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The primary form of fMRI uses the blood-oxygen-level dependent (BOLD) contrast, [4] discovered by Seiji Ogawa in 1990. This is a type of specialized brain and body scan used to map neural activity in the brain or spinal cord of humans or other animals by imaging the change in blood flow ( hemodynamic response ) related to energy use by brain ...
Main limitations of fMRS are related to signal sensitivity and the fact that many metabolites of potential interest can not be detected with current fMRS techniques. Because of limited spatial and temporal resolution fMRS can not provide information about metabolites in different cell types, for example, whether lactate is used by neurons or by ...
Measurement limitations vary amongst the techniques. For instance, MEG and EEG record the magnetic or electrical fluctuations that occur when a population of neurons is active. These methods are excellent for measuring the time-course of neural events (on the order of milliseconds,) but generally bad at measuring where those events happen.
There is also significant concern regarding the validity of some of the statistics used in fMRI analyses; hence, the validity of conclusions drawn from many fMRI studies. [22] With between 72% and 90% accuracy where chance would achieve 0.8%, [23] fMRI techniques can decide which of a set of known images the subject is viewing. [24]
When fMRI was developed one of its major limitations was the inability to randomize trials, but the event related fMRI fixed this problem. [2] Cognitive subtraction was also an issue, which tried to correlate cognitive-behavioral differences between tasks with brain activity by pairing two tasks that are assumed to be matched perfectly for ...
[3] Since then, AFNI has become one of the more commonly used analysis tools in fMRI research, alongside SPM and FSL. [4] Although AFNI initially required extensive shell scripting to execute tasks, pre-made batch scripts and improvements to the graphical user interface (GUI) have since made it possible to generate analyses with less user ...
Clinical magnets generally have a field strength in the range 0.1–3.0 T, with research systems available up to 9.4 T for human use and 21 T for animal systems. [42] In the United States, field strengths up to 7 T have been approved by the FDA for clinical use. [43] Just as important as the strength of the main magnet is its precision.
The primary tool for analyzing DFC is fMRI, but DFC has also been observed with several other mediums. DFC is a recent development within the field of functional neuroimaging whose discovery was motivated by the observation of temporal variability in the rising field of steady state connectivity research.