SUSTAINED FIELDS OF TONES AND GLIDES REFLECT TONOTOPY OF THE AUDITORY-CORTEX

CORTICAL activation in response to two types of auditory stimuli, cons tant-frequency tones and frequency glides, was studied by measuring th e magnetic field outside the head using a whole-head 122-channel magne tometer. Both the magnetic Nlm and sustained responses were located in the supratemporal plane of the primary auditory cortex. The sustained responses both to constant-frequency tones and frequency glides refle ct tonotopic organization of the auditory cortex both in depth and dir ection, thus revealing the underlying neuroanatomical structure of the auditory cortex.