Contribution of thalamic input to the specification of cytoarchitectonic cortical fields in the primate: Effects of bilateral enucleation in the fetal monkey on the boundaries, dimensions, and gyrification of striate and extrastriate cortex

Dehay, Colette; Giroud, Pascale; Berland, Michel; Killackey, Herbert P.; Kennedy, Henry

doi:10.1002/(sici)1096-9861(19960325)367:1<70::aid-cne6>3.0.co;2-g

Cited by 142 publications

(90 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, a more recent study demonstrated a tight window of opportunity during which this is possible (Gaillard & Roger, 2000). In a study in which binocular enucleation was performed at mid-gestation in macaque monkeys, loss of retinofugal connections and subsequent thalamocortical projections was observed, which ultimately altered the fate of V1 by creating a hybrid visual cortex, probably through cell ⁄ cell interactions (Rakic et al 1991;Windrem & Finlay, 1991;Dehay et al 1996). Early thalamic ablation also leads to a reduction in areal and laminar size (Windrem & Finlay, 1991).…”

Section: Thalamic Controlsupporting

confidence: 70%

Unravelling the development of the visual cortex: implications for plasticity and repair

Bourne

2010

Journal of Anatomy

View full text Add to dashboard Cite

The visual cortex comprises over 50 areas in the human, each with a specified role and distinct physiology, connectivity and cellular morphology. How these individual areas emerge during development still remains something of a mystery and, although much attention has been paid to the initial stages of the development of the visual cortex, especially its lamination, very little is known about the mechanisms responsible for the arealization and functional organization of this region of the brain. In recent years we have started to discover that it is the interplay of intrinsic (molecular) and extrinsic (afferent connections) cues that are responsible for the maturation of individual areas, and that there is a spatiotemporal sequence in the maturation of the primary visual cortex (striate cortex, V1) and the multiple extrastriate ⁄ association areas. Studies in both humans and non-human primates have started to highlight the specific neural underpinnings responsible for the maturation of the visual cortex, and how experience-dependent plasticity and perturbations to the visual system can impact upon its normal development. Furthermore, damage to specific nuclei of the visual cortex, such as the primary visual cortex (V1), is a common occurrence as a result of a stroke, neurotrauma, disease or hypoxia in both neonates and adults alike. However, the consequences of a focal injury differ between the immature and adult brain, with the immature brain demonstrating a higher level of functional resilience. With better techniques for examining specific molecular and connectional changes, we are now starting to uncover the mechanisms responsible for the increased neural plasticity that leads to significant recovery following injury during this early phase of life. Further advances in our understanding of postnatal development ⁄ maturation and plasticity observed during early life could offer new strategies to improve outcomes by recapitulating aspects of the developmental program in the adult brain.

show abstract

Section: Thalamic Controlsupporting

confidence: 70%

Unravelling the development of the visual cortex: implications for plasticity and repair

Bourne

2010

Journal of Anatomy

View full text Add to dashboard Cite

show abstract

“…Furthermore, mechanisms independent of thalamic innervation appear to initiate the formation of primary sensory areas. Additional evidence supports the view that intrinsic cortical mechanisms are operative at early stages of area specification: the cytoarchitectural differentiation of the primary visual cortex of primates (area 17), as well as the characteristic laminar pattern of monoamine receptors in this area, emerge in the absence of cues from the retina (33,34). Transplantation experiments in transgenic mice also suggest that layer IV neurons of S1 are molecularly committed as early as E14 to become a distinct subpopulation (35).…”

Section: Discussionmentioning

confidence: 97%

Area-specific regulation of γ-aminobutyric acid type A receptor subtypes by thalamic afferents in developing rat neocortex

Paysan

Kossel

Bolz

et al. 1997

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

View full text Add to dashboard Cite

Targeting and innervation of the cerebral cortex by thalamic afferents is a key event in the specification of cortical areas. The molecular targets of thalamic regulation, however, have remained elusive. We now demonstrate that thalamic afferents regulate the expression of ␥-aminobutyric acid type A (GABA A ) receptors in developing rat neocortex, leading to the area-specific expression of receptor subtypes in the primary visual (V1) and somatosensory (S1) areas. Most strikingly, the ␣1-and ␣5-GABA A receptors exhibited a reciprocal expression pattern, which precisely ref lected the distribution of thalamocortical afferents at postnatal day 7. Following unilateral lesions at the birth of the thalamic nuclei innervating V1 and S1 (lateral geniculate nucleus and ventrobasal complex, respectively), profound changes in subunit expression were detected 1 week later in the deprived cortical territories (layers III-IV of V1 and S1). The expression of the ␣1 subunit was strongly down-regulated in these layers to a level comparable to that in neighboring areas. Conversely, the ␣5 subunit was up-regulated and areal boundaries were no longer discernible in the lesioned hemisphere. Changes similar to the ␣5 subunit were also seen for the ␣2 and ␣3 subunits. These results indicate that the differential expression of GABA A receptor subtypes in developing neocortex is dependent on thalamic innervation, contributing to the emergence of functionally distinct areas.Targeting and innervation of the cerebral cortex by thalamic axons is a key event in the demarcation of the cortical anlage into a tangential map of individual areas (1-4). The specificity in targeting by thalamic axons is thought to be achieved through dynamic interactions with specific spatial or temporal cues at the appropriate cortical locus (5-9). However, the molecular postsynaptic targets regulated by thalamic afferents have remained elusive so far.Neurotransmitter receptors play a central role in shaping the functional properties of neuronal circuits. Among excitatory amino acid receptors, the N-methyl-D-aspartate (NMDA) receptors are involved in synaptic plasticity and in the refinement of synaptic connections (10-13). However, the areaspecific demarcation of the neocortex during development does not appear to involve NMDA receptor-mediated activity. The level of expression of NMDA receptors does not vary between distinct areas of developing neocortex, irrespective of thalamic innervation (14, 15). Furthermore, in primary somatosensory cortex (S1), the formation of barrels (the neuronal aggregates representing individual whiskers of the rodent snout) is not affected by chronic NMDA receptor blockade (16).In contrast to NMDA receptors, ␥-aminobutyric acid type A (GABA A ) receptors exhibit a prominent area-specific expression pattern in developing neocortex. The ␣1 subunit, which represents the vast majority of GABA A receptors in adult cortex, is highly expressed in a selective manner in layers III-IV of primary visual cortex (V1) and of S1 (17, 18). ...

show abstract

“…Using a common space based on gyral/sulcal folding patterns allowed us to compare patterns of responses across subjects' occipital cortices relative to their own gyral and sulcal landmarks and this technique has been shown to outperform linear and nonlinear volume-based registration methods at aligning functionally defined visual areas (Fischl et al 1999;Hinds et al 2008Hinds et al , 2009). However, it should be noted that cortical folding patterns may differ between early-blind and sighted subjects (Dehay et al 1989(Dehay et al , 1996.…”

Section: Bold Data Analysismentioning

confidence: 99%

Mechanisms of Cross-Modal Plasticity in Early-Blind Subjects

Lewis

Sàenz

Fine

2010

Journal of Neurophysiology

View full text Add to dashboard Cite

Lewis LB, Saenz M, Fine I. Mechanisms of cross-modal plasticity in early-blind subjects. J Neurophysiol 104: 2995-3008, 2010. First published July 28, 2010 doi:10.1152/jn.00983.2009. A variety of studies have demonstrated enhanced blood oxygenation level dependent responses to auditory and tactile stimuli within occipital cortex as a result of early blindness. However, little is known about the organizational principles that drive this cross-modal plasticity. We compared BOLD responses to a wide variety of auditory and tactile tasks (vs. rest) in early-blind and sighted subjects. As expected, cross-modal responses were larger in blind than in sighted subjects in occipital cortex for all tasks (cross-modal plasticity). Within both blind and sighted subject groups, we found patterns of cross-modal activity that were remarkably similar across tasks: a large proportion of cross-modal responses within occipital cortex are neither task nor stimulus specific. We next examined the mechanisms underlying enhanced BOLD responses within early-blind subjects. We found that the enhancement of cross-modal responses due to early blindness was best described as an additive shift, suggesting that cross-modal plasticity within blind subjects does not originate from either a scaling or unmasking of cross-modal responsivities found in sighted subjects.

show abstract

Contribution of thalamic input to the specification of cytoarchitectonic cortical fields in the primate: Effects of bilateral enucleation in the fetal monkey on the boundaries, dimensions, and gyrification of striate and extrastriate cortex

Cited by 142 publications

References 49 publications

Unravelling the development of the visual cortex: implications for plasticity and repair

Unravelling the development of the visual cortex: implications for plasticity and repair

Area-specific regulation of γ-aminobutyric acid type A receptor subtypes by thalamic afferents in developing rat neocortex

Mechanisms of Cross-Modal Plasticity in Early-Blind Subjects

Contact Info

Product

Resources

About