Effects of interaural intensity difference on the processing of interaural time difference in the owl's nucleus laminaris

Svenja Viete, José Luis Peña, Masakazu Konishi

Research output: Contribution to journalArticlepeer-review

57 Scopus citations

Abstract

Interaural time and intensity differences (ITD and IID) are processed independently in the owl's auditory system. This paper examines whether this independence is established in nucleus laminaris (NL), the first site of ITD processing. A plot of discharge rate against time difference (ITD curve) is sinusoidal in NL. The ITDs that produce the peaks are called the most favorable ITDs, and those that produce the troughs are called the least favorable ITDs. IID had little effect on the discharge rates of laminaris neurons for the most and least favorable ITDs. The degree of peak-trough modulation changed slightly with variation in IID. In contrast, IID in tonal stimuli affected the temporal aspect of ITD curves depending on the difference between the stimulus frequency and the neuron's best frequency (BF). For frequencies below BF, IID caused large and systematic shifts in ITD toward the ear in which the sound was louder, whereas for frequencies above BF, IID caused small shifts in ITD toward the opposite ear. IID had little effect on ITD curves taken with BF or broadband noise. These results can be largely accounted for by the effects of frequency and intensity on the timing of impulses at the level of the cochlear nuclei. Thus, the processing of ITD by NL neurons is independent of lid for behaviorally relevant stimuli, because the timing of impulses is insensitive to sound level when the signal is broadband.

Original languageEnglish (US)
Pages (from-to)1815-1824
Number of pages10
JournalJournal of Neuroscience
Volume17
Issue number5
DOIs
StatePublished - Mar 1 1997
Externally publishedYes

Keywords

  • interaural intensity difference
  • interaural time difference
  • nucleus laminaris
  • owl
  • parallel pathways
  • sound localization

ASJC Scopus subject areas

  • General Neuroscience

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