[Correlations between thalamic projections to different areas of the parietal association cortex of the cat]

Projections of thalamic neurons to parietal association cortex of cat were examined by means of the retrograde axonal transport of fluorescent dyes (primuline and fast blue). It has been demonstrated that a dorsal part of the pulvinar (PL) and a dorsal part of the caudal area of the lateral posterior nucleus (LP) projected mostly to the middle suprasylvian gyrus (MSSG), while a ventral part of PL and a ventral part of the rostral area of LP--to the rostral suprasylvian gyrus (RSSG). Double labelled neurons were found in PL, LP, suprageniculatus, anterior ventral, ventral lateral as well as in the central lateral, paracentral and central medial nuclei after injections of two different dyes into MSSG and RSSG. Topic organization of sources of cortical projections from the PL--LP complex can probably provide a high level of discrimination of visual signals by single cortical neurons. At the same time during integration of information of a different subcortical origin RSSG and MSSG act, probably, in concord to a considerable extent, that suggests insufficient differentiation of RSSG and MSSG corresponding approximately to cortical areas 5 and 7 of cat.