Faculty Opinions recommendation of The pontomedullary reticular formation contributes to the compensatory postural responses observed following removal of the support surface in the standing cat.

2009 ◽  
Author(s):  
Tatiana Deliagina
Keyword(s):  
Reticular Formation ◽  
Support Surface ◽  
Postural Responses

The Pontomedullary Reticular Formation Contributes to the Compensatory Postural Responses Observed Following Removal of the Support Surface in the Standing Cat

2009 ◽  
Vol 101 (3) ◽  
pp. 1334-1350 ◽  
Author(s):  
Paul J. Stapley ◽  
Trevor Drew
Keyword(s):  
Reticular Formation ◽  
Discharge Frequency ◽  
Secondary Response ◽  
Support Surface ◽  
Postural Response ◽  
Reticulospinal Neurons ◽  
Vertical Pressure ◽  
Postural Responses ◽  
Reticular Neurons ◽  
Increased Activity

This study was designed to determine the contribution of reticular neurons in the pontomedullary reticular formation (PMRF) to the postural responses produced to compensate for an unexpected perturbation. We recorded the activity of 48 neurons in the PMRF, including 41 reticulospinal neurons, to removal of the support surface under each of the four limbs in four cats. The perturbations produced robust postural responses that were divided into three periods: an initial postural response (P1) that displaced the center of vertical pressure over the two diagonal supporting limbs; a secondary response (P2) during which the cat restored a tripedal support pattern; and a prolonged tertiary response (P3) that maintained a stable posture over all three supporting limbs. Most (44/48) reticular neurons showed modified activity to perturbation of at least one limb and a majority (39/48) showed changes in activity to perturbations of more than one limb. A few (7/48) discharged to perturbations of all four limbs. Discharge frequency in neurons showing increased activity during P1 was relatively high (>100 Hz in 57% of the neurons responding to perturbations of either the left or right forelimbs, lFl and rFL) and of short latency (17 ms for the lFL and 14 ms for the rFL). Discharge activity in most neurons was sustained throughout P2 and P3 but at a reduced level. These data show that neurons in the PMRF discharge strongly in response to unexpected perturbations and in a manner consistent with a contribution to the compensatory responses that restore equilibrium.

First trial and StartReact effects induced by balance perturbations to upright stance

2013 ◽  
Vol 110 (9) ◽  
pp. 2236-2245 ◽  
Author(s):  
A. D. Campbell ◽  
J. W. Squair ◽  
R. Chua ◽  
J. T. Inglis ◽  
M. G. Carpenter
Keyword(s):  
Startle Response ◽  
Support Surface ◽  
Wrist Movement ◽  
Repeated Presentation ◽  
Trial Effect ◽  
Acoustic Stimuli ◽  
Postural Responses ◽  
Startreact Effect ◽  
Startling Stimulus ◽  
Repeated Test

Postural responses (PR) to a balance perturbation differ between the first and subsequent perturbations. One explanation for this first trial effect is that perturbations act as startling stimuli that initiate a generalized startle response (GSR) as well as the PR. Startling stimuli, such as startling acoustic stimuli (SAS), are known to elicit GSRs, as well as a StartReact effect, in which prepared movements are initiated earlier by a startling stimulus. In this study, a StartReact effect paradigm was used to determine if balance perturbations can also act as startle stimuli. Subjects completed two blocks of simple reaction time trials involving wrist extension to a visual imperative stimulus (IS). Each block included 15 CONTROL trials that involved a warning cue and subsequent IS, followed by 10 repeated TEST trials, where either a SAS (TESTSAS) or a toes-up support-surface rotation (TESTPERT) was presented coincident with the IS. StartReact effects were observed during the first trial in both TESTSAS and TESTPERT conditions as evidenced by significantly earlier wrist movement and muscle onsets compared with CONTROL. Likewise, StartReact effects were observed in all repeated TESTSAS and TESTPERT trials. In contrast, GSRs in sternocleidomastoid and PRs were large in the first trial, but significantly attenuated over repeated presentation of the TESTPERT trials. Results suggest that balance perturbations can act as startling stimuli. Thus first trial effects are likely PRs which are superimposed with a GSR that is initially large, but habituates over time with repeated exposure to the startling influence of the balance perturbation.

Organization of postural responses following a rotational support surface perturbation, after TKA: Sagittal plane rotations

2007 ◽  
Vol 25 (1) ◽  
pp. 112-120 ◽  
Author(s):  
William H. Gage ◽  
James S. Frank ◽  
Stephen D. Prentice ◽  
Peter Stevenson
Keyword(s):  
Sagittal Plane ◽  
Support Surface ◽  
Surface Perturbation ◽  
Postural Responses

Activity of neuromuscular compartments in lateral gastrocnemius evoked by postural corrections during stance

1993 ◽  
Vol 70 (6) ◽  
pp. 2337-2349 ◽  
Author(s):  
D. C. Dunbar ◽  
J. M. Macpherson
Keyword(s):  
Three Dimensional ◽  
Area Under The Curve ◽  
Gluteus Medius ◽  
Emg Activity ◽  
Support Surface ◽  
Lateral Gastrocnemius ◽  
Tuning Curves ◽  
Postural Responses ◽  
Upward Displacement ◽  
Neuromuscular Compartments

1. The electromyographic (EMG) activity of the four neuromuscular compartments in lateral gastrocnemius (LG) of cats was investigated to determine whether these intramuscular subdivisions could be activated differentially during automatic postural corrections. EMG electrodes were surgically implanted into each of the four compartments of left LG-LG1, LG2, LG3, and LGm--in two cats. Electrodes were also implanted into soleus and gluteus medius for comparative purposes. 2. Quiet quadrupedal stance was disturbed first by linearly translating the cats on a movable platform in each of 16 different horizontal directions. Mechanical events during corrections were characterized in terms of the three-dimensional forces exerted by each paw on the platform. EMG and force traces were quantified (area under the curve) and normalized, and tuning curves were constructed that relate muscle response and force change to direction of platform movement. 3. In a second series of trials, translations were presented along one direction only over a series of six velocities ranging from 5 to 16 cm/s. The third series of perturbations, termed the pop-up, consisted of a rapid upward displacement of the support under the left hindlimb only over a series of six amplitudes ranging from 1 to 10 mm. Evoked EMG activity and average change in force were normalized and regressions were computed onto velocity and amplitude, respectively. The slopes of the regressions were compared. 4. EMG tuning curves associated with the multidirectional horizontal translations revealed no differential activity across LG compartments. Similarly, there was no statistical difference among the slopes of the regressions within LG. In contrast, soleus exhibited significantly different slopes from LG for the regressions. Thus it is concluded that LG compartments are not differentially activated during automatic postural responses to perturbations of the support surface.

Postural responses to yaw rotation of support surface

2013 ◽  
Vol 37 (2) ◽  
pp. 296-299 ◽  
Author(s):  
Chiung-Ling Chen ◽  
Shu-Zon Lou ◽  
Hong-Wen Wu ◽  
Shyi-Kuen Wu ◽  
Kwok-Tak Yeung ◽  
...  
Keyword(s):  
Support Surface ◽  
Postural Responses

scholarly journals Visual Modulation of Human Responses to Support Surface Translation

2021 ◽  
Vol 15 ◽  
Author(s):  
Mustafa Emre Akçay ◽  
Vittorio Lippi ◽  
Thomas Mergner
Keyword(s):  
Inverted Pendulum ◽  
Significant Degree ◽  
The Body ◽  
Resonance Phenomenon ◽  
Continuous Illumination ◽  
Support Surface ◽  
Position Information ◽  
Eyes Closed ◽  
Postural Responses ◽  
Visual Conditions

Vision is known to improve human postural responses to external perturbations. This study investigates the role of vision for the responses to continuous pseudorandom support surface translations in the body sagittal plane in three visual conditions: with the eyes closed (EC), in stroboscopic illumination (EO/SI; only visual position information) and with eyes open in continuous illumination (EO/CI; position and velocity information) with the room as static visual scene (or the interior of a moving cabin, in some of the trials). In the frequency spectrum of the translation stimulus we distinguished on the basis of the response patterns between a low-frequency, mid-frequency, and high-frequency range (LFR: 0.0165-0.14 Hz; MFR: 0.15–0.57 Hz; HFR: 0.58–2.46 Hz). With EC, subjects’ mean sway response gain was very low in the LFR. On average it increased with EO/SI (although not to a significant degree p = 0.078) and more so with EO/CI (p < 10−6). In contrast, the average gain in the MFR decreased from EC to EO/SI (although not to a significant degree, p = 0.548) and further to EO/CI (p = 0.0002). In the HFR, all three visual conditions produced, similarly, high gain levels. A single inverted pendulum (SIP) model controlling center of mass (COM) balancing about the ankle joints formally described the EC response as being strongly shaped by a resonance phenomenon arising primarily from the control’s proprioceptive feedback loop. The effect of adding visual information in these simulations lies in a reduction of the resonance, similar as in the experiments. Extending the model to a double inverted pendulum (DIP) suggested in addition a biomechanical damping effective from trunk sway in the hip joints on the resonance.

Recovery of Postural Control After an Acute Unilateral Vestibular Lesion in Humans

1991 ◽  
Vol 1 (4) ◽  
pp. 373-383
Author(s):  
Michael Fetter ◽  
Hans-Christoph Diener ◽  
Johannes Dichgans
Keyword(s):  
Postural Control ◽  
Acute Phase ◽  
Time Course ◽  
Sensory Input ◽  
Characteristic Pattern ◽  
Support Surface ◽  
Upright Stance ◽  
Spinal Balance ◽  
Vestibular Lesion ◽  
Postural Responses

Postural control during stance was investigated using the EQUITEST® system in 10 patients during recovery after an acute unilateral vestibular lesion and was compared to the time course of recovery of the static and dynamic vestibulo-ocular imbalance. During the acute phase the patients showed a characteristic pattern with normal upright stance as long as at least one accurate sensory input (visual or somatosensory) was provided and severe postural disturbances when they had to rely primarily on vestibular afferences. Both static vestibulo-ocular and vestibulo-spinal balance recovered very fast, showing basically normal results on postural testing within about 2 weeks after the lesion. Thereafter, no pathological pattern was detectable during postural testing even in patients with persistent complete unilateral vestibular lesions. Reflexive postural responses to unexpected rapid displacements of the support surface seemed not to be influenced by vestibular imbalance even in the acute phase of the lesion.

A Novel Platform-System to Study the Effects of a Vestibular Prosthesis on Non-Human Primate Postural Control

2017 ◽  
Author(s):  
Lara A. Thompson ◽  
Csilla Haburcakova ◽  
Richard F. Lewis
Keyword(s):  
Animal Experiments ◽  
Vestibular Function ◽  
Support Surface ◽  
Blurred Vision ◽  
Vestibular Loss ◽  
Vestibular Prosthesis ◽  
Surface Conditions ◽  
Postural Responses ◽  
Platform System ◽  
Human Primate

For the several millions of vestibular loss sufferers nationwide, daily-living is severely affected in that common everyday tasks, such as getting out of bed at night, maintaining balance on a moving bus, or walking on an uneven surface, may cause loss of stability leading to falls and injury. Aside from loss of balance, blurred vision and vertigo (perceived spinning sensation) are also extremely debilitating in vestibular impaired individuals. For the investigation of implants and prostheses that are being developed towards implementation in humans, non-human primates are a key component. The purpose of our study was to implement a distinctive balance platform-system to investigate postural responses for moderate to severe vestibular loss and invasive vestibular prosthesis-assisted non-human primates (rhesus monkeys) for test balance conditions of various task-difficulty levels. Although the need for vestibular rehabilitative solutions is apparent, postural responses for a broad range of peripheral vestibular function, and for various stationary and moving support conditions, have not been systematically investigated. The measurement system used in this research was unique in that it allowed us to conduct animal experiments, not investigated previously; such experiments are necessary towards the development on an invasive vestibular prosthesis to be used in humans suffering from vestibular loss. Our platform-system facilitated the study of rhesus monkey posture for stationary support surface conditions (i.e., quiet stance and head turns; more versus fewer footplate cues and large versus small base-of-support) and for dynamic support surface conditions (i.e., pseudorandom roll-tilts of the support surface). Further, the platform-system was used to systematically study postural responses that will serve as baseline measures for future vestibular-focused human and non-human primate posture studies.

First Trial Postural Reactions to Unexpected Balance Disturbances: A Comparison With the Acoustic Startle Reaction

2010 ◽  
Vol 104 (5) ◽  
pp. 2704-2712 ◽  
Author(s):  
Lars B. Oude Nijhuis ◽  
John H. J. Allum ◽  
Josep Valls-Solé ◽  
Sebastiaan Overeem ◽  
Bastiaan R. Bloem
Keyword(s):  
Muscle Activation ◽  
Acoustic Startle ◽  
Muscle Synergy ◽  
Trunk Muscles ◽  
Common Element ◽  
Startle Reaction ◽  
Support Surface ◽  
Postural Reactions ◽  
Acoustic Stimuli ◽  
Postural Responses

Unexpected support-surface movements delivered during stance elicit “first trial” postural reactions, which are larger and cause greater instability compared with habituated responses. The nature of this first trial reaction remains unknown. We hypothesized that first trial postural reactions consist of a generalized startle reaction, with a similar muscle synergy as the acoustic startle response, combined with an automatic postural reaction. Therefore we compared acoustic startle responses to first trial postural reactions. Eight healthy subjects stood on a support surface that unexpectedly rotated backwards 10 times, followed by 10 startling acoustic stimuli, or vice versa. Outcome measures included full body kinematics and surface EMG from muscles involved in startle reactions or postural control. Postural perturbations and startling acoustic stimuli both elicited a clear first trial reaction, as reflected by larger kinematic and EMG responses. The ensuing habituation rate to repeated identical stimuli was comparable for neck and trunk muscles in both conditions. Onset latencies in neck muscles occurred significantly later for first trial perturbations compared with startle responses, but earlier in trunk muscles. Our results show that platform tilting initially induces reactions larger than needed to maintain equilibrium. For neck and trunk muscles, these first trial postural reactions resembled acoustic startle reflexes. First trial postural reactions may be triggered by interaction of afferent volleys formed by somatosensory and vestibular inputs. Acoustic startle reactions may also be partially triggered by vestibular inputs. Similar muscle activation driven by vestibular inputs may be the common element of first trial postural responses and acoustic startle reactions.

A Feedback Model Reproduces Muscle Activity During Human Postural Responses to Support-Surface Translations

2008 ◽  
Vol 99 (2) ◽  
pp. 1032-1038 ◽  
Author(s):  
Torrence D. J. Welch ◽  
Lena H. Ting
Keyword(s):  
Postural Control ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Control Process ◽  
Temporal Patterns ◽  
Human Dimensions ◽  
Support Surface ◽  
Level Control ◽  
Muscle Activation Patterns ◽  
Postural Responses

Although feedback models have been used to simulate body motions in human postural control, it is not known whether muscle activation patterns generated by the nervous system during postural responses can also be explained by a feedback control process. We investigated whether a simple feedback law could explain temporal patterns of muscle activation in response to support-surface translations in human subjects. Previously, we used a single-link inverted-pendulum model with a delayed feedback controller to reproduce temporal patterns of muscle activity during postural responses in cats. We scaled this model to human dimensions and determined whether it could reproduce human muscle activity during forward and backward support-surface perturbations. Through optimization, we found three feedback gains (on pendulum acceleration, velocity, and displacement) and a common time delay that allowed the model to best match measured electromyographic (EMG) signals. For each muscle and each subject, the entire time courses of EMG signals during postural responses were well reconstructed in muscles throughout the lower body and resembled the solution derived from an optimal control model. In ankle muscles, >75% of the EMG variability was accounted for by model reconstructions. Surprisingly, >67% of the EMG variability was also accounted for in knee, hip, and pelvis muscles, even though motion at these joints was minimal. Although not explicitly required by our optimization, pendulum kinematics were well matched to subject center-of-mass (CoM) kinematics. Together, these results suggest that a common set of feedback signals related to task-level control of CoM motion is used in the temporal formation of muscle activity during postural control.

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