Connessioni callosali reciproche tra l'area somestesica prima e seconda del Primate

Conti, Fiorenzo   ; Manzoni, Tullio

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 79 (1985) no. 1-4, pp. 37-44

Résumé

In order to study the callosal connections between the first and the second somatosensory areas (SI and SII) of primates, experiments were performed in 4 macaque monkeys in which horseradish peroxidase (HRP) was injected in area SI. Two animals received multiple HRP injections (12 injections of $0.5 \, \mu l$ each) either in the trunk or in the hand representation zone of area SI. The other two animals received two injections of HRP, one in the trunk and one in the digit zone of the same area. Two series of alternate sections of the brains were prepared. The first was processed for HRP reaction with a cobalt-enhanced method and the second according to the tetramethylbenzidine (TMB) procedure. In the series of brain sections processed according to the TMB procedure, terminals of callosal fibres and callosal projecting neurones labelled with HRP were found in the contralateral area SII. In the series of brain sections processed for HRP reaction according to the cobalt-enhanced method, labelled callosal neurones in area SII were very rare. The topography of callosal terminals and neurones in area SII depended on the zone of the body map of area SI injected with HRP. Callosal terminals occurred predominantly in layer IV. Few terminals were also present in supragranular layers and in layer VI but were absent in layer V. About 90% of the labelled callosal neurones were distributed in layer III and 10% in layers V and VI. The results confirm previous experiments showing that the hand zone of area SI of primates sends callosal fibres to the homofunctional zone of contralateral area SII and show that both hand and trunk zones of the latter area send back callosal fibres to contralateral area SI.

Bibliographie

[1] Adams J.C. (1977) - Technical considerations on the use of horseradish peroxidase as a neuronal maker. «Neuroscience», 2, 141-145.

[2] Conti F., Fabri M. e Manzoni T. (1984) - Studio anatomo-funzionale della rappresentazione del tronco nell'area somestesica prima (SI) nel Primate. Congresso della Soc. Ital. Fisiol., Abano Terme, 26-29 settembre.

[3] Friedman D.P., Jones E.G. e Burton H. (1980) - Representation pattern in the second somatosensory area of the monkey cerebral cortex. «J. Comp. Neurol.», 192, 43-67.

[4] Jones E.G. (1981) - Anatomy of cerebral cortex: columnar input-output relations. In «The cerebral cortex» F.O. Schmidt, F.F. Worden, G. Adelman e S.G. Dennis (eds.) Cambridge: MIT Press, 199-225.

[5] Jones E.G. e Friedman D.P. (1982) - Projection pattern of functional components of thalamic ventrobasal complex on somatosensory cortex. «J. Neurophysiol.», 48, 521- 544.

[6] Jones E.G. e Powell T.P.S. (1969) - Connections on the somatic sensory cortex of the Rhesus Monkey. II. Contralateral connections. «Brain», 92, 717-730.

[7] Jones E.G. e Wise S.P. (1977) - Size, laminar and columnar distribution of efferent cells in the sensory-motor cortex of monkeys. «J. Comp. Neurol.», 175, 391-431.

[8] Jones E.G., Wise S.P. e Coulter J.D. (1979) - Differential thalamic relationships of sensory-motor and parietal cortical fields in monkeys. «J. Comp. Neurol.», 183, 833-882.

[9] Killackey M.P., Gould H.J. Iii, Cusik C.G., Pons T.P. e Kaas J.M. (1983) - The relations of corpus callosum connections to architectonic fields and body surface maps in sensory-motor cortex of new and old world monkeys. «J. Comp. Neurol.», 219, 384-419.

[10] Manzoni T., Barbaresi P. e Conti F. (1984) - Callosal mechanisms for the interhemispheric transfer of hand somatosensory information in the monkey. «Behav. Brain Res.», 11, 155-170.

[11] Mellus E.L. (1902) - Bilateral relations of the cerebral cortex. «Bull. Johns Hopkins Hosp.», 12, 108-112.

[12] Mesulam H.M. (1982) - Tracing neural connections with horseradish peroxidase. John Wiley & Sons Inc. New York.

[13] Mettler F.A. (1935) - Corticofugal fiber connections of the cortex Macaca Mulatta. The parietal region. «J. Comp. Neurol.», 62, 263-291.

[14] Mountcastle V.B. (1978) - An organizing principle for cerebral functions: the unit module and the distributed system. In «The mindful brain: cortical organization and the group selective theory of higer brain function». G.M. Edelman e V.B. Mountcastle (eds.): Cambridge: MIT Press, 7-50.

[15] Pandya D.N. e Vignolo I.A. (1969) - Inter hemispheric projections of the parietal lobe in the Rhesus Monkey. «Brain Res.», 15, 49-65.

[16] Robinson C.J. e Burton H. (1980) - Somatotopographic organization in the second somatosensory area of M. fascicularis. «J. Comp. Neurol.», 192, 43-67.

[17] Whitsel B.L., Petruccelli C.M. e Werner G. (1969) - Symmetry and connectivity in the map of the body surface in somatosensory area II of Primates. «J. Neurophysiol.», 32, 170-183.

[18] Whitsel B.L., Rustioni A., Dreyer D.A., Loe P.R., Allen E.E. e Metz C.B. (1978) - Thalamic projections to SI in macaque monkey. «J. Comp. Neurol.», 178, 385-410.