Functional MR of the primary auditory cortex: an analysis of pure tone activation and tone discrimination

• Published in: American journal of neuroradiology : AJNR Vol. 18; no. 4; pp. 601 - 610
• Main Authors: Strainer, JC, Ulmer, JL, Yetkin, FZ, Haughton, VM, Daniels, DL, Millen, SJ
• Format: Journal Article
• Language: English
• Published: Oak Brook, IL Am Soc Neuroradiology 01.04.1997; American Society of Neuroradiology
• Subjects: Acoustic Stimulation; Adult; Anatomy; Audiometry, Pure-Tone; Audiometry, Speech; Auditory Cortex - physiology; Auditory Perception - physiology; Auditory Threshold - physiology; Biological and medical sciences; Central nervous system; Echo-Planar Imaging - instrumentation; Echo-Planar Imaging - methods; Female; Fundamental and applied biological sciences. Psychology; Hearing - physiology; Humans; Magnetic Resonance Imaging; Male; Speech Perception - physiology; Temporal Lobe - physiology; Vertebrates: nervous system and sense organs; Human; Primary; Medical imagery; Functional analysis; Anatomy; Nuclear magnetic resonance imaging; Auditory cortex
• ISSN: 0195-6108; 1936-959X

To use functional MR imaging to measure the effect of frequency (pitch), intensity (loudness), and complexity of auditory stimuli on activation in the primary and secondary auditory cortexes. Multiplanar echo-planar images were acquired in healthy subjects with normal hearing to whom auditory stimuli were presented intermittently. Functional images were processed from the echo-planar images with conventional postprocessing methods. The stimuli included pure tones with a single frequency and intensity, pure tones with the frequency stepped between 1,000, 2,000, 3,000, or 4,000 Hz, and spoken text. The pixels activated by each task in the transverse temporal gyrus (TTG) and the auditory association areas were tabulated. The pure tone task activated the TTG. The 1,000-Hz tone activated significantly more pixels in the TTG than did the 4,000-Hz tone. The 4,000-Hz tone activated pixels primarily in the medial TTG, whereas the 1,000-Hz tone activated more pixels in the lateral TTG. Higher intensity tones activated significantly more pixels than did lower intensity tones at the same frequency. The stepped tones activated more pixels than the pure tones, but the difference was not significant. The text task produced significantly more activation than did the pure tones in the TTG and in the auditory association areas. The more complex tasks (stepped tones and listening to text) tended to activate more pixels in the left hemisphere than in the right, whereas the simpler tasks activated similar numbers of pixels in each hemisphere. Auditory stimuli activate the TTG and the association areas. Activation in the primary auditory cortex depends on frequency, intensity, and complexity of the auditory stimulus. Activation of the auditory association areas requires more complex auditory stimuli, such as the stepped tone task or text reading.