Other Technical Issues in MRI

Operationally, fMRI differs from conventional MRI in two basic respects. First, it is tailored to be sensitive to contrasts in blood flow and/or oxygenation that reflect neural activity. Second, it is typically conducted with special hardware that permits the very rapid variation of the magnetic field gradients that are needed to create images. This permits much more rapid acquisition of whole-brain volumes than is conventionally done in MRI. This rapid data collection is crucial in most modern fMRI-based experiments.

Functional MRI is made practical and powerful by virtue of special pulse sequences (such as echo planar and spiral scanning) and hardware that permit the encoding of a brain slice while using a single RF pulse, allowing the entire brain to be imaged in a few seconds. A wide variety of different pulse sequences are used in fMRI, and this remains an area of continuous innovation. Moreover, the versatility of MRI for neuroscience extends beyond fMRI, and MR can also be used to assay various aspects of brain chemistry through a technique known as magnetic resonance spectroscopy (MRS). Because some variants of MRS can measure the presence of brain metabolites at temporal resolutions on the order of minutes and spatial resolutions similar to those of BOLD fMRI, MRS is in many ways conceptually related to fMRI.

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

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