[Results of a functional magnetic resonance study of the primary auditory cortex (I): general characteristics and individual outcomes]. / Resultados en el estudio del córtex auditivo mediante resonancia magnética funcional (I): características generales y resultados individuales.

OBJECTIVE: To demonstrate and investigate the activation patterns of the primary auditory cortex (Heschl's gyrus) using functional magnetic resonance imaging (fMRI). MATERIAL AND METHODS: Pure tone stimuli at 750 Hz and 2000 Hz were delivered to the right and left ear of 32 normal-hearing volunteers (18-49 years old) in 20-second on-off cycles. The fMRI data were obtained using a 1.5 Tesla scanner and processed with SPM2. RESULTS: For both tone frequencies, bilateral hemispheric activation was identified in the transverse temporal gyrus (Heschl's gyrus) in 29 subjects (90.62 %) in response to pure tone stimuli with a probability level of p < 0.001. For monaural stimulation, bilateral hemispheric activation was observed with generally greater extent of activation in the Heschl's gyrus (HG) contralateral to the stimulated ear. CONCLUSIONS: These results demonstrate that fMRI is a useful imaging technique to investigate the auditory cortex. The contralateral auditory cortex is more responsive than the ipsilateral cortex to tones presented monaurally.