Fos responses to short-term adaptation of the horizontal vestibuloocular reflex before and after vestibular compensation in the Mongolian gerbil

• Published in: Brain research 2005-07, Vol.1050 (1), p.79-93
• Main Authors: Shinder, Michael E., Perachio, Adrian A., Kaufman, Galen D.
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological - physiology; Animals; Biological and medical sciences; Cell Count; Female; Flocculus; Fundamental and applied biological sciences. Psychology; Gerbillinae; Immunohistochemistry; Inferior olive; Male; Medial vestibular nucleus; Meriones unguiculatus; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Neurons - cytology; Neurons - metabolism; Olivary Nucleus - cytology; Olivary Nucleus - physiology; Prepositus hypoglossi; Proto-Oncogene Proteins c-fos - metabolism; Purkinje; Reflex, Vestibulo-Ocular - physiology; Space life sciences; Vertebrates: nervous system and sense organs; Vestibular Nuclei - cytology; Vestibular Nuclei - physiology; Vestibule, Labyrinth - physiology; Video-oculography
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2005.05.029

Fos expression in vestibular brainstem and cerebellar regions was evaluated during vestibular adaptation in the Mongolian gerbil. In addition, vestibular adaptation was evaluated in both normal and compensated animals, as vestibular compensation reorganizes the vestibular pathway constraining adaptive processes. Behaviorally, discordant optokinetic and vestibular input induced appropriate high and low gain in horizontal angular vestibuloocular reflex responses. In normal animals, low gain adaptation was more complete than high gain. However, in compensated animals, only low gain adaptation produced adaptive responses both toward and away from the lesion with appropriate gain shifts. High gain adaptation in compensated animals failed to result in gain adaptation for head movements toward the side of the lesion. Fos expression during acute vestibular adaptation in normal animals was found in the flocculus/paraflocculus, the dorsal cap of the inferior olive (IOK), and the prepositus hypoglossi (PrH). Floccular Fos labeling was increased under both high and low gain conditions. IOK and PrH labeling was increased and correlated during low gain conditions, but was reduced and uncorrelated during high gain conditions. The pattern of Fos labeling in compensated animals was asymmetric—favoring the ipsilesional flocculus and contralesional vestibular brainstem. Both compensated high and low gain adaptation groups displayed increased floccular and IOK Fos labeling, but only compensated high gain adaptation produced increased Fos labeling in the medial vestibular nucleus. The behavioral and Fos labeling results are consistent with visual–vestibular adaptation requiring direct vestibular input.