Limited transfer of podokinetic after-rotation from kneeling to standing

Wong, Cheuk-Man; Hong, Minna; Earhart, Gammon M.

doi:10.1080/08990220601183741

Cited by 3 publications

(6 citation statements)

References 18 publications

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“…A major source of reafference during stepping would be length changes of hip rotator muscles, since trunk yaw rotation over the feet mainly occurs at the hip joint. However, other lower limb signals undoubtedly contribute to PKAR (e.g., more distal cutaneous, load and joint receptors; Wong et al 2007), and these additional reafferent signals may account for the increased after-effect gain seen after stepping.…”

Section: Discussionmentioning

confidence: 99%

Postural reorientation does not cause the locomotor after-effect following rotary locomotion

Osler

Reynolds

2012

Exp Brain Res

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After a period of stepping on a rotating platform, blindfolded subjects demonstrate a tendency to unconsciously turn when stepping in place, an after-effect known as podokinetic after-rotation (PKAR). Recent studies have also reported a change in postural orientation following the adaptive period and have suggested that this is causally related to PKAR. Here, we assess changes in trunk orientation following platform adaptation and determine their relationship to PKAR. Specifically, we determine whether a reorganized standing posture causes PKAR. Ten subjects stepped on a platform rotating at 60°/s for 10 min, with a cadence of 100 steps/min. Following adaptation, a significant PKAR response was seen, with a mean yaw rotation velocity of 6.0 ± 2.2°/s. In addition to this dynamic after-effect, there was a significant twist of the trunk with respect to the feet when standing still (6.9° ± 4.5°; mean ± SD), confirming the presence of a postural reorientation after-effect. However, the magnitudes of the two after-effects did not correlate (r = 0.06, p = 0.87). Furthermore, in a second experiment, a prolonged passive twist of the trunk was used to induce postural reorientation. However, in this case, PKAR was not induced. These results demonstrate that PKAR is not an automatic consequence of reorganized standing posture.

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Section: Discussionmentioning

confidence: 99%

Postural reorientation does not cause the locomotor after-effect following rotary locomotion

Osler

Reynolds

2012

Exp Brain Res

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“…This relative rotation has been hypothesized to drive the adaptive after-effects of locomotor trajectory (Earhart et al 2001). If it is the relative rotation between foot and trunk that is critical, this could also account for the reduced PKAR response when PK stimulation was performed in kneeling where there was no foot contact with the floor, and thus no rotation of the foot relative to trunk (Wong et al 2007). …”

Section: Discussionmentioning

confidence: 99%

“…As such, we investigated whether a period of kneeling PK stimulation, as compared to the standard stepping PK stimulation, would produce an equivalent PKAR after-effect. We found very little transfer of PKAR from kneeling to stepping, suggesting hip afferent information is not a major contributor to this adaptive response (Wong et al 2007). These findings have led us to hypothesize that additional afferent inputs, such as load receptors, may be of greater influence in determining the adaptive after-effect of locomotor trajectory.…”

Section: Introductionmentioning

confidence: 90%

“…This bottom-up somatosensory regulation is mediated by the podokinetic control system (Weber et al 1998). To better understand the influence of afferent input on the adaptive control of locomotor trajectory, many investigations have used the rotating circular treadmill paradigm (Earhart et al 2001, 2002a, 2002b; Hong et al 2007; Wong et al 2007). In this model, individuals perform a period of active countercircling, i.e., podokinetic (PK) stimulation, whereby they step in place relative to space on a rotating disc.…”

Section: Introductionmentioning

confidence: 99%

“…However, it remains to be established what parts of the somatosensory system mediate this adaptive after-effect of locomotor trajectory. Previously, we speculated that afferent inputs from the hip may be significant, as the hip is the primary site of yaw rotations of the lower extremity during PK stimulation (Wong et al 2007). As such, we investigated whether a period of kneeling PK stimulation, as compared to the standard stepping PK stimulation, would produce an equivalent PKAR after-effect.…”

Section: Introductionmentioning

confidence: 99%

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Podokinetic after-rotation in a simulated reduced gravity environment

Falvo

Horak

Earhart

2008

Somatosensory & Motor Research

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Stepping in place on a rotating platform for a period of 15 minutes induces an adaptive response, podokinetic after-rotation (PKAR), which causes a blindfolded individual to inadvertently rotate when attempting to step in place on the floor. The purpose of this investigation was to determine whether lower extremity load receptors were involved in this adaptation. As load receptor input is critical for locomotion, we hypothesized that manipulating load via body weight support (BWS) would influence PKAR. Eleven healthy female volunteers performed 15 minutes of stepping in place on a rotating treadmill (stimulation), followed by 10 minutes of stepping in place (response) without vision on a stationary surface. Response and stimulation periods were with 50% body weight support (BWS) and without body weight support (NoBWS) in all four possible combinations (BWS-BWS, NoBWS-NoBWS, BWS-NoBWS, and NoBWS-BWS). Conditions were randomly assigned to all subjects and performed on four separate occasions at least 48 hr apart. During the 10-min PKAR response period, trunk angular velocity was calculated and plotted versus time, and exponential models were applied to the data to obtain curve-fit parameters for each condition. Despite the manipulations of BWS, no significant differences were found for any parameter value (p = 0.13-0.98). BWS applied during stimulation only, response only, or during both stimulation and response does not appear to influence PKAR. This suggests that load receptors may not play a critical role in mediating adaptive changes in locomotor trajectory control in response to walking on a rotating surface.

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Stepping in circles: how locomotor signals of rotation adapt over time

George

Day

Butler

et al. 2020

The Journal of Physiology

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Key pointsr While it has been well described that prolonged rotational stepping will adapt the podokinetic sense of rotation, the mechanisms involved are not clearly understood.r By studying podokinetic after-rotations following conditioning rotations not previously reported we have shown that slower rotational velocities are more readily adapted than faster velocities and adaptation occurs more quickly than previously thought.r We propose a dynamic feedback model of vestibular and podokinetic adaptation that can fit rotation trajectories across multiple conditions and data sets.r Two adaptation processes were identified that may reflect central and peripheral processes and the discussion unifies prior findings in the podokinetic literature under this new framework.r The findings show the technique is feasible for people with locomotor turning problems.Abstract After a prolonged period stepping in circles, people walk with a curved trajectory when attempting to walk in a straight line without vision. Podokinetic adaptation shows promise in clinical populations to improve locomotor turning; however, the adaptive mechanisms involved are poorly understood. The first phase of this study asks: how does the podokinetic conditioning velocity affect the response velocity and how quickly can adaptation occur? The second phase of the study asks: can a mathematical feedback model account for the rotation trajectories across different conditioning parameters and different datasets? Twelve healthy participants stepped in place on the axis of a rotating surface ranging from 4 to 20 deg s −1 for durations of 1-10 min, while using visual cues to maintain a constant heading direction. Afterward on solid ground, participants were blindfolded and attempted to step without rotating. Participants unknowingly stepped in circles opposite to the direction of the prior platform rotation for all conditions. The angular velocity of this response peaked within 1 min and the ratio of the stimulus-to-response peak velocity fitted a decreasing power function. The response then decayed exponentially. The feedback model of podokinetic and vestibular adaptive processes had a good fit with the data and suggested that podokinetic adaptation is explained by a short (141 s) and a long (27 min) time constant. The podokinetic system adapts more quickly than previously thought and subjects adapt more readily to slower rotation than to faster rotation. These findings will have implications for clinical applications of the technique.

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Limited transfer of podokinetic after-rotation from kneeling to standing

Cited by 3 publications

References 18 publications

Postural reorientation does not cause the locomotor after-effect following rotary locomotion

Postural reorientation does not cause the locomotor after-effect following rotary locomotion

Podokinetic after-rotation in a simulated reduced gravity environment

Stepping in circles: how locomotor signals of rotation adapt over time

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