RT Journal Article
SR Electronic
T1 Eye Proprioception Used for Visual Localization Only If in Conflict with the Oculomotor Plan
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 8569
OP 8573
DO 10.1523/JNEUROSCI.1488-12.2012
VO 32
IS 25
A1 Balslev, Daniela
A1 Himmelbach, Marc
A1 Karnath, Hans-Otto
A1 Borchers, Svenja
A1 Odoj, Bartholomaeus
YR 2012
UL http://www.jneurosci.org/content/32/25/8569.abstract
AB Both the corollary discharge of the oculomotor command and eye muscle proprioception provide eye position information to the brain. Two contradictory models have been suggested about how these two sources contribute to visual localization: (1) only the efference copy is used whereas proprioception is a slow recalibrator of the forward model, and (2) both signals are used together as a weighted average. We had the opportunity to test these hypotheses in a patient (R.W.) with a circumscribed lesion of the right postcentral gyrus that overlapped the human eye proprioceptive representation. R.W. was as accurate and precise as the control group (n = 19) in locating a lit LED that she viewed through the eye contralateral to the lesion. However, when the task was preceded by a brief (<1 s), gentle push to the closed eye, which perturbed eye position and stimulated eye proprioceptors in the absence of a motor command, R.W.'s accuracy significantly decreased compared with both her own baseline and the healthy control group. The data suggest that in normal conditions, eye proprioception is not used for visual localization. Eye proprioception is, however, continuously monitored to be incorporated into the eye position estimate when a mismatch with the efference copy of the motor command is detected. Our result thus supports the first model and, furthermore, identifies the limits for its operation.