Visuomotor Adaptation in Healthy Humans in Standing Position under the Conditions of Destabilization of Virtual Visual Environment

In the case of dark/bad light environments cameras cannot shoot images clearly for the operator to complete the task. Also, video information from camera or robot vision is not enough for some typical applications like telesurgery to pick up an object. In this paper a novel controlling approach for humanoid teleoperation using virtual reality is presented, such that the robot can work safely and accurately in such circumstances. In this regard the work has been enhanced by developing the virtual/visual environment using joystick control interface for controlling Humanoid BHR-2 motion to complete a task safely and accurately. Software Maya is chosen for this work, which can perform all the vision-related calculations. Experiments are conducted using joystick control commands where the operator controls BHR-2 walking motion while looking at virtual scene on his computer to confirm the effectiveness of novel control technique.

Download Full-text

Postural-induced phase shift of respiratory sinus arrhythmia and blood pressure variations: insight from respiratory-phase domain analysis

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00680.2007 ◽

2008 ◽

Vol 294 (3) ◽

pp. H1481-H1489 ◽

Cited By ~ 18

Author(s):

Kiyoshi Kotani ◽

Kiyoshi Takamasu ◽

Yasuhiko Jimbo ◽

Yoshiharu Yamamoto

Keyword(s):

Blood Pressure ◽

Phase Shift ◽

Respiratory Sinus Arrhythmia ◽

Domain Analysis ◽

Standing Position ◽

Sitting Position ◽

Sinus Arrhythmia ◽

Phase Domain ◽

Healthy Humans ◽

Respiratory Phase

The purpose of this study is to evaluate the multiple effects of respiration on cardiovascular variability in different postures, by analyzing respiratory sinus arrhythmia (RSA) and respiratory-related blood pressure (BP) variations for systolic BP (SBP), diastolic BP (DBP), and pulse pressure (PP) in the respiratory-phase domain. The measurements were conducted for 420 s on healthy humans in the sitting and standing positions, while the subjects were continuously monitored for heart rate and BP variability and instantaneous lung volume. The waveforms of RSA and respiratory-related BP variations were extracted as a function of the respiratory phase. In the standing position, the waveforms of the BP variations for SBP, DBP, and PP show their maxima at around the end of expiration (π rad) and the minima at around the end of inspiration (2 π rad), while the waveform of RSA is delayed by ∼0.35 π rad compared with the BP waveforms. On the other hand, in the sitting position, the phase of the DBP waveform (1.69 π rad) greatly and significantly ( P < 0.01) differs from that in the standing position (1.20 π rad). Also, the phase of PP is delayed and that of RSA is advanced in the sitting position ( P < 0.01). In particular, the phase shift of the DBP waveform is sufficiently large to alter whole hemodynamic fluctuations, affecting the amplitudes of SBP and PP variations. We conclude that the postural change associated with an altered autonomic balance affects not only the amplitude of RSA, but also the phases of RSA and BP variations in a complicated manner, and the respiratory-phase domain analysis used in this study is useful for elucidating the dynamic mechanisms of RSA.

Download Full-text

The role of the supporting lower limb function in the premotor changes in the H-reflex of m. soleus

Visnyk of Dnipropetrovsk University Biology medicine ◽

10.15421/021608 ◽

2016 ◽

Vol 7 (1) ◽

pp. 43-47

Author(s):

E. Z. Ivanchenko

Keyword(s):

Ankle Joint ◽

Soleus Muscle ◽

Lower Limb ◽

Time Course ◽

Standing Position ◽

H Reflex ◽

Lower Limbs ◽

Emg Activity ◽

Spinal Neuron ◽

Healthy Humans

In studies on healthy humans we examined changes in the H reflex amplitude and the intensity of background EMG of the soleus muscle within the premotor period of voluntary extension of the contralateral ankle joint. The tested persons were in the lying prone position with relaxed legs, or in the standing position with support on both feet or only on one foot with additional hand support. The soleus H reflex was induced using the standard technique by transcutaneous stimulation (1 ms long current pulses) of the tibial nerve afferents in the region of the popliteal dimple. Using superficial electrodes, we recorded the integral EMG reflex discharge from the m. soleus, amplified, and visualized it using a two-channel digital oscillograph, Handiscope HS3 (TiePieEngeneering, Netherlands). In other tests, we also recorded tonic background EMG activity from the soleus muscle. After fullwave rectification and low-frequency filtration we estimated the area under the integral curve enveloping oscillations of the above mentioned EMG. In the lying position the extension of contralateral ankle joint evoked anticipatory facilitation of the testing soleus H-reflex. It manifested in 90–60 ms and reached the maximum 30 ms before the conditioning movement. Considerable changes of the soleus background EMG-activity did not occur during the premotor period. Consequently, it is supposed that the mechanism leading to the H-reflex facilitation is the decrease of presynaptic inhibition at 1a. In the standing position with support on both feet contralateral ankle joint extension caused anticipatory inhibition of the soleus H-reflex and simultaneous suppression of background EMG 90–60 ms before the conditioning movement. These results indicate the anticipatory changes of muscle tone and suggest participation of postsynaptic mechanism in the inhibition of the testing H-reflex. When the moving contralateral extremity had no support, the contralateral ancle joint extension did not cause anticipatory inhibition but facilitation of the soleus H-reflex. Its time course was similar to that observed in the lying position. The considerable changes of the soleus background EMG-activity did not arise. The results of the experiments indicate that the nature of premotor changes in the spinal neuron circuits, associated with the lower limb muscles, depends not only on the type of upcoming voluntary movement. Being caused by the contralateral limb movements, they depend greatly on the fulfillment or nonfulfillment of the support function by the lower limbs.

Download Full-text

Foreground/Background Manipulations Affect Presence

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/154193129503902111 ◽

1995 ◽

Vol 39 (21) ◽

pp. 1410-1414 ◽

Cited By ~ 8

Author(s):

Jerrold D. Prothero ◽

Hunter G. Hoffman ◽

Donald E. Parker ◽

Thomas A. Furness ◽

Maxwell J. Wells

Keyword(s):

Experimental Design ◽

Visual Scene ◽

Visual Environment ◽

Double Blind ◽

Pursuit Game ◽

Virtual Visual Environment ◽

Visual Scenes

A possible relation between vection and presence is discussed. Two experiments examined the hypothesis that “presence” is enhanced by manipulations which facilitate interpreting visual scenes as “background.” A total of 39 participants in two experiments engaged in a pursuit game while in a virtual visual environment generated by an HMD and rated their experience of “presence” on 5 questions. Experiment 1 compared two viewing conditions: visual scene masking at the eye and a paper mask mounted on the screen with the same 60° FOV, and showed that presence was enhanced by eye masking relative to screen masking. Experiment 2 replicated these findings with a double-blind experimental design.

Download Full-text