Published online Jan 28, 2017. doi: 10.4329/wjr.v9.i1.5
Peer-review started: June 24, 2016
First decision: August 16, 2016
Revised: September 6, 2016
Accepted: October 22, 2016
Article in press: October 24, 2016
Published online: January 28, 2017
Functional magnetic resonance imaging (fMRI) is employed in many behavior analysis studies, with blood oxygen level dependent- (BOLD-) contrast imaging being the main method used to generate images. The use of BOLD-contrast imaging in fMRI has been refined over the years, for example, the inclusion of a spin echo pulse and increased magnetic strength were shown to produce better recorded images. Taking careful precautions to control variables during measurement, comparisons between different specimen groups can be illustrated by fMRI imaging using both quantitative and qualitative methods. Differences have been observed in comparisons of active and resting, developing and aging, and defective and damaged brains in various studies. However, cognitive studies using fMRI still face a number of challenges in interpretation that can only be overcome by imaging large numbers of samples. Furthermore, fMRI studies of brain cancer, lesions and other brain pathologies of both humans and animals are still to be explored.
Core tip: We summarize the use of blood oxygen level dependent-contrast imaging in functional magnetic resonance imaging (fMRI) by introducing and comparing the various experimental and analysis methods used, as well as describing the results obtained, and the challenges that might occur in order to derive a hypothesis for further studies and exploration. In addition, an overview of fMRI following sensory stimulation in different specimen groups in both humans and animals is provided.