Tonotopic and heterotopic projection systems in physiologically defined auditory cortex

Lee, Charles C.; Schreiner, Christoph E.; Imaizumi, Kazuo; Winer, Jeffery A.

doi:10.1016/j.neuroscience.2004.06.062

Cited by 82 publications

(68 citation statements)

References 94 publications

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“…When frequency‐matched injections were made into the MEG of the same animals, the resulting patterns of labeling demonstrate a tendency for the AAF to connect more strongly to the ADF and the A1 to the posterior fields. This distinct pattern of connectivity to other parts of the EG is consistent with the idea that the A1 and AAF comprise independent connectional systems, as proposed for cat auditory cortex (Lee et al, 2004), in which studies using cortical cooling have provided evidence for functional differences between the A1 and AAF (Malhotra and Lomber, 2007; Lomber and Malhotra, 2008). Detailed investigation of the cortico‐thalamic connectivity (ideally combined with gene expression studies such as in Storace et al, 2010) will provide further information about the potential differences in these processing streams.…”

Section: Discussionsupporting

confidence: 88%

Cortico‐cortical connectivity within ferret auditory cortex

Bizley

Bajo

Nodal³

et al. 2015

J of Comparative Neurology

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Despite numerous studies of auditory cortical processing in the ferret (Mustela putorius), very little is known about the connections between the different regions of the auditory cortex that have been characterized cytoarchitectonically and physiologically. We examined the distribution of retrograde and anterograde labeling after injecting tracers into one or more regions of ferret auditory cortex. Injections of different tracers at frequency‐matched locations in the core areas, the primary auditory cortex (A1) and anterior auditory field (AAF), of the same animal revealed the presence of reciprocal connections with overlapping projections to and from discrete regions within the posterior pseudosylvian and suprasylvian fields (PPF and PSF), suggesting that these connections are frequency specific. In contrast, projections from the primary areas to the anterior dorsal field (ADF) on the anterior ectosylvian gyrus were scattered and non‐overlapping, consistent with the non‐tonotopic organization of this field. The relative strength of the projections originating in each of the primary fields differed, with A1 predominantly targeting the posterior bank fields PPF and PSF, which in turn project to the ventral posterior field, whereas AAF projects more heavily to the ADF, which then projects to the anteroventral field and the pseudosylvian sulcal cortex. These findings suggest that parallel anterior and posterior processing networks may exist, although the connections between different areas often overlap and interactions were present at all levels. J. Comp. Neurol. 523:2187–2210, 2015. © 2015 Wiley Periodicals, Inc.

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Section: Discussionsupporting

confidence: 88%

Cortico‐cortical connectivity within ferret auditory cortex

Bizley

Bajo

Nodal³

et al. 2015

J of Comparative Neurology

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“…1, 8B). These extrinsic clusters of labeling were focal in each area and, in the tonotopic areas, aligned with CF maps (Imaizumi et al, 2004;Lee et al, 2004b). The major extrinsic input arose from AI (>30%), with other tonotopic fields each providing ~10-20%, and non-tonotopic regions contributing <5% each (Fig.…”

Section: Anterior Auditory Field (Aaf)supporting

confidence: 55%

Connections of cat auditory cortex: III. Corticocortical system

Lee

Winer

2008

J of Comparative Neurology

101

115

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The mammalian auditory cortex (AC) is essential for computing the source and decoding the information contained in sound. Knowledge of AC corticocortical connections is modest other than in the primary auditory regions, nor is there an anatomical framework in the cat for understanding the patterns of connections among the many auditory areas. To address this issue, we investigated cat AC connectivity in thirteen auditory regions. Retrograde tracers were injected in the same area or in different areas to reveal the areal and laminar sources of convergent input to each region. Architectonic borders were established in Nissl and SMI-32 immunostained material. We assessed the topography, convergence, and divergence of the labeling. Intrinsic input constituted >50% of the projection cells in each area, and extrinsic inputs were strongest from functionally related areas. Each area received significant convergent ipsilateral input from several fields (5 to 8; mean 6). These varied in their laminar origin and projection density. Major extrinsic projections were preferentially from areas of the same functional type (tonotopic to tonotopic, non-tonotopic to non-tonotopic, limbic-related to limbic-related, multisensory-to-multisensory), while smaller projections link areas belonging to different groups. Branched projections between areas were <2% with deposits of two tracers in an area or in different areas. All extrinsic projections to each area were highly and equally topographic and clustered. Intrinsic input arose from all layers except layer I, and extrinsic input had unique, area-specific infragranular and supragranular origins. The many areal and laminar sources of input may contribute to the complexity of physiological responses in AC and suggest that many projections of modest size converge within each area rather than a simpler area-to-area serial or hierarchical pattern of corticocortical connectivity.

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“…85-23). Methods for anesthesia, surgery, physiology, and histology followed those in earlier studies (Lee et al, 2004a;Lee et al, 2004b). Experiments were conducted on seven female and one male adult cats, weighing 2.8-3.5 kg, and free of middle ear disease.…”

Section: Methodsmentioning

confidence: 99%

“…However, BAs are clearly sparser than heterotopic projections, which may also be involved in AC plasticity (Fig. 4F-H) (Lee et al, 2004b). To understand the function of these branched projections, their microanatomical organization and the electrophysiological properties of their synaptic connections must be determined.…”

Section: Auditory System Branched Axonsmentioning

confidence: 99%

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Branched projections in the auditory thalamocortical and corticocortical systems

Kishan¹,

Lee²,

Winer³

2008

Neuroscience

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Branched axons (BAs) projecting to different areas of the brain can create multiple feature-specific maps or synchronize processing in remote targets. We examined the organization of BAs in the cat auditory forebrain using two sensitive retrograde tracers. In one set of experiments (n=4), the tracers were injected into different frequency-matched loci in the primary auditory area (AI) and the anterior auditory field (AAF). In the other set (n=4), we injected primary, non-primary, or limbic cortical areas.After mapped injections, percentages of double labeled cells (PDLs) in the medial geniculate body (MGB) ranged from 1.4% (ventral division) to 2.8% (rostral pole). In both ipsilateral and contralateral areas AI and AAF, the average PDLs were <1%. In the unmapped cases, the MGB PDLs ranged from 0.6% (ventral division) after insular cortex injections to 6.7% (dorsal division) after temporal cortex injections. Cortical PDLs ranged from 0.1% (ipsilateral AI injections) to 3.7% AII (contralateral AII injections). PDLs within the smaller (minority) projection population were significantly higher than those in the overall population. About 2% of auditory forebrain projection cells have BAs and such cells are organized differently than those in the subcortical auditory system, where BAs can be far more numerous. Forebrain branched projections follow different organizational rules than their unbranched counterparts. Finally, the relatively larger proportion of visual and somatic sensory forebrain BAs suggests modality specific rules for BA organization.

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Tonotopic and heterotopic projection systems in physiologically defined auditory cortex

Cited by 82 publications

References 94 publications

Cortico‐cortical connectivity within ferret auditory cortex

Cortico‐cortical connectivity within ferret auditory cortex

Connections of cat auditory cortex: III. Corticocortical system

Branched projections in the auditory thalamocortical and corticocortical systems

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