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  • Review Article
  • Published:

Development and plasticity of cortical areas and networks

Nature Reviews Neuroscience volume 2, pages 251–262 (2001)Cite this article

Key Points

  • The development of cortical layers, areas and networks is mediated by a combination of factors that are present in the cortex and are influenced by thalamic input. So, the specification of cortical areas requires multiple cues that involve the regional and/or graded expression of molecules along with spatial and temporal signals regulated by thalamic afferents.

  • The influence of thalamic inputs has been studied intensively in the formation of thalamocortical patterns and intracortical connections. Most evidence indicates that the presence of activity might be sufficient for the establishment of early thalamic innervation. By contrast, the spatiotemporal pattern of activity often has an instructive role for the development features that develop later, such as the formation of intracortical networks.

  • Experiments that route projections from the retina to the auditory pathway alter the pattern of activity in auditory thalamocortical afferents at a very early stage and reveal the progressive influence of activity on cortical development. So, cortical features such as layers and thalamocortical innervation are unaffected, whereas features that develop later, such as intracortical connections are affected significantly.

Abstract

The development of cortical layers, areas and networks is mediated by a combination of factors that are present in the cortex and are influenced by thalamic input. Electrical activity of thalamocortical afferents has a progressive role in shaping cortex. For early thalamic innervation and patterning, the presence of activity might be sufficient; for features that develop later, such as intracortical networks that mediate emergent responses of cortex, the spatiotemporal pattern of activity often has an instructive role. Experiments that route projections from the retina to the auditory pathway alter the pattern of activity in auditory thalamocortical afferents at a very early stage and reveal the progressive influence of activity on cortical development. Thus, cortical features such as layers and thalamocortical innervation are unaffected, whereas features that develop later, such as intracortical connections, are affected significantly. Surprisingly, the behavioural role of 'rewired' cortex is also influenced profoundly, indicating the importance of patterned activity for this key aspect of cortical function.

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Figure 1: Timeline illustrating many of the main events during the development of the visual cortex and its connections with the thalamus in the ferret.
Figure 2: The development of the ferret's visual cortex and its interconnections with the thalamus.
Figure 3: Terminal patterns of subcortical afferents to the dorsal lateral geniculate nucleus and the medial geniculate nucleus in normal ferrets, and to the medial geniculate nucleus in rewired ferrets.
Figure 4: Cortical maps and thalamocortical projections in normal and rewired ferrets.
Figure 5: Orientation maps and horizontal connections in V1 of normal ferrets and in A1 of rewired ferrets.

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Acknowledgements

We thank Christine Waite for assistance, and Ania Majewska and Atomu Sawatari for their comments on the manuscript. This work was supported by grants from the NIH.

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  1. Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, 45 Carleton Street, Cambridge, 02139, Massachusetts, USA

    Mriganka Sur & Catherine A. Leamey

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DATABASE LINKS

bFGF

Latexin

Tbr-1

Cad6

Cad11

COUP-TF1

CHL1

Gbx2

Mash1

Pax6

Emx2

ephrin-A2

ephrin-A5

BDNF

NR2B

NR2A

ENCYCLOPEDIA OF LIFE SCIENCES

Cerebral cortex development

Cortex plasticity: use-dependent remodelling

Glossary

EPHRINS AND EPH RECEPTORS

Two families of molecules that mediate cell-contact-dependent signalling, and are primarily involved in the generation and maintenance of patterns of cellular organization. They accomplish this goal by the control of repulsion at a boundary or gradient, or by upregulating cell adhesion.

SOMATOSENSORY BARRELS

Discrete functional units present in layer IV of the rat cortex, which process tactile inputs derived from a single whisker.

HEBB'S RULE

“When the axon of cell A excites cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells so that A's efficiency as one of the cells firing B is increased.”

LONG-TERM POTENTIATION AND DEPRESSION

Long-lasting activity-dependent changes in the efficacy of synaptic transmission.

ORIENTATION SELECTIVITY

Property of visual cortex neurons that allows for the detection of bars and edges within visual images and the encoding of their orientations. As the cortex is organized in columns, neurons that belong to the same column share the same orientation tuning.

RETINAL GANGLION CELLS

The three main classes of retinal ganglion cells in carnivores are: X cells, which have the smallest receptive fields; Y cells, which have larger receptive fields; and W cells, which have heterogeneous properties.

ANISOTROPIC

Medium in which physical properties have different values when measured along axes orientated in different directions.

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Sur, M., Leamey, C. Development and plasticity of cortical areas and networks. Nat Rev Neurosci 2, 251–262 (2001). https://doi.org/10.1038/35067562

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