Complex Movements Evoked by Microstimulation of Precentral Cortex

Graziano, Michael S. A.; Taylor, Charlotte S. R.; Moore, Tirin

doi:10.1016/s0896-6273(02)00698-0

Cited by 805 publications

(697 citation statements)

References 53 publications

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“…Learning appropriate hand postures is essential for skills as diverse as tennis and manipulating chopsticks, in addition to the hand configurations learned by pianists to produce chords on the keyboard. Behavioral evidence suggests that postures play a privileged role in the representation of perceived movements (Marteniuk & Roy, 1972), and neurophysiological evidence indicates that postures play a critical role in the representation of produced movement (Graziano, Taylor, & Moore, 2002).…”

Section: Discussionmentioning

confidence: 99%

Configural response learning: The acquisition of a nonpredictive motor skill.

Hazeltine¹,

Aparicio²,

Weinstein³

et al. 2007

Journal of Experimental Psychology: Human Perception and Perfor

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This study examined the representational nature of configural response learning using a task that required simultaneous keypresses with 2 or 3 fingers, similar to the production of chords on the piano. If the benefits of learning are related to the retrieval of individual stimulus-response mappings, performance should depend on the frequencies of the individual responses forming each chord. Alternatively, learning may involve the encoding of configural information concerning the relationship between the chord elements. In Experiment 1, training was restricted to a subset of the 120 possible 3-element chords. Probe blocks included the practiced chords, chords composed of novel configurations of practiced elements (reconfigured), and chords that contained a new element (new). Practiced chords were performed faster than reconfigured chords, indicating learning involves the encoding of configural information. Experiment 2 showed that learning was not restricted to configurations within each hand. Experiments 3 and 4 demonstrated that learning was largely response based.

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Section: Discussionmentioning

confidence: 99%

Configural response learning: The acquisition of a nonpredictive motor skill.

Hazeltine¹,

Aparicio²,

Weinstein³

et al. 2007

Journal of Experimental Psychology: Human Perception and Perfor

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show abstract

“…Further evidence for the importance of kinematic parameters in the generation of reaching movements was provided by direct stimulation of the motor cortex (Graziano, Aflalo, & Cooke, 2005;Graziano, Taylor, & Moore, 2002). These studies imply one-toone mappings between workspace and arm posture located in the motor cortex.…”

Section: Relation To Neurophysiological Evidencementioning

confidence: 94%

Inter-joint coupling and joint angle synergies of human catching movements

Bockemühl

Troje

Dürr

2010

Human Movement Science

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A central question in motor control is how the central nervous system (CNS) deals with redundant degrees of freedom (DoFs) inherent in the musculoskeletal system. One way to simplify control of a redundant system is to combine several DoFs into synergies. In reaching movements of the human arm, redundancy occurs at the kinematic level because there are an unlimited number of arm postures for each position of the hand. Redundancy also occurs at the level of muscle forces because each arm posture can be maintained by a set of muscle activation patterns. Both postural and force-related motor synergies may contribute to simplify the control problem. The present study analyzes the kinematic complexity of natural, unrestrained human arm movements, and detects the amount of kinematic synergy in a vast variety of arm postures. We have measured interjoint coupling of the human arm and shoulder girdle during fast, unrestrained and untrained catching movements. Participants were asked to catch a ball launched towards them on 16 different trajectories. These had to be reached from two different initial positions. Movement of the right arm was recorded using optical motion capture and was transformed into 10 joint angle time courses, corresponding to 3 DoFs of the shoulder girdle and 7 of the arm. The resulting time series of the arm postures were analyzed by Principal Components Analysis (PCA). We found that the first three principal components (PCs) always captured more than 97% of the variance. Furthermore, subspaces spanned by PC sets associated with different catching positions varied smoothly across the arm's workspace. When we pooled complete sets of movements, three PCs, the theoretical minimum for reaching in 3D space, were sufficient to explain 80% of the data's variance. We assumed that the linearly correlated DoFs of each significant PC represent cardinal joint angle synergies, and showed that catching movements towards a multitude of targets in the arm's workspace can be generated efficiently by linear combinations of three of such synergies. The contribution of each synergy changed during a single catching movement and often varied systematically with target location. We conclude that unrestrained, one-handed catching movements are dominated by strong kinematic couplings between the joints that reduce the kinematic complexity of the human arm and shoulder girdle to three non-redundant DoFs. ACCEPTED MANUSCRIPT4

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“…For a review of classic work on this topic, see Georgopoulos (1991). Recently, it has been shown that neurons in the primary motor cortex and premotor cortex of the monkey code body postures rather than relative movements (Graziano, Taylor, & Moore, 2002). Electrically stimulating these neurons for behaviorally relevant periods of time (e.g., 500 ms rather than the 20-50 ms used in the classical evoked-movements studies of Penfield and Rasmussen, 1950) elicits characteristic postures of the hand, arm, and face (see Figure 9) regardless of the posture the monkey happens to be in prior to stimulation.…”

Section: Neurons For Movement and Neurons For Posturesmentioning

confidence: 99%