Spatial representation of frequency in the rat dorsal nucleus of the lateral lemniscus as revealed by acoustically induced c- fos mRNA expression

• Published in: Hearing research 1999-02, Vol.128 (1), p.70-74
• Main Authors: Saint Marie, Richard L, Luo, Lin, Ryan, Allen F
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation; Activity marker; Animals; Auditory Pathways - cytology; Auditory Pathways - metabolism; Auditory Pathways - physiology; Biological and medical sciences; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Fundamental and applied biological sciences. Psychology; Neurons - metabolism; Pons - cytology; Pons - metabolism; Pons - physiology; Proto-Oncogene Proteins c-fos - genetics; Rats; RNA, Messenger - metabolism; Tissue Distribution - physiology; Tonotopic; Vertebrates: nervous system and sense organs
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/S0378-5955(98)00188-9

The conventional view, based largely on studies in cats, holds that the dorsal nucleus of the lateral lemniscus (DNLL) is tonotopically organized with a dorsal (low-frequency) to ventral (high-frequency) representation. Based on the topography of projections between the DNLL and inferior colliculus, it has been proposed that the rat DNLL has a concentric, inside-to-outside, tonotopic organization with high frequencies represented along the rind and low frequencies represented in the core. We used acoustic stimulation and c- fos mRNA expression to examine this issue. Results suggest that the rat DNLL does have a crude tonotopic organization and that this tonotopy has a concentric component. Following high-frequency stimulation, labeled neurons were found most frequently along the margins of DNLL, although they also tended to be more concentrated ventrally. Many fewer neurons labeled following middle-frequency stimulation, and these tended to be more uniformly distributed throughout the nucleus. Still fewer neurons labeled after low-frequency stimulation and these tended to be scattered mostly in the dorsal half of the nucleus. We conclude that: (i) many more neurons in the rat DNLL are responsive to high-frequency than to low-frequency acoustic stimulation; and (ii) that the frequency representation of the rat DNLL has both concentric and dorsal-to-ventral components.