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Meredith MA, Kay JM, Lomber SG, Clemo HR. Early hearing loss induces plasticity within extra-striate visual cortex. Eur J Neurosci 2021; 53:1950-1960. [PMID: 33387377 DOI: 10.1111/ejn.15104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 11/12/2020] [Accepted: 12/22/2020] [Indexed: 11/29/2022]
Abstract
Supranormal perceptual performance has been observed within the intact senses of early-deaf or blind humans and animals. For cortical areas deprived of their normal sensory input, numerous studies have shown that the lesioned modality is replaced by that of the intact sensory modalities through a process termed crossmodal plasticity. In contrast, little is known about the effects of loss of a particular sensory modality on the cortical representations of the remaining, intact sensory modalities. In the present study, an area of extrastriate visual cortex from early-deaf adult cats was examined for features of dendritic plasticity known to occur after early-deafness. Using light-microscopy of Golgi-stained pyramidal neurons from the posterolateral lateral suprasylvian (PLLS) cortex, dendritic spine density significantly increased (~19%), while spine head size was slightly but significantly decreased (~9%) following early hearing loss. Curiously, these changes were not localized to regions of the visual PLLS known to receive auditory inputs, but instead showed a broad pattern more reflective of the distribution of the area's visual features. Whereas hearing loss results in crossmodal plasticity in auditory cortices, the same peripheral lesion can also induce intramodal plasticity within representations of the intact sensory systems that may also contribute to supranormal performance.
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Affiliation(s)
- M Alex Meredith
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - John M Kay
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Stephen G Lomber
- Department of Physiology, Department of Neurology and Neurosurgery, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - H Ruth Clemo
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
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Land R, Radecke JO, Kral A. Congenital Deafness Reduces, But Does Not Eliminate Auditory Responsiveness in Cat Extrastriate Visual Cortex. Neuroscience 2018; 375:149-157. [DOI: 10.1016/j.neuroscience.2018.01.065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 01/25/2018] [Accepted: 01/30/2018] [Indexed: 01/12/2023]
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Meredith MA, Wallace MT, Clemo HR. Do the Different Sensory Areas Within the Cat Anterior Ectosylvian Sulcal Cortex Collectively Represent a Network Multisensory Hub? Multisens Res 2018; 31:793-823. [PMID: 31157160 PMCID: PMC6542292 DOI: 10.1163/22134808-20181316] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Current theory supports that the numerous functional areas of the cerebral cortex are organized and function as a network. Using connectional databases and computational approaches, the cerebral network has been demonstrated to exhibit a hierarchical structure composed of areas, clusters and, ultimately, hubs. Hubs are highly connected, higher-order regions that also facilitate communication between different sensory modalities. One region computationally identified network hub is the visual area of the Anterior Ectosylvian Sulcal cortex (AESc) of the cat. The Anterior Ectosylvian Visual area (AEV) is but one component of the AESc that also includes the auditory (Field of the Anterior Ectosylvian Sulcus - FAES) and somatosensory (Fourth somatosensory representation - SIV). To better understand the nature of cortical network hubs, the present report reviews the biological features of the AESc. Within the AESc, each area has extensive external cortical connections as well as among one another. Each of these core representations is separated by a transition zone characterized by bimodal neurons that share sensory properties of both adjoining core areas. Finally, core and transition zones are underlain by a continuous sheet of layer 5 neurons that project to common output structures. Altogether, these shared properties suggest that the collective AESc region represents a multiple sensory/multisensory cortical network hub. Ultimately, such an interconnected, composite structure adds complexity and biological detail to the understanding of cortical network hubs and their function in cortical processing.
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Affiliation(s)
- M. Alex Meredith
- Department of Anatomy and Neurobiology, Virginia
Commonwealth University School of Medicine, Richmond, VA 23298 USA
| | - Mark T. Wallace
- Vanderbilt Brain Institute, Vanderbilt University,
Nashville, TN 37240 USA
| | - H. Ruth Clemo
- Department of Anatomy and Neurobiology, Virginia
Commonwealth University School of Medicine, Richmond, VA 23298 USA
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Origin of the thalamic projection to dorsal auditory cortex in hearing and deafness. Hear Res 2017; 343:108-117. [DOI: 10.1016/j.heares.2016.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 05/18/2016] [Accepted: 05/26/2016] [Indexed: 10/21/2022]
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Wong C, Chabot N, Kok MA, Lomber SG. Amplified somatosensory and visual cortical projections to a core auditory area, the anterior auditory field, following early- and late-onset deafness. J Comp Neurol 2015; 523:1925-47. [DOI: 10.1002/cne.23771] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 02/25/2015] [Accepted: 02/26/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Carmen Wong
- Cerebral Systems Laboratory, University of Western Ontario; London Ontario N6A 5K8 Canada
- Graduate Program in Neuroscience; University of Western Ontario; London Ontario N6A 5K8 Canada
| | - Nicole Chabot
- Cerebral Systems Laboratory, University of Western Ontario; London Ontario N6A 5K8 Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario N6A 5K8 Canada
| | - Melanie A. Kok
- Cerebral Systems Laboratory, University of Western Ontario; London Ontario N6A 5K8 Canada
- Graduate Program in Neuroscience; University of Western Ontario; London Ontario N6A 5K8 Canada
| | - Stephen G. Lomber
- Cerebral Systems Laboratory, University of Western Ontario; London Ontario N6A 5K8 Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario N6A 5K8 Canada
- Department of Psychology; University of Western Ontario; London Ontario N6A 5K8 Canada
- Brain and Mind Institute, University of Western Ontario; London Ontario N6A 5K8 Canada
- National Centre for Audiology, University of Western Ontario; London Ontario N6A 5K8 Canada
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Foxworthy WA, Clemo HR, Meredith MA. Laminar and connectional organization of a multisensory cortex. J Comp Neurol 2013; 521:1867-90. [PMID: 23172137 DOI: 10.1002/cne.23264] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/07/2012] [Accepted: 11/06/2012] [Indexed: 11/07/2022]
Abstract
The transformation of sensory signals as they pass through cortical circuits has been revealed almost exclusively through studies of the primary sensory cortices, for which principles of laminar organization, local connectivity, and parallel processing have been elucidated. In contrast, almost nothing is known about the circuitry or laminar features of multisensory processing in higher order, multisensory cortex. Therefore, using the ferret higher order multisensory rostral posterior parietal (PPr) cortex, the present investigation employed a combination of multichannel recording and neuroanatomical techniques to elucidate the laminar basis of multisensory cortical processing. The proportion of multisensory neurons, the share of neurons showing multisensory integration, and the magnitude of multisensory integration were all found to differ by layer in a way that matched the functional or connectional characteristics of the PPr. Specifically, the supragranular layers (L2/3) demonstrated among the highest proportions of multisensory neurons and the highest incidence of multisensory response enhancement, while also receiving the highest levels of extrinsic inputs, exhibiting the highest dendritic spine densities, and providing a major source of local connectivity. In contrast, layer 6 showed the highest proportion of unisensory neurons while receiving the fewest external and local projections and exhibiting the lowest dendritic spine densities. Coupled with a lack of input from principal thalamic nuclei and a minimal layer 4, these observations indicate that this higher level multisensory cortex shows functional and organizational modifications from the well-known patterns identified for primary sensory cortical regions.
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Affiliation(s)
- W Alex Foxworthy
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298, USA
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Horie M, Meguro R, Hoshino K, Ishida N, Norita M. Neuroanatomical study on the tecto-suprageniculate-dorsal auditory cortex pathway in the rat. Neuroscience 2013; 228:382-94. [DOI: 10.1016/j.neuroscience.2012.10.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 10/10/2012] [Accepted: 10/23/2012] [Indexed: 10/27/2022]
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Clemo H, Keniston L, Meredith M. Structural Basis of Multisensory Processing. Front Neurosci 2011. [DOI: 10.1201/b11092-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Clemo HR, Sharma GK, Allman BL, Meredith MA. Auditory projections to extrastriate visual cortex: connectional basis for multisensory processing in 'unimodal' visual neurons. Exp Brain Res 2008; 191:37-47. [PMID: 18648784 PMCID: PMC2827203 DOI: 10.1007/s00221-008-1493-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Accepted: 07/07/2008] [Indexed: 02/02/2023]
Abstract
Neurophysiological studies have recently documented multisensory properties in 'unimodal' visual neurons of the cat posterolateral lateral suprasylvian (PLLS) cortex, a retinotopically organized area involved in visual motion processing. In this extrastriate visual area, a region has been identified where both visual and auditory stimuli were independently effective in activating neurons (bimodal zone), as well as a second region where visually-evoked activity was significantly facilitated by concurrent auditory stimulation but was unaffected by auditory stimulation alone (subthreshold multisensory region). Given their different distributions, the possible corticocortical connectivity underlying these distinct forms of crossmodal convergence was examined using biotinylated dextran amine (BDA) tracer methods in 21 adult cats. The auditory cortical areas examined included the anterior auditory field (AAF), primary auditory cortex (AI), dorsal zone (DZ), secondary auditory cortex (AII), field of the rostral suprasylvian sulcus (FRS), field anterior ectosylvian sulcus (FAES) and the posterior auditory field (PAF). Of these regions, the DZ, AI, AII, and FAES were found to project to the both the bimodal zone and the subthreshold region of the PLLS. This convergence of crossmodal inputs to the PLLS suggests not only that complex auditory information has access to this region but also that these connections provide the substrate for the different forms (bimodal versus subthreshold) of multisensory processing which may facilitate its functional role in visual motion processing.
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Affiliation(s)
- H Ruth Clemo
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298-0709, USA.
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Allman BL, Meredith MA. Multisensory Processing in “Unimodal” Neurons: Cross-Modal Subthreshold Auditory Effects in Cat Extrastriate Visual Cortex. J Neurophysiol 2007; 98:545-9. [PMID: 17475717 DOI: 10.1152/jn.00173.2007] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Historically, the study of multisensory processing has examined the function of the definitive neuron type, the bimodal neuron. These neurons are excited by inputs from more than one sensory modality, and when multisensory stimuli are present, they can integrate their responses in a predictable manner. However, recent studies have revealed that multisensory processing in the cortex is not restricted to bimodal neurons. The present investigation sought to examine the potential for multisensory processing in nonbimodal (unimodal) neurons in the retinotopically organized posterolateral lateral suprasylvian (PLLS) area of the cat. Standard extracellular recordings were used to measure responses of all neurons encountered to both separate- and combined-modality stimulation. Whereas bimodal neurons behaved as predicted, the surprising result was that 16% of unimodal visual neurons encountered were significantly facilitated by auditory stimuli. Because these unimodal visual neurons did not respond to an auditory stimulus presented alone but had their visual responses modulated by concurrent auditory stimulation, they represent a new form of multisensory neuron: the subthreshold multisensory neuron. These data also demonstrate that bimodal neurons can no longer be regarded as the exclusive basis for multisensory processing.
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Affiliation(s)
- Brian L Allman
- Dept of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298-0709, USA.
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Ouellette BG, Minville K, Faubert J, Casanova C. Simple and complex visual motion response properties in the anterior medial bank of the lateral suprasylvian cortex. Neuroscience 2004; 123:231-45. [PMID: 14667458 DOI: 10.1016/j.neuroscience.2003.09.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The cortical regions surrounding the suprasylvian sulcus have previously been associated with motion processing. Of the six areas originally described by Palmer et al. [J Comp Neurol 177 (1978) 237], the posteromedial lateral suprasylvian (PMLS) cortex has attracted the greatest attention. Very little physiological information is available concerning other suprasylvian visual areas, and in particular, the anteromedial lateral suprasylvian cortex (AMLS). Based on its cortical and sub-cortical connectivity patterns, the AMLS cortex is a likely candidate for higher-order motion processing in cat visual cortex. We have investigated this possibility by studying the receptive field sensitivity of AMLS neurons to complex motion stimuli. Neurons in AMLS cortex exhibited large (mean of 354 degrees (2)) and complex-like receptive fields, and most of them (74%) were classified as direction selective on the basis of their responses to sinusoidal drifting gratings. Most importantly, direction selectivity was present for complex motion stimuli. A subset of the neurons sampled (eight of 38 cells; 21%) exhibited pattern-motion selectivity in response to moving plaid patterns. The capacity of AMLS neurons to signal higher-order stimuli was further supported by their selectivity to moving complex random-dot kinematograms. Finally, 45% of 20 neurons were direction selective to a radial optic flow stimulus. Overall, these results suggest that AMLS cortex is involved in higher-order analyses of visual motion. It is possible that the AMLS cortex represents a region between PMLS and the anterior ectosylvian visual area in a functional hierarchy of areas involved in motion integration.
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Affiliation(s)
- B G Ouellette
- Visual Neuroscience Laboratory, School of Optometry, Université de Montréal, CP 6128, Succ. Centre-ville, H3C 3J7, Montréal, Quebec, Canada
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