Table 1.
Characteristics about the animals used in these experiments, as well as the maximal voltage delivered to the labyrinths to induce motion sickness and the period of acclimation to experimental conditions prior to the stimulation session.
Table 2.
Behaviors exhibited by animals during galvanic vestibular stimulation: A, sinusoidal head roll at the frequency of the stimulus; B, nystagmus; C, frequent licking; D, retching; E, excessive salivation; F, sinusoidal pinna movement at the frequency of the stimulus; G, vocalization; H, panting; I, thrashing in the restraint bag, presumably as an attempt to escape the stimulus; J, defecation during the stimulation session; K, urination during the stimulation session; L, sinusoidal limb movements at the frequency of the stimulus; M, sedation (sleeping during the majority of the stimulation session).
Figure 1.
Locations of Fos-labeled neurons in two animals exhibiting strong symptoms of motion sickness (response type 1) during galvanic vestibular stimulation.
Neuronal locations were plotted on photomontages of sections taken using a 4X objective. Sections (A, E) are from animal C52, whereas (B–D) are from animal C39. The sections were located at the following approximate distances posterior to stereotaxic zero, in accordance with Berman’s atlas [85]: A, 13.5 mm; B, 10 mm; C, 9 mm; D, 7 mm; E, 3 mm. Abbreviations: BC, brachium conjunctivum; CN, cochlear nuclei; DMV, dorsal motor nucleus of the vagus; DRNL, lateral division of dorsal raphe nucleus; DRNM, medial division of dorsal raphe nucleus; EC, external cuneate nucleus; G, genu of facial nerve; IO, inferior olivary nucleus; LRN, lateral reticular nucleus; PBN, parabrachial nucleus; PH, prepositus hypoglossi; RB, restiform body; RM, raphe magnus; RO, raphe obscurus; RP, raphe pallidus; SNV, spinal trigeminal nucleus; STN, subtrigeminal nucleus; STV, spinal trigeminal tract; VI, abducens nucleus; VII, facial nucleus; VIN, inferior vestibular nucleus; VLD, dorsal division of lateral vestibular nucleus; VLV, ventral division of lateral vestibular nucleus; VMN, medial vestibular nucleus; XII, hypoglossal nucleus.
Figure 2.
Locations of Fos-labeled neurons in the two unstimulated control animals (C83 and C84).
Neuronal locations were plotted on photomontages of sections taken using a 4X objective. Sections (A, B, E) are from animal C83, whereas (C, D) are from animal C84. The sections were located at the following approximate distances posterior to stereotaxic zero, in accordance with Berman’s atlas: A, 13.5 mm; B, 12 mm; C, 8 mm; D, 6 mm; E, 4 mm. Abbreviations are the same as in Fig. 1, with the following additions: 5M, motor trigeminal nucleus; 5P, principal trigeminal nucleus; LC, locus coeruleus; S, solitary nucleus; SO, superior olivary nucleus; SVN, superior vestibular nucleus.
Figure 3.
Photomicrographs of Fos-labeled neurons in a response type 1 animal (C52).
In each row, a rectangular box on the left diagram (generated from photomontages of sections taken using a 4X objective) shows the region depicted at higher magnification to the right. Scale bars on the right photomicrographs designate 500 µm. A, Fos labeling in nucleus tractus solitarius, approximately 13.5 mm posterior to stereotaxic zero. B, Fos labeling in the rostral portion of the medial vestibular nucleus, approximately 6 mm posterior to stereotaxic zero. C, Fos labeling in the periaqueductal gray, approximately 3 mm rostral to stereotaxic zero. Abbreviations are the same as in Figs. 1–2, with the following additions: III, oculomotor nucleus; MR, magnocellular portion of the red nucleus; PAG, periaqueductal gray; SC, superior colliculus.
Figure 4.
Photomicrograph illustrating examples of neurons that were immunopositive for Fos (solid black arrows), TPH-2 (solid gray arrows) and both TPH-2 and Fos (open arrow).
A rectangular box on the inset diagram indicates the region of the dorsal raphe nucleus depicted in the photomicrograph. The scale bar represents 250 µm.
Table 3.
Correlation of labeling with symptom score and component loadings from principal component analysis with equamax rotation.
Table 4.
Correlation of labeling with symptom score and component loadings from principal component analysis with equamax rotation, with nuclear subdivisions included.