Italian Air Force Medical Corps, IML Roma, Via Piero Gobetti 2, 00185 Rome, Italy.
Eur Arch Otorhinolaryngol. 2011 Jul;268(7):1067-75. doi: 10.1007/s00405-011-1493-2. Epub 2011 Feb 4.
Perception of the subjective visual vertical (SVV) is mainly based on the contributions from the visual, vestibular, and proprioceptive systems, and participates to the process of spatial orientation in relation to the surrounding environment and to the gravito-inertial force. The SVV can be significantly influenced by the presence of a displaced visual field, as in the case of the rod and frame test (RFT). A series of studies showed the effects of haematic mass shifts to and from the lower limbs on SVV, due to visceral mechanoreceptors (VM) located at the level of the kidneys and of the thorax. These sensors may be artificially activated with a lower body negative pressure (LBNP) device. In this study, the role of visual and VM cues to orientation perception have been evaluated using the RFT and the LBNP devices under a microgravity environment. A preliminary investigation was conducted in a sample of military pilots to develop a RFT protocol to be used in microgravity environments. This protocol was adopted to evaluate the contribution of VM to the SVV in a cosmonaut before, during and after a 10 day space flight, with and without concurrent activation of LBNP. The same test sequence, including LBNP exposure, was repeated a few months later on Earth on the same subject. As expected, the influence of the frame on rod positioning was statistically significant in all test conditions. During the in-flight experimental step, a substantial lack of significant changes compared to the pre-flight condition was observed. Moreover, substantially no effects due to LBNP were observed. A mild rod displacement from the body axis was detected under microgravity compared to the pre-flight recording. Such a finding was in part reduced during LBNP. The same findings were observed during the post-flight repetition of the experiment. Our results showed an absence in this subject of significant effects on the RFT due to microgravity. In conclusion, no effects from his VM on the RFT and minor changes in the SVV could be detected.
主观垂直视觉（SVV）的感知主要基于视觉、前庭和本体感觉系统的贡献，并参与到与周围环境和重力惯性力有关的空间定位过程中。SVV 会受到视野位移的显著影响，如在杆和框架测试（RFT）中。一系列研究表明，由于位于肾脏和胸部水平的内脏机械感受器（VM），血液质量向四肢和远离四肢的转移会对 SVV 产生影响。这些传感器可以通过下体负压（LBNP）设备人工激活。在这项研究中，使用 RFT 和 LBNP 设备在微重力环境下评估了视觉和 VM 线索对定向感知的作用。在一组军事飞行员样本中进行了初步研究，以开发一种可在微重力环境中使用的 RFT 方案。该方案用于评估 VM 对一名宇航员在 10 天太空飞行期间和之后的 SVV 的贡献，同时和不同时激活 LBNP。在几个月后，在同一受试者身上，在地球上重复了相同的测试序列，包括 LBNP 暴露。不出所料，在所有测试条件下，框架对杆定位的影响在统计学上都是显著的。在飞行实验阶段，与飞行前条件相比，观察到的显著变化很少。此外，基本上没有观察到 LBNP 的影响。与飞行前记录相比，在微重力下检测到杆从身体轴的轻微位移。在 LBNP 下，这种发现部分减少了。在飞行后的实验重复中观察到了相同的发现。我们的结果表明，在该受试者中，由于微重力，RFT 没有显著的影响。总之，在 RFT 上没有检测到 VM 的显著影响，SVV 也只有轻微变化。
