2000 Fiscal Year Final Research Report Summary
The Role of the Frontal Lobe in Human Memory : Non-invasive Functional Imaging and Clinical Studies
| Project/Area Number |
10557059
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Neurology
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| Research Institution | Tohoku University |
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Principal Investigator |
SUZUKI Kyoko Tohoku Uni., Hospital, Lecturer, 医学部・附属病院, 講師 (20271934)
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| Co-Investigator(Kenkyū-buntansha) |
NAKASATO Nobukazu Kohnan Nospitla, Dept Neurosurgery, Head of Clinical Research, 臨床研究部長 (80207753)
FUJII Toshikatsu Tohoku Uni Grad Sch Med, Ass Prof, 大学院・医学系研究科, 助教授 (70271913)
YAMADORI Atsushi Tohoku Uni Grad Sch Med, Professor, 大学院・医学系研究科, 教授 (10030892)
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| Project Period (FY) |
1998 – 2000
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| Keywords | working memory / frontal lobe / magnetoencephalography / functional MRI / event-related magnetic field |
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| Research Abstract |
Objects
We performed clinical and neuroimaging studies to investigate neuronal basis of human memory.
Methods
1. Episodic memory ; In clinical cases, investigations were performed about dissociation between encoding and recall, between anterograde and retrograde amnesia, and between episodic and semantic memory. Furthermore we measured event-related magnetic field using whole-head magnetoencephalography (MEG) which was related episodic and semantic memory. Positron emission tomography (PET) was used to invesigate activated cerebral areas related to storing registered information.
2. Working memory and Prospective memory. Animal studies reported that both working memory and prospective memory was related to the frontal lobe function. We examined effects of aging on working memory using reading span tests in normal volunteers. In addition, working memory and propective memory tasks were performed in patients with basal forebrain amnesia. Neuroimaging studies using functional magnetic resonan
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ce imaging (fMRI) was also performed to demonstrate activated areas relating to working memory. Neuronal basis of prospective memory was investigated using PET.
3. Non -declaretive memory (Procedural memory, Priming) Procedural memory in a patient with amnesia was systematically examined. Priming effects was investigated in patients with right-sided or left-sided brain damage and the results were compared between the two groups.
4. Semantic memroy. Retrieval of semantic memory in various categories was investigated in patients with left-sided brain damage. Semantic memory of objects including their visual and functional associates was examined in detail in patients with visual agnosia or apraxia.
Results
Episodic memory ; In some patients with amnesia, encoding and recall of episodic memory or anterograde and retrograde memory were clearly dissociable, which suggested different neuronal basis of each memory system. Event-related magnetic responses revealed that not only semantic but also episodic incongruity of word pairs was processed in the left fronto-temporal areas.
Working memory and Prospective memory : Aging affects working memory and impaired subsystems of working memory were different depending on age groups. Patients with basal forebrain amnesia performed fairty good in working and prospective memory tasks, which suggested that basal forebrain might not be critical to these types of memory. Functional MRI study demonstrated that partially different cerebral regions were related to maintain and to manipulate information in working memory. PET study revealed that prefrontal areas were related to prospective memory.
Non-declaretive memory ; Procedural memory and priming was differentially impaired in patients with amnesia and without amnesia.
Semantic memory ; Selective impairment to retrieve semantic information in some restricted categories suggested that semantics in different categories could be organized in different ways.
Discussion
Clinical and neuroimaging studies indicated that various types of memory were based on different but partially overlapped neuronal network. The prefrontal areas seem to be closely related to working memory, prospective memory and judging based on episodic and semantic memory. The basal forebrain may be important to retrieve episodes as a whole. Less
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