The maturation of corticocollicular neurons in mice

Khachab, Maha; Bruce, Laura L.

doi:10.1016/s0165-3806(98)00159-x

Cited by 6 publications

(5 citation statements)

References 17 publications

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“…In the Efna3 KI animals, retinal EFNA3 oscillation in the SC organizes neighbor-neighbor relationships of V1 and RGC TZs locally through repulsion inducing a small distance of map duplication. Our model is consistent with a retinal-matching model, suggesting that retinal inputs are required for proper cortico-collicular mapping (Khachab and Bruce, 1999; Triplett et al, 2009; Cang and Feldheim, 2013). …”

Section: Discussionsupporting

confidence: 84%

“…In V1, gradients of EPHA4/A7, running from high-lateral to low-medial have also been observed, and evidence from genetic analyses suggests their involvement in the development of cortico-collicular projections (Cang et al, 2005; Wilks et al, 2010). Moreover, the formation of the cortico-collicular map requires retinal input (Khachab and Bruce, 1999; Triplett et al, 2009), but again, the underlying molecular mechanisms remain elusive.…”

Section: Introductionmentioning

confidence: 99%

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A molecular mechanism for the topographic alignment of convergent neural maps

Savier

Eglen

Bathélémy

et al. 2017

eLife

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Sensory processing requires proper alignment of neural maps throughout the brain. In the superficial layers of the superior colliculus of the midbrain, converging projections from retinal ganglion cells and neurons in visual cortex must be aligned to form a visuotopic map, but the basic mechanisms mediating this alignment remain elusive. In a new mouse model, ectopic expression of ephrin-A3 (Efna3) in a subset of retinal ganglion cells, quantitatively altering the retinal EFNAs gradient, disrupts cortico-collicular map alignment onto the retino-collicular map, creating a visuotopic mismatch. Genetic inactivation of ectopic EFNA3 restores a wild-type cortico-collicular map. Theoretical analyses using a new mapping algorithm model both map formation and alignment, and recapitulate our experimental observations. The algorithm is based on an initial sensory map, the retino-collicular map, which carries intrinsic topographic information, the retinal EFNAs, to the superior colliculus. These EFNAs subsequently topographically align ingrowing visual cortical axons to the retino-collicular map.DOI: http://dx.doi.org/10.7554/eLife.20470.001

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Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

A molecular mechanism for the topographic alignment of convergent neural maps

Savier

Eglen

Bathélémy

et al. 2017

eLife

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“…The origin of the very first synapses is not known. It can be synapses formed by axon collaterals of SGS neurons, well described in adult animals (Langer and Lund, 1974), or contacts from extrinsic axons, of retinal (Lund and Bunt, 1976) or even cortical (Khachab and Bruce, 1999) origin.…”

Section: Introductionmentioning

confidence: 99%

Early onset of glutamatergic and GABAergic synaptic activity in the visual layers of the rodent superior colliculus

Jüttner

Henneberger

Grantyn

et al. 2001

Intl J of Devlp Neuroscience

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During postnatal development, the retinocollicular pathway undergoes activity-dependent refinement, resulting in the precise retinotopic map seen in adults. Previous studies established that retinal efferents reach the mouse superior colliculus (SC) by embryonic day 16. Morphologically, synapses were found in the rat SC before birth. As part of an extended project aimed at understanding the development of synaptic transmission in the visual layers of the SC, we report here the presence of functionally active synapses immediately after birth. Circuit activity in mouse SC neurons was detected in horizontal slices of the visual layers using cell-attached voltage clamp. The spontaneous discharge of action potentials was abolished by glutamatergic blockers and facilitated by bicuculline, showing that circuit activity is based on synaptic transmission and that the action of gamma-aminobutyric acid is inhibitory. Using whole-cell voltage clamp, spontaneous glutamatergic postsynaptic currents as well as miniature GABAergic postsynaptic currents were recorded on postnatal day 1. Excitatory and inhibitory postsynaptic currents could also be evoked by electrical stimulation. Glutamatergic postsynaptic currents comprised both (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and N-methyl-D-aspartate receptor-mediated components. The early function of glutamatergic and GABAergic synaptic transmission in the visual layers of SC suggests that SC neurons are able to process information originating from retinal axons immediately after birth.

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“…64Interestingly, the formation of the retino-collicular map occurs prior to the establishment of the 65 cortico-collicular map. Other studies have shown that the existence of the retino-collicular map is 66 necessary for the formation of the cortico-collicular map, suggesting an interdependence of the 67 two mechanisms (Khachab and Bruce, 1999;Rhoades et al, 1985;Triplett et al, 2009). Similar 68 observations have been made in other part of the visual system (Shanks et al, 2016).…”

mentioning

confidence: 64%

New insights on the modelling of the molecular mechanisms underlying neural maps alignment in the midbrain

Savier

Dunbar

Cheung

et al. 2020

Preprint

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16We previously identified and modelled a principle of visual maps alignment in the midbrain 17 involving the mapping of the retinal projections and concurrent transposition of retinal guidance 18 cues into the superior colliculus providing positional information for the organization of cortical V1 19 projections onto the retinal map . This principle relies on mechanisms involving 20 Epha/Efna signaling, correlated neuronal activity and axon competition. Here, using the 3-step 21 map alignment computational model, we predict and validate in vivo the visual mapping defects in 22 a well-characterized mouse model. Our results challenge previous hypotheses and provide an 23 alternative, although complementary, explanation for the phenotype observed. In addition, we 24 propose a new quantification method to assess the degree of alignment and organization between 25 maps, allowing inter-model comparisons. This work generalizes the validity and robustness of the 26 3-step map alignment algorithm as a predictive tool and confirms the basic mechanisms of visual 27 maps organization. Savier and Reber, 56 2018). Several hypotheses have been made to account for the phenotypes observed in mouse 57 genetic models and this extensive body of work has been used to generate computational 58 approaches which attempt to replicate experimental findings 62 Savier et al., 2017). However, until recently, these models have not been able to explain how 63 collicular visual maps are aligned during development. 64Interestingly, the formation of the retino-collicular map occurs prior to the establishment of the 65 cortico-collicular map. Other studies have shown that the existence of the retino-collicular map is 66 necessary for the formation of the cortico-collicular map, suggesting an interdependence of the 67 two mechanisms (Khachab and Bruce, 1999;Rhoades et al., 1985;Triplett et al., 2009). Similar 68 observations have been made in other part of the visual system (Shanks et al., 2016). Another 69 piece of evidence came from the study of map alignment in the Isl2-Epha3KI, one of the best 70 characterized mutant in the field. In these mutants, the Epha3 receptor is ectopically expressed in 71 50% of RGCs, leading to a duplication of the retino-collicular map . Strikingly, 72 a full duplication of the cortico-collicular map is also observed in the Isl2-Epha3 KI/KI homozygous 73 mutants, which display a normal retinotopy in the visual cortex (Triplett et al., 2009). The authors 74 concluded that a retinal-matching mechanism involving spontaneous correlated activity in the 75 retina instructs cortico-collicular projections and alignment onto the retino-collicular map. 76Alternative explanations can also be suggested. For instance, the ectopic expression of Epha3 77 specifically in the retina may alter the expression of other members of Epha/Efna throughout the 78 visual system disrupting maps formation and alignment. In another example, molecular cues 79 originating from the retina could be carried over to the colliculus and provide mapping/...

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The maturation of corticocollicular neurons in mice

Cited by 6 publications

References 17 publications

A molecular mechanism for the topographic alignment of convergent neural maps

A molecular mechanism for the topographic alignment of convergent neural maps

Early onset of glutamatergic and GABAergic synaptic activity in the visual layers of the rodent superior colliculus

New insights on the modelling of the molecular mechanisms underlying neural maps alignment in the midbrain

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