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Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. [1] [2] This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases. [3]
Resting state fMRI (rs-fMRI or R-fMRI), also referred to as task-independent fMRI or task-free fMRI, is a method of functional magnetic resonance imaging (fMRI) that is used in brain mapping to evaluate regional interactions that occur in a resting or task-negative state, when an explicit task is not being performed.
Typically in MRS a single spectrum is acquired by averaging enough spectra over a long acquisition time. [8] Averaging is necessary because of the complex spectral structures and relatively low concentrations of many brain metabolites, which result in a low signal-to-noise ratio (SNR) in MRS of a living brain.
Within fMRI methodology, there are two different ways that are typically employed to present stimuli. One method is a block related design, in which two or more different conditions are alternated in order to determine the differences between the two conditions, or a control may be included in the presentation occurring between the two conditions.
Exploding head syndrome (EHS) is an abnormal sensory perception during sleep in which a person experiences auditory hallucinations that are loud and of short duration when falling asleep or waking up. [2] [4] The noise may be frightening, typically occurs only occasionally, and is not a serious health concern. [2]
A leak in the head gasket - often called a "blown head gasket" - can result in a leak of coolant, the combustion gasses, or both. Blue smoke from the exhaust suggests that excess oil is entering the combustion chambers (although there are other possible causes than a head gasket leak). White smoke from the exhaust suggests that coolant is ...
Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) show that musical hallucinations activate a wide variety of areas in the brain including the following: auditory areas, motor cortex, visual areas, basal ganglia, brainstem, pons, tegmentum, cerebellum, hippocampi, amygdala, and peripheral auditory system.
All patients are reviewed for contraindications prior to MRI scanning. Medical devices and implants are categorized as MR Safe, MR Conditional or MR Unsafe: [6] MR-Safe – The device or implant is completely non-magnetic, non-electrically conductive, and non-RF reactive, eliminating all of the primary potential threats during an MRI procedure.