Brainstem inputs to the ferret medial geniculate nucleus and the effect of early deafferentation on novel retinal projections to the auditory thalamus

Angelucci, Alessandra; Clascá, Francisco; Sur, Mriganka

doi:10.1002/(sici)1096-9861(19981026)400:3<417::aid-cne10>3.0.co;2-o

Cited by 40 publications

(18 citation statements)

References 64 publications

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“…Three earlier studies based on retrograde transport of horseradish peroxidase suggest similarities as well as differences between the present data and results from cats (Henkel, 1983), mustache bat (Casseday et al, 1989) and ferrets (Angelucci et al, 1998). The mustache bat is the most unique, with nearly all subcollicular MG-projecting cells located in a single nucleus, the nucleus of the central acoustic tract (Casseday et al, 1989).…”

Section: Discussionsupporting

confidence: 60%

“…Henkel (1983) and Casseday et al (1989) described projections to the MG from cells in or near the ventral nucleus of the lateral lemniscus (VLL). Angelucci et al (1998) subsequently described subcollicular projections to the MG that originated from the dorsal tegmental regions and areas near the VLL, as described in earlier studies, and also from additional cells in medial and lateral superior olivary nuclei. Finally, more recent work has revealed a direct projection to the MG from the cochlear nucleus (Malmierca et al, 2002; Anderson et al, 2006; Schofield et al, 2014).…”

Section: Introductionmentioning

confidence: 88%

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Subcollicular projections to the auditory thalamus and collateral projections to the inferior colliculus

2014

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Experiments in several species have identified direct projections to the medial geniculate nucleus (MG) from cells in subcollicular auditory nuclei. Moreover, many cochlear nucleus cells that project to the MG send collateral projections to the inferior colliculus (IC) (Schofield et al., 2014). We conducted three experiments to characterize projections to the MG from the superior olivary and the lateral lemniscal regions in guinea pigs. For experiment 1, we made large injections of retrograde tracer into the MG. Labeled cells were most numerous in the superior paraolivary nucleus, ventral nucleus of the trapezoid body, lateral superior olivary nucleus, ventral nucleus of the lateral lemniscus, ventrolateral tegmental nucleus, paralemniscal region and sagulum. Additional sources include other periolivary nuclei and the medial superior olivary nucleus. The projections are bilateral with an ipsilateral dominance (66%). For experiment 2, we injected tracer into individual MG subdivisions. The results show that the subcollicular projections terminate primarily in the medial MG, with the dorsal MG a secondary target. The variety of projecting nuclei suggest a range of functions, including monaural and binaural aspects of hearing. These direct projections could provide the thalamus with some of the earliest (i.e., fastest) information regarding acoustic stimuli. For experiment 3, we made large injections of different retrograde tracers into one MG and the homolateral IC to identify cells that project to both targets. Such cells were numerous and distributed across many of the nuclei listed above, mostly ipsilateral to the injections. The prominence of the collateral projections suggests that the same information is delivered to both the IC and the MG, or perhaps that a common signal is being delivered as a preparatory indicator or temporal reference point. The results are discussed from functional and evolutionary perspectives.

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Section: Discussionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 88%

Subcollicular projections to the auditory thalamus and collateral projections to the inferior colliculus

2014

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“…Thus, the increase in c‐Fos and Arc/Arg3.1 immunoreactivity in the VCA shown herein suggests a homeostatic response after thalamic glutamatergic overactivation of the VCA, most likely after intermodal reorganization. A crossmodal invasion from LGN (lateral geniculate nucleus) to MGN (medial geniculate nucleus) has been shown by tract tracing experiments after early extensive removal of visual inputs, providing an anatomical substrate for understanding polimodal conversion of thalamo cortical inputs (Angelucci, Clascá, & Sur, ). Accordingly, recent studies have indicated an effective induction of thalamic plasticity in adult cortices (Cooke & Bear, ; Heynen & Bear, ; Montey & Quinlan, ; Oberlaender, Ramirez, & Bruno, ; Yu et al, ).…”

Section: Discussionmentioning

confidence: 99%

c‐Fos and Arc/Arg3.1 expression in auditory and visual cortices after hearing loss: Evidence of sensory crossmodal reorganization in adult rats

Pernìa

Estévez

Poveda

et al. 2017

J of Comparative Neurology

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Cross-modal reorganization in the auditory and visual cortices has been reported after hearing and visual deficits mostly during the developmental period, possibly underlying sensory compensation mechanisms. However, there are very few data on the existence or nature and timeline of such reorganization events during sensory deficits in adulthood. In this study, we assessed long-term changes in activity-dependent immediate early genes c-Fos and Arc/Arg3.1 in auditory and neighboring visual cortical areas after bilateral deafness in young adult rats. Specifically, we analyzed qualitatively and quantitatively c-Fos and Arc/Arg3.1 immunoreactivity at 15 and 90 days after cochlea removal. We report extensive, global loss of c-Fos and Arc/Arg3.1 immunoreactive neurons in the auditory cortex 15 days after permanent auditory deprivation in adult rats, which is partly reversed 90 days after deafness. Simultaneously, the number and labeling intensity of c-Fos-and Arc/Arg3.1-immunoreactive neurons progressively increase in neighboring visual cortical areas from 2 weeks after deafness and these changes stabilize three months after inducing the cochlear lesion. These findings support plastic, compensatory, long-term changes in activity in the auditory and visual cortices after auditory deprivation in the adult rats. Further studies may clarify whether those changes result in perceptual potentiation of visual drives on auditory regions of the adult cortex.

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“…1). Under these conditions, retinal axons project to the contralateral medial geniculate nucleus (MGN) and to a lesser extent to the ipsilateral MGN (11,(23)(24)(25)(26).…”

Section: Methodsmentioning

confidence: 99%

Cross-modal reorganization of callosal connectivity without altering thalamocortical projections

Pallas

Littman

Moore

1999

Proc. Natl. Acad. Sci. U.S.A.

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Mammalian cerebral cortex is composed of a multitude of different areas that are each specialized for a unique purpose. It is unclear whether the activity pattern and modality of sensory inputs to cortex play an important role in the development of cortical regionalization. The modality of sensory inputs to cerebral cortex can be altered experimentally. Neonatal diversion of retinal axons to the auditory thalamus (cross-modal rewiring) results in a primary auditory cortex (AI) that resembles the primary visual cortex in its visual response properties and topography. Functional reorganization could occur because the visual inputs use existing circuitry in AI, or because the early visual inputs promote changes in AI's circuitry that make it capable of constructing visual receptive field properties. The present study begins to distinguish between these possibilities by exploring whether the callosal connectivity of AI is altered by early visual experience. Here we show that early visual inputs to auditory thalamus can reorganize callosal connections in auditory cortex, causing both a reduction in their extent and a reorganization of the pattern. This result is distinctly different from that in deafened animals, which have widespread callosal connections, as in early postnatal development. Thus, profound changes in cortical circuitry can result simply from a change in the modality of afferent input. Similar changes may underlie cortical compensatory processes in deaf and blind humans.

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Brainstem inputs to the ferret medial geniculate nucleus and the effect of early deafferentation on novel retinal projections to the auditory thalamus

Cited by 40 publications

References 64 publications

Subcollicular projections to the auditory thalamus and collateral projections to the inferior colliculus

Subcollicular projections to the auditory thalamus and collateral projections to the inferior colliculus

c‐Fos and Arc/Arg3.1 expression in auditory and visual cortices after hearing loss: Evidence of sensory crossmodal reorganization in adult rats

Cross-modal reorganization of callosal connectivity without altering thalamocortical projections

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