Abstract:
:Two versions of the hypothesis that discrete movements are produced by shifts in the system's equilibrium point are considered. The first suggests that shifts are monotonic and end near the peak velocity of movement, and the second presumes that they are nonmonotonic ("N-shaped") and proceed until the end of movement. The first version, in contrast to the second, predicts that movement time may be significantly reduced by opposing loads without changes in the control pattern. The purpose of the present study was to test the two hypotheses about the duration and shape of the shift in the equilibrium point based on their respective predictions concerning the effects of perturbations on kinematic and EMG patterns in fast elbow flexor movements. Subjects performed unopposed flexions of about 55-70 degrees (control trials) and, in random test trials, movements were opposed by spring-like loads generated by a torque motor. Subjects had no visual feedback and were instructed not to correct arm deflections in case of perturbations. After the end of the movement, the load was removed leading to a secondary movement to the same final position as that in control trials (equifinality). When the load was varied, the static arm positions before unloading and associated joint torques (ranging from 0 to 80-90% of maximum voluntary contraction) had a monotonic relationship. Test movements opposed by a high load (80-90% of maximal voluntary contraction) ended near the peak velocity of control movements. Phasic and tonic electromyographic patterns were load-dependent. In movements opposed by high loads, the first agonist burst was significantly prolonged and displayed a high level of tonic activity for as long as the load was maintained. In the same load conditions, the antagonist burst was suppressed during the dynamic and static phases of movement. The findings of suppression of the antagonist burst does not support the hypothesis of an N-shaped control signal. Equally, the substantial reduction in movement time by the introduction of an opposing load cannot be reconciled in this model. Instead, our data indicate that the shifts in the equilibrium point underlying fast flexor movements are of short duration, ending near the peak velocity of unopposed movement. This suggests that kinematic and electromyographic patterns represent a long-lasting oscillatory response of the system to the short-duration monotonic control pattern, external forces and proprioceptive feedback.
journal_name
Exp Brain Resjournal_title
Experimental brain researchauthors
Feldman AG,Adamovich SV,Levin MFdoi
10.1007/BF00241503subject
Has Abstractpub_date
1995-01-01 00:00:00pages
440-50issue
3eissn
0014-4819issn
1432-1106journal_volume
103pub_type
临床试验,杂志文章,随机对照试验abstract::A force-matching task was used to study the influence of constraining tactile information from the hand on the perception of forces generated with the index finger flexors, the palmar prehensile grasp and with the elbow flexors. Subjects generated the same reference forces (2-10 N) with each muscle group and matched t...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-005-0259-8
更新日期:2006-01-01 00:00:00
abstract::During transient, high-acceleration rotation, performance of the normal vestibulo-ocular reflex (VOR) depends on viewing distance. With near targets, gain (eye velocity/head velocity) enhancement is manifest almost immediately after ocular rotation begins. Later in the response, VOR gain depends on both head rotation ...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s002219900266
更新日期:2000-02-01 00:00:00
abstract::The extent and strength of long-distance coupling between locomotor networks in the rostral and caudal spinal cord of larval lamprey were examined with in vitro brain/spinal cord preparations, in which spinal locomotor activity was initiated by chemical microstimulation in the brain, as well as with computer modeling....
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s002210050719
更新日期:1999-05-01 00:00:00
abstract::The aim of this study was to investigate the effect of single joint displacement on the pattern of leg muscle electromyographic (EMG) activity during locomotion. For the first time, unilateral rotational hip or knee joint displacements were applied by a driven orthotic device at three phases of swing during locomotion...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-004-1904-3
更新日期:2004-10-01 00:00:00
abstract::Adult-like fine control of cyclical motor patterns found in locomotion develops into adolescence. Single-leg hopping in place is one such motor pattern where children have demonstrated a reduced capacity to control horizontal motion and match metronome cues. These developmental differences might arise from immature in...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-019-05548-5
更新日期:2019-07-01 00:00:00
abstract::When a target moves to a new location during a rapid aiming movement, the hand follows it, even when the participant intends not to. Pisella et al. (Nat Neurosci 3:729-736, 2000) claim that the posterior parietal cortex, in the dorsal visual stream, is responsible for this 'automatic pilot'. Here we study the limits o...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-007-0935-y
更新日期:2007-08-01 00:00:00
abstract::Although maintenance of steady contractions is required for many daily tasks, there is little understanding of brain areas that modulate lower limb force accuracy. Functional magnetic resonance imaging was used to determine brain areas associated with steadiness and force during static (isometric) lower limb target-ma...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-014-3976-z
更新日期:2014-10-01 00:00:00
abstract::In order to determine whether neurones in the parvicellular reticular formation are in direct synaptic contact with motoneurones innervating facial muscles, a combined retrograde and anterograde transport study was carried out in the rat. Animals received injections of the retrograde tracer cholera toxin B conjugated ...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00227336
更新日期:1994-01-01 00:00:00
abstract::In order to investigate the role of mental rotation in the directional control of eye movements, we instructed subjects to make saccades in directions different from that of a visual stimulus (rotated saccades). Saccadic latency increased linearly with the amount of directional transformation imposed between the stimu...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s002210050765
更新日期:1999-06-01 00:00:00
abstract::Growing evidence suggests that blind subjects outperform the sighted on certain tactile discrimination tasks depending on cutaneous inputs. The purpose of this study was to compare the performance of blind (n = 14) and sighted (n = 15) subjects in a haptic angle discrimination task, depending on both cutaneous and pro...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-008-1327-7
更新日期:2008-06-01 00:00:00
abstract::Neurostimulation, e.g., transcranial direct current stimulation (tDCS), shows promise as an effective cognitive intervention. In spite of low spatial resolution, limited penetration, and temporary influence, evidence highlights tDCS-linked cognitive benefits in a range of cognitive domains. The left posterior parietal...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-014-4090-y
更新日期:2014-12-01 00:00:00
abstract::We examined the effects of cerebellar cortical lesions upon conditioned nictitating membrane responses in rabbits. Using extended postoperative conditioning and unpaired presentations of the conditioned stimuli (CSs), we confirmed that combined lesions of lobules HVI and ansiform lobe abolished conditioned responses (...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00228191
更新日期:1992-01-01 00:00:00
abstract::After several days of exposure to optically-imposed post-saccadic retinal slip, the saccades of normal monkeys acquire an exponential ocular drift. This drift is in the direction of the imposed image motion, and persists in the dark. It has been argued that these changes result from the operation of a visually mediate...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00340497
更新日期:1986-01-01 00:00:00
abstract::Several recent studies indicate that saccades elicited in the absence of a visual target are slower than visually-guided movements of the same size. In addition, we have shown earlier that the slower saccades observed in two different paradigms had more asymmetrical (skewed) velocity profiles. Recently, it has been re...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00253624
更新日期:1989-01-01 00:00:00
abstract::Limb proprioception is an awareness by the central nervous system (CNS) of the location of a limb in three-dimensional space and is essential for movement and postural control. The CNS uses the position of the head and neck when interpreting the position of the upper limb, and altered input from neck muscles may affec...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-015-4240-x
更新日期:2015-05-01 00:00:00
abstract::Predicted motion (PM) tasks test the accuracy of predicting the future position of a moving target. Previous PM studies using audiovisual stimuli have suggested that observers rely primarily on visual motion cues. To clarify the role of auditory signals in predicting future positions of bimodal targets, we designed a ...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-010-2224-4
更新日期:2010-06-01 00:00:00
abstract::Changes in cognition due to age have been associated with falls and reduced standing postural control. Sensory integration is one component of postural control that may be influenced by certain aspects of cognitive functioning. This study investigated associations between measures of cognitive function and sensory int...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-018-5394-0
更新日期:2019-01-01 00:00:00
abstract::Anticipatory pursuit is not exclusively based on the recent history of target motion ("temporal anticipation"): it can also use static visual cues ("non-temporal anticipation"). Large non-temporal anticipatory changes of the direction of smooth pursuit are observed when the future trajectory of the target can be infer...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-009-1840-3
更新日期:2009-06-01 00:00:00
abstract::After injection of S35-methionine into cervical and lumbar dorsal root ganglia in turtle, a primary afferent projection was demonstrated on to the cerebellum. Few, but consistent patches of silver grains were found within the granular layer suggesting mossy fiber terminations. The projection was mainly ipsilateral and...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF01208609
更新日期:1982-01-01 00:00:00
abstract::We conducted a series of experiments to determine whether negative priming is used in the process of target selection for a saccadic eye movement. The key questions addressed the circumstances in which the negative priming of an object takes place, and the distinction between spatial and object-based effects. Experime...
journal_title:Experimental brain research
pub_type: 杂志文章,随机对照试验
doi:10.1007/s00221-012-3234-1
更新日期:2012-10-01 00:00:00
abstract::The tuberomammillary nucleus (TM) located in the posterior part of the hypothalamus is the main source of neuronal histamine in the central nervous system. Recent work from our laboratories has indicated an involvement of the TM region in neuronal plasticity and reinforcement processes. In the present study, we invest...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s002210050301
更新日期:1998-02-01 00:00:00
abstract::It was previously proposed that a linkage between the optokinetic system and the stereoscopic system in higher mammals serves to allow these animals to selectively stabilize those parts of the visual scene which lie in the plane of convergence as the animals move forward in a three-dimensional world (Howard and Ohmi, ...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00228902
更新日期:1989-01-01 00:00:00
abstract::The principal goal of our study is to gain an insight into the representation of peripersonal space. Two different experiments were conducted in this study. In the first experiment, subjects were asked to represent principal anatomical reference planes by drawing ellipses in the sagittal, frontal and horizontal planes...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-005-0121-z
更新日期:2006-02-01 00:00:00
abstract::It has recently been suggested that time perception and motor timing are influenced by the presence of biological movements and animacy in the visual scene. Here, we investigated the interactions among timing, speed and animacy in two experiments. In Experiment 1, observers had to press a button in synchrony with the ...
journal_title:Experimental brain research
pub_type: 杂志文章,随机对照试验
doi:10.1007/s00221-012-3338-7
更新日期:2013-02-01 00:00:00
abstract::Experimental neurogenic tumors were induced transplacentally in rats by single injections of ethylnitrosourea (ENU). The resulting primary tumors as well as isogenic transplantation tumor lines and clonal cell lines derived therefrom were examined for their content of the brain specific protein 14-3-2 by a quantitativ...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00237328
更新日期:1976-05-10 00:00:00
abstract::Visual stimulation alone is sufficient to produce visually induced postural reactivity (VIPR). While some studies have shown that VIPR increases with the velocity of a moving visual stimulus, others have shown that it decreases with the temporal frequency of an oscillating visual stimulus. These results seem contradic...
journal_title:Experimental brain research
pub_type: 杂志文章,随机对照试验
doi:10.1007/s00221-013-3592-3
更新日期:2013-08-01 00:00:00
abstract::Reaching to a veridical target permits an egocentric spatial code (i.e., absolute limb and target position) to effect fast and effective online trajectory corrections supported via the visuomotor networks of the dorsal visual pathway. In contrast, a response entailing decoupled spatial relations between stimulus and r...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-018-5205-7
更新日期:2018-04-01 00:00:00
abstract::N-methyl-D-aspartate (NMDA) receptor-mediated activity is considered important for experience-dependent plasticity in the developing visual system. We investigated the influence of age and experience on the role of NMDA receptors in the visual transmission in the superficial grey layer of the superior colliculus (SGS)...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s002210050407
更新日期:1998-06-01 00:00:00
abstract::The effect of unilateral vestibular deafferentation (UVD) on the linear vestibulo-ocular reflex (LVOR) was studied in 11 humans an average of 52 months following surgical UVD. Controls consisted of seven healthy age-matched subjects. The LVOR was evoked by directionally random, transient whole body interaural (heave) ...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-004-2089-5
更新日期:2005-03-01 00:00:00
abstract::Limitations in visual working memory (VWM) have been extensively studied in psychophysical tasks, but not well understood in terms of how these memory limits translate to performance in more natural domains. For example, in reaching to grasp an object based on a spatial memory representation, overshooting the intended...
journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/s00221-016-4553-4
更新日期:2016-06-01 00:00:00