Neuroimaging Psych 100 Monday 9 21 2015 Maggie Ugolini Neuroimaging STRUCTURAL How the brain looks How things in the brain are physically connected What happened after injury Relies on physical properties of brain structures Neuroimaging STRUCTURAL How the brain looks How things in the brain are physically connected What happened after injury Relies on physical properties of brain structures FUNCTIONAL What the brain is doing What parts of the brain work together What parts of the brain are active in what situation How do we measure brain activity Electricity Fast Action potentials Postsynaptic potentials How do we measure brain activity Electricity Fast Action potentials Postsynaptic potentials Blood flow Slow Increased activity increased demand for glucose and O2 increase in blood flow Neuroimaging Methods Goals Understand each method What are we measuring What are the strengths What are the weaknesses What does the data look like Electroencephalography EEG Measures electrical potentials on the scalp Generated by post synaptic potentials Temporally sensitive Spatially poor EEG Data Continuous EEG Identify very abnormal brain activity Epilepsy EEG Data Continuous EEG Identify very abnormal brain activity Epilepsy Study sleep Event Related Potentials Measure how the brain responds to a specific stimulus or stimulus type Averaging gets rid of noise ERP Components Magnetoencephalography MEG Measures magnetic fields Generated by post synaptic potentials Temporally sensitive Spatially sensitive Research Use of MEG Almost any EEG study can be an MEG study Data will be better More spatially accurate Skull does not distort magnetic fields We can work backwards to localize source of brain activity This is controversial in EEG Clinical Use of MEG Localization of start point of seizures Informs surgeons performing brain surgery on individuals with epilepsy Is it practical CONS PROS Better spatial resolution than EEG Skull does not distort magnetic fields Same great temporal resolution as EEG Noninvasive Subject just lays there A few electrodes may need to be taped to the face Is it practical CONS SO EXPENSIVE 800 per hour Rare PROS Better spatial resolution that EEG Skull does not distort magnetic fields Same great temporal resolution as EEG Noninvasive Subject just lays there A few electrodes may need to be taped to the face Is it practical PROS Better spatial resolution that EEG Skull does not distort magnetic fields Same great temporal resolution as EEG Noninvasive Subject just lays there A few electrodes may need to be taped to the face CONS SO EXPENSIVE 800 per hour Rare Magnetically shielded room in the basement of a facility Specialized training is necessary functional Magnetic Resonance Imaging fMRI Measures BOLD signal Blood flow Temporally Poor Blood flow is slow Spatially Sensitive Diffusion Tensor Imaging DTI Measures water molecules all diffusing in the same direction White matter tracts Not interested in temporal info Very spatially sensitive Computed Axial Tomography Scan CT or CAT scan Computed Axial Tomography Scan CT or CAT scan Specialized X Rays for soft tissue Relies on physical properties of the brain Arranged to be 3 D Computed Axial Tomography Scan CT or CAT scan Specialized X Rays for soft tissue Relies on physical properties of the brain Arranged to be 3 D No temporal resolution Good spatial resolution Common after injury or to look for tumors Post Concussion CT Positron Emission Tomography PET Uses a radioactive trace to determine what parts of the brain are active Poor temporal resolution Good spatial resolution
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