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| Gérard Percheron |
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Lab. Neuromorphologie informationelle et de neurologie expérimentale du mouvement, Hốpital de la Salpệtriere, Paris , France
e-mail: perchero@ccr.jussieu.fr |
Presentation: |
| 2002-10-07, 11:30-12:10 |
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| Our (human) thalamus. |
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| Until recently the anatomofunctional description of the human thalamus
was difficult. A return to the classical model (Burdach, Dejerine) is pertinent, with separating elements (lamellae ) and classical nuclei. These at the Louvain symposium were proposed to be Regions or formations. Whith regards to neuronal types, there is a distinction between allo- and isothalamus. The first comprises two elements of the involucrum (paramedian and intralaminar formations) and the regio centralis. Topographically intralaminar and posterior non-intralaminar elements form the Formatio intralaminaris- limitans. The Regio centralis (centre médian- parafascicular complex), starting from Cercopithecideae composed of 3 and not 2 parts, a basal ganglia system regulator, must be separated from this ensemble . The isothalamus is built with two genera of neurons (thalamo-cortical neurons and local circuit microns) and axonal afferents. The main difficulties were met in the lateral region. In the last decades, reliable tracing and cartographic methods have led to a major progress in monkeys . It has been shown indeed that the spaces occupied by the axonal endings from major prethalamic sources (territories) were separate with no distinction between ventral and dorsal "nuclei". This allowed a simple and functional description . During the last years, it has been found that the topography of the main territories could be observed using immuno- chemistry. The observation of similar entities in the human brain allowed the transfer from simian to the human thalamus. The postero- anterior sequence of main territories is: somesthetic, cutaneous part VPC (VPL and VPM), kinesthetic (VPO), cerebellar, VIm or VL with two parts (VImL and VIMM), pallidal VO and nigral VA. A basal region dealing with pain is added. Hassler's plates have been redrawn and data from stereotaxy reinterpreted. |
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