Tuning to natural stimulus dynamics in primary auditory cortex

Curr Biol. 2006 Feb 7;16(3):264-71. doi: 10.1016/j.cub.2005.12.013.


The amplitude and pitch fluctuations of natural soundscapes often exhibit "1/f spectra", which means that large, abrupt changes in pitch or loudness occur proportionally less frequently in nature than gentle, gradual fluctuations. Furthermore, human listeners reportedly prefer 1/f distributed random melodies to melodies with faster (1/f0) or slower (1/f2) dynamics. One might therefore suspect that neurons in the central auditory system may be tuned to 1/f dynamics, particularly given that recent reports provide evidence for tuning to 1/f dynamics in primary visual cortex. To test whether neurons in primary auditory cortex (A1) are tuned to 1/f dynamics, we recorded responses to random tone complexes in which the fundamental frequency and the envelope were determined by statistically independent "1/f(gamma) random walks," with gamma set to values between 0.5 and 4. Many A1 neurons showed clear evidence of tuning and responded with higher firing rates to stimuli with gamma between 1 and 1.5. Response patterns elicited by 1/f(gamma) stimuli were more reproducible for values of gamma close to 1. These findings indicate that auditory cortex is indeed tuned to the 1/f dynamics commonly found in the statistical distributions of natural soundscapes.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation
  • Animals
  • Auditory Cortex / physiology*
  • Electrophysiology
  • Ferrets
  • Neurons / physiology*
  • Pitch Perception / physiology*
  • Sound Spectrography
  • Sound*
  • Stochastic Processes