Functional brain imaging with use of a new and powerful neuroimaging technique

Abstract

Most of the information available on the human brain came from subjects who had sustained major head wounds, or who suffered from various mental disorders. By determining the extent of brain damage, and the nature of the loss of function, it was possible to infer which regions of the brain were responsible for which function. With the development of the imaging techniques of computerised tomography (CT) and magnetic resonance imaging it was possi-ble to be more specific as to the location of damage in brain injured patients. The meas-urement of the electrical signals on the scalp, arising from the synchronous firing of the neu-rons in response to a stimulus, known as elec-troencephalography (EEG), opened up new possibilities in studying brain function in nor-mal subjects. However it was the advent of the functional imaging modalities of positron emis-sion tomography (PET), single photon emission computed tomography (SPECT), functional magnetic resonance imaging (fMRI), and mag-netoencephalography (MEG) that led to a new era in the study of brain function. In this paper the mechanisms of the techniques mentioned above are outlined, together with an assess-ment of their strengths and weaknesses. Then an introduction to the Metabolism and Blood Flow in the Brain is given. This is followed by a more detailed explanation of functional MRI and how such experiments are performed.