scholarly journals Manual Tracking Performance in Patients with Cerebellar Incoordination: Effects of Mechanical Loading

1990 ◽  
Vol 17 (3) ◽  
pp. 275-285 ◽  
Author(s):  
Betty-Lynn Morrice ◽  
Werner J. Becker ◽  
J.A. Hoffer ◽  
Robert G. Lee
Keyword(s):  
High Velocity ◽  
Time Lag ◽  
Normal Subjects ◽  
Elastic Stiffness ◽  
Tracking Performance ◽  
Cerebellar Hemisphere ◽  
Manual Tracking ◽  
Improve Performance ◽  
Oscilloscope Screen ◽  
Flexion Extension

ABSTRACT:Manual tracking performance was studied in five patients with cerebellar incoordination due to unilateral cerebellar hemisphere lesions. The subjects were required to track a target on an oscilloscope screen by moving a cursor controlled by flexion-extension movements of the wrist. In comparison to normal subjects, the cerebellar patients, using their clinically affected arm, demonstrated irregular tracking patterns with inappropriate accelerations and decelerations, numerous high velocity peaks of movement, and an increased time lag between the cursor and the target.The addition of a viscous load provided by feeding back wrist velocity to a torque motor coupled to the apparatus resulted in significant improvement in tracking performance and suppression of the high velocity peaks. Increasing elastic stiffness by feeding back wrist position or inertial load by adding weights to the hand did not improve performance on this task. It is proposed that a hypotonic cerebellar limb behaves like an underdamped mechanical system. The addition of viscous loads helps restore more normal damping during voluntary movements of the arm.

Rehearsal and Learning of Embedded Movement Sequences during a Tracking Task

1982 ◽  
Vol 55 (2) ◽  
pp. 615-622 ◽  
Author(s):  
Ian M. Franks
Keyword(s):  
Time Lag ◽  
Specific Pattern ◽  
Tracking Task ◽  
Stimulus Sequence ◽  
Tracking Performance ◽  
Second Phase ◽  
Movement Sequences ◽  
Perceptual Changes

The first phase of the experiment was undertaken to examine the response changes that occur when a subject learns to track a repeating sequence that is embedded in a stimulus signal. The subject's tracking performance as measured by consistency and time-lag indices improved despite having no reportable knowledge of the repeating segment of the stimulus signal. The second phase investigated the perceptual changes that accompany the learning of the tracking task. It appeared that a subject's perception of the speed of a stimulus sequence while tracking varied depended upon the familiarity of the specific pattern of movements that comprised the signal.

Interference of Left and Right Cerebellar rTMS with Procedural Learning

2004 ◽  
Vol 16 (9) ◽  
pp. 1605-1611 ◽  
Author(s):  
Sara Torriero ◽  
Massimiliano Oliveri ◽  
Giacomo Koch ◽  
Carlo Caltagirone ◽  
Laura Petrosini
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Reaction Time Task ◽  
Normal Subjects ◽  
Serial Reaction Time Task ◽  
Procedural Learning ◽  
Cerebellar Hemisphere ◽  
Serial Reaction ◽  
The Right

Increasing evidence suggests cerebellar involvement in procedural learning. To further analyze its role and to assess whether it has a lateralized influence, in the present study we used a repetitive transcranial magnetic stimulation interference approach in a group of normal subjects performing a serial reaction time task. We studied 36 normal volunteers: 13 subjects underwent repetitive transcranial magnetic stimulation on the left cerebellum and performed the task with the right (6 subjects) or left (7 subjects) hand; 10 subjects underwent repetitive transcranial magnetic stimulation on the right cerebellum and performed the task with the hand ipsilateral (5 subjects) or contralateral (5 subjects) to the stimulation; another 13 subjects served as controls and were not submitted to repetitive transcranial magnetic stimulation; 7 of them performed the task with the right hand and 6 with the left hand. The main results show that interference with the activity of the lateral cerebellum induces a significant decrease of procedural learning: Interference with the right cerebellar hemisphere activity induces a significant decrease in procedural learning regardless of the hand used to perform the serial reaction time task, whereas left cerebellar hemisphere activity seems more linked with procedural learning through the ipsilateral hand. In conclusion, the present study shows for the first time that a transient interference with the functions of the cerebellar cortex results in an impairment of procedural learning in normal subjects and it provides new evidences for interhemispheric differences in the lateral cerebellum.

Cholinergic stimulation induces asynchrony between the circular and longitudinal muscle contraction during esophageal peristalsis

2008 ◽  
Vol 294 (3) ◽  
pp. G694-G698 ◽  
Author(s):  
Hariprasad Korsapati ◽  
Arash Babaei ◽  
Valmik Bhargava ◽  
Ravinder K. Mittal
Keyword(s):  
Longitudinal Muscle ◽  
Acetylcholinesterase Inhibitor ◽  
Time Lag ◽  
Control Period ◽  
Temporal Correlation ◽  
Normal Subjects ◽  
Esophageal Peristalsis ◽  
Nutcracker Esophagus ◽  
The Mean ◽  
Mean Time

In healthy subjects, a close temporal correlation exists between contractions of the circular muscle (CM) and longitudinal muscle (LM) layers of the esophagus. Patients with nutcracker esophagus show disassociation between the peak of contractions of the CM and LM layers and the peak of contraction 1–3 s apart (Jung HY, Puckett JL, Bhalla V, Rojas-Feria M, Bhargava V, Liu J, Mittal RK. Gastroenterology 128: 1179–1186, 2005). The purpose of the present study was to evaluate the effect of acetylcholinesterase inhibitor (edrophonium) and acetylcholine receptor antagonist (atropine) on human esophageal peristalsis in normal subjects. High-frequency intraluminal ultrasound imaging and manometry were performed simultaneously during swallow-induced peristalsis in ten normal subjects. Standardized 5-ml water swallows were recorded 2 cm above the lower esophageal sphincter under three study conditions: control, edrophonium (80 μg/kg iv), and atropine (10 μg/kg iv). A close temporal correlation exists between the peak pressure and peak wall thickness during the control period. The mean time lag between the peak LM and peak CM contraction was 0.03 s. After edrophonium administration, the mean contraction amplitude increased from 101 ± 9 mmHg to 150 ± 20 mmHg ( P < 0.05) and mean peak muscle thickness increased from 3.0 ± 0.2 mm to 3.6 ± 0.3 mm ( P < 0.01), and duration of both CM and LM contractions were also increased. Furthermore, the mean time difference between the peak LM and CM was increased to 1.1 s, (ranging 0.2 to 3.4 s) ( P < 0.0001). We conclude that cholinomimetic agent induces discoordination between the two muscle layers of the esophagus.

Urea activation of K-Cl transport in human erythrocytes

1995 ◽  
Vol 268 (4) ◽  
pp. C1018-C1025 ◽  
Author(s):  
D. M. Kaji ◽  
C. Gasson
Keyword(s):  
Time Lag ◽  
Renal Medulla ◽  
Normal Subjects ◽  
Lag Time ◽  
Human Erythrocytes ◽  
Cell Swelling ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Activated State ◽  
High Concentrations

This report prompted us to examine the effect of urea on K-Cl cotransport in human erythrocytes. In human erythrocytes, urea activated K-Cl cotransport reversibly and in a concentration-dependent manner. Pretreatment with okadaic acid abolished the urea activation of transport, suggesting that exposure to urea resulted in net dephosphorylation of the transporter or a key regulator and that the action of urea was exerted proximal to the phosphorylation-dephosphorylation step. At a concentration of 200 mM, urea activated K-Cl cotransport without any delay, even in the absence of cell swelling. However, with increasing urea concentrations, an appreciable increase in lag time was observed before the final steady-state flux was reached, suggesting that urea inhibits a regulatory kinase. The latter conclusion was also supported by the finding that, at any given urea concentration, the lag time for activation was greater than the lag time for deactivation. Mg depletion activated cotransport, and urea had no additional stimulatory effect in Mg-depleted cells. In urea-pretreated cells, swelling further activated cotransport, but without any measurable delay, in contrast to a time lag of 8 min when control cells (not exposed to urea) were swollen. The latter finding suggests that urea promotes the conversion of transporters from the resting to the partially activated state. These findings raise the possibility that high concentrations of urea in the renal medulla may play a role in the decrease in cell volume that occurs during the maturation of reticulocytes and young erythrocytes, both in normal subjects and in subjects with hemoglobinopathies.

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