Functional organization and population dynamics in the mouse primary auditory cortex

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Cortical processing of auditory stimuli involves large populations of neurons with distinct individual response profiles. However, the functional organization and dynamics of local populations in the auditory cortex have remained largely unknown. Using in vivo two-photon calcium imaging, we examined the response profiles and network dynamics of layer 2/3 neurons in the primary auditory cortex (A1) of mice in response to pure tones. We found that local populations in A1 were highly heterogeneous in the large-scale tonotopic organization. Despite the spatial heterogeneity, the tendency of neurons to respond together (measured as noise correlation) was high on average. This functional organization and high levels of noise correlations are consistent with the existence of partially overlapping cortical subnetworks. Our findings may account for apparent discrepancies between ordered large-scale organization and local heterogeneity.

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Figure 1: In vivo two-photon calcium imaging from dozens of neurons simultaneously in A1.
Figure 2: Identification of spike-induced calcium transients.
Figure 3: Single-trial and mean response profiles to pure tones.
Figure 4: Functional micro-architecture in A1 is heterogeneous.
Figure 5: Local populations in A1 are not organized tonotopically.
Figure 6: Signal correlations between neurons in local networks are low on average and are variable and decrease with distance.
Figure 7: Noise correlations in local networks are high on average and variable and decrease with distance.


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We thank H. Sompolinsky and E. Zohary for critically commenting on early versions of this manuscript. We thank N. Taaseh and A. Yaron-Jakoubovitch for their kind technical assistance during the early stages of this project. We thank Y. Rubin and J. Schiller for the software module of the line scan. We thank J. Linden for her help on cortical recordings in mice. We thank all the members of the Mizrahi laboratory and A. Eban-Rothschild for their helpful comments and discussions. This work was supported in part by a grant from Citizens United for Research in Epilepsy and by a European Research Council grant to A.M. (#203994), and by a grant of the European Union FP6 to I.N. (NOVELTUNE consortium).

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G.R., I.N. and A.M. designed the experiments together and wrote the paper together. G.R. performed the experiments and analyzed the data.

Correspondence to Adi Mizrahi.

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The authors declare no competing financial interests.

Supplementary information

Supplementary Text and Figures

Supplementary Figures 1–7 and Supplementary Discussion (PDF 2835 kb)

Supplementary Movie 1

Image stack from A1 following Fluo4-AM and SR101 loading. (WMV 5966 kb)

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Rothschild, G., Nelken, I. & Mizrahi, A. Functional organization and population dynamics in the mouse primary auditory cortex. Nat Neurosci 13, 353–360 (2010) doi:10.1038/nn.2484

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