scholarly journals Efference copy is necessary for the attenuation of self-generated touch

2019 ◽  
Author(s):  
Konstantina Kilteni ◽  
Patrick Engeler ◽  
H. Henrik Ehrsson
Keyword(s):  
Index Finger ◽  
Alternative Hypothesis ◽  
Motor Command ◽  
Passive Movement ◽  
Efference Copy ◽  
Tactile Feedback ◽  
Left Index Finger ◽  
Body Parts ◽  
Computational Theory ◽  
The Right

AbstractA self-generated touch feels less intense than an external touch of the exact same intensity. According to a prevalent computational theory of motor control, this attenuation occurs because the brain uses internal forward models to predict the somatosensory consequences of our movements using a copy of the motor command, i.e., the efference copy. These tactile predictions are then used to suppress the perceived intensity of the actual tactile feedback. Despite being highly influential, the core assumption of theory has never been tested; that is, whether the efference copy is necessary for somatosensory attenuation. A possible alternative hypothesis is that a predictable contact of two of one’s own body parts is sufficient. Using a psychophysical task, we quantified the attenuation of touch applied on the participants’ left index finger when the touch was triggered by the active or passive movement of the participants’ right index finger and when it was externally generated in the absence of any movement. We observed somatosensory attenuation only when the touch was triggered by the voluntary movement of the participants’ finger. In contrast, during the passive movement, the intensity of the touch was perceived to be as strong as when the touch was externally triggered. In both active and passive movement conditions, the participants showed the same discrimination capacity. Electromyographic recordings confirmed minimal activity of the right hand during the passive movement. Together, our results suggest that the efference copy is necessary for computing the somatosensory predictions that produce the attenuation of self-generated touch.

scholarly journals Response preparation involves a release of intracortical inhibition in task-irrelevant muscles

2020 ◽  
Author(s):  
Isaac N. Gomez ◽  
Kara Ormiston ◽  
Ian Greenhouse
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Index Finger ◽  
Intracortical Inhibition ◽  
Left Index Finger ◽  
Task Condition ◽  
Response Preparation ◽  
Action Preparation ◽  
The Right ◽  
Task Irrelevant

AbstractAction preparation involves widespread modulation of motor system excitability, but the precise mechanisms are unknown. In this study, we investigated whether intracortical inhibition changes in task-irrelevant muscle representations during action preparation. We used transcranial magnetic stimulation (TMS) combined with electromyography in healthy human adults to measure motor evoked potentials (MEPs) and cortical silent periods (CSPs) in task-irrelevant muscles during the preparatory period of simple delayed response tasks. In Experiment 1, participants responded with the left-index finger in one task condition and the right-index finger in another task condition, while MEPs and CSPs were measured from the contralateral non-responding and tonically contracted index finger. During Experiment 2, participants responded with the right pinky finger while MEPs and CSPs were measured from the tonically contracted left-index finger. In both experiments, MEPs and CSPs were compared between the task preparatory period and a resting intertrial baseline. The CSP duration during response preparation decreased from baseline in every case. A laterality difference was also observed in Experiment 1, with a greater CSP reduction during the preparation of left finger responses compared to right finger responses. MEP amplitudes showed no modulation during movement preparation in any of the three response conditions. These findings indicate cortical inhibition associated with task-irrelevant muscles is transiently released during action preparation and implicate a novel mechanism for the controlled and coordinated release of motor cortex inhibition.New & NoteworthyIn this study we observed the first evidence of a release of intracortical inhibition in task-irrelevant muscle representations during response preparation. We applied transcranial magnetic stimulation to elicit cortical silent periods in task-irrelevant muscles during response preparation and observed a consistent decrease in the silent period duration relative to a resting baseline. These findings address the question of whether cortical mechanisms underlie widespread modulation in motor excitability during response preparation.

scholarly journals PROSTHETIC REHABILITATION OF EXTRA-ORAL DEFECTS WITH SILICONE PROSTHESIS

2012 ◽  
Vol 02 (04) ◽  
pp. 12-15
Author(s):  
Harshitha Alva ◽  
Krishna Prasad D. ◽  
Manoj Shetty
Keyword(s):  
Index Finger ◽  
Left Index Finger ◽  
Body Parts ◽  
Prosthetic Rehabilitation ◽  
Silicone Prosthesis ◽  
Normal Life ◽  
Facial Defects ◽  
Custom Made ◽  
The Ideal

AbstractMan's need for artificial replacements to supply missing or lost body parts has probably existed as long as man himself. Body abnormalities or defects compromise appearance, function and render an individual incapable of leading a relatively normal life. Extraoral defects involving ear, eye, nose, finger and few others are commonly encountered. Prosthetic restoration of these facial defects is an ancient art, in which success has always been limited due to the unavailability of adequate materials or because the available materials do not fulfil the ideal requirements. The most accepted materials today are the silicones because of their better esthetics.This paper presents prosthetic rehabilitation of the distal phalynx of left index finger with custom-made silicone prosthesis.

Assessment of Radiation Protection in Hand-Shielding Products With Mini C-Arm Fluoroscopy

Hand ◽  
2019 ◽  
pp. 155894471986593 ◽  
Author(s):  
Matthew B. Cantlon ◽  
Asif M. Ilyas
Keyword(s):  
Radiation Exposure ◽  
Index Finger ◽  
Proximal Phalanx ◽  
Left Index Finger ◽  
Surgical Glove ◽  
Thermoluminescent Dosimeters ◽  
Intraoperative Fluoroscopy ◽  
The Mean ◽  
The Right ◽  
Free Metal

Background: Previous studies have highlighted the particular risk of radiation exposure to the surgeon’s hands with intraoperative fluoroscopy. Although evidence exists that shielding equipment for the hands reduces exposure, the extent of protection is not well understood. Therefore, we set out to determine the degree to which radiation exposure to the surgeon’s hands is decreased with hand-shielding products. Methods: An anthropomorphic model was positioned to simulate a surgeon sitting at a hand table. Thermoluminescent dosimeters were placed on the proximal phalanx of each index finger. The right index finger dosimeter was covered with a standard polyisoprene surgical glove (control arm), whereas the left index finger dosimeter was covered with commercially available hand-shielding products (study arm): lead-free metal-oxide gloves, leaded gloves, and radiation-attenuating cream. Mini fluoroscope position, configuration, and settings were standardized. The model was scanned for 15 continuous minutes in each test run, and each comparative arm was run 3 times. Results: The mean radiation dose absorbed by the control and variable dosimeters across all tests was 44.8 mrem (range, 30-54) and 18.6 mrem (range, 14-26), respectively. Each hand-shielding product resulted in statistically lower radiation exposure than a single polyisoprene surgical glove. Conclusions: The mean radiation exposure to the hands was significantly decreased when protected by radiation-attenuating options. Each product individually resulted in a statistically significant decrease in hand exposure compared with the control. We recommend that in addition to efforts to decrease radiation exposure, surgeons consider routine use of hand-shielding products when using mini c-arm fluoroscopy.

Music Affects Learning of a Braille-Like Task by Sighted Subjects

1989 ◽  
Vol 69 (3-1) ◽  
pp. 923-929
Author(s):  
Robert F. Kennison ◽  
Richard A. Mcfarland
Keyword(s):  
College Students ◽  
Sensory Input ◽  
Index Finger ◽  
Practical Importance ◽  
Left Index Finger ◽  
Interhemispheric Competition ◽  
Male College ◽  
The Right ◽  
The Brain ◽  
Male College Students

24 consistently right-handed male college students felt sets of four Braille symbols with either the right or the left index finger and identified by touch alone which two of the four symbols in each set were identical. During the task music was played to either the right ear, the left ear, both ears, or neither ear. Significantly fewer errors were made when the music was in the ear contralateral to whichever hand performed the task. The ipsilateral, binaural, and no-music groups did not differ significantly from each other. It is suggested that monaural music to the ear contralateral to the engaged hand led to reduced interhemispheric competition acting on the hemisphere controlling the hand. Such a facilitating effect may be of practical importance in tasks during which one hemisphere receives the bulk of the task-related sensory input and/or processes the final order from the brain to the task-related muscles.

Shifts in Kinesthesis through Time and after Active and Passive Movement

1975 ◽  
Vol 40 (3) ◽  
pp. 755-761 ◽  
Author(s):  
Brian Craske ◽  
Martin Crawshaw
Keyword(s):  
Shoulder Joint ◽  
Index Finger ◽  
Position Sense ◽  
Passive Movement ◽  
Active Movement ◽  
Final Position ◽  
Left Hand ◽  
Limb Position ◽  
Test Position ◽  
The Right

The position sense of a stationary arm was investigated subsequent to an horizontally adductive movement with axis the shoulder joint. The right arm was the treated arm: it reached a test position actively, using minimal voluntary effort, or passively from each of 10 starting positions. The blindfolded S localized the index finger of the treated arm by attempting to touch it with the index finger of his left hand. The results indicate that subsequent to active movement the final position of a limb is more accurately known than a position resulting from passive movement. A second finding is that concomitant with both forms of limb placement there is a unidirectional drift of perceived limb position over trials.

Cortical Representation of Swallowing: A Modified Dual Task Paradigm

2002 ◽  
Vol 94 (3) ◽  
pp. 1029-1040 ◽  
Author(s):  
Stephanie K. Daniels ◽  
David M. Corey ◽  
Cristen L. Barnes ◽  
Nikki M. Faucheaux ◽  
Daniel H. Priestly ◽  
...  
Keyword(s):  
Dual Task ◽  
Right Hemisphere ◽  
Index Finger ◽  
Finger Tapping ◽  
Left Index Finger ◽  
Cortical Representation ◽  
Word Repetition ◽  
Dual Task Paradigm ◽  
Left And Right ◽  
The Right

It is unclear whether the cortical representation of swallowing is lateralized to the left cerebral hemisphere, right hemisphere, or bilaterally represented. As dysphagia is common in acute stroke, it is important to elucidate swallowing lateralization to facilitate earlier detection of stroke patients who may be at greater risk for dysphagia and aspiration. In this study, a modified dual task paradigm was designed to study laterality of swallowing in a group of 14 healthy, young, right-handed, male adults. The subjects were studied at baseline and with interference. Baseline conditions, performed separately, were continuous swallowing, finger tapping using the right and left index fingers, and word repetition. Interference tasks, including tapping with the right index finger, tapping with the left index finger, and word repetition, were completed with and without swallowing. Finger-tapping rate was measured, and x-ray samples of the swallowing task were taped to measure swallowing rate and volume swallowed. At baseline, the rate of tapping the right index finger was significantly faster than that of the left index finger. There was a significant decline in the tapping rates of both left and right index fingers with swallowing interference. The volume per swallow was significantly reduced during the interfering language task of silent repetition. These results offer partial support for a bilateral representation of swallowing as well as suggest an important left hemispheric contribution to swallowing. However, it cannot be concluded that the left hemisphere is more important than the right, as a comparable right hemisphere task was not studied.

scholarly journals Effect of Repetitive Passive Movement Before Motor Skill Training on Corticospinal Excitability and Motor Learning Depend on BDNF Polymorphisms

2021 ◽  
Vol 15 ◽  
Author(s):  
Manh Van Pham ◽  
Shota Miyaguchi ◽  
Hiraku Watanabe ◽  
Kei Saito ◽  
Naofumi Otsuru ◽  
...  
Keyword(s):  
Motor Learning ◽  
Index Finger ◽  
Learning Task ◽  
Passive Movement ◽  
Corticospinal Excitability ◽  
Homeostatic Plasticity ◽  
Learning Ability ◽  
Learning Efficiency ◽  
Learning Tasks ◽  
The Right

A decrease in cortical excitability tends to be easily followed by an increase induced by external stimuli via a mechanism aimed at restoring it; this phenomenon is called “homeostatic plasticity.” In recent years, although intervention methods aimed at promoting motor learning using this phenomenon have been studied, an optimal intervention method has not been established. In the present study, we examined whether subsequent motor learning can be promoted further by a repetitive passive movement, which reduces the excitability of the primary motor cortex (M1) before motor learning tasks. We also examined the relationship between motor learning and the brain-derived neurotrophic factor. Forty healthy subjects (Val/Val genotype, 17 subjects; Met carrier genotype, 23 subjects) participated. Subjects were divided into two groups of 20 individuals each. The first group was assigned to perform the motor learning task after an intervention consisting in the passive adduction–abduction movement of the right index finger at 5 Hz for 10 min (RPM condition), while the second group was assigned to perform the task without the passive movement (control condition). The motor learning task consisted in the visual tracking of the right index finger. The results showed that the corticospinal excitability was transiently reduced after the passive movement in the RPM condition, whereas it was increased to the level detected in the control condition after the motor learning task. Furthermore, the motor learning ability was decreased immediately after the passive movement; however, the motor performance finally improved to the level observed in the control condition. In individuals carrying the Val/Val genotype, higher motor learning was also found to be related to the more remarkable changes in corticospinal excitability caused by the RPM condition. This study revealed that the implementation of a passive movement before a motor learning tasks did not affect M1 excitatory changes and motor learning efficiency; in contrast, in subjects carrying the Val/Val polymorphism, the more significant excitatory changes in the M1 induced by the passive movement and motor learning task led to the improvement of motor learning efficiency. Our results also suggest that homeostatic plasticity occurring in the M1 is involved in this improvement.

Anterior Interosseous Neuropathy in Instrumental Musicians

2006 ◽  
Vol 21 (3) ◽  
pp. 137-141
Author(s):  
Richard J Lederman
Keyword(s):  
Index Finger ◽  
Age At Onset ◽  
Flexor Digitorum Profundus ◽  
Left Index Finger ◽  
Pronator Quadratus ◽  
Motor Branch ◽  
Neuralgic Amyotrophy ◽  
Electrodiagnostic Testing ◽  
The Right ◽  
Flexor Digitorum

The anterior interosseous nerve is a pure motor branch of the median nerve supplying the flexor pollicis longus, flexor digitorum profundus of the index and middle fingers, and pronator quadratus. Anterior interosseous neuropathy is rare and typically causes weakness of flexion of the tips of the thumb and index finger. Four instrumentalists, 3 violinists and 1 pianist (3 males, 1 female), seen from 1986 to 2002 at our clinic, are the subjects of this report. Age at onset ranged from 16 to 76 yrs. A possible precipitating factor was identified in each. One violinist could not hold the bow; two others noted inability to stabilize the distal left first (index) finger. The pianist noted impaired dexterity of the right hand. Examination showed weakness of flexion of the distal phalanx of the index finger and thumb and variable weakness of forearm pronation. Electrodiagnostic testing confirmed the diagnosis in all four patients. All improved over time. One symphony violinist continued to play for over 15 yrs, despite some persisting difficulty with the left index finger. Another violinist recovered function almost completely but suffered a stroke affecting the opposite hand 2.5 years later. The third violinist retired from the symphony on disability because his recovery was delayed for >1 yr. The young pianist is playing 4 to 5 hrs/day. It is likely that at least three of the four had a localized form of neuralgic amyotrophy.

scholarly journals Responses of somatosensory area 2 neurons to actively and passively generated limb movements

2013 ◽  
Vol 109 (6) ◽  
pp. 1505-1513 ◽  
Author(s):  
Brian M. London ◽  
Lee E. Miller
Keyword(s):  
Motor Command ◽  
Accurate Estimate ◽  
Passive Movement ◽  
Efference Copy ◽  
Forward Model ◽  
Sensor Data ◽  
Active Movement ◽  
Noisy Input ◽  
Neural Discharge ◽  
Passive Movements

Control of reaching movements requires an accurate estimate of the state of the limb, yet sensory signals are inherently noisy, because of both noise at the receptors themselves and the stochastic nature of the information representation by neural discharge. One way to derive an accurate representation from noisy sensor data is to combine it with the output of a forward model that considers both the previous state estimate and the noisy input. We recorded from primary somatosensory cortex (S1) in macaques ( Macaca mulatta) during both active and passive movements to investigate how the proprioceptive representation of movement in S1 may be modified by the motor command (through efference copy). We found neurons in S1 that respond to one or both movement types covering a broad distribution from active movement only, to both, to passive movement only. Those neurons that responded to both active and passive movements responded with similar directional tuning. Confirming earlier results, some, but not all, neurons responded before the onset of volitional movements, possibly as a result of efference copy. Consequently, many of the features necessary to combine the forward model with proprioceptive feedback appear to be present in S1. These features would not be expected from combinations of afferent receptor responses alone.

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