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The aim of this research was to give further evidence for the influence of vestibularand proprioceptive information on distance perception, and to verify how perceived distancechanges if we use matching versus verbal judgment task. That is, the aim was to investigate how perceived distance changes when we bend over and look between the legs. The experiment was performed on a daylight open field (full-cue situation), with 20 participants, high school students from the Petnica Science Center. Participants had the task to match distances of two stimuli, one of which was in front of them at eye level, whereas the other was behind them, and they could observe it by bending their body forward and looking between the legs .Stimuli were 7cm*5cm large, and rectangular in shape. Results have shown that perceived distance changes in such a way that distances observed between the legs are perceived as longer than distances observed from an upright position. This difference in perceived distances exists only for larger physical distances (3m and 5m), but not for smaller physical distances (1m. Results coincide with our previous findings which indicate that vestibular and proprioceptive information change elongates perceived distance. On the other hand, the results contradict some findings gained in experiments in which the verbal judgment task was used. These contrary results probably appear because the verbal judgment task leaves more space for higher cognitive processes to be involved.

Neuroimaging combined with transcranial magnetic stimulation (TMS) to primary motor cortex (M1) is an emerging technique that can examine motor-system functionality through evoked activity. However, because sensory afferents from twitching muscles are widely represented in motor areas the amount of evoked activity directly resulting from TMS remains unclear. We delivered suprathreshold TMS to left M1 or electrically stimulated the right median nerve (MNS) in 18 healthy volunteers while simultaneously conducting functional magnetic resonance imaging and monitoring with electromyography (EMG). We examined in detail the localization of TMS-, muscle afferent- and superficial afferent-induced activity in M1 subdivisions. Muscle afferent- and TMS-evoked activity occurred mainly in rostral M1, while superficial afferents generated a slightly different activation distribution. In 12 participants who yielded quantifiable EMG, differences in brain activity ascribed to differences in movement-size were adjusted using integrated information from the EMGs. Sensory components only explained 10-20% of the suprathreshold TMS-induced activity, indicating that locally and remotely evoked activity in motor areas mostly resulted from the recruitment of neural and synaptic activity. The present study appears to justify the use of fMRI combined with suprathreshold TMS to M1 for evoked motor network imaging.

Four experiments investigated how observers' consciousness about their control of stimulus change affects the visual perception associated with the illusory flash-lag effect. In previous study (Ichikawa & Masakura, 2006), we found that the flash-lag effect in motion is reduced if observers were conscious that they were controlling stimulus movements by the use of computer mouse, even if the stimulus moved automatically, independently of observer’s mouse control. In the other study (Ichikawa & Masakura, 2010a), we found that the consistent directional relationship between the observer’s mouse control and stimulus movement, which is learned in our everyday computer use, is important for the reduction of the flash-lag effect in active observation. In the present study, we examined whether the reduction of the flash-lag effect in active observation requires the observers’ consciousness about their control of stimulus change, and consistency in coupling mouse movement direction and stimulus change across trials in experiments. We used the flash-lag effect in luminance change because there is no intrinsic relationship between observer’s mouse control and luminance change in our everyday computer use. We compared the illusory flash-lag effects for automatic change of the luminance with luminance change that was controlled by the observers’ active manipulation of a computer mouse. Because the flash occurs randomly in time, observers could not anticipate when the flash was presented. Results suggest that the not only observer’s consciousness of controlling the stimulus, but also consistency in coupling mouse movement direction with stimulus change, are required for the reduction of the flash-lag effect in active observation. The basis of the reduction of the flash-lag effect in active observation is discussed.

The ankles play an important role in human balance. In most studies investigating balance control the contribution of the left and right leg is not separated. However, in certain pathologies such as stroke and Parkinson's disease, balance control can be asymmetric. Here, a bilateral ankle perturbator (BAP) is presented, which applies support surface rotations to both ankles independently. The device consists of two small foot-size support surfaces, which are independently actuated. The BAP device can operate in either angle or torque control mode. The device is able to apply support surface rotations up to 8.6° with a bandwidth of 42 Hz. Additionally the platforms can be replaced by 6-DoF force plates to measure the center of pressure underneath each foot. With the optional force plates the bandwidth decreases to 16 Hz as a result of the additional weight. Two possible applications of the device to investigate human balance control are demonstrated: ankle stiffness by applying minimum jerk profiles and sensory reweighting of the proprioceptive information. In conclusion, we developed a bilateral ankle perturbator which is able to apply support surface rotations to both ankles independently. The major application of the device will be to investigate the contribution of both ankles to human balance control, and the interactions in balance control between both legs. [ABSTRACT FROM AUTHOR]

Four experiments investigated how observers' consciousness about their control of stimulus change affects the visual perception associated with the illusory flash-lag effect. In previous study (Ichikawa and Masakura, 2006), we found that the flash-lag effect in motion is reduced if observers were conscious that they were controlling stimulus movements by the use of computer mouse, even if the stimulus moved automatically, independently of observer's mouse control. In the other study (Ichikawa and Masakura, 2010a), we found that the consistent directional relationship between the observer's mouse control and stimulus movement, which is learned in our everyday computer use, is important for the reduction of the flash-lag effect in active observation. In the present study, we examined whether the reduction of the flash-lag effect in active observation requires the observers' consciousness about their control of stimulus change, and consistency in coupling mouse movement direction and stimulus change across trials in experiments. We used the flash-lag effect in luminance change because there is no intrinsic relationship between observer's mouse control and luminance change in our everyday computer use. We compared the illusory flash-lag effects for automatic change of the luminance with luminance change that was controlled by the observers' active manipulation of a computer mouse. Because the flash occurs randomly in time, observers could not anticipate when the flash was presented. Results suggest that the not only observer's consciousness of controlling the stimulus, but also consistency in coupling mouse movement direction with stimulus change, are required for the reduction of the flash-lag effect in active observation. The basis of the reduction of the flash-lag effect in active observation is discussed.