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Long-term motor cortex plasticity induced by an electronic neural implant


It has been proposed that the efficacy of neuronal connections is strengthened when there is a persistent causal relationship between presynaptic and postsynaptic activity. Such activity-dependent plasticity may underlie the reorganization of cortical representations during learning, although direct in vivo evidence is lacking. Here we show that stable reorganization of motor output can be induced by an artificial connection between two sites in the motor cortex of freely behaving primates. An autonomously operating electronic implant used action potentials recorded on one electrode to trigger electrical stimuli delivered at another location. Over one or more days of continuous operation, the output evoked from the recording site shifted to resemble the output from the corresponding stimulation site, in a manner consistent with the potentiation of synaptic connections between the artificially synchronized populations of neurons. Changes persisted in some cases for more than one week, whereas the output from sites not incorporated in the connection was unaffected. This method for inducing functional reorganization in vivo by using physiologically derived stimulus trains may have practical application in neurorehabilitation after injury.

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Figure 1: Conditioning protocol and experimental design.
Figure 2: Reorganization of motor output after conditioning.
Figure 3: Summary of conditioning results.
Figure 4: Dependence of conditioning effects on delay between spikes and stimuli.
Figure 5: Suggested mechanism for the conditioning effect documented in Fig. 2 .

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We thank C. Kirby for technical help, F. Miles for development of the Neurochip stimulator, L. Shupe for programming, and S. Perlmutter for advice. This work was supported by grants from the National Institutes of Health, the Office of Naval Research and the University of Washington Royalty Research Fund. Author Contributions A.J. and E.E.F. conceived and designed the experiment. J.M. designed the Neurochip electronics. A.J. and J.M. performed the experiments. A.J. and E.E.F. wrote the paper.

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Correspondence to Eberhard E. Fetz.

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Supplementary information

Supplementary Table 1

Supplementary material details surgical procedures, the Neurochip electronics and additional methods. Supporting data includes documentation of cell firing patterns, further examples of conditioning experiments and a table summarising all sessions. (PDF 620 kb)

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Jackson, A., Mavoori, J. & Fetz, E. Long-term motor cortex plasticity induced by an electronic neural implant. Nature 444, 56–60 (2006).

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