepsy Surgery 11
2.3.1. Aims of Surgery 11
2.3.2. Resective Surgery for TLE 12
2.4. Consequence of TLE Surgery 14
2.4.1. Seizure Outcome 14
2.4.2. Cognitive Outcome 16
CHAPTER 3: Functional Neuroimaging Studies of Episodic Memory 18
3.1. Introduction of fMRI Memory Studies 18
3.2. MTL Regions of Interest 19
3.2.1. MTL Activations in Healthy Controls 19
3.2.2. MTL Activations in Patients with TLE and MTLR 20
3.3. Large-scale Memory Network 21
3.3.1. Episodic Memory-related Whole-brain Regions 21
3.3.2. Introduction to Functional Connectivity of fMRI 26
3.3.3. Resting-state Network and Memory. 29
3.3.4. Task-related Memory Network 33
3.4. Findings from Brain Stimulation Studies 36
CHAPTER 4: Purpose of the Present Study 39
SECTION II. EXPERIMENTAL STUDY 42
CHAPTER 5: Materials and Methods 42
5.1. Subjects 42
5.2. Neuropsychological Tests 46
5.3. Magnetic Resonance Data Acquisition 47
5.4. Memory Task Paradigm 48
5.5. Data Analysis 51
5.5.1. Preprocessing 51
5.5.2. Event-related Analysis 52
5.5.3. Hippocampal ROIs 54
5.5.4. Task-based Functional Connectivity 54
CHAPTER 6: Results 56
6.1. Neuropsychological Performance 56
6.2. Behavioral Results 58
6.3. Hippocampal ROI Activations 59
6.4. Whole-brain Activations during Memory Encoding 60
6.4.1. Less Activation in MTLR than in HC 63
6.4.2. Greater Activation in MTLR than HC 64
6.5. Task-based Functional Connectivity 67
SECTION III. DISCUSSION AND CONCLUSION 75
CHAPTER 7: Discussion 75
7.1. Behavioral Results 75
7.2. Hippocampal ROI Activities 76
7.3. Whole-brain Activations during Memory Encoding 77
7.4. Functional Interactions during Memory Encoding 79
7.5. Implications of the Present Study 81
7.6. Methodological Considerations and Future Directions 83
CHAPTER 8: Conclusion 85
References 86
Abstract in Korean 103
-
dc.formatapplication/pdf-
dc.format.extent2389433 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subjectEpisodic memory-
dc.subjectTemporal lobe epilepsy-
dc.subjectMedial temporal lobe resection-
dc.subjectFunctional MRI-
dc.subjectFunctional connectivity-
dc.subjectMedial prefrontal cortex-
dc.subject.ddc611.81-
dc.titleFunctional characterization of memory-encoding networks after medial temporal lobe resection-
dc.typeThesis-
dc.description.degreeDoctor-
dc.contributor.affiliation자연과학대학 협동과정 뇌과학전공-
dc.date.awarded2017-08-
Appears in Collections:
College of Natural Sciences (자연과학대학)Program in Brain Science (협동과정-뇌과학전공)Theses (Ph.D. / Sc.D._협동과정-뇌과학전공)
Files in This Item:
  • mendeley

Items in S-Space are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse