Skip to main content
NCBI home page
Journal of Anatomy logoLink to Journal of Anatomy
. 2000 Apr;196(Pt 3):379–390. doi: 10.1046/j.1469-7580.2000.19630379.x

Corticofugal axons from adjacent ‘barrel’ columns of rat somatosensory cortex: cortical and thalamic terminal patterns

A K WRIGHT 1, L NORRIE 1, G W ARBUTHNOTT 1,✉
PMCID: PMC1468074  PMID: 10853960

Abstract

The cortical representations of the vibrissae of the rat form a matrix in which each whisker has its own area of cortex, called a ‘barrel’. The afferent pathways from the periphery travel first to the trigeminal nuclei and thence via the ventroposteromedial thalamus (VPM) to the cortical barrels have been described in detail. We have studied the output from barrels by filling adjacent areas of the primary somatosensory cortex (SI) with either Phaseolus vulgaris leucoagglutinin (PHA-L) or biotinylated dextran amine (BDA) and demonstrating the course and terminations of the axons that arise within the barrel fields. The method not only dramatically illustrates the previously described corticothalamic pathway to VPM but also demonstrates a strict topography in the cortical afferents to the thalamic reticular nucleus (RT). Cells supplying the RT projection are found below the barrels in layer IV. Connections to the posterior thalamus, on the other hand, have no discernible topography and are derived from cortical areas surrounding the barrels. Thus the outputs of these ‘septal’ areas return to the region from which they receive thalamic input. The corticocortical connections are also visible in the same material. Contralateral cortical connections arise from the cells of the septa between barrels. The projections to secondary somatosensory area (SII) are mirror images of the barrel pattern in SI with rather more overlap but nonetheless a recognisable topography.

Keywords: Mystacial vibrissae, cortical barrels, thalamic nuclei, thalamic barreloids

Full Text

The Full Text of this article is available as a PDF (665.1 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Agmon A., Yang L. T., Jones E. G., O'Dowd D. K. Topological precision in the thalamic projection to neonatal mouse barrel cortex. J Neurosci. 1995 Jan;15(1 Pt 2):549–561. doi: 10.1523/JNEUROSCI.15-01-00549.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Arbuthnott G. W., MacLeod N. K., Maxwell D. J., Wright A. K. Distribution and synaptic contacts of the cortical terminals arising from neurons in the rat ventromedial thalamic nucleus. Neuroscience. 1990;38(1):47–60. doi: 10.1016/0306-4522(90)90373-c. [DOI] [PubMed] [Google Scholar]
  3. Armstrong-James M., Callahan C. A., Friedman M. A. Thalamo-cortical processing of vibrissal information in the rat. I. Intracortical origins of surround but not centre-receptive fields of layer IV neurones in the rat S1 barrel field cortex. J Comp Neurol. 1991 Jan 8;303(2):193–210. doi: 10.1002/cne.903030203. [DOI] [PubMed] [Google Scholar]
  4. Armstrong-James M., Callahan C. A. Thalamo-cortical processing of vibrissal information in the rat. II. spatiotemporal convergence in the thalamic ventroposterior medial nucleus (VPm) and its relevance to generation of receptive fields of S1 cortical "barrel" neurones. J Comp Neurol. 1991 Jan 8;303(2):211–224. doi: 10.1002/cne.903030204. [DOI] [PubMed] [Google Scholar]
  5. Beaulieu C., Colonnier M. Number of neurons in individual laminae of areas 3B, 4 gamma, and 6a alpha of the cat cerebral cortex: a comparison with major visual areas. J Comp Neurol. 1989 Jan 8;279(2):228–234. doi: 10.1002/cne.902790206. [DOI] [PubMed] [Google Scholar]
  6. Belford G. R., Killackey H. P. The development of vibrissae representation in subcortical trigeminal centers of the neonatal rat. J Comp Neurol. 1979 Nov 1;188(1):63–74. doi: 10.1002/cne.901880106. [DOI] [PubMed] [Google Scholar]
  7. Belford G. R., Killackey H. P. The sensitive period in the development of the trigeminal system of the neonatal rat. J Comp Neurol. 1980 Sep 15;193(2):335–350. doi: 10.1002/cne.901930203. [DOI] [PubMed] [Google Scholar]
  8. Bernardo K. L., McCasland J. S., Woolsey T. A., Strominger R. N. Local intra- and interlaminar connections in mouse barrel cortex. J Comp Neurol. 1990 Jan 8;291(2):231–255. doi: 10.1002/cne.902910207. [DOI] [PubMed] [Google Scholar]
  9. Bourassa J., Pinault D., Deschênes M. Corticothalamic projections from the cortical barrel field to the somatosensory thalamus in rats: a single-fibre study using biocytin as an anterograde tracer. Eur J Neurosci. 1995 Jan 1;7(1):19–30. doi: 10.1111/j.1460-9568.1995.tb01016.x. [DOI] [PubMed] [Google Scholar]
  10. Chmielowska J., Carvell G. E., Simons D. J. Spatial organization of thalamocortical and corticothalamic projection systems in the rat SmI barrel cortex. J Comp Neurol. 1989 Jul 15;285(3):325–338. doi: 10.1002/cne.902850304. [DOI] [PubMed] [Google Scholar]
  11. Cooper N. G., Steindler D. A. Lectins demarcate the barrel subfield in the somatosensory cortex of the early postnatal mouse. J Comp Neurol. 1986 Jul 8;249(2):157–169. doi: 10.1002/cne.902490204. [DOI] [PubMed] [Google Scholar]
  12. Diamond M. E., Armstrong-James M., Budway M. J., Ebner F. F. Somatic sensory responses in the rostral sector of the posterior group (POm) and in the ventral posterior medial nucleus (VPM) of the rat thalamus: dependence on the barrel field cortex. J Comp Neurol. 1992 May 1;319(1):66–84. doi: 10.1002/cne.903190108. [DOI] [PubMed] [Google Scholar]
  13. Donaldson L., Hand P. J., Morrison A. R. Cortical-thalamic relationships in the rat. Exp Neurol. 1975 Jun;47(3):448–458. doi: 10.1016/0014-4886(75)90077-1. [DOI] [PubMed] [Google Scholar]
  14. Fox K. The cortical component of experience-dependent synaptic plasticity in the rat barrel cortex. J Neurosci. 1994 Dec;14(12):7665–7679. doi: 10.1523/JNEUROSCI.14-12-07665.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Gonzalez M. F., Sharp F. R. Vibrissae tactile stimulation: (14C) 2-deoxyglucose uptake in rat brainstem, thalamus, and cortex. J Comp Neurol. 1985 Jan 22;231(4):457–472. doi: 10.1002/cne.902310405. [DOI] [PubMed] [Google Scholar]
  16. Hoeflinger B. F., Bennett-Clarke C. A., Chiaia N. L., Killackey H. P., Rhoades R. W. Patterning of local intracortical projections within the vibrissae representation of rat primary somatosensory cortex. J Comp Neurol. 1995 Apr 17;354(4):551–563. doi: 10.1002/cne.903540406. [DOI] [PubMed] [Google Scholar]
  17. Hoogland P. V., Welker E., Van der Loos H. Organization of the projections from barrel cortex to thalamus in mice studied with Phaseolus vulgaris-leucoagglutinin and HRP. Exp Brain Res. 1987;68(1):73–87. doi: 10.1007/BF00255235. [DOI] [PubMed] [Google Scholar]
  18. Hoogland P. V., Wouterlood F. G., Welker E., Van der Loos H. Ultrastructure of giant and small thalamic terminals of cortical origin: a study of the projections from the barrel cortex in mice using Phaseolus vulgaris leuco-agglutinin (PHA-L). Exp Brain Res. 1991;87(1):159–172. doi: 10.1007/BF00228517. [DOI] [PubMed] [Google Scholar]
  19. Hutson K. A., Masterton R. B. The sensory contribution of a single vibrissa's cortical barrel. J Neurophysiol. 1986 Oct;56(4):1196–1223. doi: 10.1152/jn.1986.56.4.1196. [DOI] [PubMed] [Google Scholar]
  20. Ito M. Processing of vibrissa sensory information within the rat neocortex. J Neurophysiol. 1985 Sep;54(3):479–490. doi: 10.1152/jn.1985.54.3.479. [DOI] [PubMed] [Google Scholar]
  21. Izraeli R., Porter L. L. Vibrissal motor cortex in the rat: connections with the barrel field. Exp Brain Res. 1995;104(1):41–54. doi: 10.1007/BF00229854. [DOI] [PubMed] [Google Scholar]
  22. Jensen K. F., Killackey H. P. Terminal arbors of axons projecting to the somatosensory cortex of the adult rat. I. The normal morphology of specific thalamocortical afferents. J Neurosci. 1987 Nov;7(11):3529–3543. doi: 10.1523/JNEUROSCI.07-11-03529.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Jensen K. F., Killackey H. P. Terminal arbors of axons projecting to the somatosensory cortex of the adult rat. II. The altered morphology of thalamocortical afferents following neonatal infraorbital nerve cut. J Neurosci. 1987 Nov;7(11):3544–3553. doi: 10.1523/JNEUROSCI.07-11-03544.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Koralek K. A., Jensen K. F., Killackey H. P. Evidence for two complementary patterns of thalamic input to the rat somatosensory cortex. Brain Res. 1988 Nov 1;463(2):346–351. doi: 10.1016/0006-8993(88)90408-8. [DOI] [PubMed] [Google Scholar]
  25. Land P. W., Buffer S. A., Jr, Yaskosky J. D. Barreloids in adult rat thalamus: three-dimensional architecture and relationship to somatosensory cortical barrels. J Comp Neurol. 1995 May 15;355(4):573–588. doi: 10.1002/cne.903550407. [DOI] [PubMed] [Google Scholar]
  26. Lu S. M., Lin R. C. Thalamic afferents of the rat barrel cortex: a light- and electron-microscopic study using Phaseolus vulgaris leucoagglutinin as an anterograde tracer. Somatosens Mot Res. 1993;10(1):1–16. doi: 10.3109/08990229309028819. [DOI] [PubMed] [Google Scholar]
  27. Sharp F. R., Gonzalez M. F., Morgan C. W., Morton M. T., Sharp J. W. Common fur and mystacial vibrissae parallel sensory pathways: 14 C 2-deoxyglucose and WGA-HRP studies in the rat. J Comp Neurol. 1988 Apr 15;270(3):446–469. doi: 10.1002/cne.902700312. [DOI] [PubMed] [Google Scholar]
  28. Sherman S. M., Koch C. The control of retinogeniculate transmission in the mammalian lateral geniculate nucleus. Exp Brain Res. 1986;63(1):1–20. doi: 10.1007/BF00235642. [DOI] [PubMed] [Google Scholar]
  29. Simons D. J., Carvell G. E. Thalamocortical response transformation in the rat vibrissa/barrel system. J Neurophysiol. 1989 Feb;61(2):311–330. doi: 10.1152/jn.1989.61.2.311. [DOI] [PubMed] [Google Scholar]
  30. Simons D. J., Land P. W. Early experience of tactile stimulation influences organization of somatic sensory cortex. Nature. 1987 Apr 16;326(6114):694–697. doi: 10.1038/326694a0. [DOI] [PubMed] [Google Scholar]
  31. Simons D. J. Response properties of vibrissa units in rat SI somatosensory neocortex. J Neurophysiol. 1978 May;41(3):798–820. doi: 10.1152/jn.1978.41.3.798. [DOI] [PubMed] [Google Scholar]
  32. Steffen H., Van der Loos H. Early lesions of mouse vibrissal follicles:: their influence on dendrite orientation in the cortical barrelfield. Exp Brain Res. 1980;40(4):419–431. doi: 10.1007/BF00236150. [DOI] [PubMed] [Google Scholar]
  33. Waite P. M., Taylor P. K. Removal of whiskers in young rats causes functional changes in cerebral cortex. Nature. 1978 Aug 10;274(5671):600–602. doi: 10.1038/274600a0. [DOI] [PubMed] [Google Scholar]
  34. Welker C. Microelectrode delineation of fine grain somatotopic organization of (SmI) cerebral neocortex in albino rat. Brain Res. 1971 Mar 5;26(2):259–275. [PubMed] [Google Scholar]
  35. Welker E., Armstrong-James M., Van der Loos H., Kraftsik R. The mode of activation of a barrel column: response properties of single units in the somatosensory cortex of the mouse upon whisker deflection. Eur J Neurosci. 1993 Jun 1;5(6):691–712. doi: 10.1111/j.1460-9568.1993.tb00534.x. [DOI] [PubMed] [Google Scholar]
  36. Welker E., Hoogland P. V., Van der Loos H. Organization of feedback and feedforward projections of the barrel cortex: a PHA-L study in the mouse. Exp Brain Res. 1988;73(2):411–435. doi: 10.1007/BF00248234. [DOI] [PubMed] [Google Scholar]
  37. White E. L., DeAmicis R. A. Afferent and efferent projections of the region in mouse SmL cortex which contains the posteromedial barrel subfield. J Comp Neurol. 1977 Oct 15;175(4):455–482. doi: 10.1002/cne.901750405. [DOI] [PubMed] [Google Scholar]
  38. Wise S. P., Jones E. G. Cells of origin and terminal distribution of descending projections of the rat somatic sensory cortex. J Comp Neurol. 1977 Sep 15;175(2):129–157. doi: 10.1002/cne.901750202. [DOI] [PubMed] [Google Scholar]
  39. Wong-Riley M. T., Welt C. Histochemical changes in cytochrome oxidase of cortical barrels after vibrissal removal in neonatal and adult mice. Proc Natl Acad Sci U S A. 1980 Apr;77(4):2333–2337. doi: 10.1073/pnas.77.4.2333. [DOI] [PMC free article] [PubMed] [Google Scholar]
  40. Woolsey T. A., Van der Loos H. The structural organization of layer IV in the somatosensory region (SI) of mouse cerebral cortex. The description of a cortical field composed of discrete cytoarchitectonic units. Brain Res. 1970 Jan 20;17(2):205–242. doi: 10.1016/0006-8993(70)90079-x. [DOI] [PubMed] [Google Scholar]
  41. Woolsey T. A., Wann J. R. Areal changes in mouse cortical barrels following vibrissal damage at different postnatal ages. J Comp Neurol. 1976 Nov 1;170(1):53–66. doi: 10.1002/cne.901700105. [DOI] [PubMed] [Google Scholar]
  42. Wright A. K., Norrie L., Ingham C. A., Hutton E. A., Arbuthnott G. W. Double anterograde tracing of outputs from adjacent "barrel columns" of rat somatosensory cortex. Neostriatal projection patterns and terminal ultrastructure. Neuroscience. 1999 Jan;88(1):119–133. doi: 10.1016/s0306-4522(98)00186-9. [DOI] [PubMed] [Google Scholar]

Articles from Journal of Anatomy are provided here courtesy of Anatomical Society of Great Britain and Ireland

RESOURCES