Performance of sequential arm movements with and without advance knowledge of motor pathways in Parkinson's disease

Authors

  • Antonio Currà,

    1. Department of Neurological Sciences, “La Sapienza” University of Rome, Rome, Italy
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  • Dr. Alfredo Berardelli,

    Corresponding author
    1. Department of Neurological Sciences, “La Sapienza” University of Rome, Rome, Italy
    2. Mediterranean Neurologic Institute, NEUROMED, Pozzilli (IS), Italy
    • Dipartimento di Scienze Neurologiche, Università degli Studi di Roma “La Sapienza,” Viale dell'Università 30, 00185 Rome, Italy
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  • Rocco Agostino,

    1. Department of Neurological Sciences, “La Sapienza” University of Rome, Rome, Italy
    2. Mediterranean Neurologic Institute, NEUROMED, Pozzilli (IS), Italy
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  • Nicola Modugno,

    1. Department of Neurological Sciences, “La Sapienza” University of Rome, Rome, Italy
    2. Mediterranean Neurologic Institute, NEUROMED, Pozzilli (IS), Italy
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  • Cristiana Conti Puorger,

    1. Department of Neurological Sciences, “La Sapienza” University of Rome, Rome, Italy
    2. Mediterranean Neurologic Institute, NEUROMED, Pozzilli (IS), Italy
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  • Neri Accornero,

    1. Department of Neurological Sciences, “La Sapienza” University of Rome, Rome, Italy
    2. Mediterranean Neurologic Institute, NEUROMED, Pozzilli (IS), Italy
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  • Mario Manfredi

    1. Department of Neurological Sciences, “La Sapienza” University of Rome, Rome, Italy
    2. Mediterranean Neurologic Institute, NEUROMED, Pozzilli (IS), Italy
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Abstract

Patients with Parkinson's disease are slower than normal subjects in executing sequential arm movements, and their bradykinesia worsens as the execution of motor sequences progresses. In parkinsonian and normal subjects, we studied the execution of two types of fast sequential arm movements. The subjects had to perform a motor sequence following with their arm a path marked by six targets on a screen In one experimental condition, they performed the motor sequence without advance knowledge of its path and executed each submovement in response to the consecutive appearance of the targets on the screen (unknown motor sequences). In the other condition, all the targets appeared simultaneously on the screen before the subject moved, and the subject internally determined when to execute each submovement (known motor sequences). Patients were slower than normal subjects in executing both sequences. Patients and normal subjects were faster in executing known than unknown sequences, but the patients' percentage of total movement time diminished less. During the unknown condition, both groups tended to lengthen submovement duration whereas, during the known condition, both groups tended to correct this trend. Patients performed submovements during both sequences with longer acceleration phases. The submovement symmetry ratio of the velocity profile changed according to the direction of movement (up or down). We conclude that these findings depend mainly on the mode of movement execution. They also suggest that patients with Parkinson's disease have more difficulty in executing internally determined than externally triggered sequential movements.

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