Show Reference: "Neurons in the primate superior colliculus coding for arm movements in gaze-related coordinates"

Neurons in the primate superior colliculus coding for arm movements in gaze-related coordinates. Journal of Neurophysiology, Vol. 83, No. 3. (1 March 2000), pp. 1283-1299 by Veit Stuphorn, Erhard Bauswein, Klaus-Peter Hoffmann
@article{stuphorn-et-al-2000,
    abstract = {In the intermediate and deep layers of the superior colliculus ({SC}), a well-established oculomotor structure, a substantial population of cells is involved in the control of arm movements. To examine the reference frame of these neurons, we recorded in two rhesus monkeys (Macaca mulatta) the discharges of 331 neurons in the {SC} and the underlying mesencephalic reticular formation ({MRF}) while monkeys reached to the same target location during different gaze orientations. For 65 reach-related cells with sufficient data and for simultaneously recorded electromyograms ({EMGs}) of 11 arm muscles, we calculated an {ANOVA} (factors: target position, gaze angle) and a gaze-dependency ({GD}) index. {EMGs} and the activity of many (60\%) of the reach-related neurons were not influenced by the target representation on the retina or eye position. We refer to these as "gaze-independent" reach neurons. For 40\%, however, the {GD} fell outside the range of the muscle modulation, and the {ANOVA} showed a significant influence of gaze. These "gaze-related" reach neurons discharge only when the monkey reaches for targets having specific coordinates in relation to the gaze axis, i.e., for targets in a gaze-related "reach movement field" ({RMF}). Neuronal activity was not modulated by the specific path of the arm movement, the muscle pattern that is necessary for its realization or the arm that was used for the reach. In each {SC} we found gaze-related neurons with {RMFs} both in the contralateral and in the ipsilateral hemifield. The topographical organization of the gaze-related reach neurons in the {SC} could not be matched with the well-known visual and oculomotor maps. Gaze-related neurons were more modulated in their strength of activity with different directions of arm movements than were gaze-independent reach neurons. Gaze-related reach neurons were recorded at a median depth of 2.03 mm below {SC} surface in the intermediate layers, where they overlap with saccade-related burst neurons (median depth: 1.55 mm). Most of the gaze-independent reach cells were found in a median depth of 4.01 mm below the {SC} surface in the deep layers and in the underlying {MRF}. The gaze-related reach neurons operating in a gaze-centered coordinate system could signal either the desired target position with respect to gaze direction or the motor error between gaze axis and reach target. The gaze-independent reach neurons, possibly operating in a shoulder- or arm-centered reference frame, might carry signals closer to motor output. Together these two types of reach neurons add evidence to our hypothesis that the {SC} is involved in the sensorimotor transformation for eye-hand coordination in primates.},
    address = {Allgemeine Zoologie und Neurobiologie, Ruhr-Universit\"{a}t, 44780 Bochum, Germany.},
    author = {Stuphorn, Veit and Bauswein, Erhard and Hoffmann, Klaus-Peter},
    day = {1},
    issn = {0022-3077},
    journal = {Journal of Neurophysiology},
    keywords = {biology, motor, sc, visual},
    month = mar,
    number = {3},
    pages = {1283--1299},
    pmid = {10712456},
    posted-at = {2012-11-05 11:55:20},
    priority = {2},
    title = {Neurons in the primate superior colliculus coding for arm movements in gaze-related coordinates.},
    url = {http://jn.physiology.org/content/83/3/1283.abstract},
    volume = {83},
    year = {2000}
}

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Stuphorn et al. found neurons in the monkey SC whose activity was dependent on the retinotopic position of the target in a reaching task, but not to the actual path taken in reaching.

The SC also seems to be involved in reaching and other forelimb-related motor tasks and has been associated with complex vision-guided arm-gestures in humans.