Functional Magnetic Resonance Imaging (fMRI): What Can it Offer? What are the Limitations?

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Table of Contents Functional Magnetic Resonance Imaging (ƒMRI): What Can it Offer? What are the Limitations? fMRI: What it Offers/What it doesn’t William James (1890) Brain “Activation” Leads to: Signal Losses from Spin Dephasing DeoxyHb Induces Susceptibility Signal Loss (dR2,dR2*) 8 Hz Patterned Flash Stimulation Gradient-Recalled Echo Neurovascular Coupling and ƒMRI latency Inversion Recovery Inversion Recovery Multi-Slice Hemifield Activation Hemifield Alternation Hemifield Alternation - 20 seconds Photic Stimulation - 133 msec/image Response Latency vs. Stimulus Duration Average of 10 recordings Binocular vs Monocular Activation Primary Auditory Activation Auditory and Visual Naming RepeatedStimulation Human Neocortex Activation with Moving Visual Stimuli Contrast Response Test Motion Sensitivity Test 8 Hz Patterned Flash Stimulation Some Applications of ƒMRI Clinical Mapping Summary Geographic Imagery Attentional Modulation Mental Rotation - Stimuli Mental Rotation - Localization Obsessive Compulsive Disorder Results - Auditory Hallucinations Some Theoretical Considerations Blocked vs. Single Trial Blocked Experiments Single Trial Designs Brain Impulse Response Convolution of Impulse Responses with Stimuli Amplitude-weighted Linear Estimate Estimated vs. Actual ƒMRI Response Sources of Variance in Hemodynamic Imaging Scan Times and Physiology the ƒMRI Temporal Resolution is Limiting Why High Field? Current MRI Performance

Author: Mark Cohen Email: mscohen@ucla.edu Home Page: http://www.brainmapping.org