Language Activation Tests - a Functional Magnetic Resonance Imaging (fMRI) Study
Essay by Anna Klasson, Medical Biology
Magnetic Resonance (MR) and Functional Magnetic Resonance Imaging (fMRI) can be used to observe brain activity and the aim of this study was to evaluate different language area activating paradigms to see if one or more were suitable for mapping language function. Six subjects were tested and the different paradigms were: picture naming, word generation, question-assertion distinguishment and synonym generation.
The physics underlying the phenomenon of MR was discovered in the 1920s and is based upon the magnetic properties of certain nuclei in the periodic system. When placed in a magnetic field, these nuclei absorb energy in the radiofrequency range and re-emit energy during the transition back to their original orientation. This is the basis of MR. fMRI and BOLD (Blood Oxygen Level Dependent) imaging are techniques that have developed from this phenomenon.
Language areas are in most people located in the left hemisphere and the major ones are Broca’s and Wernicke’s area. These areas were differently activated from the different paradigms, but the picture naming test and the word generation test seemed to cause most activity. However, the picture naming test showed a lot of activated areas scattered all over the brain, as much in the right hemisphere as in the left. The question-assertion test and the synonym test did not show very much activation.
Perhaps six subjects are not enough to come to any reliable conclusions regarding these tests, but it seems like the word generation test is the most useful paradigm for studying language area activation in the brain.