Asymmetries of representation in the visual system of pigeons

ALTHOUGH functional asymmetries in the course of visual information process ing have been known for a long time in humans as well as in non-human speci es, the structural basis of these asymmetries is largely unknown. We now re port that due to an asymmetry of commissural projections in the pigeon the left nucleus rotundus of the ascending tectofugal visual system predominant ly represents inputs from both eyes while the right nucleus rotundus mainly represents the contralateral left eye. We suggest that a comparable organi zation exists for several asymmetries in humans. A representation of both h emifields can provide the dominant hemisphere with direct access to all sti mulus features when objects cross the vertical meridian. NeuroReport 9: 412 7-4130 (C) 1998 Lippincott Williams & Wilkins.