scholarly journals Cerebellar damage diminishes long-latency responses to multijoint perturbations

2013 ◽  
Vol 109 (8) ◽  
pp. 2228-2241 ◽  
Author(s):  
Isaac Kurtzer ◽  
Paxson Trautman ◽  
Russell J. Rasquinha ◽  
Nasir H. Bhanpuri ◽  
Stephen H. Scott ◽  
...  
Keyword(s):  
Motor Pattern ◽  
Latency Period ◽  
Feedback Stabilization ◽  
Elderly Subjects ◽  
Cerebellar Damage ◽  
Intersegmental Dynamics ◽  
Long Latency ◽  
Flexion Extension ◽  
Latency Response ◽  
Elbow Motion

Damage to the cerebellum can cause significant problems in the coordination of voluntary arm movements. One prominent idea is that incoordination stems from an inability to predictively account for the complex mechanical interactions between the arm's several joints. Motivated by growing evidence that corrective feedback control shares important capabilities and neural substrates with feedforward control, we asked whether cerebellar damage impacts feedback stabilization of the multijoint arm appropriate for the arm's intersegmental dynamics. Specifically, we tested whether cerebellar dysfunction impacts the ability of posterior deltoid to incorporate elbow motion in its long-latency response (R2 = 45–75 ms and R3 = 75–100 ms after perturbation) to an unexpected torque perturbation. Healthy and cerebellar-damaged subjects were exposed to a selected pattern of shoulder-elbow displacements to probe the response pattern from this shoulder extensor muscle. The healthy elderly subjects expressed a long-latency response linked to both shoulder and elbow motion, including an increase/decrease in shoulder extensor activity with elbow flexion/extension. Critically, cerebellar-damaged subjects displayed the normal pattern of activity in the R3 period indicating an intact ability to rapidly integrate multijoint motion appropriate to the arm's intersegmental dynamics. However, cerebellar-damaged subjects had a lower magnitude of activity that was specific to the long-latency period (both R2 and R3) and a slightly delayed onset of multijoint sensitivity. Taken together, our results suggest that the basic motor pattern of the long-latency response is housed outside the cerebellum and is scaled by processes within the cerebellum.

Fast corrective responses are evoked by perturbations approaching the natural variability of posture and movement tasks

2012 ◽  
Vol 107 (10) ◽  
pp. 2821-2832 ◽  
Author(s):  
F. Crevecoeur ◽  
I. Kurtzer ◽  
S. H. Scott
Keyword(s):  
Motor Tasks ◽  
Small Perturbations ◽  
Voluntary Motor ◽  
Intersegmental Dynamics ◽  
Shoulder Muscles ◽  
Long Latency ◽  
Evoked Activity ◽  
Perturbation Magnitude ◽  
Elbow Motion ◽  
Muscle Responses

A wealth of studies highlight the importance of rapid corrective responses during voluntary motor tasks. These studies used relatively large perturbations to evoke robust muscle activity. Thus it remains unknown whether these corrective responses (latency 20–100 ms) are evoked at perturbation levels approaching the inherent variability of voluntary control. To fill this gap, we examined responses for large to small perturbations applied while participants either performed postural or reaching tasks. To address multijoint corrective responses, we induced various amounts of single-joint elbow motion with scaled amounts of combined elbow and shoulder torques. Indeed, such perturbations are known to elicit a response at the unstretched shoulder muscle, which reflects an internal model of arm intersegmental dynamics. Significant muscle responses were observed during both postural control and reaching, even when perturbation-related joint angle, velocity, and acceleration overlapped in distribution with deviations encountered in unperturbed trials. The response onsets were consistent across the explored range of perturbation loads, with short-latency onset for the muscles spanning the elbow joints (20–40 ms), and long-latency for shoulder muscles (onset > 45 ms). In addition, the evoked activity was strongly modulated by perturbation magnitude. These results suggest that multijoint responses are not specifically engaged to counter motor errors that exceed a certain threshold. Instead, we suggest that these corrective processes operate continuously during voluntary motor control.

Context-dependent inhibition of unloaded muscles during the long-latency epoch

2015 ◽  
Vol 113 (1) ◽  
pp. 192-202 ◽  
Author(s):  
Joseph Y. Nashed ◽  
Isaac L. Kurtzer ◽  
Stephen H. Scott
Keyword(s):  
Inhibitory Activity ◽  
Muscle Activity ◽  
Inhibitory Response ◽  
Short Latency ◽  
Peripheral Target ◽  
Intersegmental Dynamics ◽  
Long Latency ◽  
Dependent Inhibition ◽  
Elbow Motion ◽  
Different Levels

A number of studies have highlighted the sophistication of corrective responses in lengthened muscles during the long-latency epoch. However, in various contexts, unloading can occur, which requires corrective actions from a shortened muscle. Here, we investigate the sophistication of inhibitory responses in shortened muscles due to unloading. Our first experiment quantified the inhibitory responses following an unloading torque that displaced the hand either into or away from a peripheral target. We observed larger long-latency inhibitory responses when perturbed into the peripheral target compared with away from the target. In our second experiment, we characterized the degree of inhibition following unloading with respect to different levels of preperturbation muscle activity. We initially observed that the inhibitory activity during the short-latency epoch scaled with increased levels of preperturbation muscle activity. However, this scaling peaked early in the R2 epoch (∼50 ms) but then quickly diminished through the rest of the long-latency epoch. Finally, in experiment 3, we investigated whether inhibitory perturbation responses consider intersegmental dynamics of the limb. We quantified unloading responses for either pure shoulder or pure elbow torques that evoked similar motion at the shoulder but different elbow motion. The long-latency inhibitory response in the shoulder, unlike the short-latency, was greater for the shoulder torque compared with the response following an elbow torque, as previously observed for a loading response. Taken together, these results illustrate that the long-latency unloading response is capable of a similar level of complexity as observed when loads are applied to the limb.

scholarly journals Long-latency reflexes of elbow and shoulder muscles suggest reciprocal excitation of flexors, reciprocal excitation of extensors, and reciprocal inhibition between flexors and extensors

2016 ◽  
Vol 115 (4) ◽  
pp. 2176-2190 ◽  
Author(s):  
Isaac Kurtzer ◽  
Jenna Meriggi ◽  
Nidhi Parikh ◽  
Kenneth Saad
Keyword(s):  
General Pattern ◽  
Reciprocal Inhibition ◽  
Elbow Flexors ◽  
Mechanical Interaction ◽  
Intersegmental Dynamics ◽  
Shoulder Muscles ◽  
Long Latency ◽  
Flexion Extension ◽  
Reciprocal Excitation ◽  
Long Latency Reflexes

Postural corrections of the upper limb are required in tasks ranging from handling an umbrella in the changing wind to securing a wriggling baby. One complication in this process is the mechanical interaction between the different segments of the arm where torque applied at one joint induces motion at multiple joints. Previous studies have shown the long-latency reflexes of shoulder muscles (50–100 ms after a limb perturbation) account for these mechanical interactions by integrating information about motion of both the shoulder and elbow. It is less clear whether long-latency reflexes of elbow muscles exhibit a similar capability and what is the relation between the responses of shoulder and elbow muscles. The present study utilized joint-based loads tailored to the subjects' arm dynamics to induce well-controlled displacements of their shoulder and elbow. Our results demonstrate that the long-latency reflexes of shoulder and elbow muscles integrate motion from both joints: the shoulder and elbow flexors respond to extension at both joints, whereas the shoulder and elbow extensors respond to flexion at both joints. This general pattern accounts for the inherent flexion-extension coupling of the two joints arising from the arm's intersegmental dynamics and is consistent with spindle-based reciprocal excitation of shoulder and elbow flexors, reciprocal excitation of shoulder and elbow extensors, and across-joint inhibition between the flexors and extensors.

scholarly journals Metastatic Extraskeletal Mesenchymal Chondrosarcoma of the Pancreas: Report of an Unusual Case with Review of Literature

2021 ◽  
Author(s):  
Saloni Naresh Shah ◽  
Ashok Parameswaran ◽  
Prasanna Kumar Reddy
Keyword(s):  
Unusual Case ◽  
English Literature ◽  
Latency Period ◽  
Sudden Onset ◽  
Mesenchymal Chondrosarcoma ◽  
Pancreatic Tumors ◽  
Good Survival ◽  
Review Of Literature ◽  
Long Latency ◽  
Extraskeletal Mesenchymal Chondrosarcoma

AbstractExtraskeletal mesenchymal chondrosarcoma (ESMC) metastasizing to the pancreas in isolation is a rare occurrence. We report a 49-year-old gentleman who had undergone excision of an ESMC of the thigh in 2009 and presented with sudden onset abdominal pain and icterus in 2019. Radiological imaging revealed calcified mass of the pancreas with multiple nodules with extension into the adipose tissue. Distal pancreatectomy was performed and the pathology revealed a bimorphic tumor composed of undifferentiated round blue cells with abrupt transition to hyaline cartilage, typical of mesenchymal chondrosarcoma. To the best of our knowledge, there are only seven prior cases of metastatic ESMC of the pancreas in the English literature. Surgical intervention appears to be the preferred modality of treatment for metastatic pancreatic tumors. These patients may have long latency period before metastasizing and seem to have a good survival period post excision.

scholarly journals Paracoccidioidomycosis Diagnosed in Europe—A Systematic Literature Review

2021 ◽  
Vol 7 (2) ◽  
pp. 157
Author(s):  
Gernot Wagner ◽  
Deddo Moertl ◽  
Anna Glechner ◽  
Verena Mayr ◽  
Irma Klerings ◽  
...  
Keyword(s):  
Latency Period ◽  
European Countries ◽  
Systemic Mycosis ◽  
Endemic Region ◽  
Travel History ◽  
Long Latency ◽  
Geographical Regions ◽  
The World ◽  
First Occurrence ◽  
Full Text Screening

Paracoccidioidomycosis is a systemic mycosis that is endemic in geographical regions of Central and South America. Cases that occur in nonendemic regions of the world are imported through migration and travel. Due to the limited number of cases in Europe, most physicians are not familiar with paracoccidioidomycosis and its close clinical and histopathological resemblance to other infectious and noninfectious disease. To increase awareness of this insidious mycosis, we conducted a systematic review to summarize the evidence on cases diagnosed and reported in Europe. We searched PubMed and Embase to identify cases of paracoccidioidomycosis diagnosed in European countries. In addition, we used Scopus for citation tracking and manually screened bibliographies of relevant articles. We conducted dual abstract and full-text screening of references yielded by our searches. To identify publications published prior to 1985, we used the previously published review by Ajello et al. Overall, we identified 83 cases of paracoccidioidomycosis diagnosed in 11 European countries, published in 68 articles. Age of patients ranged from 24 to 77 years; the majority were male. Time from leaving the endemic region and first occurrence of symptoms considerably varied. Our review illustrates the challenges of considering systemic mycosis in the differential diagnosis of people returning or immigrating to Europe from endemic areas. Travel history is important for diagnostic-workup, though it might be difficult to obtain due to possible long latency period of the disease.

“Re-Emergence” of Silicosis and Coal Workers Pneumoconiosis in Australia

2020 ◽  
Vol 119 (1) ◽  
pp. 65-92
Author(s):  
Beris Penrose
Keyword(s):  
Data Collection ◽  
Coal Mining ◽  
Disease Onset ◽  
Latency Period ◽  
Dust Exposure ◽  
Long Latency ◽  
History Of ◽  
Coal Workers Pneumoconiosis ◽  
Coal Workers

Some reporters, politicians, and doctors have described current cases as a “re-emergence” of these diseases, based on the notion that they had been eliminated. However, silicosis persisted in centuries-old industries like sandblasting and stonemasonry and coal workers pneumoconiosis (CWP) continued in coal mining. Until recently, their presence was obscured by a combination of factors such as misdiagnosis, especially if there was a history of smoking; the failure to follow up workers thought to have silicosis or CWP; the long latency period between dust exposure and disease onset that can conceal the link between the two; and the lack of data collection that may have revealed their presence. As the recent Queensland government inquiry into CWP noted, current cases are more accurately a reidentification.

scholarly journals Transient Responses of Rabbit Retinal Ganglion Cells to Photic and Electrical Stimuli

1976 ◽  
Vol 3 (1) ◽  
pp. 73-79 ◽  
Author(s):  
S. Molotchnikoff
Keyword(s):  
Receptive Field ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Electrical Activation ◽  
Retinal Ganglion ◽  
Transient Responses ◽  
Long Latency ◽  
Latency Response ◽  
Electrical Stimuli ◽  
Inhibitory Period

SUMMARY:The relationships between the center and the surround of the receptive field of the rabbit retinal ganglion cell were investigated. This was done by coupling localized light spots and electrical activation of the retina and by analyzing the time of the excitatory and inhibitory periods. The responsiveness to the electrical transretinal pulse revealed a) that ON stimulation in OFF-center cells and OFF stimulation in ON-center cells, elicited a primary period of inhibition with a short latency; b) the long latency response of surround stimulation was not preceded by an inhibitory period unless the center was simultaneously stimulated in the same direction; c) a transient response to a stationary spot of light is followed by a period of inhibition. These results are discussed in relation to the known cellular retinal networks.

scholarly journals Temporal Evolution of “Automatic Gain-Scaling”

2009 ◽  
Vol 102 (2) ◽  
pp. 992-1003 ◽  
Author(s):  
J. Andrew Pruszynski ◽  
Isaac Kurtzer ◽  
Timothy P. Lillicrap ◽  
Stephen H. Scott
Keyword(s):  
Steady State ◽  
Muscle Activity ◽  
Temporal Evolution ◽  
Rapid Decrease ◽  
Short Latency ◽  
State Activity ◽  
Long Latency ◽  
Short Latency Response ◽  
Latency Response ◽  
Steady State Activity

The earliest neural response to a mechanical perturbation, the short-latency stretch response (R1: 20–45 ms), is known to exhibit “automatic gain-scaling” whereby its magnitude is proportional to preperturbation muscle activity. Because gain-scaling likely reflects an intrinsic property of the motoneuron pool (via the size-recruitment principle), counteracting this property poses a fundamental challenge for the nervous system, which must ultimately counter the absolute change in load regardless of the initial muscle activity (i.e., show no gain-scaling). Here we explore the temporal evolution of gain-scaling in a simple behavioral task where subjects stabilize their arm against different background loads and randomly occurring torque perturbations. We quantified gain-scaling in four elbow muscles (brachioradialis, biceps long, triceps lateral, triceps long) over the entire sequence of muscle activity following perturbation onset—the short-latency response, long-latency response (R2: 50–75 ms; R3: 75–105 ms), early voluntary corrections (120–180 ms), and steady-state activity (750–1250 ms). In agreement with previous observations, we found that the short-latency response demonstrated substantial gain-scaling with a threefold increase in background load resulting in an approximately twofold increase in muscle activity for the same perturbation. Following the short-latency response, we found a rapid decrease in gain-scaling starting in the long-latency epoch (∼75-ms postperturbation) such that no significant gain-scaling was observed for the early voluntary corrections or steady-state activity. The rapid decrease in gain-scaling supports our recent suggestion that long-latency responses and voluntary control are inherently linked as part of an evolving sensorimotor control process through similar neural circuitry.

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