Smith_Kinshwer_Uttal

Smith_Kinshwer_Uttal - Smith, Kanwisher, Uttal S. Smith 1....

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Smith, Kanwisher, Uttal S. Smith 1. What does the acronym fMRI refer to? Functional Magnetic Resonance Imaging 2. What does fMRI measure? fMRI is a technique for determining which parts of the brain are activated by different types of physical sensation or activity, such as sight, sound or the movement of a subject's fingers. This "brain mapping" is achieved by setting up an advanced MRI scanner in a special way so that the increased blood flow to the activated areas of the brain shows up on Functional MRI scans. 3. What are the main steps in obtaining fMRI data? Person lays down in magnet. A high-resolution single scan is taken as the background for highlighting the activated brain areas. Next, a series of low resolution scans are taken over time. During some of these scans the stimulus will be presented, but not for all of them. 4. How are fMRI data analyzed? The raw input images from the MRI scanner require mathematical transformation to reconstruct the images into “real space” (so they look like brains). Need to correct for distortions, remove a moving effect and compare the low resolution images taken when the stimulus was off with those taken when it was on. Kanwisher 1. What are the suspected category-specific regions of the ventral visual pathway and what perceptual categories are they specific to? The ventral visual pathway extends from the occipital lobe into the inferior and lateral regions of the temporal lobe, involved in visually perceiving people, places, and things. 2. If you find more activity in a region to faces than to other objects, does that mean the region is involved in face perception per se? A greater response to faces than objects could be produced by processes that have nothing to do with face perception per se, including attentional engagement, which may be greater for faces than nonfaces, a general response to anything animate or anything human, or a response to the low-level visual features present in face stimuli. 3. What are the appropriate control stimuli for demonstrating that a region is involved in face perception per se? To test these and other hypotheses, we first identified the candidate face-selective fusiform region individually in each subject with the comparison of faces to objects, and then measured the response in this region of interest (ROI) to a number of subsequent contrasting conditions. After demonstrating that the same region responded at least twice as strongly to faces as to any of the other control stimuli, we concluded that this
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region is indeed selectively involved in face processing, and named it the fusiform face area, or FFA. These
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Smith_Kinshwer_Uttal - Smith, Kanwisher, Uttal S. Smith 1....

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