Olfactory asymmetry in the rat brain.

Based on cytoarchitecture, myeloarchitecture, and physiological observations in the literature, two concentric strata are identified in the olfactory bulb of the albino rat. Stimulated by a report of physiologic asymmetry between the left and right bulb of the rodent brain, we parcelled the inner and outer strata of the olfactory bulbs of 16 albino rats and measured the volume of these olfactory subdivisions. The volume of the entire olfactory bulb was found to be significantly greater in the right hemisphere. This volume asymmetry was the result of a significantly larger right outer stratum. No significant asymmetry was demonstrated for the inner stratum. These findings are discussed in the light of some physiologic and anatomic properties of the olfactory bulb.