Auditory Spatial Tuning at the Crossroads of the Midbrain and Forebrain

Pérez, María Lucía; Shanbhag, Sharad J.; Peña, José Luis

doi:10.1152/jn.00400.2009

Cited by 17 publications

(20 citation statements)

References 61 publications

(47 reference statements)

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“…Some neurons in the owl's thalamus bear similarity to AAR in that they represent ITDs in the low-frequency and high-frequency ranges. Notably, these neurons did not display strong changes in their auditory spatial receptive fields compared with those in the midbrain ICX (Pérez et al, 2009). While we cannot exclude the possibility that the transformation to frequency-dependent ITD tuning observed in AAR is functionally irrelevant, our data offer a strong incentive to test functional decoding of ITDs in behavioral experiments.…”

Section: Itd Sensitivity In Different Frequency Bands Across the Popumentioning

confidence: 90%

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Transformation from a Pure Time Delay to a Mixed Time and Phase Delay Representation in the Auditory Forebrain Pathway

Vonderschen¹,

Wagner²

2012

J. Neurosci.

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Birds and mammals exploit interaural time differences (ITDs) for sound localization. Subsequent to ITD detection by brainstem neurons, ITD processing continues in parallel midbrain and forebrain pathways. In the barn owl, both ITD detection and processing in the midbrain are specialized to extract ITDs independent of frequency, which amounts to a pure time delay representation. Recent results have elucidated different mechanisms of ITD detection in mammals, which lead to a representation of small ITDs in high-frequency channels and large ITDs in low-frequency channels, resembling a phase delay representation. However, the detection mechanism does not prevent a change in ITD representation at higher processing stages. Here we analyze ITD tuning across frequency channels with pure tone and noise stimuli in neurons of the barn owl's auditory arcopallium, a nucleus at the endpoint of the forebrain pathway. To extend the analysis of ITD representation across frequency bands to a large neural population, we employed Fourier analysis for the spectral decomposition of ITD curves recorded with noise stimuli. This method was validated using physiological as well as model data. We found that low frequencies convey sensitivity to large ITDs, whereas high frequencies convey sensitivity to small ITDs. Moreover, different linear phase frequency regimes in the high-frequency and low-frequency ranges suggested an independent convergence of inputs from these frequency channels. Our results are consistent with ITD being remodeled toward a phase delay representation along the forebrain pathway. This indicates that sensory representations may undergo substantial reorganization, presumably in relation to specific behavioral output.

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Section: Itd Sensitivity In Different Frequency Bands Across the Popumentioning

confidence: 90%

“…Fig. 2, also Pérez et al, 2009;Vonderschen and Wagner, 2009). ICX neurons typically respond to frequencies Ͼ3 kHz.…”

Section: Contributions Of Low-frequency and High-frequency Ranges To mentioning

confidence: 94%

Transformation from a Pure Time Delay to a Mixed Time and Phase Delay Representation in the Auditory Forebrain Pathway

Vonderschen¹,

Wagner²

2012

J. Neurosci.

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“…OV receives projections from ICc and forms part of a sound localization pathway to field L in the telencephalon [Cohen et al, 1998], independent of the ICx-tectal pathway [Knudsen et al, 1993;Wagner, 1993;Cohen and Knudsen, 1999;Pérez et al, 2009]. Cells in OV show spatially selective fields that are as sharp as neurons in ICx [Proctor and Konishi, 1997;Pérez et al, 2009], but their ITD and ILD tunings vary more across frequencies and respond to a much broader frequency range than ICx neurons, especially lower frequencies [Pérez et al, 2009]. The enlargement of OV in both Strix species may reflect a greater reliance on the OV-forebrain pathway for sound localization.…”

Section: Discussionmentioning

confidence: 99%

“…ICc-ls projects to ICx, the site of an auditory space map [Knudsen and Konishi, 1978a;Knudsen, 1983]. All divisions of ICc project to the nucleus ovoidalis (OV) [Proctor and Konishi, 1997;Cohen et al, 1998;Arthur, 2005], which in turn projects to field L in the telencephalon [Cohen et al, 1998] where auditory space is also processed [Pérez et al, 2009].…”

Section: Introductionmentioning

confidence: 99%

Relative Size of Auditory Pathways in Symmetrically and Asymmetrically Eared Owls

2011

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Owls are highly efficient predators with a specialized auditory system designed to aid in the localization of prey. One of the most unique anatomical features of the owl auditory system is the evolution of vertically asymmetrical ears in some species, which improves their ability to localize the elevational component of a sound stimulus. In the asymmetrically eared barn owl, interaural time differences (ITD) are used to localize sounds in azimuth, whereas interaural level differences (ILD) are used to localize sounds in elevation. These two features are processed independently in two separate neural pathways that converge in the external nucleus of the inferior colliculus to form an auditory map of space. Here, we present a comparison of the relative volume of 11 auditory nuclei in both the ITD and the ILD pathways of 8 species of symmetrically and asymmetrically eared owls in order to investigate evolutionary changes in the auditory pathways in relation to ear asymmetry. Overall, our results indicate that asymmetrically eared owls have much larger auditory nuclei than owls with symmetrical ears. In asymmetrically eared owls we found that both the ITD and ILD pathways are equally enlarged, and other auditory nuclei, not directly involved in binaural comparisons, are also enlarged. We suggest that the hypertrophy of auditory nuclei in asymmetrically eared owls likely reflects both an improved ability to precisely locate sounds in space and an expansion of the hearing range. Additionally, our results suggest that the hypertrophy of nuclei that compute space may have preceded that of the expansion of the hearing range and evolutionary changes in the size of the auditory system occurred independently of phylogeny.

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“…For this purpose, we recorded simultaneously using two electrodes, one in the OT and the other either in the entopallium or in the nOv. The nOv, the main thalamic auditory nucleus, represents a station along the thalmofugal pathway (Perez et al 2009), whereas the entopallium represents a station along the tectofugal pathway ). Figure 6 shows two examples of such dual recording sites in the OT and the entopallium (Fig.…”

Section: Trial-by-trial Correlationsmentioning

confidence: 99%

Ongoing activity in the optic tectum is correlated on a trial-by-trial basis with the pupil dilation response

Netser¹,

Dutta²,

Gutfreund³

2014

Journal of Neurophysiology

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Netser S, Dutta A, Gutfreund Y. Ongoing activity in the optic tectum is correlated on a trial-by-trial basis with the pupil dilation response. J Neurophysiol 111: 918 -929, 2014. First published December 4, 2013; doi:10.1152/jn.00527.2013.-The selection of the appropriate stimulus to induce an orienting response is a basic task thought to be partly achieved by tectal circuitry. Here we addressed the relationship between neural activity in the optic tectum (OT) and orienting behavioral responses. We recorded multiunit activity in the intermediate/deep layers of the OT of the barn owl simultaneously with pupil dilation responses (PDR, a well-known orienting response common to birds and mammals). A trial-by-trial analysis of the responses revealed that the PDR generally did not correlate with the evoked neural responses but significantly correlated with the rate of ongoing neural activity measured shortly before the stimulus. Following this finding, we characterized ongoing activity in the OT and showed that in the intermediate/ deep layers it tended to fluctuate spontaneously. It is characterized by short periods of high ongoing activity during which the probability of a PDR to an auditory stimulus inside the receptive field is increased. These high-ongoing activity periods were correlated with increase in the power of gamma band local field potential oscillations. Through dual recordings, we showed that the correlation coefficients of ongoing activity decreased as a function of distance between recording sites in the tectal map. Significant correlations were also found between recording sites in the OT and the forebrain entopallium. Our results suggest that an increase of ongoing activity in the OT reflects an internal state during which coupling between sensory stimulation and behavioral responses increases.

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Auditory Spatial Tuning at the Crossroads of the Midbrain and Forebrain

Cited by 17 publications

References 61 publications

Transformation from a Pure Time Delay to a Mixed Time and Phase Delay Representation in the Auditory Forebrain Pathway

Transformation from a Pure Time Delay to a Mixed Time and Phase Delay Representation in the Auditory Forebrain Pathway

Relative Size of Auditory Pathways in Symmetrically and Asymmetrically Eared Owls

Ongoing activity in the optic tectum is correlated on a trial-by-trial basis with the pupil dilation response

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