1 / 33

fMRI 를 이용한 대뇌기능평가

fMRI 를 이용한 대뇌기능평가. 서울대학교 의과대학 신경과학교실 대학원 인지과학 협동과정 이경민, MD, PhD. 주요 논의 내용. fMRI 연구의 주요 관찰 결과 요약 대뇌기능평가의 실례: 산술기능에 관여하는 대뇌피질의 기능적 분화 양상. BOLD 신호 ( blood-oxygenation level dependent). behavior neural activation increased cerebral blood flow decreased deoxyhemoglobin

aian
Download Presentation

fMRI 를 이용한 대뇌기능평가

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. fMRI를 이용한 대뇌기능평가 서울대학교 의과대학 신경과학교실 대학원 인지과학 협동과정 이경민, MD, PhD

  2. 주요 논의 내용 fMRI 연구의 주요 관찰 결과 요약 대뇌기능평가의 실례:산술기능에 관여하는 대뇌피질의 기능적 분화 양상

  3. BOLD 신호(blood-oxygenation level dependent) behavior neural activation increased cerebral blood flow decreased deoxyhemoglobin decreased perturbation of magnetic field homogeneity increased T2* signal

  4. fMRI 신호에 관한 세가지 관찰사실 Local increases and decreases in brain activity are reliably accompanied by changes in blood flow. These blood flow changes exceed any accompanying change in the oxygen consumption. Blood flow changes are accompanied by changes in glucose metabolism of approximately equal magnitude and spatial extent.

  5. Activity-circulation coupling in the brain 일반적인 해석: oxydative metabolism of glucose 상반되는 관찰결과: CBF increase in excess of oxygen consumption CBF decrease from baseline

  6. 산소소모량을 초과하는 국소 혈류 증가 reactive hyperemia to localized oxygen depletion transient decrease of oxygen level before increase increased CBF in wider and greater extent due to nonlinear coupling between oxydative metabolism of glucose and oxygen supply questions: matching between glucose utilization and CBF more tight spatial relationship in neurovascular coupling no decrease in oxyHgb with increase in deoxyHgb: Capillary recruitment ? What happens with a negative BOLD signal ?

  7. CBF decrease from baseline inhibitory activity ?  but, energy-requiring process group reduction of activity ? by diffuse projecting system from brainstemas in cerebellar diaschisis

  8. Characteristics of fMRI data • Hemodynamic response to neural activity • 지연반응: • 2 ~ 3 초 후 신호변화시작 • 4 ~ 6 초 후 최대 신호 변화 • Hemodynamic transfer function applied to instantaneous neural event • Almost linear summation of signals

  9. fMRI 와 기존의 대뇌피질 신경생리학 연구 • 기존 신경생리학적 지식의 확인 • 새로운 발견 • Examples • HERA model of memory encoding / retrieval • Decrease of signal at retrosplenial / precuneus area & medial orbitofrontal cortex

  10. 뇌기능 분화에 대한 새로운 시각 • Holistic vs. localistic viewpoints • Brain “mass” vs. Brain “center” • Network of cortical areas as a functional unit

  11. fMRI 연구의 방향 • High SNR(signal-to-noise ratio) • 개인별 뇌활성화 연구 • Parametric study designcf) cognitive subtraction • 뇌규준 지도 작성 • 뇌기능의 정상적 변이 • 뇌질환자에 대한 임상적 활용

  12. fMRI에 의한 대뇌피질 기능 평가 • 산술기능에 관여하는 대뇌피질의 기능적 분화 양상

  13. Case 1 56 year-old woman with ICHat left temporoparietal area Mild attentional dysfunctionMild motor aphasiaGerstmann featuresIntact memory except initial recall dysfunction

  14. KBJ

  15. Case 2 66 year-old man with general weakness, confusion, and urinary incontinence Impaired complex attentionCallosal disconnection syndrome - impaired inter-manual transferDyscalculia: worse with subtraction (RT ca. 5 sec) than with multiplication (RT ca. 2 sec).

  16. JIS

  17. Issues Cognitive components of calculation Neural substrates underlying such components Neural codes used in arithmetic operations

  18. Impairments of calculation Attentional acalculia Frontal dysfunction metabolic encephalopathy etc. True acalculia part of Gerstmann syndrome isolated acalculia

  19. Experiment 1 Tasks: calculation vs. number reading Block design : (30 seconds for each task) X 10 Subjects: 7 men, 4 women (25-35 y.o.) EPI gradient echo sequenceVoxel size: 3.75 x 3.75 x 5 mmSPM96

  20. Calculation - Number reading (p < 0.001) Reading numbers - Calculation (p < 0.001)

  21. Experiment 2 Tasks: subtraction vs. multiplicationof single digit numbers multiplication  rote arithmetic factssubtraction  quantitative numerical knowledge(Dehaene & Cohen, 1997) Block design : (30 seconds for each task) X 10 Subjects: 6 men, 4 women (25-35 y.o.)

  22. Multiplication - Subtraction (p < 0.001) a 7 6 5 4 3 2 1 0 Subtraction - Multiplication (p < 0.001) b 7 6 5 4 3 2 1 0 Figure 1 Lee

  23. a 101.5 MR signal (%) 101.0 100.5 100.0 99.5 S M S M S M S M S M 101.0 b MR signal (%) 100.5 100.0 99.5 99.0 1 20 40 60 80 100 Scan number Figure 2 Lee

  24. Patient with more impaired multiplication than subtraction Brain activation by fMRI Subtraction > Multi. (Red) Multi. > Subtraction (Green) Z = 32 mm Z = 36 mm KBJ

  25. a 22.5 30 37.5 45 b 24 32 36 44 Figure 3 Lee

  26. Multiplication > Subtraction Patient with more slowing of subtraction than multiplication Subtraction > Multiplication JIS

  27. Conclusions Cases showing dissociation among arithmetic operations Differential brain activation by arithmetic operations Arithmetic operations in brain Left fronto-parietal areas for multiplication by rote number-fact memory Bilateral parietal areas for subtraction by quantitative manipulation

  28. 1400 * 1271.2 * 1169.5 1200 Reaction time (msec) 996.0 995.9 993.0 992.8 1000 800 Multiplication Subtraction Lee & Kang, Cognition (2002)

More Related