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Kremers J, Aher AJ, Popov Y, Mirsalehi M, Huchzermeyer C. The influence of temporal frequency and stimulus size on the relative contribution of luminance and L-/M-cone opponent mechanisms in heterochromatic flicker ERGs. Doc Ophthalmol 2021; 143:207-220. [PMID: 33886039 PMCID: PMC8494685 DOI: 10.1007/s10633-021-09837-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/08/2021] [Indexed: 11/27/2022]
Abstract
PURPOSE To study the effect of stimulus size and temporal frequency on the relative contribution of luminance and L-/M-cone opponent signals in the ERG. METHODS In four healthy, color normal subjects, ERG responses to heterochromatic stimuli with sinusoidal, counter-phase modulation of red and green LEDs were measured. By inverse variation of red and green contrasts, we varied luminance contrast while keeping L-/M-cone opponent chromatic contrast constant. The first harmonic components in the full field ERGs are independent of stimulus contrast at 12 Hz, while responses to 36 Hz stimuli vary, reaching a minimum close to isoluminance. It was assumed that ERG responses reflect L-/M-cone opponency at 12 Hz and luminance at 36 Hz. In this study, we modeled the influence of temporal frequency on the relative contribution of these mechanisms at intermediate frequencies, measured the influence of stimulus size on model parameters, and analyzed the second harmonic component at 12 Hz. RESULTS The responses at all frequencies and stimulus sizes could be described by a linear vector addition of luminance and L-/M-cone opponent reflecting ERGs. The contribution of the luminance mechanism increased with increasing temporal frequency and with increasing stimulus size, whereas the gain of the L-/M-cone opponent mechanism was independent of stimulus size and was larger at lower temporal frequencies. Thus, the luminance mechanism dominated at lower temporal frequencies with large stimuli. At 12 Hz, the second harmonic component reflected the luminance mechanism. CONCLUSIONS The ERGs to heterochromatic stimuli can be fully described in terms of linear combinations of responses in the (magnocellular) luminance and the (parvocellular) L-/M-opponent retino-geniculate pathways. The non-invasive study of these pathways in human subjects may have implications for basic research and for clinical research.
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Affiliation(s)
- Jan Kremers
- Section for Retinal Physiology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany.
| | - Avinash J Aher
- Section for Retinal Physiology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany
| | - Yassen Popov
- Section for Retinal Physiology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany
| | - Maziar Mirsalehi
- Section for Retinal Physiology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany
| | - Cord Huchzermeyer
- Section for Retinal Physiology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany
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Nittmann MG, Aher AJ, Kremers J, Tzekov R. Relationship between stimulus size and different components of the electroretinogram (ERG) elicited by flashed stimuli. Doc Ophthalmol 2021; 142:213-31. [PMID: 33063285 DOI: 10.1007/s10633-020-09797-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 10/01/2020] [Indexed: 10/23/2022]
Abstract
PURPOSE To investigate how light stimulus conditions of varying spatial sizes affect components of the flash and long-flash electroretinogram (ERG) in normal subjects. METHOD Three stimulus conditions were generated by a Ganzfeld stimulator: a white flash on white background (WoW), a red flash on a blue background (RoB) and an L+M-cone isolating on-off (long flash) stimulus (Cone Iso). ERGs were recorded from six subjects (5 M, 1 F) with DTL electrodes to full-field (FF), 70°, 60°, 50°, 40°, 30° and 20° diameter circular stimuli. Amplitudes and peak times for a-, b-, d- and i-wave, and PhNR were examined. PhNR amplitudes were estimated in two different ways: from baseline (fB) and from preceding b-wave peak (fP). RESULTS With decreasing stimulus size, amplitudes for all ERG waveform components attenuated and peak times increased, although the effect varied across different components. An exponential fit described the relationship between amplitudes and size of stimulated retinal area well for most components and conditions (R2= 0.75-0.99), except for PhNR(fB) (R2= - 0.16-0.88). For peak times, an exponential decay function also fitted the data well (R2= 0.81-0.97), except in a few cases where the exponential constant was too small and a linear regression function was applied instead (a-wave Cone Iso, b- and i-wave WoW). The exponential constants for RoB amplitudes (b-wave, PhNR(fB), PhNR(fP)) were larger compared to their counterparts under WoW (p < 0.05), while there was no difference between the constants for a-wave amplitudes and peak times and for PhNR peak times. The exponential constants of amplitudes vs. area under WoW and Cone Iso were remarkably similar, while under RoB PhNR(fB) showed larger constants compared to either a- or b-wave (p < 0.05). CONCLUSION ERG components change in a predictable way with stimulus size and spectral characteristics of the stimulus under these conditions. This predictability could allow a modified version of these sets of stimuli to be tested for clinical applicability.
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Aher AJ, Jacob MM, Kremers J. High-frequency characteristics of L- and M-cone driven electroretinograms. Vision Res 2019; 159:35-41. [PMID: 30926305 DOI: 10.1016/j.visres.2019.03.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 03/14/2019] [Accepted: 03/25/2019] [Indexed: 10/27/2022]
Abstract
Electroretinograms (ERGs) elicited by high temporal frequency (26-95 Hz) L- and M-cone isolating sine-wave stimuli were investigated in human observers for full-field (FF) and different spatially restricted stimulus sizes (70°, 50°, 30°, and 10° diameter). Responses to L- and M-cone isolating FF stimuli were maximal around 48 Hz and decreased gradually with increasing temporal frequency up to 95 Hz. The response maximum was shifted to about 30-32 Hz for both L- and M-cone driven responses obtained with spatially restricted stimuli. The M-cone driven responses could only be measured up to 54 Hz with 70° stimuli. The response amplitudes for L- and M-cones and L-/M-cone amplitude ratios decreased with decreasing stimulus size. The ERG response phases to L- and M-cone isolating stimuli decreased with increasing temporal frequency and were about -160° apart for all stimulus sizes up to 34 Hz. Further increase in the temporal frequency displayed a positive correlation between stimulus size and L-M phase difference. The ERG data indicate that the responses evoked by high temporal frequency cone isolating stimuli reflect two mechanisms, one that is more centrally located and displays a maximum at about 30-32 Hz and a peripheral mechanism that is sensitive to higher temporal modulations. We propose that the peripheral mechanism (FF ERGs) reflects magnocellular activity, whereas the central mechanism (ERGs with spatially restricted stimuli) is based on a parvocellular activity up to about 30 Hz.
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Affiliation(s)
- Avinash J Aher
- Department of Ophthalmology, University Hospital Erlangen, Schwabachanlage 6, Erlangen 91054, Germany
| | - Mellina M Jacob
- Department of Ophthalmology, University Hospital Erlangen, Schwabachanlage 6, Erlangen 91054, Germany; Laboratory of Tropical Neurology, Institute of Biological Sciences, UFPA, Augusto Correa St., Number 01, Belém CEP 66075-110, Brazil
| | - Jan Kremers
- Department of Ophthalmology, University Hospital Erlangen, Schwabachanlage 6, Erlangen 91054, Germany; School of Optometry and Vision Science, University of Bradford, Richmond Rd., Bradford, West Yorkshire BD7 1DP, United Kingdom.
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Morgan AM, Mazzoli LS, Caixeta-Umbelino C, Kasahara N. Expediency of the Automated Perimetry Using the Goldmann V Stimulus Size in Visually Impaired Patients with Glaucoma. Ophthalmol Ther 2019; 8:305-11. [PMID: 30868416 DOI: 10.1007/s40123-019-0175-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Indexed: 11/04/2022] Open
Abstract
Introduction White-on-white standard automated perimetry (AP) uses a white round stimulus with 0.43° diameter and 4.0 mm2 area (Goldmann size III). Patients with low vision have difficulty seeing such a small stimulus and are often tested with perimetry using the size V stimulus with 1.72° diameter and 64 mm2 area. We undertook an observational case-control study to compare the performance of patients on AP using two differently sized stimuli. Methods Patients with glaucoma and visual acuity worse than 20/100 underwent AP using the standard size III stimulus Swedish Interactive Threshold Algorithm (SITA) standard test and size V stimulus full threshold test. All patients were familiar with the procedure, having done the test at least twice previously. Another group of glaucoma patients with visual acuity better than 20/40 served as controls. The main outcome measures included test time, mean retinal sensitivity (MRS), foveal sensitivity (FS), fixation loss (FL), false positive (FP), false negative (FN), and the patient's subjective preference. Results Fifty patients were included in the study. Most preferred the size V stimulus target size test. For glaucoma patients, test time was shorter with size III; MRS and FS were higher with size V; FL, FP, and FN did not differ between the tests. Conclusion AP with stimulus size V may be a good alternative to standard size III in selected visually debilitated patients who report difficulty undergoing a standard SITA 24-2 test. Electronic supplementary material The online version of this article (10.1007/s40123-019-0175-9) contains supplementary material, which is available to authorized users.
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Aher AJ, McKeefry DJ, Parry NRA, Maguire J, Murray IJ, Tsai TI, Huchzermeyer C, Kremers J. Rod- versus cone-driven ERGs at different stimulus sizes in normal subjects and retinitis pigmentosa patients. Doc Ophthalmol 2017; 136:27-43. [PMID: 29134295 DOI: 10.1007/s10633-017-9619-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 11/02/2017] [Indexed: 10/18/2022]
Abstract
PURPOSE To study how rod- and cone-driven responses depend on stimulus size in normal subjects and patients with retinitis pigmentosa (RP), and to show that comparisons between responses to full-field (FF) and smaller stimuli can be useful in diagnosing and monitoring disorders of the peripheral retina without the need for lengthy dark adaptation periods. METHOD The triple silent substitution technique was used to isolate L-cone-, M-cone- and rod-driven ERGs with 19, 18 and 33% photoreceptor contrasts, respectively, under identical mean luminance conditions. Experiments were conducted on five normal subjects and three RP patients. ERGs on control subjects were recorded at nine different temporal frequencies (between 2 and 60 Hz) for five different stimulus sizes: FF, 70°, 60°, 50° and 40° diameter circular stimuli. Experiments on RP patients involved rod- and L-cone-driven ERG measurements with FF and 40° stimuli at 8 and 48 Hz. Response amplitudes were defined as those of the first harmonic component after Fourier analysis. RESULTS In normal subjects, rod-driven responses displayed a fundamentally different behavior than cone-driven responses, particularly at low temporal frequencies. At low and intermediate temporal frequencies (≤ 12 Hz), rod-driven signals increased by a factor of about four when measured with smaller stimuli. In contrast, L- and M-cone-driven responses in this frequency region did not change substantially with stimulus size. At high temporal frequencies (≥ 24 Hz), both rod- and cone-driven response amplitudes decreased with decreasing stimulus size. Signals obtained from rod-isolating stimuli under these conditions are likely artefactual. Interestingly, in RP patients, both rod-driven and L-cone-driven ERGs were similar using 40° and FF stimuli. CONCLUSION The increased responses with smaller stimuli in normal subjects to rod-isolating stimuli indicate that a fundamentally different mechanism drives the ERGs in comparison with the cone-driven responses. We propose that the increased responses are caused by stray light stimulating the peripheral retina, thereby allowing peripheral rod-driven function to be studied using the triple silent substitution technique at photopic luminances. The method is effective in studying impaired peripheral rod- and cone- function in RP patients.
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Affiliation(s)
- Avinash J Aher
- Department of Ophthalmology, University Hospital Erlangen, Erlangen, Germany
| | - Declan J McKeefry
- School of Optometry and Vision Science, University of Bradford, Bradford, UK
| | - Neil R A Parry
- School of Optometry and Vision Science, University of Bradford, Bradford, UK.,Center for Hearing and Vision Research, Institute of Human Development, University of Manchester, Manchester, UK.,Vision Science Center, Manchester Royal Eye Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Center, Manchester, UK
| | - John Maguire
- School of Optometry and Vision Science, University of Bradford, Bradford, UK
| | - I J Murray
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Tina I Tsai
- Department of Ophthalmology, University Hospital Erlangen, Erlangen, Germany
| | - Cord Huchzermeyer
- Department of Ophthalmology, University Hospital Erlangen, Erlangen, Germany
| | - Jan Kremers
- Department of Ophthalmology, University Hospital Erlangen, Erlangen, Germany. .,School of Optometry and Vision Science, University of Bradford, Bradford, UK.
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Gebodh N, Vanegas MI, Kelly SP. Effects of Stimulus Size and Contrast on the Initial Primary Visual Cortical Response in Humans. Brain Topogr 2017; 30:450-60. [PMID: 28474167 DOI: 10.1007/s10548-016-0530-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 10/11/2016] [Indexed: 10/19/2022]
Abstract
Decades of intracranial electrophysiological investigation into the primary visual cortex (V1) have produced many fundamental insights into the computations carried out in low-level visual circuits of the brain. Some of the most important work has been simply concerned with the precise measurement of neural response variations as a function of elementary stimulus attributes such as contrast and size. Surprisingly, such simple but fundamental characterization of V1 responses has not been carried out in human electrophysiology. Here we report such a detailed characterization for the initial "C1" component of the scalp-recorded visual evoked potential (VEP). The C1 is known to be dominantly generated by initial afferent activation in V1, but is difficult to record reliably due to interindividual anatomical variability. We used pattern-pulse multifocal VEP mapping to identify a stimulus position that activates the left lower calcarine bank in each individual, and afterwards measured robust negative C1s over posterior midline scalp to gratings presented sequentially at that location. We found clear and systematic increases in C1 peak amplitude and decreases in peak latency with increasing size as well as with increasing contrast. With a sample of 15 subjects and ~180 trials per condition, reliable C1 amplitudes of -0.46 µV were evoked at as low a contrast as 3.13% and as large as -4.82 µV at 100% contrast, using stimuli of 3.33° diameter. A practical implication is that by placing sufficiently-sized stimuli to target favorable calcarine cortical loci, robust V1 responses can be measured at contrasts close to perceptual thresholds, which could greatly facilitate principled studies of early visual perception and attention.
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Gunther KL, Downey CO. Influence of stimulus size on revealing non-cardinal color mechanisms. Vision Res 2016; 127:57-66. [PMID: 27470702 DOI: 10.1016/j.visres.2016.06.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 06/14/2016] [Accepted: 06/22/2016] [Indexed: 10/21/2022]
Abstract
Multiple studies have shown that performance of subjects on a number of visual tasks is worse for non-cardinal than cardinal colors, especially in the red-green/luminance (RG/LUM) and tritan/luminance (TRIT/LUM) color planes. Inspired by neurophysiological evidence that suppressive surround input to receptive fields is particularly sensitive to luminance, we hypothesized that non-cardinal mechanisms in the RG/LUM and TRIT/LUM planes would be more sensitive to stimulus size than are isoluminant non-cardinal mechanisms. In Experiment 1 we tested 9-10 color-normal subjects in each of the three color planes (RG/TRIT, RG/LUM, and TRIT/LUM) on visual search at four bull's-eye dot sizes (0.5°/1°, 1°/2°, 2°/4°, and 3°/6° center/annulus dot diameter). This study yielded a significant main effect of dot size in each of the three color planes. In Experiment 2 we tested the same hypothesis using noise masking, at three stimulus sizes (3°, 6° and 9° diameter Gabors), again in all three color planes (5 subjects per color plane). This experiment yielded, in the RG/TRIT plane, a significant main effect of stimulus size; in the RG/LUM plane, significant evidence for non-cardinal mechanisms only for the 9° stimulus; but in the TRIT/LUM plane no evidence for non-cardinal mechanisms at any stimulus size. These results suggest that non-cardinal mechanisms, particularly in the RG/LUM color plane, are more sensitive to stimulus size than are non-cardinals in the RG/TRIT plane, supporting our hypothesis.
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Affiliation(s)
- Karen L Gunther
- Department of Psychology, Wabash College, 301 West Wabash Avenue, Crawfordsville, IN 47933, USA.
| | - Colin O Downey
- Department of Psychology, Wabash College, 301 West Wabash Avenue, Crawfordsville, IN 47933, USA
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Massendari D, Tandonnet C, Vitu F. On the reduced influence of contour on saccade metrics and its competition with stimulus size. Vision Res 2014; 101:158-66. [PMID: 25003561 DOI: 10.1016/j.visres.2014.06.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Revised: 06/25/2014] [Accepted: 06/26/2014] [Indexed: 11/18/2022]
Abstract
It is well known that the metrical properties of saccadic eye movements are strongly influenced by the extraction of low-level visual features (e.g., luminance). Higher-level visual features (e.g., contour) also play a role, but their relative contribution and time course remain undetermined. Here, we investigated this issue, by testing the influence of contour on saccade metrics. We used a saccade-targeting task in which a peripheral target was, on some trials, simultaneously displayed with a less eccentric distractor. This paradigm is known to yield a global effect, that is a deviation of the eyes towards an intermediate location between the stimuli. The novelty was to test whether this effect would vary with the alignment of the distractor's elementary features. Distractors were of high vs. low luminance, and composed of 16 pixels that were either aligned or misaligned by 0.23° or 0.43°. Our prediction, under the hypothesis that contour intervenes, was that aligned distractors, which formed a definite contour, would deviate the eyes more strongly than misaligned distractors. On the contrary, we found that distractors of high luminance produced greater eye deviations when they were misaligned, and hence more largely spread, than when they were aligned. Furthermore, low-luminance distractors deviated the eyes to the same extent irrespective of their alignment, though showing a reversed, contour-like, effect of alignment for early-triggered saccades. We proposed that contour has only limited influence on saccade metrics, when other, lower-level and more salient visual features, such as the extent of the stimulus pattern, are available.
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Affiliation(s)
- Delphine Massendari
- Laboratoire de Psychologie Cognitive, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France.
| | - Christophe Tandonnet
- Laboratoire de Psychologie Cognitive, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France; Faculté de Psychologie et des Sciences de l'Education, Université de Genève, Genève, Switzerland.
| | - Françoise Vitu
- Laboratoire de Psychologie Cognitive, Centre National de la Recherche Scientifique, Aix-Marseille Université, Marseille, France.
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