Functional organization of some auditory nuclei in the Guinea Fowl demonstrated by the 2-Deoxyglucose technique

Abstract

The auditory pathway of the Guinea Fowl was labeled with [C¹⁴]2-deoxy-D-glucose after stimulation with pure tones, harmonic tones and species-specific calls. In addition to other auditory nuclei, which showed more or less uniform labeling with the present technique, the n. mesencephalicus lateralis dorsalis (MLD) of the midbrain, as well as field L and parts of the hyperstriatum ventrale in the telencephalon, showed a stripe-pattern of labeling after stimulation with a pure tone. The position and orientation of the tone-activated striped areas in field L, observed after stimulation with different tones, correspond to isofrequency contours obtained with microelectrode recordings. The labeling of the three congruent tonotopically organized layers of field L (L₁, L₂, and L₃) was not uniform along the anterior-posterior axis of the field. Harmonic tones produced multiple reactive stripes each of which corresponded to the stripe characteristic of a particular harmonic presented as a pure tone. The species-specific Iambus-call labeled the tonotopic area of field L that corresponds to the frequency band with the highest energy of the call. The hyperstriatum ventrale generally showed a weaker pattern of labeling that, however, resembled the labeling in field L.