A Brief Outline I. Hypothesis of functional specificity Neuroscience 2004 A. Single Areas B. Multiple Areas Functional Brain Imaging II. Brain Mapping Techniques A. Lesion- Based Methods 1. Positron Emission Tomography, PET 2. Functional Magnetic Resonance Imaging, fMRI B. Cardiovascular Based Methods Joy Hirsch, Ph.D., Professor 1. Positron Emission Tomography, PET Director, fMRI Research Center 2. Functional Magnetic Resonance Imaging, fMRI C. Electromagnetic-Based Methods Columbia University Health Sciences 1. SSEP Somatosensory Potentials NI Basement 2. Cortical Stimulation 3. Magnetoencephalography, MEG www.fmri.org 4. Electroencephalography, EEG III. Integration of Brain Mapping Techniques Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al 7 7 7 7 I. Hypothesis of functional specificity 6 6 6 6 Primary Primary Flashing Flashing Specializations of single brain areas Visual Cortex LED Display Visual Cortex LED Display 5 5 5 5 4 4 4 4 Calcarine Sulcus Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al I. Hypothesis of functional specificity Functional Organization of Visual Cortex Functional Organization of Visual Cortex Specializations of single brain areas Specializations of multiple brain areas Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al Page 1
Harrington, 1964 II. Brain Mapping Techniques R R lesion A. Lesion-Based Methods Previous Previous Surgical Surgical lesion lesion Visual Field Visual Field BINOCULAR BINOCULAR FLASHING FLASHING LIGHTS Left Eye Left Eye LIGHTS Right Eye Right Eye Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al HISTORICAL MILESTONES Phineas Gage Phineas Gage FUNCTIONAL SPECIFICITY AND NEUROIMAGING Neuroscience and Medicine Physics and Engineering BROCA 1841 FARADAY Aphasia and lesions in GFi 1845 Magnetic properties of blood HARLOW 1861 Phineas Gage WERNICKE 1874 Aphasia and lesions in GTs MOSSO PAULING 1881 Blood flow and cognitive Change of magnetic state of events hemoglobin with oxygenation 1890 ROY & SHERRINGTON RABI 1909 Relationship between neural Discovery of Magnetic activity and vascular changes 1936 Resonance PURCELL / BLOCK BRODMANN 1945 Demonstration of NMR in Cytoarchitectonic regions condensed matter of cortex HAHN PENFIELD 1949 Discoverer of spin echo Damasio, H., et al; Science 264: 1102-1105, 20 May 1994 Intraoperative cortical maps 1950 phenomenon Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al HISTORICAL MILESTONES FUNCTIONAL SPECIFICITY AND NEUROIMAGING II. Brain Mapping Techniques Neuroscience and Medicine Physics and Engineering DAMADIAN Discovery that biological tissues have B. Cardiovascular Based Methods different relaxation rates 1971 HOUNSFIELD CORMACK 1. Positron Emission Tomography, PET Invention of Computed Tomography LAUTERBUR 1972 First MR image TER-POGOSSOAN SOKOLOFF 1976 MANSFIELD First PET studies of brain metabolism, blood 1977 First MRI of a body part flow, and correlates of human behavior invention of EPI 1981 (scans whole brain in secs.) PETERSON/FOX POSNER/RAICHLE 1984 PET study of human language HILAL Radiolabeled blood flow and neural events First clinical MRI scanner OGAWA 1990 Blood Oxygen dependent signal EPI/MRI and neural events BELLIVEAU 1992 Columbia fMRI Columbia fMRI Columbia fMRI Cortical map of the human visual system: fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al Page 2
a. Source of Signal a. Source of Signal Principle of PET Positron Emission Tomography Radionuclides that emit positrons A 2 Positron and electron annihilation and emission of gamma rays such as 15 O and 18 F are PET is based on the radioactive decay of positrons from the nucleus introduced into the brain. Gamma ray of the unstable atoms ( 15 O has 8 protons and 7 neutrons) H 2 15 O behaves like H 2 16 O and Site of positron indicates blood flow (rCBF) (half annihilation A 1 Positron emission Electron life = 123 seconds) integration (imaged point) in the brain time ≈ 60 seconds. Gamma ray 0-9mm 18 F – deoxyglucose behaves like Unstable Positron photon deoxyglucose and indicates resolution radionuclide limit metabolic activity (half-life = 110 PET SCANNER minutes) integration time ≈ 20 minutes From: Principles of Neural Science (4th. Ed.) Kandel, Schwartz, & Jessell, p. 377. From: www.epub.org.br/cm/n011pet/pet.htm Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al Gamma Ray Detections to Location of Function II. Brain Mapping Techniques B. Cardiovascular Based Methods 1. Positron Emission Tomography, PET a. Source of signal b. Measurement techniques From: Principles of Neural Science (4th. Ed.) Kandel,Schwartz, & Jessell, p. 377. Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al Injection of radioactive-labeled water for PET scanning II. Brain Mapping Techniques B. Cardiovascular Based Methods 1. Positron Emission Tomography, PET a. Source of signal b. Measurement techniques c. Computation for analysis Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al Page 3
Analysis of PET Results II. Brain Mapping Techniques Stimulation Fixation Difference Flashing B. Cardiovascular Based Methods Checkerboard Fixation 1. Positron Emission Tomography, PET Individual difference images 2. Functional Magnetic Resonance Imaging, fMRI Mean difference image From: Images of Mind by Posner, M. and Raichle, M. Scientific American Library, 1994, p. 24 Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al HISTORICAL MILESTONES II. Brain Mapping Techniques 1990 1977 1. Functional Magnetic Resonance Imaging, fMRI TER-POGOSSIAN OGAWA SOKOLOFF 1992 fMRI a. Source of signal First PET studies of brain BELLIVEAU metabolism, blood flow, and correlates of human behavior Cortical Map: Blood Oxygen human visual 1971 1972 1976 dependent signal system EPI / MRI Behavior MANSFIELD DAMADIAN LAUTERBUR First MRI of a body part Discovered that First MR image biological tissues Invented EPI (scans whole have different brain in secs.) relaxation rates Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI Hirsch, J., et al Hirsch, J., et al a. Source of Signal a. Source of Signal Principles of fMRI Principles of fMRI Vision-related cortical effects The MR Signal and 4 Magnetic Fields The MR Signal and 4 Magnetic Fields Sagittal Coronal MAGNETIC FIELD 1: MAGNETIC FIELD 1: MAGNETIC FIELD 2: MAGNETIC FIELD 2: • Created when a radio frequency pulse • (63.3 mgHz) is applied Scanner Environment [1.5] T • Protons precess around the axis and create Protons align along an axis a small current (MRI signal) • Protons return to aligned state when radio frequency pulse is turned off Axial MAGNETIC FIELD 3: MAGNETIC FIELD 4: MAGNETIC FIELD 3: MAGNETIC FIELD 4: • Location of the MR signal • Local signal change at a single voxel is • • QuickTime™ and a Video decompressor are needed to see this picture. due to change in proportions of • A detectable radio frequency is emitted by the oxyhemoglobin/deoxyhemoglobin protons as they relax into their aligned state • Deoxyhemoglobin is paramagentic and • The frequency is dependent upon field strength reduces the uniformity of the precessing and therefore the signal intensity • Application of magnetic field gradient (mT) is sufficient to convert detected frequencies to • This change is called BOLD Columbia fMRI Columbia fMRI Columbia fMRI Columbia fMRI location Hirsch, J., et al Page 4
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