Demonstration of a direct projection from the intralaminar central lateral nucleus to the primary visual cortex

Orthograde autoradiographic and retrograde horseradish peroxidase (HRP) tracing techniques were used to demonstrate the existence of a direct projection from the central lateral nucleus of the intralaminar complex of the thalamus to the primary visual cortex of the cat. The projection is sparser than the projections from the thalamic non-specific nuclei to other cortical areas of the cat which have been described in the past [9,20,21]. The projection to primary visual cortex is most dense in cortical layers I and VI. It does not appear to have a well-defined topographical organization within this cortical area.