Functional Anatomy and Plasticity of the Auditory Cortex
Because it is very difficult to directly record neuronal activities in the human brain, the function of the auditory cortex has been investigated primarily in experimental animals using pure tones and some complex sound stimuli. However, recent advances in brain imaging have made it possible to analyze the functional anatomy of the auditory cortex in human subjects. In addition, many recent reports on the primate auditory cortex deal with communication sound processing. Thus, medical and
... medical and biological approaches in this field are coming close to each other, thereby developing a new field of research. This article reviews recent reports, including ours, on functional anatomy and plasticity of the auditory cortex in both human and monkey brains. PET (positron emission tomography) studies on pre-and postlingually deafened cochlear implant users have brought about many new findings not only on developmental plasticity but also on adult plasticity of the human auditory cortex. Human results of the central processing of speech obtained through PET, MEG (magneto-encephalogram), and fMRI (functional magnetic resonance imaging) were re-evaluated from a biological viewpoint based on animal experiments. Biological approaches in the research on the human auditory cortex may shed new light on the understanding of the function and plasticity of our hearing and spoken language processing.