UI  - 97045228
AU  - Cariani PA
AU  - Delgutte B
TI  - Neural correlates of the pitch of complex tones. I. Pitch and pitch
      salience.
LA  - Eng
MH  - Acoustic Stimulation
MH  - Algorithms
MH  - Animal
MH  - Cats
MH  - Evoked Potentials, Auditory/physiology
MH  - Nerve Fibers/physiology
MH  - Neurons, Afferent/*physiology
MH  - Pitch Perception/*physiology
MH  - Support, U.S. Gov't, P.H.S.
PT  - JOURNAL ARTICLE
ID  - DC-00019/DC/NIDCD
ID  - DC-00006/DC/NIDCD
ID  - DC-02356/DC/NIDCD
ID  - +
DA  - 19970220
DP  - 1996 Sep
IS  - 0022-3077
TA  - J Neurophysiol
PG  - 1698-716
SB  - M
CY  - UNITED STATES
IP  - 3
VI  - 76
JC  - JC7
AA  - Author
EM  - 199704
AB  - 1. The temporal discharge patterns of auditory nerve fibers in Dial-
      anesthetized cats were studied in response to periodic complex acoustic
      waveforms that evoke pitches at their fundamental frequencies. Single-
      formant vowels, amplitude-modulated (AM) and quasi-frequency-modulated
      tones. AM noise, click trains, and other complex tones were utilized.
      Distributions of intervals between successive spikes ("1st-order
      intervals") and between both successive and nonsuccessive spikes ("all-
      order intervals") were computed from spike trains. Intervals from many
      fibers were pooled to estimate interspike interval distributions for
      the entire auditory nerve. Properties of these "pooled interspike
      interval distributions," such as the positions of interval peaks and
      their relative heights, were examined for correspondence to the
      psychophysical data on pitch frequency and pitch salience. 2. For a
      diverse set of complex stimuli and levels, the most frequent all-order
      interspike interval present in the pooled distribution corresponded to
      the pitch heard in psychophysical experiments. Pitch estimates based on
      pooled interval distributions (30-85 fibers, 100 stimulus presentations
      per fiber) were highly accurate (within 1%) for harmonic stimuli that
      produce strong pitches at 60 dB SPL. 3. Although the most frequent
      intervals in pooled all-order interval distributions were very stable
      with respect to sound intensity level (40, 60, and 80 dB total SPL),
      this was not necessarily the case for first-order interval
      distributions. Because the low pitches of complex tones are largely
      invariant with respect to level, pitches estimated from all-order
      interval distributions correspond better to perception. 4. Spectrally
      diverse stimuli that evoke similar low pitches produce pooled interval
      distributions with similar most-frequent intervals. This suggests that
      the pitch equivalence of these different stimuli could result from
      central auditory processing mechanisms that analyze interspike interval
      patterns. 5. Complex stimuli that evoke strong or "salient" pitches
      produce pooled interval distributions with high peak-to-mean ratios.
      Those stimuli that evoke weak pitches produce pooled interval
      distributions with low peak-to-mean ratios. 6. Pooled interspike
      interval distributions for stimuli consisting of low-frequency
      components generally resembled the short-time auto-correlation function
      of stimulus waveforms. Pooled interval distributions for stimuli
      consisting of high-frequency components resembled the short-time
      autocorrelation function of the waveform envelope. 7. Interval
      distributions in populations of neurons constitute a general,
      distributed means of encoding, transmitting, and representing
      information. Existence of a central processor capable of analyzing
      these interval patterns could provide a unified explanation for many
      different aspects of pitch perception.
AD  - Department of Otology and Laryngology, Harvard Medical School, Boston,
      Massachusetts, USA.
PMID- 0008890286
SO  - J Neurophysiol 1996 Sep;76(3):1698-716

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