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Article: The coding of head orientations in neurons of bilateral vestibular nuclei of cats after unilateral labyrinthectomy: Response to off-vertical axis rotation

TitleThe coding of head orientations in neurons of bilateral vestibular nuclei of cats after unilateral labyrinthectomy: Response to off-vertical axis rotation
Authors
Issue Date1997
PublisherSpringer Verlag. The Journal's web site is located at http://link.springer.de/link/service/journals/00221/index.htm
Citation
Experimental Brain Research, 1997, v. 114 n. 2, p. 293-303 How to Cite?
AbstractIn decerebrate cats that had been acutely hemilabyrinthectomized (HL), the extracellular activities of vestibular nuclear neurons on the lesioned and labyrinth-intact sides were studied during constant-velocity off-vertical axis rotations (OVAR) in the clockwise (CW) and counterclockwise (CCW) directions (at 10°tilt). Over the range of 1.75-15°/s, two types of neuronal responses were identified on both sides. Some neurons showed symmetric and velocity-stable bidirectional response sensitivity (δ defined as the CW gain over the CCW gain) while other neurons exhibited asymmetric and velocity-variable δ. The mathematically derived gain tuning ratios of these two groups of neurons were within the range of one-dimensional and two-dimensional neurons respectively. The best response orientations in one-dimensional neurons and the orientations of the maximum response vector, S(max), in two-dimensional neurons were found to point in all directions on the horizontal plane. On the labyrinth-intact side, both the one-dimensional and two-dimensional neurons showed asymmetry in the neuron numbers and/or the response gains between the two roll quadrants as well as between the two pitch quadrants. In addition, both the neuron number and gain were significantly higher for neurons in the head-down/ipsilateral-side-down half-circle than those in the head-up/contralateral-side-down half-circle. None of the aforementioned asymmetries was observed on the lesioned side. That a comparable pattern of distribution was observed in the one-dimensional and two-dimensional neurons suggests that these neurons maintain a common spatial. reference frame in encoding head orientational signals arising from the ipsilateral and contralateral otoliths. Furthermore, a predominance of two-dimensional neurons that exhibited a greater gain with CW rotations was observed on both sides of HL cats. Of the response dynamics observed amongst neurons on the two sides of HL cats, no difference was found with regard to the response gain and the pattern of response lead. However, a difference in response lag was observed between neurons on the two sides of HL cats. These suggest that there is a segregation of otolithic signals to reach the ipsilateral and contralateral vestibular nuclei. Taken together, the present study demonstrates that one-dimensional and two-dimensional neuronal responses could be elicited with inputs arising solely from the ipsilateral or contralateral otoliths. The observed orientational tuning and the CW-CCW asymmetry to bidirectional rotation may provide the essential directional coding of head orientations. Further, the imbalance of spatial/dynamic response patterns between the bilateral vestibular nuclei following the restriction of otolith inputs by HL implies that converging otolithic inputs from the bilateral labyrinths are essential for producing the neuronal responses in control animals. The results are also discussed in terms of the possible contribution of the various neural asymmetries between neuronal subpopulations in the bilateral vestibular nuclei to the behavioral symptoms accompanying acute HL.
Persistent Identifierhttp://hdl.handle.net/10722/171638
ISSN
2015 Impact Factor: 2.057
2015 SCImago Journal Rankings: 1.140
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorChan, YSen_US
dc.date.accessioned2012-10-30T06:16:05Z-
dc.date.available2012-10-30T06:16:05Z-
dc.date.issued1997en_US
dc.identifier.citationExperimental Brain Research, 1997, v. 114 n. 2, p. 293-303en_US
dc.identifier.issn0014-4819en_US
dc.identifier.urihttp://hdl.handle.net/10722/171638-
dc.description.abstractIn decerebrate cats that had been acutely hemilabyrinthectomized (HL), the extracellular activities of vestibular nuclear neurons on the lesioned and labyrinth-intact sides were studied during constant-velocity off-vertical axis rotations (OVAR) in the clockwise (CW) and counterclockwise (CCW) directions (at 10°tilt). Over the range of 1.75-15°/s, two types of neuronal responses were identified on both sides. Some neurons showed symmetric and velocity-stable bidirectional response sensitivity (δ defined as the CW gain over the CCW gain) while other neurons exhibited asymmetric and velocity-variable δ. The mathematically derived gain tuning ratios of these two groups of neurons were within the range of one-dimensional and two-dimensional neurons respectively. The best response orientations in one-dimensional neurons and the orientations of the maximum response vector, S(max), in two-dimensional neurons were found to point in all directions on the horizontal plane. On the labyrinth-intact side, both the one-dimensional and two-dimensional neurons showed asymmetry in the neuron numbers and/or the response gains between the two roll quadrants as well as between the two pitch quadrants. In addition, both the neuron number and gain were significantly higher for neurons in the head-down/ipsilateral-side-down half-circle than those in the head-up/contralateral-side-down half-circle. None of the aforementioned asymmetries was observed on the lesioned side. That a comparable pattern of distribution was observed in the one-dimensional and two-dimensional neurons suggests that these neurons maintain a common spatial. reference frame in encoding head orientational signals arising from the ipsilateral and contralateral otoliths. Furthermore, a predominance of two-dimensional neurons that exhibited a greater gain with CW rotations was observed on both sides of HL cats. Of the response dynamics observed amongst neurons on the two sides of HL cats, no difference was found with regard to the response gain and the pattern of response lead. However, a difference in response lag was observed between neurons on the two sides of HL cats. These suggest that there is a segregation of otolithic signals to reach the ipsilateral and contralateral vestibular nuclei. Taken together, the present study demonstrates that one-dimensional and two-dimensional neuronal responses could be elicited with inputs arising solely from the ipsilateral or contralateral otoliths. The observed orientational tuning and the CW-CCW asymmetry to bidirectional rotation may provide the essential directional coding of head orientations. Further, the imbalance of spatial/dynamic response patterns between the bilateral vestibular nuclei following the restriction of otolith inputs by HL implies that converging otolithic inputs from the bilateral labyrinths are essential for producing the neuronal responses in control animals. The results are also discussed in terms of the possible contribution of the various neural asymmetries between neuronal subpopulations in the bilateral vestibular nuclei to the behavioral symptoms accompanying acute HL.en_US
dc.languageengen_US
dc.publisherSpringer Verlag. The Journal's web site is located at http://link.springer.de/link/service/journals/00221/index.htmen_US
dc.relation.ispartofExperimental Brain Researchen_US
dc.subject.meshAnimalsen_US
dc.subject.meshCatsen_US
dc.subject.meshEar, Inner - Physiologyen_US
dc.subject.meshElectric Stimulationen_US
dc.subject.meshEvoked Potentialsen_US
dc.subject.meshFunctional Lateralityen_US
dc.subject.meshHeaden_US
dc.subject.meshMotor Activityen_US
dc.subject.meshMovementen_US
dc.subject.meshNeurons - Physiologyen_US
dc.subject.meshOrientationen_US
dc.subject.meshPostureen_US
dc.subject.meshSpace Perceptionen_US
dc.subject.meshTime Factorsen_US
dc.subject.meshVestibular Nuclei - Physiologyen_US
dc.titleThe coding of head orientations in neurons of bilateral vestibular nuclei of cats after unilateral labyrinthectomy: Response to off-vertical axis rotationen_US
dc.typeArticleen_US
dc.identifier.emailChan, YS:yschan@hkucc.hku.hken_US
dc.identifier.authorityChan, YS=rp00318en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1007/PL00005638-
dc.identifier.pmid9166919-
dc.identifier.scopuseid_2-s2.0-0030980082en_US
dc.identifier.hkuros25730-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0030980082&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume114en_US
dc.identifier.issue2en_US
dc.identifier.spage293en_US
dc.identifier.epage303en_US
dc.identifier.isiWOS:A1997WX44100011-
dc.publisher.placeGermanyen_US
dc.identifier.scopusauthoridChan, YS=7403676627en_US

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