Microcolumns in the Cerebral Cortex

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Background


The following is an excerpt from:
  • L. Cruz, S. V. Buldyrev, S. Peng, D. L. Roe, B. Urbanc, H. E. Stanley, and D. L. Rosene, ``A Statistically Based Density Map Method for Identification and Quantification of Regional Differences in Microcolumnarity in the Monkey Brain,'' Journal of Neuroscience Methods, 141/2, p. 321-332 (2005). [PDF]

The most prominent feature of cortex is the arrangement of neurons into layers with classical “neocortex” identified as having six layers. Because these layers differ in thickness, cell type, and cell density from one part of the cortex to another, these “laminar” differences have been used to subdivide the cortex into different regions (e.g. Brodmann, 1909; Vogt and Vogt, 1919; von Economo and Koskinas, 1925; Von Bonin and Bailey, 1947; Petrides and Pandya, 1994). It has also been noted that different cortical regions display a “vertical” organization of neurons grouped into columnar arrangements that take two forms: macrocolumns, approximately 0.4–0.5 mm in diameter (Mountcastle, 1957; Calvin, 1995), and microcolumns or minicolumns approximately 30 microns in diameter (Jones, 2000).

Macrocolumns were first identified functionally by Mountcastle (1957), who described groups of neurons in somatosensory cortex that respond to light touch alternating with laterally adjacent groups that respond to joint and/or muscle stimulation. These groups form a mosaic with a periodicity of about 0.5 mm. Similarly, Hubel and Wiesel (1963, 1969, 1977) using both monkeys and cats discovered alternating macrocolumns of neurons in the visual cortex that respond preferentially to the right or to the left eye. These “ocular dominance columns” have a spacing of about 0.4 mm. In addition, they discovered within the ocular dominance columns smaller micro- or minicolumns of neurons that respond preferentially to lines in a particular orientation.

Once these physiological minicolumns were recognized, it was noted that vertically organized columns of this approximate size are visible in many cortical areas under low magnification and are composed of perhaps 100 neurons stretching from layer V through layer II. To prove that the physiological and morphologically defined minicolumns or microcolumns are identical to the physiologically defined minicolumn would require directly measuring the response of a majority of the neurons in a single histologically identified microcolumn, but this has yet to be done. Nevertheless, current data on the microcolumn indicate that the neurons within the microcolumn receive common inputs, have common outputs, are interconnected, and may well constitute a fundamental computational unit of the cerebral cortex (e.g. Szentagothai, 1975; Swindale, 1990; Purves et al., 1992; Saleem et al., 1993; Van Hoesen and Solodkin, 1993; Buxhoeveden et al., 1996; Mountcastle, 1997; Buxhoeveden and Casanova, 2002a,b; Mountcastle, 2003). These microcolumns vary in spacing across the cortex and species, but are about 30 microns apart in human visual cortex (Calvin, 1995).

The microcolumn has recently been shown to be disrupted in a number of different conditions including Alzheimer’s Disease (AD) and Lewy Body dementia (LBD) (Buldyrev et al., 2000), autism (Casanova et al., 2002a), dyslexia (Casanova et al., 2002b), and schizophrenia (Buxhoeveden et al., 2000b). Interestingly, in normal aging monkeys where cortical neurons are largely preserved (e.g. Peters et al., 1998) there is evidence of age-related functional disruption of orientation selectivity in the visual cortex of aged monkeys (Schmolesky et al., 2000; Leventhal et al., 2003). In these studies, Leventhal and colleagues reported a loss of two functional properties of microcolumns—orientation and direction selectivity. Moreover, they demonstrated that administration of GABA agonists restored these functions. Since the small GABAergic interneurons are important components of the microcolumn, this suggests that there may well be a disruption of at least this or a related component of the microcolumn in normal aging.

References

  • Brodmann K. Vergleichende Lokalisationslehre der Grosshirnrinde. Leipzig, Germany: Barth; 1909.
  • Buldyrev SV, Cruz L, Gomez-Isla T, Gomez-Tortosa E, Havlin S, Le R, Stanley HE, Urbanc B, Hyman BT. Description of microcolumnar ensembles in association cortex and their disruption in Alzheimer and Lewy body dementias. Proc Natl Acad Sci 2000;97(10):5039–43.
  • Buxhoeveden D, Lefkowitz W, Loats P, Armstrong E. The linear organi- zation of cell columns in human and nonhuman anthropoid Tpt cortex. Anat Embryol 1996;194:23–36.
  • Buxhoeveden D, Roy E, Switala A, Casanova MF. Reduced interneuronal space in schizophrenia. Biol Psychiatry 2000b;47:681–3.
  • Buxhoeveden DP, Casanova MF. The minicolumn and evolution of the brain. Brain Behav Evol 2002a;60:125–51.
  • Buxhoeveden DP, Casanova MF. The minicolumn hypothesis in neuro- science. Brain 2002b;125:935–51.
  • Calvin WH. Cortical columns, modules, and hebbian cell assemblies. In: Arbib MA, editor. The handbook of brain theory and neural networks. MIT Press: Cambridge, MA; 1995. p. 269–72.
  • Casanova MF, Buxhoeveden DP, Switala AE, Roy E. Minicolumnar pathology in autism. Neurology 2002a;58:428–32.
  • Casanova MF, Buxhoeveden DP, Cohen M, Switala AE, Roy EL. Mini- columnar pathology in dyslexia. Ann Neurol 2002b;52:108–10.
  • Hubel DH, Wiesel TN. Shape and arrangement of columns in cat’s striate cortex. J Physiol 1963;165:559–68.
  • Hubel DH, Wiesel TN. Anatomical demonstration of columns in the mon- key striate cortex. Nature 1969;221(182):747–50.
  • Hubel DH, Wiesel TN. Functional architecture of macaque visual cortex. Proc R Soc Lond B 1977;198:1–59.
  • Jones EG. Microcolumns in the cerebral cortex. Proc Natl Acad Sci 2000;97(10):5019–21.
  • Leventhal AG, Wang Y, Pu M, Zhou Y, Ma Y. GABA and its ago- nists improved visual cortical function in senescent monkeys. Science 2003;300:812–5.
  • Mountcastle VB. Modality and topographic properties of single neu- rons of cat’s somatic sensory cortex. J Neurophysiol 1957;20:408– 34.
  • Mountcastle VB. The columnar organization of the neocortex. Brain 1997;120:701–22.
  • Mountcastle VB. Untitled-introduction. Cereb Cortex 2003;13(1):2–4.
  • Peters A, Morrison JH, Rosene DL, Hyman BT. Feature article: are neu- rons lost from the primate cerebral cortex during normal aging? Cereb Cortex 1998;8(4):295–300.
  • Petrides M, Pandya DN. Comparative architectonic analysis of the human and macaque frontal cortex. In: Grafman J, Boller F, editors. Hand- book of neuropsychology. Amsterdam: Elsevier A Science Publisher BV; 1994.
  • Purves D, Riddle DR, LaMantia AS. Iterated patterns of brain circuitry (or how the cortex gets its spots). Trends Neurosci 1992;15:362– 8.
  • Saleem KS, Tanaka K, Rockland KS. Specific and columnar projection from Area TEO to TE in the Macaque inferotemporal cortex. Cerebral Cortex 1993;3:454–64.
  • Schmolesky MT, Wang Y, Pu M, Leventhal AG. Degradation of stimulus selectivity of visual cortical cells in senescent rhesus monkeys. Nat Neurosci 2000;3(4):384–90.
  • Swindale NV. Is the cerebral cortex modular? Trends Neurosci 1990;13:487–92.
  • Szentagothai J. The module-concept in cerebral cortex architecture. Brain Res 1975;95:475–96.
  • Van Hoesen GW, Solodkin A. Some modular features of temporal cor- tex in humans as revealed by pathological changes in Alzheimer’s Disease. Cerebral Cortex 1993;3:465–75.
  • Vogt C, Vogt O. Die physiologische Bedeutung der architektonishcen Rindenfelderung auf Grund neuer Rindenreizungen. J Psychol Neurol 1919;25:399–429.
  • Von Bonin G, Bailey P. The neocortex of Macaca mulatta. Urbana, IL: University of Illinois Press; 1947.
  • von Economo C, Koskinas GN. Die Cytoarchitektonik der Hirnrinde des erwachsenen Menchen. Berlin: Springer; 1925.