Learning and Memory Formation of Arm Movements

Shadmehr, Reza; Thoroughman, Kurt A.

doi:10.1007/978-1-4612-2104-3_27

Cited by 9 publications

(6 citation statements)

References 23 publications

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“…However, syringeal motor gestures reflect motor activity that is directly controlled by premotor activity in RA and thus reflect the population output signal from RA. This motor information parallels insights gained from studying peripheral activation patterns in the process of learning other motor skills (Shadmehr and Holcomb 1997;Shadmehr and Thoroughman 2000;Thoroughman and Shadmehr 1999). However, the song learning system is unique in that it does not only represent a motor learning process but motor learning as a consequence of the acquisition of an acoustic template for song.…”

Section: Implications For How Experience Shapes Vocal Motor Programssupporting

confidence: 56%

Acquisition of an Acoustic Template Leads to Refinement of Song Motor Gestures

Méndez

Dall'Asén

Cooper

et al. 2010

Journal of Neurophysiology

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Méndez JM, Dall'Asén AG, Cooper BG, Goller F. Acquisition of an acoustic template leads to refinement of song motor gestures. J Neurophysiol 104: 984 -993, 2010. First published June 16, 2010 doi:10.1152/jn.01031.2009. Vocal learning, a key behavior in human speech development, occurs only in a small number of animal taxa. Ontogeny of vocal behavior in humans and songbirds involves acquisition of an acoustic model, which guides the development of selfgenerated vocalizations (sensorimotor period). How vocal development proceeds in the absence of an acoustic model is largely unknown and cannot be studied directly in humans. Here we explored the effects of an acoustic model on song motor control by comparing peripheral motor gestures (respiration and syringeal muscles) of tutored birds with those of birds raised in acoustic isolation. Although the overall use of syringeal muscles during song was similar in both groups, tutored birds displayed enhanced temporal patterns of activation in respiratory and syringeal motor gestures. Muscle activation was more uniformly distributed throughout the song of tutored birds than that of untutored birds. Similarly, the respiratory effort was similar for both groups, but the expiratory pulses of song contained more modulations and temporal complexity in tutored birds. These results indicate that the acquisition of an acoustic template guides a refinement of experience-independent motor gestures by increasing temporal fine structure, but there is no difference in bilateral activation patterns for a given sound between the two groups. Nevertheless, these subtle temporal changes in muscle activation give rise to pronounced acoustic differences between the songs of the tutored and untutored birds. Experience with song during ontogeny therefore guides a more refined use of experience-independent motor programs.

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Section: Implications For How Experience Shapes Vocal Motor Programssupporting

confidence: 56%

Acquisition of an Acoustic Template Leads to Refinement of Song Motor Gestures

Méndez

Dall'Asén

Cooper

et al. 2010

Journal of Neurophysiology

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“…The association requires few (if any) changes in the kinematics to dynamics transformations since there was no alternation in the relationship between movement and muscle activity. We therefore hypothesize that in force-field adaptation tasks (Shadmehr and Thoroughman, 1998;Li et al, 2001) that require changes of kinematics to dynamics transformations, trial-to-trial variability should be observed during movement as well.…”

Section: Premovement Variability and Motor Statesmentioning

confidence: 99%

Trial-to-Trial Variability of Single Cells in Motor Cortices Is Dynamically Modified during Visuomotor Adaptation

Mandelblat-Cerf¹,

Paz²,

Vaadia³

2009

J. Neurosci.

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Neurons in all brain areas exhibit variability in their spiking activity. Although part of this variability can be considered as noise that is detrimental to information processing, recent findings indicate that variability can also be beneficial. In particular, it was suggested that variability in the motor system allows for exploration of possible motor states and therefore can facilitate learning and adaptation to new environments. Here, we provide evidence to support this idea by analyzing the variability of neurons in the primary motor cortex (M1) and in the supplementary motor area (SMA-proper) of monkeys adapting to new rotational visuomotor tasks. We found that trial-to-trial variability increased during learning and exhibited four main characteristics: (1) modulation occurred preferentially during a delay period when the target of movement was already known, but before movement onset; (2) variability returned to its initial levels toward the end of learning; (3) the increase in variability was more apparent in cells with preferred movement directions close to those experienced during learning; and (4) the increase in variability emerged at early phases of learning in the SMA, whereas in M1 behavior reached plateau levels of performance. These results are highly consistent with previous findings that showed similar trends in variability across a population of neurons. Together, the results strengthen the idea that single-cell variability can be much more than mere noise and may be an integral part of the underlying mechanism of sensorimotor learning.

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“…Flash and Hogan (1985) chose the jerk (integral of the third time derivative of the hand coordinates squared) as a cost function to be minimized (Hoff and Arbib 1993). The applied model of population coding does precisely this, given the provision that the Gestalt of the trajectories is evaluated in visual space (Wolpert et al 1995a,b;Shadmehr and Thoroughman 2000;Buneo and Andersen 2006). However, point-to-point movements are not in general performed on a straight line or result in a bell-shaped velocity profile (Fleischer and Becker 1986).…”

Section: Discussionmentioning

confidence: 97%

Schema generation in recurrent neural nets for intercepting a moving target

Fleischer¹

2010

Biol Cybern

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The grasping of a moving object requires the development of a motor strategy to anticipate the trajectory of the target and to compute an optimal course of interception. During the performance of perception-action cycles, a preprogrammed prototypical movement trajectory, a motor schema, may highly reduce the control load. Subjects were asked to hit a target that was moving along a circular path by means of a cursor. Randomized initial target positions and velocities were detected in the periphery of the eyes, resulting in a saccade toward the target. Even when the target disappeared, the eyes followed the target's anticipated course. The Gestalt of the trajectories was dependent on target velocity. The prediction capability of the motor schema was investigated by varying the visibility range of cursor and target. Motor schemata were determined to be of limited precision, and therefore visual feedback was continuously required to intercept the moving target. To intercept a target, the motor schema caused the hand to aim ahead and to adapt to the target trajectory. The control of cursor velocity determined the point of interception. From a modeling point of view, a neural network was developed that allowed the implementation of a motor schema interacting with feedback control in an iterative manner. The neural net of the Wilson type consists of an excitation-diffusion layer allowing the generation of a moving bubble. This activation bubble runs down an eye-centered motor schema and causes a planar arm model to move toward the target. A bubble provides local integration and straightening of the trajectory during repetitive moves. The schema adapts to task demands by learning and serves as forward controller. On the basis of these model considerations the principal problem of embedding motor schemata in generalized control strategies is discussed.

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Learning and Memory Formation of Arm Movements

Cited by 9 publications

References 23 publications

Acquisition of an Acoustic Template Leads to Refinement of Song Motor Gestures

Acquisition of an Acoustic Template Leads to Refinement of Song Motor Gestures

Trial-to-Trial Variability of Single Cells in Motor Cortices Is Dynamically Modified during Visuomotor Adaptation

Schema generation in recurrent neural nets for intercepting a moving target

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