@Article{2019ACLI4754,
  author   = {Guigon, E and Chafik , O and Jarrassé, N and Roby-Brami, A},
  journal  = {Journal of neurophysiology},
  title    = {Experimental and theoretical study of velocity fluctuations during slow movements in humans},
  year     = {2019},
  pages    = {715-727},
  volume   = {2},
  abstract = {Moving smoothly is generally considered as a higher-order goal of motor control and moving jerkily as a witness of clumsiness or pathology, yet many common and well-controlled movements (e.g., tracking movements) have irregular velocity profiles with widespread fluctuations. The origin and nature of these fluctuations have been associated with the operation of an intermittent process but in fact remain poorly understood. Here we studied velocity fluctuations during slow movements, using combined experimental and theoretical tools. We recorded arm movement trajectories in a group of healthy participants performing back-and-forth movements at different speeds, and we analyzed velocity profiles in terms of series of segments (portions of velocity between 2 minima). We found that most of the segments were smooth (i.e., corresponding to a biphasic acceleration) and had constant duration irrespective of movement speed and linearly increasing amplitude with movement speed. We accounted for these observations with an optimal feedback control model driven by a staircase goal position signal in the presence of sensory noise. Our study suggests that one and the same control process can explain the production of fast and slow movements, i.e., fast movements emerge from the immediate tracking of a global goal position and slow movements from the successive tracking of intermittently updated intermediate goal positions.},
  category = {ACLI},
  crac     = {y},
  doi      = {10.1152/jn.00576.2018},
  file     = {:http\://hal.archives-ouvertes.fr/hal-02109365/document:PDF;:http\://www.n-jarrasse.fr/publis_medias/2019ACLI4754.jpg:JPG image;},
  hal      = {y},
  hal_id   = {hal-02109365},
}