Variability of High Frequency Head Rotation Test in Normal Subjects

Functions of macular organ have not been understood completely, but the function of the saccular macula is considered to be different from that of the utricular macula as a peripheral vestibular receptor organ. Because distinctive secondary vestibular projections arise from particular regions within individual vestibular nucleus, the pattern of termination of primary vestibular fibers has special functional significance. So projection patterns of the saccular macula and the utricular macula to the vestibular nuclei were investigated in the 16 Mongolian gerbils applying the scratch method and HRP. The results were as follows: 1) In superior vestibular nucleus, afferent fibers from the utricular macula(AFU) projected to the lateral part and afferent fibers from the saccular macula(AFS) Projected to the periphery with concentration on the lateral part. 2) In lateral vestibular nucleus, AFU projected to the ventral part and AFS projected to the lateral part. 3) In medial vestibular nucleus, AFU projected to the central part in the rostral half of the nucleus and the dorsal part in the caudal half of the nucleus, but AFS projected to the ventral part in the rostral portion and the dorsal part in the mid portion of the nucleus, but not to the caudal part of the nucleus. 4) In descending vestibular nucleus, AFU projected to the lateral part, but AFS projected diffusely. 5) Both AFU and AFS projected to interstitial nucleus, but in group Y projections were observed only from AFS.ope