title: The sources of variability in saccadic eye movements.
abstract: Our movements are variable, but the origin of this variability is poorly understood. We examined the sources of variability in human saccadic eye movements. In two experiments, we measured the spatiotemporal variability in saccade trajectories as a function of movement direction and amplitude. One of our new observations is that the variability in movement direction is smaller for purely horizontal and vertical saccades than for saccades in oblique directions. We also found that saccade amplitude, duration, and peak velocity are all correlated with one another. To determine the origin of the observed variability, we estimated the noise in motor commands from the observed spatiotemporal variability, while taking into account the variability resulting from uncertainty in localization of the target. This analysis revealed that uncertainty in target localization is the major source of variability in saccade endpoints, whereas noise in the magnitude of the motor commands explains a slightly smaller fraction. In addition, there is temporal variability such that saccades with a longer than average duration have a smaller than average peak velocity. This noise model has a large generality because it correctly predicts the variability in other data sets, which contain saccades starting from very different initial locations. Because the temporal noise most likely originates in movement planning, and the motor command noise in movement execution, we conclude that uncertainty in sensory signals and noise in movement planning and execution all contribute to the variability in saccade trajectories. These results are important for understanding how the brain controls movement.
authors: Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands. r.j.vanbeers@phys.uu.nl
authors: Robert J
authors: RJ
authors: van Beers
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008954:Models, Biological; D009949:Orientation / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011237:Predictive Value of Tests; D012438:Saccades / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*
references: Invest Ophthalmol Vis Sci. 2000 May;41(6):1280-90
references: 10798641
references: Exp Brain Res. 2000 May;132(1):39-51
references: 10836634
references: Invest Ophthalmol Vis Sci. 2001 Jan;42(1):10-6
references: 11133842
references: Proc Biol Sci. 2001 May 22;268(1471):995-9
references: 11375081
references: J Neurosci Methods. 2002 Mar 15;114(2):185-95
references: 11856570
references: J Neurophysiol. 2002 Aug;88(2):692-8
references: 12163522
references: J Neurophysiol. 2002 Sep;88(3):1533-44
references: 12205173
references: J Neurophysiol. 2003 Jul;90(1):12-20
references: 12611965
references: Vision Res. 1992 Nov;32(11):2055-64
references: 1304083
references: Schweiz Arch Neurol Psychiatr. 1953;72(1-2):362-76
references: 13168272
references: J Physiol. 1964 Nov;174:245-64
references: 14244121
references: Vision Res. 1992 Sep;32(9):1729-37
references: 1455744
references: J Neurophysiol. 2004 Feb;91(2):1050-63
references: 14561687
references: Exp Brain Res. 2004 Aug;157(4):417-30
references: 15014922
references: Vision Res. 1992 Jun;32(6):1099-113
references: 1509700
references: Neural Comput. 2004 Oct;16(10):2021-40
references: 15333205
references: Spat Vis. 2005;18(2):159-67
references: 15856934
references: Vision Res. 1992 Mar;32(3):513-26
references: 1604838
references: Nature. 2005 Sep 15;437(7057):412-6
references: 16163357
references: Invest Ophthalmol Vis Sci. 2006 Jan;47(1):179-87
references: 16384960
references: Vision Res. 2006 May;46(11):1724-31
references: 16413594
references: J Neurophysiol. 2006 Jun;95(6):3875-86
references: 16571740
references: Neuron. 2006 Dec 21;52(6):1085-96
references: 17178410
references: J Neurophysiol. 1991 Dec;66(6):2125-40
references: 1725880
references: J Neurosci. 2007 Mar 14;27(11):2987-98
references: 17360922
references: Proc Natl Acad Sci U S A. 2007 May 8;104(19):8137-42
references: 17470812
references: Exp Brain Res. 1991;86(1):209-15
references: 1756791
references: Acta Otolaryngol Suppl. 1991;481:382-7
references: 1927423
references: Vision Res. 1990;30(1):111-27
references: 2321357
references: Vision Res. 1990;30(4):557-85
references: 2339510
references: Rev Oculomot Res. 1989;3:13-67
references: 2486323
references: Vision Res. 1989;29(9):1183-96
references: 2617864
references: Vision Res. 1989;29(12):1737-48
references: 2631395
references: J Physiol. 1988 Oct;404:157-82
references: 3253429
references: J Physiol. 1988 Oct;404:183-97
references: 3253430
references: Vision Res. 1987;27(10):1745-62
references: 3445465
references: J Opt Soc Am A. 1987 Aug;4(8):1562-7
references: 3625337
references: Vision Res. 1987;27(6):929-38
references: 3660654
references: J Neurophysiol. 1987 Oct;58(4):832-49
references: 3681398
references: Brain Res. 1986 Sep 3;381(2):401-4
references: 3756515
references: Biol Cybern. 1986;55(1):43-57
references: 3801529
references: Jpn J Ophthalmol. 1983;27(4):631-46
references: 6668756
references: J Neurophysiol. 1981 Mar;45(3):417-42
references: 7218009
references: Biol Cybern. 1981;39(2):87-96
references: 7236748
references: Vision Res. 1995 Jun;35(12):1727-39
references: 7660581
references: Invest Ophthalmol Vis Sci. 1995 May;36(6):1125-36
references: 7730022
references: J Neurophysiol. 1994 Sep;72(3):1425-9
references: 7807223
references: Exp Brain Res. 1994;101(3):525-8
references: 7851520
references: Exp Brain Res. 1994;99(1):97-111
references: 7925800
references: J Neurophysiol. 1994 Feb;71(2):623-38
references: 8176431
references: Vision Res. 1995 Dec;35(23-24):3243-54
references: 8560796
references: Vision Res. 1995 Dec;35(23-24):3321-34
references: 8560803
references: Vision Res. 1997 Apr;37(7):935-47
references: 9156190
references: Vision Res. 1997 Aug;37(16):2271-82
references: 9578908
references: J Neurophysiol. 1998 May;79(5):2653-67
references: 9582236
references: J Neurophysiol. 1998 Jun;79(6):3197-215
references: 9636119
references: Nature. 1998 Aug 20;394(6695):780-4
references: 9723616