[Horseradish peroxidase labeled neurons of the ventrobasal complex of the thalamus projecting to the somatosensory zone I of the cat cerebral cortex].

The morphology and topography of the neurons in the ventro-basal complex (VB) projecting to the somatic sensory cortex (SI) were studied by the method of the retrograde axonic transport of horseradish peroxidase (HRP). Different types of HRP-labelled cells were found in this structure. The concentration of labelled cells was the greatest in the central part of the VB. The most peculiar feature in the distribution of HRP-positive neurons was their organization in two large populations in the dorsal and ventral portions of the VB. A comparison with the somatotopic map of the VB revealed that the central region of this complex is the area of the representation of the forelimb and the head. Our morphological results confirm the neurophysiological conception about the organization of the thalamo-cortical input on the "point-to-point" projection principles.