SBNeC 2010
Resumo:C.023


Prêmio
C.023Thalamic Projections to the Representation of the Hand and Forepaw in the Parietal Cortex of the Primate Cebus apella
Autores:Glauber José de Oliveira Amancio (UFRJ-IBCCF - Universidade Federal do Rio de Janeiro) ; Ruben Ernesto de Bittencourt Navarrete (UFRJ-IBCCF - Universidade Federal do Rio de Janeiro) ; Andrei Mayer de Oliveira (UFRJ-IBCCF - Universidade Federal do Rio de Janeiro) ; Juliana Gomes Soares (UFRJ-IBCCF - Universidade Federal do Rio de Janeiro) ; Dylan F. Cooke (UC DAVIS - University of California, Davis) ; Jeffrey Padberg (UC DAVIS - University of California, Davis) ; Mário Fiorani Junior (UFRJ-IBCCF - Universidade Federal do Rio de Janeiro) ; Ricardo Gattass (UFRJ-IBCCF - Universidade Federal do Rio de Janeiro) ; Leah Krubtizer (UC DAVIS - University of California, Davis) ; João Guedes da Franca (UFRJ-IBCCF - Universidade Federal do Rio de Janeiro)

Resumo

Cebus monkeys are the only known New World primate able to perform a precision grip by bringing its opposable thumb in contact to the forefinger. Such feature is strongly associated with manual dexterity and involves processing of somatosensory information through the thalamus and parietal cortex. In order to examine the thalamocortical connections associated with the forepaw representations in the parietal cortex we performed neurotracer injections (DY, FR, FE, and BDA) in areas 1, 2, and 5 guided by multiunit electrophysiological mapping in three subjects of this species. Neuronal labeling was digitized in drawings of thalamic coronal sections using a fluorescence microscope attached to a PC-driven stage controlled by the Neurolucida system (MBF, Inc). Thalamic nuclei were identified in adjacent sections processed either for cytochrome oxidase or Nissl staining. A total of 700 hundred labeled cells were plotted along 39 coronal thalamic sections. In case R05-01 the main thalamic projections to area 2, identified by two different injections (of DY and FR), arose from the anterior pulvinar nucleus (Pla, 37.5% and 43.1% respectively), and from the ventral posterior superior nucleus (VPs, 35.3% and 27.5%). Projections to area 1 originated mainly from Pla (50,5%), from ventral posterior inferior nucleus (VPi, 26.9%), and from the ventral posterior lateral nucleus (VPl, 8.9%). In case R07-01, one injection encompassing areas 2 and 5 (FR) and another one in area 5 alone (FE) revealed Pla as the major projecting nucleus (100% of FR-labeled cells and 31.7% of FE-labeled cells). Area 5 also received projections from VPs (29.6%), lateral posterior nucleus (LP, 11%), and central lateral nucleus (CL, 21.3%). In case R07-03, a BDA injection in area 2 revealed projections from Pla (29.4%), VPs (32.3%) and VPl (32.3%). Another injection of FR in area 2 (including a small portion of area 5) revealed projections from VPs (37%). An additional injection of FE encompassing areas 2 and 5, showed projections originating from VPs (41.6%), medial pulvinar nucleus (Plm, 20.8%), Pla (16.6%) and VPl (12.5%). In conclusion, most of thalamic projections arriving on the forepaw representation of areas 1, 2, and 5 originate in VP and pulvinar complexes. The main relays of VP complex are VPs and VPi, with minor contributions of VPl. For the pulvinar, the main projection originates in Pla. We conclude that there is a high degree of divergence and convergence in the projections from the thalamus to the parietal cortex. Different thalamic nuclei project to multiple areas, and simultaneously, each cortical field receives projections from a number of thalamic nuclei; indicating a high degree of parallel processing of sensory information.


Palavras-chave:  Cebus apella, Posterior Parietal Cortex, Neuroanatomy, Thalamocortical connections