scholarly journals Spatial summation properties of the human ocular following response (OFR): Dependence upon the spatial frequency of the stimulus

2011 ◽  
Vol 11 (11) ◽  
pp. 526-526 ◽  
Author(s):  
B. M. Sheliga ◽  
C. Quaia ◽  
L. M. Optican ◽  
E. J. FitzGibbon
Keyword(s):  
Spatial Frequency ◽  
Spatial Summation ◽  
Ocular Following ◽  
Ocular Following Response

scholarly journals Anisotropy in spatial summation properties of human Ocular-Following Response (OFR)

2015 ◽  
Vol 109 ◽  
pp. 11-19
Author(s):  
B.M. Sheliga ◽  
C. Quaia ◽  
E.J. FitzGibbon ◽  
B.G. Cumming
Keyword(s):  
Spatial Summation ◽  
Ocular Following ◽  
Ocular Following Response

scholarly journals Effect of Vergence on Human Ocular Following Response (OFR)

2009 ◽  
Vol 102 (1) ◽  
pp. 513-522 ◽  
Author(s):  
Anand C. Joshi ◽  
Matthew J. Thurtell ◽  
Mark F. Walker ◽  
Alessandro Serra ◽  
R. John Leigh
Keyword(s):  
Visual Field ◽  
Temporal Frequency ◽  
Open Loop ◽  
Motion Processing ◽  
Sinusoidal Grating ◽  
Video Monitor ◽  
Gaze Shifts ◽  
Ocular Following ◽  
Moving Stimulus ◽  
Ocular Following Response

The human ocular following response (OFR) is a preattentive, short-latency visual-field–holding mechanism, which is enhanced if the moving stimulus is applied in the wake of a saccade. Since most natural gaze shifts incorporate both saccadic and vergence components, we asked whether the OFR was also enhanced during vergence. Ten subjects viewed vertically moving sine-wave gratings on a video monitor at 45 cm that had a temporal frequency of 16.7 Hz, contrast of 32%, and spatial frequency of 0.17, 0.27, or 0.44 cycle/deg. In Fixation/OFR experiments, subjects fixed on a white central dot on the video monitor, which disappeared at the beginning of each trial, just as the sinusoidal grating started moving up or down. We measured the change in eye position in the 70- to 150-ms open-loop interval following stimulus onset. Group mean downward responses were larger (0.14°) and made at shorter latency (85 ms) than upward responses (0.10° and 96 ms). The direction of eye drifts during control trials, when gratings remained stationary, was unrelated to the prior response. During vergence/OFR experiments, subjects switched their fixation point between the white dot at 45 cm and a red spot at 15 cm, cued by the disappearance of one target and appearance of the other. When horizontal vergence velocity exceeded 15°/s, motion of sinusoidal gratings commenced and elicited the vertical OFR. Subjects showed significantly ( P < 0.001) larger OFR when the moving stimulus was presented during convergence (group mean increase of 46%) or divergence (group mean increase of 36%) compared with following fixation. Since gaze shifts between near and far are common during natural activities, we postulate that the increase of OFR during vergence movements reflects enhancement of early cortical motion processing, which serves to stabilize the visual field as the eyes approach their new fixation point.

scholarly journals Behavioral Receptive Field for Ocular Following in Humans: Dynamics of Spatial Summation and Center-Surround Interactions

2006 ◽  
Vol 95 (6) ◽  
pp. 3712-3726 ◽  
Author(s):  
Frédéric V. Barthélemy ◽  
Ivo Vanzetta ◽  
Guillaume S. Masson
Keyword(s):  
Visual Field ◽  
Receptive Field ◽  
Visual Motion ◽  
Neuronal Response ◽  
Spatial Summation ◽  
Visuomotor Transformations ◽  
Ocular Following ◽  
Linear Integration ◽  
Response Onset ◽  
Linear Contrast

Visual neurons integrate information over a finite part of the visual field with high selectivity. This classical receptive field is modulated by peripheral inputs that play a role in both neuronal response normalization and contextual modulations. However, the consequences of these properties for visuomotor transformations are yet incompletely understood. To explore those, we recorded short-latency ocular following responses in humans to large center-only and center-surround stimuli. We found that eye movements are triggered by a mechanism that integrates motion over a restricted portion of the visual field, the size of which depends on stimulus contrast and increases as a function of time after response onset. We also found evidence for a strong nonisodirectional center-surround organization, responsible for normalizing the central, driving input so that motor responses are set to their most linear contrast dynamics. Such response normalization is delayed about 20 ms relative to tracking onset, gradually builds up over time, and is partly tuned for surround orientation/direction. These results outline the spatiotemporal organization of a behavioral receptive field, which might reflect a linear integration among subpopulations of cortical visual motion detectors.

The effect of threshold on the relationship between the receptive-field profile and the spatial-frequency tuning cure in simple cells of the cat's striate cortex

1989 ◽  
Vol 3 (5) ◽  
pp. 445-454 ◽  
Author(s):  
Y. Tadmor ◽  
D. J. Tolhurst
Keyword(s):  
Fourier Transform ◽  
Spatial Frequency ◽  
Fourier Transforms ◽  
Frequency Tuning ◽  
Weighting Function ◽  
Tuning Curve ◽  
Spatial Summation ◽  
Response Threshold ◽  
Simple Cells ◽  
Spatial Frequency Tuning

AbstractIt is believed that spatial summation in most simple cells is a linear process. If this were so, then the Fourier transform of a simple cell's line weighting function should predict the cell's spatial frequency tuning curve. We have compared such predictions with experimental measurements and have found a consistent discrepancy: the predicted tuning curve is much too broad. We show qualitatively that this kind of discrepancy is consistent with the well-known threshold nonlinearity shown by most cortical cells. We have tested quantitatively whether a response threshold could explain the observed disagreements between predictions and measurements: a least-squares minimization routine was used to fit the inverse Fourier Transform of the measured frequency tuning curve to the measured line weighting function. The fitting procedure permitted us to introduce a threshold to the reconstructed line weighting function. The results of the analysis show that, for all of the cells tested, the Fourier transforms produced better predictions when a response threshold was included in the model. For some cells, the actual magnitude of the response threshold was measured independently and found to be compatible with that suggested by the model. The effects of nonlinearities of spatial summation are considered.

scholarly journals Ocular following response to sampled motion

2009 ◽  
Vol 49 (13) ◽  
pp. 1693-1701 ◽  
Author(s):  
Kim Joris Boström ◽  
Anne-Kathrin Warzecha
Keyword(s):  
Ocular Following ◽  
Ocular Following Response
Sign in / Sign up

Export Citation Format

Share Document