title: Activation patterns of the primary auditory cortex in normal-hearing subjects: a functional magnetic resonance imaging study.
abstract: CONCLUSIONS
  These results demonstrate that functional magnetic resonance imaging (fMRI) is an optimal tool to investigate the auditory cortex. The study suggests that there is a medio-lateral gradient of responsiveness to high frequencies medially and low frequencies laterally. The contralateral auditory cortex is more responsive than the ipsilateral cortex to tones presented monaurally.
  
  
  OBJECTIVE
  To demonstrate the activation of the primary auditory cortex in normal-hearing subjects using fMRI and to examine the response and topographic location of activation in the human auditory brain to stimulation with two different frequencies in a large group of volunteers.
  
  
  METHODS
  Scanning was performed on a 1.5 Tesla MR with head gradient coils and a birdcage radiofrequency coil. Multiplanar echo-planar images were acquired in 32 subjects aged between 18 and 49 years. Two groups were defined, according to age (group A, 18 to <35 years old; group B, 35 to <50 years old). We studied normal-hearing subjects scanned while listening to auditory stimuli: narrative text in one volunteer and non-speech noise (pure tones 750 Hz and pure tones 2 KHz) in all subjects.
  
  
  RESULTS
  For both tone frequencies, auditory activation was observed bilaterally across the supratemporal plane in 29 of the 32 subjects (90.62%) with a probability level of p<0.001. In Heschl's gyrus (HG) contralateral to the stimulated ear, the extent of activation was generally greater than in homolateral HG. There were no statistical differences in HG activation according to age or sex. The 750 Hz tone activated more voxels in the medial area of the transverse temporal gyrus (TTG) whereas the 2000 Hz tone activated more voxels in the lateral TTG.
authors.affiliation: Department of Otorhinolaryngology, V. Salud Hospital, Toledo, Spain. 34227lmc@comb.es
authors.forename: Luis-Miguel
authors.initials: LM
authors.lastname: Menéndez-Colino
authors.forename: Carlos
authors.initials: C
authors.lastname: Falcón
authors.forename: Jose
authors.initials: J
authors.lastname: Traserra
authors.forename: Joan
authors.initials: J
authors.lastname: Berenguer
authors.forename: Teresa
authors.initials: T
authors.lastname: Pujol
authors.forename: Joan
authors.initials: J
authors.lastname: Doménech
authors.forename: Manuel
authors.initials: M
authors.lastname: Bernal-Sprekelsen
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged