Dataset Information

Reliable coding of small, behaviourally relevant interaural intensity differences in a pair of interneurons of an insect.

ABSTRACT: Insects, as vertebrates and humans, use interaural intensity differences (IIDs) between the two ears for sound localization. They are remarkably sensitive for small IIDs of the order of 1-2dB. Here, we investigated, using an independent ear stimulation paradigm, how such small IIDs are reliably encoded in the binaural discharge differences of a prominent pair of interneurons. Starting with an IID of 1dB, these differences are large and significant, with the louder side being more strongly excited. In a comparison of simultaneous responses of left and right interneurons, more than 70 and 90 per cent correct responses occur at IIDs of 1 and 2.5dB, respectively.

SUBMITTER: Stradner J

PROVIDER: S-EPMC2614154 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature

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Reliable coding of small, behaviourally relevant interaural intensity differences in a pair of interneurons of an insect.

Stradner Jürgen J Römer Heiner H

Biology letters 20081201 6

Insects, as vertebrates and humans, use interaural intensity differences (IIDs) between the two ears for sound localization. They are remarkably sensitive for small IIDs of the order of 1-2dB. Here, we investigated, using an independent ear stimulation paradigm, how such small IIDs are reliably encoded in the binaural discharge differences of a prominent pair of interneurons. Starting with an IID of 1dB, these differences are large and significant, with the louder side being more strongly excite ...[more]

PMID: 18713711

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Project description:While motion is important for parsing a complex auditory scene into perceptual objects, how it is encoded in the auditory system is unclear. Perceptual studies suggest that the ability to identify the direction of motion is limited by the duration of the moving sound, yet we can detect changes in interaural differences at even shorter durations. To understand the source of these distinct temporal limits, we recorded from single units in the inferior colliculus (IC) of unanesthetized rabbits in response to noise stimuli containing a brief segment with linearly time-varying interaural time difference ("ITD sweep") temporally embedded in interaurally uncorrelated noise. We also tested the ability of human listeners to either detect the ITD sweeps or identify the motion direction. Using a point-process model to separate the contributions of stimulus dependence and spiking history to single-neuron responses, we found that the neurons respond primarily by following the instantaneous ITD rather than exhibiting true direction selectivity. Furthermore, using an optimal classifier to decode the single-neuron responses, we found that neural threshold durations of ITD sweeps for both direction identification and detection overlapped with human threshold durations even though the average response of the neurons could track the instantaneous ITD beyond psychophysical limits. Our results suggest that the IC does not explicitly encode motion direction, but internal neural noise may limit the speed at which we can identify the direction of motion.NEW & NOTEWORTHY Recognizing motion and identifying an object's trajectory are important for parsing a complex auditory scene, but how we do so is unclear. We show that neurons in the auditory midbrain do not exhibit direction selectivity as found in the visual system but instead follow the trajectory of the motion in their temporal firing patterns. Our results suggest that the inherent variability in neural firings may limit our ability to identify motion direction at short durations.

Dataset Information

Reliable coding of small, behaviourally relevant interaural intensity differences in a pair of interneurons of an insect.

Publications

Reliable coding of small, behaviourally relevant interaural intensity differences in a pair of interneurons of an insect.

Similar Datasets

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