Trends in Neurosciences
Volume 21, Issue 1, 1 January 1998, Pages 28-32
Journal home page for Trends in Neurosciences

Paying attention to the thalamic reticular nucleus

https://doi.org/10.1016/S0166-2236(97)01157-0Get rights and content

Abstract

The thalamic reticular nucleus can be divided into a number of sectors, each concerned with a different function (sight, touch, hearing, movement or `limbic' functions).  Each sector is connected to more than one thalamic nucleus and to more than one cortical area, and each sector has topographically mapped connections with the thalamus and the cortex. We consider the known details of these connections and show: (1) that they are not the same for each sector; (2) that the reticular nucleus serves as a nexus, where several functionally related cortical areas and thalamic nuclei can interact, modifying thalamocortical transmission through the inhibitory connections that go from the reticular cells to thalamic relay cells; and (3) that we need much more detailed information about these highly organized connections before we can understand exactly how the thalamic reticular nucleus might be influencing thalamocortical pathways in attentional mechanisms or in other, as yet undefined, roles.

Section snippets

Multiple inputs to single sectors of TRN

For any single functional thalamocortical pathway and its related TRN sector, there is usually more than one connected thalamic nucleus or cortical area. Thus, visual, auditory and somatosensory systems have many cortical areas22, 23, 24 and more than one related thalamic nucleus connected to TRN (6, 9, 10, 11, 12). The way in which several thalamocortical circuits relate to each other in TRN must be crucial to the influence that any one cortical area can exert on the modulation going from a

Functional implications

At present, evidence on details of reticular connections is incomplete. One reason for writing this article is to stress the importance of defining the connections. It is clear that no simple general rule governing cortical and thalamic connections in TRN applies to all sectors. Each sector appears to follow distinct rules. To understand how any one sector responds to its several inputs and then produces modulatory effects in the thalamus, we have to look at its particular pattern of

Concluding remarks

The organization of TRN involves the interaction of several thalamocortical circuits for each functionally distinct sector of TRN. We have discussed two cortical areas and two thalamic nuclei for each sector, but generally more cortical areas and more thalamic nuclei are involved in any one sector. The important point is that each sector provides a nexus for the interaction of several thalamocortical and corticothalamic circuits, and will prove to be a key site where many cortical areas

Acknowledgements

This work was supported by grants from the Wellcome Trust and the NIH (EY11494). We thank Dr D. Pinault for a critical reading of the manuscript.

References (44)

  • M.E. Scheibel et al.

    Brain Res

    (1966)
  • H. Künzle

    Brain Res

    (1976)
  • D. McCormick

    Prog. Neurobiol

    (1992)
  • D.A. McCormick et al.

    Neuroscience

    (1990)
  • D.C. Van Essen et al.

    Trends Neurosci

    (1983)
  • B.P. Abramson et al.

    Neuroscience

    (1985)
  • J. Bourassa et al.

    Neuroscience

    (1995)
  • E.M. Rouiller et al.

    Hearing Res

    (1991)
  • J. Mitrofanis et al.

    Trends Neurosci

    (1993)
  • P.T. Ohara et al.

    Brain Res

    (1996)
  • A. Gonzalo-Ruiz et al.

    Brain Res. Bull

    (1995)
  • C.E. Schreiner

    Curr. Opinion Neurobiol

    (1995)
  • F. Crick

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

    (1984)
  • E.G. Jones

    The Thalamus,

    (1985)
  • P.T. Ohara et al.

    J. Neurocytol

    (1985)
  • M. Steriade

    Science

    (1993)
  • J.W. Crabtree et al.

    Eur. J. Neurosci

    (1989)
  • J.W. Crabtree

    Eur. J. Neurosci

    (1992)
  • J.W. Crabtree

    Eur. J. Neurosci

    (1992)
  • J.W. Crabtree

    J. Comp. Neurol

    (1996)
  • M. Conley

    Eur. J. Neurosci

    (1991)
  • M. Conley et al.

    Eur. J. Neurosci

    (1990)
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