Manzoni D, Pompeiano O, Barnes CD, Stampacchia G, d'Ascanio P. Convergence and interaction of neck and macular vestibular inputs on locus coeruleus and subcoeruleus neurons.
Pflugers Arch 1989;
413:580-98. [PMID:
2657645 DOI:
10.1007/bf00581807]
[Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Extracellular recordings were obtained in precollicular decerebrate cats from 90 neurons located in the noradrenergic area of the dorsal pontine tegmentum, namely in the dorsal (LCd, n = 24) and the ventral part (LC alpha, n = 40) of the locus coeruleus (LC) as well as in the locus subcoeruleus (SC, n = 26). Among these units of the LC complex, 13 were coerulospinal (CS) neurons antidromically identified following stimulation of the spinal cord at T12-L1. Some of these neurons showed the main physiological characteristics of the norepinephrine (NE)-containing LC neurons, i.e., a slow and regular resting discharge and a typical biphasic response to fore- and hindpaw compression consisting of a short burst of excitation followed by a period of quiescence, due, in part at least, to recurrent and/or lateral inhibition. Unit firing rate was analyzed under separate stimulation of macular vestibular, neck, or combined receptors by using sinusoidal rotation about the longitudinal axis at 0.15 Hz, +/- 10 degrees peak amplitude. Among the 90 LC-complex neurons, 60 (66.7%) responded with a periodic modulation of their firing rate to roll tilt of the animal and 67 (74.4%) responded to neck rotation. Convergence of macular and neck inputs was found in 52/90 (57.8%) LC-complex neurons; in these units, the gain and the sensitivity of the first harmonic of the response corresponded on the average to 0.34 +/- 0.45, SD, impulses.s-1.deg-1 and 3.55 +/- 2.82, SD, %/deg for the neck responses and to 0.23 +/- 0.29, SD, impulses.s-1.deg-1 and 3.13 +/- 3.04, SD, %/deg for the macular responses. In addition to these convergent units, 8/90 (8.9%) and 15/90 (16.7%) LC-complex units responded to selective stimulation either of macular or of neck receptors only. These units displayed a significantly lower response gain and sensitivity to animal tilt and neck rotation with respect to those obtained from convergent units. Most of the convergent LC-complex units were maximally excited by the direction of stimulus orientation, the first harmonic of responses showing an average phase lead of about +31.0 degrees with respect to neck position and +17.6 degrees with respect to animal position. Two populations of convergent neurons were observed. The first group of units (43/52, i.e., 82.7%) showed reciprocal ("out of phase") responses to the two inputs; moreover, most of these units were excited during side-down neck rotation, but inhibited during side-down animal tilt.(ABSTRACT TRUNCATED AT 400 WORDS)
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