Physiological activation of the human cerebral cortex during auditory perception and speech revealed by regional increases in cerebral blood flow

Specific types of brain activity as sensory perception auditory, somato-sensory or visual -or the performance of movements are accompanied by increases of blood flow and oxygen consumption in the cortical areas involved with performing the respective tasks. The activation patterns observed by measuring regional cerebral blood flow CBF after intracarotid Xenon-133 injection are reviewed with emphasis on tests involving auditory perception and speech, and approach allowing to visualize Wernicke and Broca's areas and their contralateral homologues in vivo. The completely atraumatic tomographic CBF methods, that are based of the use of radioactive tracers, can be applied in the same manner for mapping cortex activity. In particular single photon tomography SPECT is readily applicable to clinical audiology, so that the cortical components of the auditory processing can be more closely investigated.