The interaction of visual and proprioceptive inputs in pointing to actual and remembered targets

Abstract

Errors in pointing to actual and remembered targets presented in three-dimensional (3D) space in a dark room were studied under various conditions of visual feedback. During their movements, subjects either had no vision of their arms or of the target, vision of the target but not of their arms, vision of a light-emitting diode (LED) on their moving index fingertip but not of the target, or vision of an LED on their moving index fingertip and of the target. Errors depended critically upon feedback condition. 3D errors were largest for movements to remembered targets without visual feedback, diminished with vision of the moving fingertip, and diminished further with vision of the target and vision of the finger and the target. Moreover, the different conditions differentially influenced the radial distance, azimuth, and elevation errors, indicating that subjects control motion along all three axes relatively independently. The pattern of errors suggest that the neural systems that mediate processing of actual versus remembered targets may have different capacities for integrating visual and proprioceptive information in order to program spatially directed arm movements.

Behavioral Reference Frames for Planning Human Reaching Movements

“…These errors were found to depend critically on visual feedback (Berkinblit et al 1995), proprioceptive information (Hocherman 1993;Soechting and Flanders 1989a,b), eye orientation (Enright 1995;Henriques and Crawford 2002;Medendorp and Crawford 2002;Neggers and Bekkering 2000), initial hand position (Gordon et al 1994;Sainburg et al 2003;Vindras et al 1998Vindras et al , 2005, and delay between target offset and pointing ). It has also been shown that vision of the hand prior to movement initiation improves the accuracy of the movements performed (Carrozzo et al 1999;Prablanc et al 1979;Rossetti et al 1994;Vindras et al 1998).…”

“…This complication arises because in the respective early sensory areas, the position of the target and the position of the hand are coded in different frames of reference. For example, if the hand is not visible, its position must be derived through proprioception (Berkinblit et al 1995). It is known that proprioceptive information about the position of the hand is somatotopically encoded along the posterior bank of the postcentral gyrus, as relative joint angles (Gardner and Costanzo 1981).…”

Contribution of execution noise to arm movement variability in three-dimensional space

“…However, since constant errors tend to be idiosyncratic (Berkinblit et al 1995;Darling and Miller 1993;Foley and Held 1972;Soechting and Flanders 1989), we did not explore their nature in detail here. Instead, analysis focused on the variable errors, which provide more direct information about planning-and execution-related noise (McIntyre et al 1998;Carrozzo et al 1999;van Beers et al 2004).…”

The Trainable Model of Memorization of Movement Sequence Based on Heteroassociative Neural Network

“…Элементами векторов являются направление α и величина перемещения ρ. Направление α хранится дискретно, с шагом 11.5 градусов, максимальная величина перемещения составляет 6 квадратов (из одного угла листа в другой по диагонали), поэтому для хранения α и ρ в бинаризованной форме требуется 5 формальных нейронов и 3 формальных нейрона соответственно. Параметры α и ρ хранятся в рамках двух отдельных сетей (подсетей), между которыми отсутствуют связи, что соответствует имеющимся в литературе сведениям о раздельном кодировании в мозге направления и амплитуды движения [19][20][21]. Предварительные опыты с моделью показали, что если использовать только симметричные матрицы, то не удается добиться результатов, подобных психофизиологическим экспериментам.…”

“…И такая «гибридная» сеть несколько лучше запоминает направление, чем амплитуду «движения». Существуют данные психофизических опытов о том, что и человек лучше запоминает направление движения, чем амплитуду [20].…”