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

• Published in: Nature 2006-11, Vol.444 (7115), p.56-60
• Main Authors: Fetz, Eberhard E, Jackson, Andrew, Mavoori, Jaideep
• Format: Article
• Language: English
• Subjects: Action Potentials; Animals; Biological and medical sciences; Biophysics; Electric Stimulation; Electrodes; Electrodes, Implanted; Fundamental and applied biological sciences. Psychology; Humanities and Social Sciences; Macaca nemestrina - physiology; Male; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Motor Cortex - physiology; Movement - physiology; multidisciplinary; Neuronal Plasticity - physiology; Neurons; Neurosciences; Plasticity; Primates; Science; Science (multidisciplinary); Time Factors; Torque; Transplants & implants; Vertebrates: nervous system and sense organs
• ISSN: 0028-0836; 1476-4687; 1476-4679
• DOI: 10.1038/nature05226

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. Making connections As part of a project to develop implantable electronic circuits or 'neurochips' to replace damaged pathways in the nervous system, Jackson et al . have produced a neural implant that forms an artificial connection between two cortical sites in the primate brain. The implant uses action potentials recorded on one electrode to deliver electric stimuli to another. After a few days, the output from the recording site resembles that from the stimulation site, consistent with the potentiation of synaptic connections between synchronized neuronal populations. This way of reorganizing neurons in vivo may have practical application in neurorehabilitation after injury.