Projections from the vestibular nuclei to the parabrachial complex (PB) have been described in rats, rabbits, and monkeys, and have been proposed as a neuronal substrate for clinically-observed linkages between disorders of balance and of affect. This raised the questions of whether PB units respond to vestibular stimulation, and what details of whole-body motion are present in PB. The caudal two-thirds of the parabrachial and Kölliker-Fuse nuclei were explored by Balaban and coworkers (2002), and found to contain neurons responsive to whole-body, periodic rotations in vertical and horizontal planes. Responses to brief 'position trapezoid' stimuli indicated that PB units were sensitive to both angular velocity and static tilt, consistent with the presence of angular- and linear-acceleration sensitive inputs from the vestibular nuclei. In the majority of units, responses to brief static tilts (of 1.5s duration) appeared to reflect a sensitivity to linear acceleration in the head-horizontal plane, consistent with the presence of linear-acceleration sensitive inputs from the vestibular nuclei. We have replicated these results and further investigated the linear acceleration sensitivity of PB units using off-vertical axis rotations (OVAR). We have confirmed the general hypothesis that responses of many PB units to a rotating linear acceleration vector are consistent with the behavior of first- and second-order vestibular neurons. The majority of units responded to OVAR in a manner consistent with responses of vestibular neurons previously described as linear, one-dimensional accelerometers. Fewer units showed a variety of responses consistent with previously described central vestibular neurons suggestive of convergence of labyrinthine inputs with different spatial and temporal response properties, as well as prominent 'bias' type responses consisting of significant changes in mean firing rate during rotation, in the absence of significant modulation.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-05072007-065852 |
| Date | 07 May 2007 |
| Creators | McCandless, Cyrus Henderson |
| Contributors | Daniel J. Simons, PhD, Carey D. Balaban, PhD, Kathleen E. Cullen, PhD, Carl R. Olson, PhD, Mark S. Redfern, PhD, Robert H. Schor |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-05072007-065852/ |
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