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Maturation of otolith‐related brainstem neurons in the detection of vertical linear acceleration in rats
Author(s) -
Lai SukKing,
Lai ChunHong,
Yung Ken K. L.,
Shum Daisy K. Y.,
Chan YingShing
Publication year - 2006
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2006.04762.x
Subject(s) - brainstem , medial vestibular nucleus , vestibular nuclei , vestibular system , nucleus , neuroscience , reticular formation , locus coeruleus , anatomy , lateral vestibular nucleus , biology , hypoglossal nucleus
To investigate the critical maturation time of otolith‐related neurons in processing vertical orientations, rats (postnatal day 4 to adults) were studied for functional activation of c‐fos expression in brainstem neurons by immuno‐/hybridization histochemistry. Conscious rats were subjected to sinusoidal linear acceleration along the vertical plane. Labyrinthectomized and/or stationary controls showed only sporadically scattered Fos‐labeled neurons in the vestibular nuclei, confirming an otolithic origin of c‐fos expression. Functionally activated Fos expression in neurons of the medial and spinal vestibular nuclei and group x were identifiable by P7 and those in group y by P9. A small number of Fos‐labeled neurons characterized by small soma size were found in the ventral part of lateral vestibular nucleus by P9. Other vestibular‐related areas such as prepostitus hypoglossal nucleus, gigantocellular reticular nucleus and locus coeruleus of normal experimental rats showed functionally activated c‐fos expression at P7. Neurons in dorsal medial cell column and beta subnucleus of the inferior olive only showed functionally activated c‐fos expression by the second postnatal week. These findings revealed a unique critical maturation time for each of the vestibular‐related brainstem areas in the recognition of gravity‐related vertical head orientations. By mapping the three‐dimensional distribution of Fos‐immunoreactive neurons, we found an even distribution of otolith‐related neurons within the spinal vestibular nucleus in groups x and y but a clustered distribution in the middle–lateral–ventral part of the medial vestibular nucleus. Taken together, our findings reveal the developmental profile of neuronal subpopulations within the vertical otolith system, thereby providing an anatomical basis for postnatal coding of gravity‐related vertical head movements.