Dichotomy of functional organization in the mouse auditory cortex

Abstract

The sensory areas of the cerebral cortex possess multiple topographic representations of sensory dimensions. Gradient of frequency selectivity (tonotopy) is the dominant organizational feature in the primary auditory cortex, while other feature-based organizations are less well established. We probed the topographic organization of the mouse auditory cortex at the single cell level using in vivo two-photon Ca2+ imaging. Tonotopy was present on a large scale but was fractured on a fine scale. Intensity tuning, important in level-invariant representation, was observed in individual cells but was not topographically organized. The presence or near-absence of putative sub-threshold responses revealed a dichotomy in topographic organization. Inclusion of sub-threshold responses revealed a topographic clustering of neurons with similar response properties, while such clustering was absent in supra-threshold responses. This dichotomy indicates that groups of nearby neurons with locally shared inputs can perform independent parallel computations in ACX.

Response to Comment on “Universality in the Evolution of Orientation Columns in the Visual Cortex“

“…Meng et al suggest greater variation in pinwheel density across species; however, those data were derived from studies with small sample sizes using first-generation optical imaging methods that are subject to various systematic errors described in detail in [SOM of (1), figures S2 and S3 and pp. [3][4][5][6][7][8][9][10][11][12]. Our analysis unambiguously indicates that pinwheel density is a genuine invariant feature of orientation column layout over a wide range of V1 sizes and that it is insensitive to hypercolumn size (Fig.…”

“…Siegrid Löwel, 7,8 David M. Coppola, 9 Leonard E. White, 10 Fred Wolf 1,2,7 * Meng et al conjecture that pinwheel density scales with body and brain size. Our data, spanning a 40-fold range of body sizes in Laurasiatheria and Euarchonta, do not support this conclusion.…”

“…Glires exhibit this layout for V1 sizes that vary from 3 to 80 mm 2 , irrespective of ecological niche and visual behavior (3). Indeed, Glires cortex generally deviates in cellular composition from primate or carnivore cortex (6, 7) and exhibits interspersed organization also for direction selectivity in primary somatosensory cortex and characteristic frequency in primary auditory cortex (8,9). Thus, the interspersed layout is a putative Glires-typical trait.…”

Local Diversity and Fine-Scale Organization of Receptive Fields in Mouse Visual Cortex

“…5), additional nonlinear mechanisms (Vinje and Gallant, 2000;Haider et al, 2010), or noise in the measurements. This diversity is reminiscent of that observed in mouse barrel (Sato et al, 2007) and auditory cortices (Bandyopadhyay et al, 2010;Rothschild et al, 2010) where neurons with distinct properties are found next to each other.…”

Spectral Integration in Primary Auditory Cortex Attributable to Temporally Precise Convergence of Thalamocortical and Intracortical Input

“…Thalamocortical and intracortical input systems in primary auditory cortex A1 receives a grossly topographically organized afferent input from thalamic nuclei (Merzenich et al, 1975;Velenovsky et al, 2003;Lee and Winer, 2005;Bandyopadhyay et al, 2010;Rothschild et al, 2010). These anatomical connections are much broader, as the fine suprathreshold spectral tuning of a cortical site in A1 would suggest (Wehr and Zador, 2003;Bitterman et al, 2008).…”