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  • 1
    Electronic Resource
    Electronic Resource
    Human perception of horizontal trunk and head rotation in space during vestibular and neck stimulation (1991)
    Springer
    Experimental brain research 85 (1991), S. 389-404 
    Details
    ISSN: 1432-1106
    Keywords: Perception ; Self-motion ; Vestibular-neck interaction ; Coordinate systems ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The vestibular signal of head motion in space must be complemented by a neck signal of the trunk-to-head excursion in order to provide the individual with information on trunk motion in space. This consideration led us to study psychophysically the role of vestibular-neck interaction for human self-motion perception. Subjects (Ss) were presented with passive horizontal rotations of their trunk and/or head (sinusoidal rotations, f=0.025 –0.4 Hz) in the dark for vestibular and neck stimulation, as well as for combinations of both. Ss' perception was evaluated in terms of gain (veridical perception of stimulus magnitude, G=1), phase, and detection threshold. (1) Perception of trunk rotation in space. During vestibular stimulation (whole-body rotation) and neck stimulation (trunk rotation with the head kept stationary) the frequency-transfer characteristics underlying this perception were very similar. The gain fell short; it was only about 0.7 at 0.4 and 0.2 Hz stimulus frequency and was further attenuated with decreasing frequency. In contrast, the phase was close to that of actual trunk position. The gain attenuation was found to be a function of the peak angular velocity of the stimulus, a fact, which we related to a ‘velocity threshold’ of the order of 1 deg/s. During the various vestibular-neck combinations used, Ss' perception was again erroneous, reflecting essentially the sum of its two non-ideal constituents. However, there was one noticeable exception; during the combination ‘head rotation on stationary trunk’, Ss veridically perceived their trunk as stationary (compatible with the notion that the sum yielded ‘zero’). (2) Perception of head rotation in space. During vestibular stimulation, Ss' estimates showed the same non-ideal gain-vs.-frequency characteristics as described above for the trunk. Neck stimulation induced an illusion as if the head had been rotated in space. This neck contribution was such that, when it was combined with its vestibular counterpart during head rotation on stationary trunk, the perception became almost veridical. On closer inspection, however, this neck contribution was found to reflect the sum of two components; one was the non-ideal neck signal contributing to the perception of ‘trunk in space’, the other was an almost ideal neck signal of head-on-trunk rotation. (3) The results could be described by a simple model. In this model, the erroneous vestibular signal ‘head in space’ is primarily used to create an internal representation of ‘trunk in space’. To this end, it is combined with the closely matching neck signal of ‘trunk to head’. The perception of head rotation in space is achieved by summing this ‘trunk in space’ signal with the almost ideal ‘head on trunk’ signal, again of nuchal origin. These seeming complex interactions have two implications: (i) the head is referred to trunk coordinates, whereas the trunk is referred to space coordinates; (ii) there is at least one condition in the dark where orientation is correct (despite an erroneous vestibular signal), i.e., during head rotation on stationary trunk.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229416
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  • 2
    Electronic Resource
    Electronic Resource
    Role of vestibular and neck inputs for the perception of object motion in space (1992)
    Springer
    Experimental brain research 89 (1992), S. 655-668 
    Details
    ISSN: 1432-1106
    Keywords: Perception ; Visual object motion ; Vestibular-neck interaction ; Coordinate systems ; Oculogyral illusion ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The contribution of vestibular and neck inputs to the perception of visual object motion in space was studied in the absence of a visual background (in the dark) in normal human subjects (Ss). Measures of these contributions were obtained by means of a closed loop nulling procedure; Ss fixed their eyes on a luminous spot (object) and nulled its actual or apparent motion in space during head rotation in space (vestibular stimulus) and/ or trunk rotation relative to the head (neck stimulus) with the help of a joystick. Vestibular and neck contributions were expressed in terms of gain and phase with respect to the visuo-oculomotor/joystick feedback loop which was assumed to have almost ideal transfer characteristics. The stimuli were applied as sinusoidal rotations in the horizontal plane (f= 0.025–0.8 Hz; peak angular displacements, 1–16°). Results: (1) During vestibular stimulation, Ss perceived the object, when kept in fixed alignment with the moving body, as moving in space. However, they underestimated the object motion; the gain was only about 0.7 at 0.2–0.8 Hz and clearly decreased at lower stimulus frequencies, while the phase exhibited a small lead. (2) During pure neck stimulation (trunk rotating relative to the stationary head), the object, when stationary, appeared to move in space counter to the trunk excursion. This neck-contingent object motion illusion was small at 0.2–0.8 Hz, but increased considerably with decreasing frequency, while its phase developed a small lag. (3) Vestibular, neck, and visuo-oculomotor effects summed linearly during combined stimulations. (4) The erroneous vestibular and neck contributions to the object motion perception were complementary to each other, and the perception became about veridical (G≈1, φ≈0°), when both inputs were combined during head rotation with the trunk stationary. The results are simulated by an extended version of a computer model that previously had been developed to describe vestibular and neck effects on human perception of head motion in space. In the model, the perception of object motion in space is derived from the superposition of three signals, representing “object to head”, (visuo-oculomotor; head coordinates), “head on trunk” (neck; trunk coordinates), and “trunk in space” (vestibular-neck interaction; space coordinates).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229890
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Perception of horizontal head and trunk rotation: modification of neck input following loss of vestibular function (1993)
    Springer
    Experimental brain research 95 (1993), S. 533-546 
    Details
    ISSN: 1432-1106
    Keywords: Self-motion perception ; Loss of vestibular function ; Neck input ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Chronic loss of vestibular function modifies the role of neck afferents in human perception of self-motion. We characterized this change by comparing the self-motion perception of patients with chronic vestibular loss (Ps) to that of normal subjects (Ns). Stimuli consisted of sinusoidal horizontal rotations (0.025–0.4 Hz) of the trunk relative to the head (neck stimulation) and/or of the head in space (vestibular stimulation). Perception of head rotation relative to the trunk, of trunk rotation in space, or of head rotation in space was assessed in terms of gain and phase (veridical perception, G=1 and ϕ=0°) as well as detection threshold using a pointing procedure. (1) Perception of head rotation relative to the trunk (neck proprioception). Ps' detection threshold of head-to-trunk rotation was normal (i.e. similar to that of Ns) across all frequencies tested. Also, with peak angular velocities above 5°/s, the gain of their perception was approximately normal. When peak velocity was decreased below this value, however, either by lowering stimulus frequency with peak displacement kept constant (±8°) or by decreasing peak displacement at constant frequency (0.05 Hz), the gain increased above unity, unlike in Ns. In contrast, the phase remained normal (approximately 0°). (2) Perception of trunk rotation in space. Ps perceived their trunks as stationary during neck stimulation and all vestibular-neck combinations at medium to low frequencies. At 0.4 Hz, however, Ps consistently perceived the trunk rotation, conceivably due to somatosensory selfmotion cues arising from high body acceleration. In contrast, Ns perceive a trunk-in-space rotation with the neck stimulation and most of the stimulus combinations across the whole frequency range tested. Ns perceived their trunks as stationary only during head rotation on the stationary trunk (presumed to reflect a mutual cancellation of neck and vestibular signals). (3) Perception of head rotation in space. In Ps, unlike Ns, this perception always resembled that of head rotation relative to the trunk. (4) When Ps were presented with a visual or somatosensory space reference (not motion cues), their perception of trunk and head rotation in space became approximately normal. (5) We suggest that there are basically two changes in the neck induced self motion perception associated with chronic vestibular loss. First, neck proprioception shows a non linear gain that overemphasizes low stimulus velocities, for unknown reasons. Second, the neck signal which normally is used for the perception of trunk rotation in space is suppressed (Ps in the dark, deprived of any space reference, resort to the notion that their trunks are stationary). The change in Ps' perception of head rotation in space is attributed to the former two changes (assuming that they superimposed their notion of head on trunk rotation on that of a stationary trunk).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00227147
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    Paper (German National Licenses)
    Fulltext
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