title: Influence of gravitoinertial force level on the subjective vertical during recumbent yaw axis body tilt.
abstract: We tilted recumbent subjects at various angles about their yaw (foot to head) axis and had them indicate the direction of their subjective vertical and apparent head midline about the same axis. One set of tests was conducted during parabolic flight maneuvers where the background gravitoinertial acceleration varied from 0 to 1.8g. The blindfolded subjects (n = 6) were tested supine and at tilts of 60 degrees and 30 degrees left and right about their horizontal long body axis. They used a gravity neutral joystick to indicate their subjective vertical or their head midline continuously from the high force through the 0g portions of parabolas. In 0g, all subjects felt supine and oriented the joystick perpendicular to their body when indicating the subjective vertical. This points to strong influences of the symmetric somatic touch and pressure cues from the apparatus on orientation when the otolith organs are unloaded. In contrast to the settings in 0g, settings of the subjective vertical in 1g and 1.8g varied as a function of body orientation. However, the settings did not differ between 1g and 1.8g test conditions. Subjective vertical judgments were also made by subjects (n = 11) in the Brandeis slow rotation room, with the room stationary and rotating at a speed that produced a 2g resultant of gravitational and centrifugal acceleration. There were no differences between settings of the subjective vertical made in 1g and 2g. The similarity of 1g and hyper-g settings during recumbent yaw tilts, both in parabolic flight and in the rotating room, contrasts with the previously observed, strong influence which force levels above 1g have on settings of the subjective vertical during tilt of the body in pitch or roll. The findings for all three axes are consistent with a recently developed model of static spatial orientation.
authors: Ashton Graybiel Spatial Orientation Laboratory, Brandeis University, MS 033, Waltham, MA, 02454-9110, USA.
authors: A S
authors: AS
authors: Bryan
authors: S B
authors: SB
authors: Bortolami
authors: J
authors: J
authors: Ventura
authors: P
authors: P
authors: DiZio
authors: J R
authors: JR
authors: Lackner
mesh_terms: D000328:Adult; D005260:Female; D018466:Gravity Sensing / Q000502:physiology*; D019416:Head Movements / Q000502:physiology; D018594:Human Body; D006801:Humans; D008297:Male; D008875:Middle Aged; D009949:Orientation; D010037:Otolithic Membrane / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*
references: Aerosp Med. 1967 Nov;38(11):1099-103
references: 6057306
references: J Neurophysiol. 2000 Jul;84(1):11-27
references: 10899179
references: Exp Brain Res. 1995;106(1):123-34
references: 8542968
references: Exp Brain Res. 2006 Aug;173(3):374-88
references: 16628400
references: Acta Astronaut. 2005 May-Jun;56(9-12):1025-32
references: 15838949
references: J Exp Psychol. 1962 Mar;63:294-301
references: 13879665
references: Aeromed Acta. 1963-1964;9:45-91
references: 14284242
references: J Neurophysiol. 2004 May;91(5):2205-14
references: 14668294
references: Exp Brain Res. 2001 Jun;138(4):410-8
references: 11465738
references: J Neurosci. 1999 Jan 1;19(1):316-27
references: 9870961
references: Brain Res Bull. 1996;40(5-6):393-7; discussion 397-8
references: 8886364
references: J Vestib Res. 1990-1991;1(2):199-209
references: 1670153
references: J Neurophysiol. 2001 Jun;85(6):2455-60
references: 11387391
references: Science. 1979 Nov 30;206(4422):1105-8
references: 493998
references: J Vestib Res. 1993 Fall;3(3):361-72
references: 8275269
references: Naturwissenschaften. 1983 Jun;70(6):272-81
references: 6877388
references: Am J Psychol. 1964 Sep;77:451-6
references: 14198668
references: Aerosp Med. 1964 Aug;35:764-72
references: 14215796
references: Acta Astronaut. 1992 Jul;27:1-9
references: 11537572
references: Ann N Y Acad Sci. 1992 May 22;656:124-39
references: 1599138
references: Exp Brain Res. 2006 Aug;173(3):364-73
references: 16628401
references: Hum Physiol. 1996 May;21(4):344-51
references: 11541519
references: News Physiol Sci. 2001 Oct;16:234-8
references: 11572928
references: Biol Cybern. 2002 Mar;86(3):191-207
references: 12068786
references: Perception. 1992;21(6):803-12
references: 1297983
references: J Exp Psychol. 1966 Mar;71(3):452-60
references: 5908830
references: Acta Otolaryngol. 1968;:Suppl 230:1-20
references: 5650275
references: Biol Cybern. 2002 Mar;86(3):209-30
references: 12068787
references: J Gravit Physiol. 1997 Jul;4(2):P5-8
references: 11540697
references: Aviat Space Environ Med. 1976 Feb;47(2):159-64
references: 1082746
references: J Neurophysiol. 2002 Feb;87(2):819-33
references: 11826049