The effects of aging on neuron number in the rat superior olivary complex

• Published in: Neurobiology of aging Vol. 11; no. 4; pp. 391 - 394
• Main Author: Casey, Michael A.
• Format: Journal Article
• Language: English
• Published: London Elsevier Inc 01.07.1990; Elsevier Science
• Subjects: Aging; Aging - physiology; Animals; Auditory system; Biological and medical sciences; Brain Stem - cytology; Brain Stem - physiology; Cell Count; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Fundamental and applied biological sciences. Psychology; In Vitro Techniques; Lateral superior olivary nucleus; Male; Medial nucleus of the trapezoid body; Medial superior olivary nucleus; Neuron loss; Neurons - cytology; Neurons - physiology; Olivary Nucleus - cytology; Olivary Nucleus - physiology; Rats; Rats, Inbred F344 - genetics; Superior olivary complex; Vertebrates: nervous system and sense organs; Medial superior olivary nucleus; Neuron loss; Medial nucleus of the trapezoid body; Auditory system; Aging; Rats; Superior olivary complex; Lateral superior olivary nucleus; Brain; Senescence; Rat; Interspecific comparison; Superior olivary nucleus; Rodentia; Central nervous system; Cell density; Vertebrata; Mammalia; Morphology; Auditory pathway; Age; Cryomicrotomy
• ISSN: 0197-4580; 1558-1497
• DOI: 10.1016/0197-4580(90)90004-J

The superior olivary complex (SOC) is an auditory center in the brainstem involved in the processing of binaural information. The ability to localize sounds is dependent on the efficient processing of binaural signals by the SOC and other auditory centers. It has been demonstrated that sound localization ability is impaired in aged rats, and morphological changes in the SOC may contribute to this deficit. In the present study, neuron counts were done on three key nuclei of the SOC: the medial nucleus of the trapezoid body (MNTB), the lateral superior olivary nucleus (LSO), and the medial superior olivary nucleus (MSO) in groups of Fischer 344 rats aged 3, 12, 24, and 30 months. Neuron number remains stable between 3 and 30 months of age in the LSO and MSO, however, in the MNTB, neuron number is significantly reduced at 24 and 30 months of age. Neuron loss in the MNTB of 24-month-old Fischer 344 rats is not as heavy as that reported earlier in 24-month-old Sprague-Dawley rats (8% loss versus 34% loss), indicating a strain difference with regard to aging in the SOC.