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The readiness potential and conscious will: the impact of spontaneous neural activity| old_uid | 11286 |
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| title | The readiness potential and conscious will: the impact of spontaneous neural activity |
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| start_date | 2012/04/17 |
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| schedule | 12h-13h30 |
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| online | no |
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| summary | The origin of voluntary, self-initiated movements poses a particularly puzzling problem for neuroscience. Where do self-initiated movements “come from” in the brain and what determines their precise time of onset? A gradual buildup of neuronal activity commonly known as the “readiness potential” (or Bereitschaftspotential) reliably precedes self-initiated movements, in the average over many epochs time-locked to movement onset. The onset of this buildup is presumed to reflect the onset of planning and preparation for movement. Its discovery in the mid 1960's by Kornhuber and Deecke has given birth to an entire field of research. However, we still lack a precise mechanistic account of what the RP reflects, beyond descriptive phrases such as "planning and preparation for movement". Here we will offer such an account in terms of ongoing spontaneous fluctuations in neural activity, a neural accumulator, and a threshold. Our account departs dramatically from the assumptions about the nature of the readiness potential that have prevailed for more than 40 years.
According to our model, self-initiated movements are most likely to occur when spontaneous random fluctuations in neural activity bring the motor system closer to the threshold for movement. Time-locking to movement onset ensures that the spontaneous fluctuations that contributed to the threshold crossing will appear in the average as a gradual exponential-looking increase in neural activity. Our model accounts for the pattern of behavioral and electrophysiology data associated with spontaneous movement tasks, and also makes a novel prediction that we confirmed with an electroencephalography experiment: fast responses to temporally unpredictable interruptions should be preceded by a slow negative-going voltage deflection beginning well before the interruption itself, even when the subject was not preparing to move at that particular moment. |
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| oncancel | Séance annulée. |
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| responsibles | Sackur |
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