The claustrum is a telencephalic structure which consists of dorsal segment adjoining the insular cortex and a ventral segment termed also endopiriform nucleus (END). The dorsal segment (claustrum) is divided into a dorsal and ventral zone, while the END is parcellated into dorsal, ventral and intermediate END. The claustrum and the END consist of glutamatergic projection neurons and GABAergic local interneurons coexpressing calcium binding proteins. Among neurons expressing calcium binding proteins the calretinin (CR)-immunoreactive interneurons exert specific functions in neuronal circuits, including disinhibition of excitatory neurons. Previous anatomical data indicate extensive and reciprocally organized claustral projections with cerebral cortex. We asked if the distribution of cells immunoreactive for CR delineates anatomical or functional subdivisions in the claustrum and in the END. Both segments of the claustrum and all subdivisions of the END contained CR immunoreactive neurons with varying distribution. The ventral zone of the claustrum exhibited weak labeling with isolated cell bodies and thin fibers and is devoid of immunoreactive puncta. Within the medial margin of the intermediate END we noted a group of strongly positive neurons. Cells immunoreactive for CR in all subdivisions of the claustrum and END were bipolar, multipolar and oval with smooth, beaded aspiny dendrites. Small number of CR-immunoreactive neurons displayed thin dendrites which enter to adjoining structures. Penetration of dendrites was reciprocal. These results show an inhomogenity over the claustrum and the END in distribution and types of CR immunoreactive neurons. The distribution of the CR-immunoreactive neurons respects the anatomical but not functional zones of the claustral complex.

Department of Anatomy Charles University Prague 2nd Faculty of Medicine Prague Czech Republic

Department of Anatomy Charles University Prague 2nd Faculty of Medicine Prague Czech Republic ; Department of Anatomy Charles University Prague 1st Faculty of Medicine Prague Czech Republic ; Department of Developmental Epileptology Institute of Physiology Academy of Sciences of the Czech Republic Prague Czech Republic

Department of Developmental Epileptology Institute of Physiology Academy of Sciences of the Czech Republic Prague Czech Republic

Department of Neurology University of Regensburg Regensburg Germany

Medimark Corporation Del Mar CA USA

See more in PubMed

Allen G. V., Saper C. F., Hurley K. M., Cechetto D. F. (1991). Organization of visceral and limbic connections in the insular cortex of the rat. J. Comp. Neurol 311, 1–16. 10.1002/cne.903110102 PubMed DOI

Barak S., Wang Z., Miettinen M. (2012). Immunoreactivity for calretinin and keratins in desmoid fibromatosis and in other myofibroblastic tumors: a diagnostic pitfall. Am. J. Surg. Pathol. 36, 1404–1409. 10.1097/pas.0b013e3182556def PubMed DOI PMC

Barinka F., Druga R. (2010). Calretinin expression in the mammalian neocortex: a review. Physiol. Res. 59, 665–677. PubMed

Barinka F., Salaj M., Rybar J., Krajcovicova E., Kubová H., Druga R. (2012). Calretinin, parvalbumin and calbindin immunoreactive interneurons in perirhinal cortex and temporal area Te3V of the rat brain: qualitative and quantitative analyses. Brain. Res. 1436, 68–80. 10.1016/j.brainres.2011.12.014 PubMed DOI

Callaway E. M. (2004). Feedforward, feedback and inhibitory connections in primate visual cortex. Neural Netw. 17, 625–632. 10.1016/j.neunet.2004.04.004 PubMed DOI

Camp A. J., Wijesinghe R. (2009). Calretinin: modulator of neuronal excitability. Int. J. Biochem. Cell Biol 41, 2118–2121. 10.1016/j.biocel.2009.05.007 PubMed DOI

Cozzi B., Roncon G., Granato A., Guirisato M., Castagna M., Peruffo A., et al. . (2014). The claustrum of the bottlenose dolphin Torsiops truncatus(Montagu 1821). Front. Syst. Neurosci. 8:42. 10.3389/fnsys.2014.00042 PubMed DOI PMC

Crick F. C., Koch C. (2005). What is the function of the claustrum? Philos. Trans. R. Soc. Lond. B Biol. Sci. 360, 1271–1279. 10.1098/rstb.2005.1661 PubMed DOI PMC

Druga R. (2014). “The structure and connections of the claustrum,” in The Claustrum: Structural, Functional and Clinical Neuroscience, eds Smythies J. R., Edelstein L. R., Ramachandran V. S. (Oxford: Elsevier; ), 29–84.

Druga R., Chen S., Bentivoglio M. (1993). Parvalbumin and calbindin in the rat claustrum: an immunohistochemical study combined with retrograde tracing from frontoparietal cortex. J. Chem. Neuroanat. 6, 399–406. 10.1016/0891-0618(93)90014-u PubMed DOI

Edelstein L., Denaro F. J. (2004). The claustrum: a historical review of its anatomy, physiology, cytochemistry amd functional significance. Cell. Mol. Biol. (Noisy-le-grand) 50, 675–702. PubMed

Edelstein L., Druga R., Stamm J., Cerman J., Salaj M. (2010). “Calretinin immunoreactivity in the rat and guinea pig claustrum,” in Society for Neuroscience, 40th Annual Meeting, 2010, Abstract #900.2.

Gulyás A. I., Hájos N., Freund T. F. (1996). Interneurons containing calretinin are specialized to control other interneurons in the rat hippocampus. J. Neurosci. 16, 3397–3411. PubMed PMC

Kowiański P., Dziewiątkowski J., Moryś J. M., Majak K., Wójcik W. S., Edelstein L. R., et al. . (2009). Colocalization of neuropeptides with calcium-binding proteins in the claustral interneurons during postnatal development of the rat. Brain Res. Bull. 80, 100–106. 10.1016/j.brainresbull.2009.06.020 PubMed DOI

Kowiański P., Moryś J. M., Karwacki Z., Dziewiątkowski J., Narkiewicz O. (1998). The cortico-related zones of the rabbit claustrum—study of the claustrocortical connectionms based on the retrograde axonal transport of fluorescent tracers. Brain Res. 784, 199–209. 10.1016/s0006-8993(97)01326-7 PubMed DOI

Medina L., Legaz I., Gonzáles G., De Castro F., Rubenstein J. L., Puelles L. (2004). Expression of Dbx 1, Neurogenin 2, Semaphorin 5A, Catherin 8 and Emx 1 distinguish ventral and lateral pallial histogenetic division in the developing mouse claustroamygdaloid complex. J. Comp. Neurol. 474, 504–523. 10.1002/cne.20141 PubMed DOI

Paxinos G., Kus L., Ashwell K., Watson C. (1999). Chemoarchitecture of The Rat Forebrain. San Diego: Academic Press.

Paxinos G., Watson C. (1997). The Rat Brain in Stereotaxic Coordinates. Amsterdam: Elsevier Academic Press.

Paxinos G., Watson C. (2007). The Rat Brain is Stereotaxic Coordinates. Amsterdam: Elsevier Academic Press.

Rahman F. E., Baizer J. S. (2007). Neurochemically defined cell types in the claustrum of the cat. Brain Res. 1159, 94–111. 10.1016/j.brainres.2007.05.011 PubMed DOI

Real A. M., Dávila J. C., Guirado S. (2003). Expression of calcium-binding proteins in the mouse claustrum. J. Chem. Neuroanat. 25, 151–160. 10.1016/s0891-0618(02)00104-7 PubMed DOI

Real M. A., Dávila J. C., Guirado S. (2006). Immunohistochemical localization of the vesicular glutamate transporter VGLUT2 in the developing and adult mouse claustrum. J. Chem. Neuroanat. 31, 169–177. 10.1016/j.jchemneu.2005.12.002 PubMed DOI

Reynhout K., Baizer J. S. (1999). Immunoreactivity for calcium-binding proteins in the claustrum of the monkey. Anat. Embryol. (Berl) 199, 75–83. 10.1007/s004290050211 PubMed DOI

Sadowski M., Moryś J., Jakubowska—Sadowska K., Narkiewicz O. (1997). Rat’s claustrum shows two main cortico-related zones. Brain Res. 765, 147–152. 10.1016/S0006-8993(97)00135-2 PubMed DOI

Schwaller B. (2014). Calretinin: from a “simple” Ca 2++ buffer to a multifunctional protein implicated in many biological processes. Front. Neuroanat. 8:3. 10.3389/fnana.2014.00003 PubMed DOI PMC

Sloniewski P., Usunoff K. G., Pilgrim C. (1986). Retrograde transport of fluorescent tracers reveals extensive ipsi—and contralateral claustrocortical connections in the rat. J. Comp. Neurol 246, 467–477. 10.1002/cne.902460405 PubMed DOI

Smythies J., Edelstein L., Ramachandran V. (2012). Hypotheses relating to the function of the claustrum. Front. Integr. Neurosci. 6:53. 10.3389/fnint.2012.00053 PubMed DOI PMC

Smythies J., Edelstein L., Ramachandran V. (2014). Hypotheses relating to the function of the claustrum II: does the claustrum use frequency codes? Front. Integr. Neurosci. 8:7. 10.3389/fnint.2014.00007 PubMed DOI PMC

Spahn B., Braak H. (1985). Percentage of projection neurons and various types of interneurons in the human claustrum. Acta Anat. (Basel) 122, 245–248. 10.1159/000146023 PubMed DOI

Wójcik S., Dziewiątkowski S., Spodnik E., Ludkiewicz B., Domaradzka—Pytel B., Kowiański P., et al. . (2004). Analysis of calcium bidning protein immunoreactivity in the claustrum and the endopiriform nucleus of the rabbit. Acta Neurobiol. Exp. (Wars) 64, 449–460. PubMed

Epilepsy Research in the Institute of Physiology of the Czech Academy of Sciences in Prague

Degenerative Changes in the Claustrum and Endopiriform Nucleus after Early-Life Status Epilepticus in Rats