101
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Weyand TG. The multifunctional lateral geniculate nucleus. Rev Neurosci 2016; 27:135-57. [PMID: 26479339 DOI: 10.1515/revneuro-2015-0018] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/01/2015] [Indexed: 01/22/2023]
Abstract
Providing the critical link between the retina and visual cortex, the well-studied lateral geniculate nucleus (LGN) has stood out as a structure in search of a function exceeding the mundane 'relay'. For many mammals, it is structurally impressive: Exquisite lamination, sophisticated microcircuits, and blending of multiple inputs suggest some fundamental transform. This impression is bolstered by the fact that numerically, the retina accounts for a small fraction of its input. Despite such promise, the extent to which an LGN neuron separates itself from its retinal brethren has proven difficult to appreciate. Here, I argue that whereas retinogeniculate coupling is strong, what occurs in the LGN is judicious pruning of a retinal drive by nonretinal inputs. These nonretinal inputs reshape a receptive field that under the right conditions departs significantly from its retinal drive, even if transiently. I first review design features of the LGN and follow with evidence for 10 putative functions. Only two of these tend to surface in textbooks: parsing retinal axons by eye and functional group and gating by state. Among the remaining putative functions, implementation of the principle of graceful degradation and temporal decorrelation are at least as interesting but much less promoted. The retina solves formidable problems imposed by physics to yield multiple efficient and sensitive representations of the world. The LGN applies context, increasing content, and gates several of these representations. Even if the basic concentric receptive field remains, information transmitted for each LGN spike relative to each retinal spike is measurably increased.
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102
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The Development and Aging of the Magnocellular and Parvocellular Visual Pathways as Indicated by VEP Recordings between 5 and 84 Years of Age. Vision (Basel) 2016; 1:vision1010007. [PMID: 31740632 PMCID: PMC6849023 DOI: 10.3390/vision1010007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/26/2016] [Accepted: 10/08/2016] [Indexed: 11/17/2022] Open
Abstract
It is well known that pattern reversal visual evoked potentials (VEPs) are age-sensitive. Through the use of this technique, it is possible to assess both of the major visual pathways (i.e., the magnocellular and parvocellular ones) in terms of function and development. What developmental path these pathways follow, and if they develop/age in parallel across the human lifespan is a matter of ongoing debate, yet, only a few VEP studies have dealt with this issue. This cross-sectional study examined a sample of 115 healthy volunteers aged 5 to 84 years. Beyond the standard checkerboard pattern reversal stimulation at 97% contrast, we recorded pattern-reversal VEPs at 6% contrast to selectively stimulate the M pathway and isoluminant red and green checkerboard stimulation was also used to selectively stimulate the P pathway. Our results do not support the developmental advantage of any of the pathways. The development of both pathways appear to take a remarkably long time (well into the 30s), and the signs of aging become marked over 50 years of age, especially in the case of the magnocellular pathway.
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103
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Vieira PG, de Sousa JPM, Baron J. Contrast response functions in the visual wulst of the alert burrowing owl: a single-unit study. J Neurophysiol 2016; 116:1765-1784. [PMID: 27466135 DOI: 10.1152/jn.00505.2015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 07/15/2016] [Indexed: 11/22/2022] Open
Abstract
The neuronal representation of luminance contrast has not been thoroughly studied in birds. Here we present a detailed quantitative analysis of the contrast response of 120 individual neurons recorded from the visual wulst of awake burrowing owls (Athene cunicularia). Stimuli were sine-wave gratings presented within the cell classical receptive field and optimized in terms of eye preference, direction of drift, and spatiotemporal frequency. As contrast intensity was increased from zero to near 100%, most cells exhibited a monotonic response profile with a compressive, at times saturating, nonlinearity at higher contrasts. However, contrast response functions were found to have a highly variable shape across cells. With the view to capture a systematic trend in the data, we assessed the performance of four plausible models (linear, power, logarithmic, and hyperbolic ratio) using classical goodness-of-fit measures and more rigorous statistical tools for multimodel inferences based on the Akaike information criterion. From this analysis, we conclude that a high degree of model uncertainty is present in our data, meaning that no single descriptor is able on its own to capture the heterogeneous nature of single-unit contrast responses in the wulst. We further show that the generalizability of the hyperbolic ratio model established, for example, in the primary visual cortex of cats and monkeys is not tenable in the owl wulst mainly because most neurons in this area have a much wider dynamic range that starts at low contrast. The challenge for future research will be to understand the functional implications of these findings.
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Affiliation(s)
- Pedro Gabrielle Vieira
- Graduate Program in Physiology and Pharmacology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - João Paulo Machado de Sousa
- Graduate Program in Electrical Engineering, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; and
| | - Jerome Baron
- Graduate Program in Physiology and Pharmacology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Graduate Program in Electrical Engineering, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; and Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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104
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Bellot E, Coizet V, Warnking J, Knoblauch K, Moro E, Dojat M. Effects of aging on low luminance contrast processing in humans. Neuroimage 2016; 139:415-426. [DOI: 10.1016/j.neuroimage.2016.06.051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/02/2016] [Accepted: 06/26/2016] [Indexed: 10/21/2022] Open
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105
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de Moraes CG, Liebmann JM, Medeiros FA, Weinreb RN. Management of advanced glaucoma: Characterization and monitoring. Surv Ophthalmol 2016; 61:597-615. [PMID: 27018149 DOI: 10.1016/j.survophthal.2016.03.006] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 01/27/2023]
Abstract
Recent advances in glaucoma diagnosis focus on diagnosing the disease in early stages. Despite the importance of such efforts, a meaningful proportion of patients present in advanced stages. The cost for treatment and monitoring of advanced glaucoma often exceeds that with earlier disease, not to mention the significant effect of visual impairment on quality of life. Moreover, structural and functional tests used to monitor changes encounter technical limitations in advanced cases that can delay detection of true progression. New technologies and methods to analyze longitudinal data may prove helpful for monitoring patients with advanced glaucoma and reduce the burdens of the disease.
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Affiliation(s)
- C Gustavo de Moraes
- Bernard and Shirlee Brown Glaucoma Research Laboratory, Edward S. Harkness Eye Institute, Department of Ophthalmology, Columbia University Medical Center, New York, New York, USA.
| | - Jeffrey M Liebmann
- Bernard and Shirlee Brown Glaucoma Research Laboratory, Edward S. Harkness Eye Institute, Department of Ophthalmology, Columbia University Medical Center, New York, New York, USA
| | - Felipe A Medeiros
- Shiley Eye Institute, Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, USA
| | - Robert N Weinreb
- Shiley Eye Institute, Hamilton Glaucoma Center and Department of Ophthalmology, University of California San Diego, La Jolla, California, USA
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106
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Lawton T. Improving Dorsal Stream Function in Dyslexics by Training Figure/Ground Motion Discrimination Improves Attention, Reading Fluency, and Working Memory. Front Hum Neurosci 2016; 10:397. [PMID: 27551263 PMCID: PMC4976098 DOI: 10.3389/fnhum.2016.00397] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 07/25/2016] [Indexed: 11/13/2022] Open
Abstract
There is an ongoing debate about whether the cause of dyslexia is based on linguistic, auditory, or visual timing deficits. To investigate this issue three interventions were compared in 58 dyslexics in second grade (7 years on average), two targeting the temporal dynamics (timing) of either the auditory or visual pathways with a third reading intervention (control group) targeting linguistic word building. Visual pathway training in dyslexics to improve direction-discrimination of moving test patterns relative to a stationary background (figure/ground discrimination) significantly improved attention, reading fluency, both speed and comprehension, phonological processing, and both auditory and visual working memory relative to controls, whereas auditory training to improve phonological processing did not improve these academic skills significantly more than found for controls. This study supports the hypothesis that faulty timing in synchronizing the activity of magnocellular with parvocellular visual pathways is a fundamental cause of dyslexia, and argues against the assumption that reading deficiencies in dyslexia are caused by phonological deficits. This study demonstrates that visual movement direction-discrimination can be used to not only detect dyslexia early, but also for its successful treatment, so that reading problems do not prevent children from readily learning.
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Affiliation(s)
- Teri Lawton
- Perception Dynamics InstituteDel Mar, CA, USA
- Department of Computer Science and Engineering, University of California, San DiegoLa Jolla, CA, USA
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107
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Cormenzana Méndez I, Martín A, Charmichael TL, Jacob MM, Lacerda EMCB, Gomes BD, Fitzgerald MEC, Ventura DF, Silveira LCL, O'Donell BM, Souza GS. Color Discrimination Is Affected by Modulation of Luminance Noise in Pseudoisochromatic Stimuli. Front Psychol 2016; 7:1006. [PMID: 27458404 PMCID: PMC4934133 DOI: 10.3389/fpsyg.2016.01006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/20/2016] [Indexed: 11/13/2022] Open
Abstract
Pseudoisochromatic stimuli have been widely used to evaluate color discrimination and to identify color vision deficits. Luminance noise is one of the stimulus parameters used to ensure that subject's response is due to their ability to discriminate target stimulus from the background based solely on the hue between the colors that compose such stimuli. We studied the influence of contrast modulation of the stimulus luminance noise on threshold and reaction time color discrimination. We evaluated color discrimination thresholds using the Cambridge Color Test (CCT) at six different stimulus mean luminances. Each mean luminance condition was tested using two protocols: constant absolute difference between maximum and minimum luminance of the luminance noise (constant delta protocol, CDP), and constant contrast modulation of the luminance noise (constant contrast protocol, CCP). MacAdam ellipses were fitted to the color discrimination thresholds in the CIE 1976 color space to quantify the color discrimination ellipses at threshold level. The same CDP and CCP protocols were applied in the experiment measuring RTs at three levels of stimulus mean luminance. The color threshold measurements show that for the CDP, ellipse areas decreased as a function of the mean luminance and they were significantly larger at the two lowest mean luminances, 10 cd/m2 and 13 cd/m2, compared to the highest one, 25 cd/m2. For the CCP, the ellipses areas also decreased as a function of the mean luminance, but there was no significant difference between ellipses areas estimated at six stimulus mean luminances. The exponent of the decrease of ellipse areas as a function of stimulus mean luminance was steeper in the CDP than CCP. Further, reaction time increased linearly with the reciprocal of the length of the chromatic vectors varying along the four chromatic half-axes. It decreased as a function of stimulus mean luminance in the CDP but not in the CCP. The findings indicated that visual performance using pseudoisochromatic stimuli was dependent on the Weber's contrast of the luminance noise. Low Weber's contrast in the luminance noise is suggested to have a reduced effect on chromatic information and, hence, facilitate desegregation of the hue-defined target from the background.
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Affiliation(s)
- Iñaki Cormenzana Méndez
- Departamento de Luminotecnia, Luz y Visión "Ing. Herberto C. Bühler", Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán Tucumán, Argentina
| | - Andrés Martín
- Departamento de Luminotecnia, Luz y Visión "Ing. Herberto C. Bühler", Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán Tucumán, Argentina
| | | | - Mellina M Jacob
- Instituto de Ciências Biológicas, Universidade Federal do Pará Belém, Brazil
| | | | - Bruno D Gomes
- Instituto de Ciências Biológicas, Universidade Federal do Pará Belém, Brazil
| | - Malinda E C Fitzgerald
- Department of Biology, Christian Brothers UniversityMemphis, TN, USA; Department of Anatomy and Neurobiology, University of Tennessee Health Science CenterMemphis, TN, USA
| | - Dora F Ventura
- Department of Experimental Psychology, Instituto de Psicologia, Universidade de São Paulo São Paulo, Brazil
| | - Luiz C L Silveira
- Instituto de Ciências Biológicas, Universidade Federal do ParáBelém, Brazil; Núcleo de Medicina Tropical, Universidade Federal do ParáBelém, Brazil; Universidade do CeumaSão Luís, Brazil
| | - Beatriz M O'Donell
- Departamento de Luminotecnia, Luz y Visión "Ing. Herberto C. Bühler", Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán Tucumán, Argentina
| | - Givago S Souza
- Instituto de Ciências Biológicas, Universidade Federal do ParáBelém, Brazil; Núcleo de Medicina Tropical, Universidade Federal do ParáBelém, Brazil
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108
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Temporal structure of human magnetic evoked fields. Exp Brain Res 2016; 234:1987-1995. [PMID: 26952050 DOI: 10.1007/s00221-016-4601-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/16/2016] [Indexed: 01/29/2023]
Abstract
Nonlinear analysis of the multifocal cortical visual evoked potential has allowed the identification of neural generation of higher-order nonlinear components by magnocellular and parvocellular neural streams. However, the location of individual brain sources that make such contributions to these evoked responses has not been studied. Thus, an m-sequence pseudorandom stimulus system was developed for use in magnetoencephalographic (MEG) studies. Five normal young adults were recorded using an Elekta TRIUX MEG with 306 sensors. Visual stimuli comprised a nine-patch dartboard stimulus, and each patch fluctuated between two luminance levels with separate recordings carried out at low (24 %) and high (96 %) temporal contrast. Sensor-space analysis of MEG evoked fields identified components of the first- and second-order Wiener kernel decomposition that showed qualitative similarity with EEG-based cortical VEP recordings. The first slice of the second-order response (K2.1) was already saturated at 24 % contrast, while the major waveform of the second slice of the second-order response (K2.2) grew strongly with contrast, consistent with properties of the magnocellular and parvocellular neurons. Minimum norm estimates of cortical source localization showed almost simultaneous activation of V1 and MT+ activations with latencies only a little greater that those reported for first neural spikes in primate single cell studies. Time-frequency analysis of the kernel responses from five minimum norm estimate scout sources shows contributions from higher-frequency bands for the first compared with the second slice response, consistent with the proposed neural sources. In support of this magno/parvo break-up, the onset latencies of the K2.2 responses were delayed by approximately 30 ms compared with K2.1 responses.
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109
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Cooper B, Lee BB, Cao D. Macaque retinal ganglion cell responses to visual patterns: harmonic composition, noise, and psychophysical detectability. J Neurophysiol 2016; 115:2976-88. [PMID: 26936977 DOI: 10.1152/jn.00411.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 03/01/2016] [Indexed: 11/22/2022] Open
Abstract
The goal of these experiments was to test how well cell responses to visual patterns can be predicted from the sinewave tuning curve. Magnocellular (MC) and parvocellular (PC) ganglion cell responses to different spatial waveforms (sinewave, squarewave, and ramp waveforms) were measured across a range of spatial frequencies. Sinewave spatial tuning curves were fit with standard Gaussian models. From these fits, waveforms and spatial tuning of a cell's responses to the other waveforms were predicted for different harmonics by scaling in amplitude for the power in the waveform's Fourier expansion series over spatial frequency. Since higher spatial harmonics move at a higher temporal frequency, an additional scaling for each harmonic by the MC (bandpass) or PC (lowpass) temporal response was included, together with response phase. Finally, the model included a rectifying nonlinearity. This provided a largely satisfactory estimation of MC and PC cell responses to complex waveforms. As a consequence of their transient responses, MC responses to complex waveforms were found to have significantly more energy in higher spatial harmonic components than PC responses. Response variance (noise) was also quantified as a function of harmonic component. Noise increased to some degree for the higher harmonics. The data are relevant for psychophysical detection or discrimination of visual patterns, and we discuss the results in this context.
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Affiliation(s)
- Bonnie Cooper
- College of Optometry, State University of New York, New York, New York
| | - Barry B Lee
- College of Optometry, State University of New York, New York, New York; Max Planck Institute for Biophysical Chemistry, Göttingen, Germany; and
| | - Dingcai Cao
- Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois
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110
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Awasthi B, Williams MA, Friedman J. Examining the role of red background in magnocellular contribution to face perception. PeerJ 2016; 4:e1617. [PMID: 26925312 PMCID: PMC4768705 DOI: 10.7717/peerj.1617] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/01/2016] [Indexed: 02/05/2023] Open
Abstract
This study examines the role of the magnocellular system in the early stages of face perception, in particular sex categorization. Utilizing the specific property of magnocellular suppression in red light, we investigated visually guided reaching to low and high spatial frequency hybrid faces against red and grey backgrounds. The arm movement curvature measure shows that reduced response of the magnocellular pathway interferes with the low spatial frequency component of face perception. This finding provides behavioral evidence for magnocellular contribution to non-emotional aspect of face perception.
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Affiliation(s)
- Bhuvanesh Awasthi
- Centre for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia; ARC Centre of Excellence in Cognition and its Disorders, Department of Cognitive Science, Macquarie University, Sydney, Australia
| | - Mark A Williams
- ARC Centre of Excellence in Cognition and its Disorders, Department of Cognitive Science, Macquarie University , Sydney , Australia
| | - Jason Friedman
- Department of Physical Therapy, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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111
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Maher S, Ekstrom T, Tong Y, Nickerson LD, Frederick B, Chen Y. Greater sensitivity of the cortical face processing system to perceptually-equated face detection. Brain Res 2016; 1631:13-21. [PMID: 26592952 DOI: 10.1016/j.brainres.2015.11.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 11/04/2015] [Accepted: 11/05/2015] [Indexed: 11/30/2022]
Abstract
Face detection, the perceptual capacity to identify a visual stimulus as a face before probing deeper into specific attributes (such as its identity or emotion), is essential for social functioning. Despite the importance of this functional capacity, face detection and its underlying brain mechanisms are not well understood. This study evaluated the roles that the cortical face processing system, which is identified largely through studying other aspects of face perception, play in face detection. Specifically, we used functional magnetic resonance imaging (fMRI) to examine the activations of the fusifom face area (FFA), occipital face area (OFA) and superior temporal sulcus (STS) when face detection was isolated from other aspects of face perception and when face detection was perceptually-equated across individual human participants (n=20). During face detection, FFA and OFA were significantly activated, even for stimuli presented at perceptual-threshold levels, whereas STS was not. During tree detection, however, FFA and OFA were responsive only for highly salient (i.e., high contrast) stimuli. Moreover, activation of FFA during face detection predicted a significant portion of the perceptual performance levels that were determined psychophysically for each participant. This pattern of result indicates that FFA and OFA have a greater sensitivity to face detection signals and selectively support the initial process of face vs. non-face object perception.
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Affiliation(s)
- S Maher
- McLean Hospital, Department of Psychiatry, Harvard Medical School, United States
| | - T Ekstrom
- McLean Hospital, Department of Psychiatry, Harvard Medical School, United States
| | - Y Tong
- McLean Hospital, Department of Psychiatry, Harvard Medical School, United States
| | - L D Nickerson
- McLean Hospital, Department of Psychiatry, Harvard Medical School, United States
| | - B Frederick
- McLean Hospital, Department of Psychiatry, Harvard Medical School, United States
| | - Y Chen
- McLean Hospital, Department of Psychiatry, Harvard Medical School, United States.
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112
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Rucker F, Britton S, Spatcher M, Hanowsky S. Blue Light Protects Against Temporal Frequency Sensitive Refractive Changes. Invest Ophthalmol Vis Sci 2016; 56:6121-31. [PMID: 26393671 DOI: 10.1167/iovs.15-17238] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Time spent outdoors is protective against myopia. The outdoors allows exposure to short-wavelength (blue light) rich sunlight, while indoor illuminants can be deficient at short-wavelengths. In the current experiment, we investigate the role of blue light, and temporal sensitivity, in the emmetropization response. METHODS Five-day-old chicks were exposed to sinusoidal luminance modulation of white light (with blue; N = 82) or yellow light (without blue; N = 83) at 80% contrast, at one of six temporal frequencies: 0, 0.2, 1, 2, 5, 10 Hz daily for 3 days. Mean illumination was 680 lux. Changes in ocular components and corneal curvature were measured. RESULTS Refraction, eye length, and choroidal changes were dependent on the presence of blue light (P < 0.03, all) and on temporal frequency (P < 0.03, all). In the presence of blue light, refraction did not change across frequencies (mean change -0.24 [diopters] D), while in the absence of blue light, we observed a hyperopic shift (>1 D) at high frequencies, and a myopic shift (>-0.6 D) at low frequencies. With blue light there was little difference in eye growth across frequencies (77 μm), while in the absence of blue light, eyes grew more at low temporal frequencies and less at high temporal frequencies (10 vs. 0.2 Hz: 145 μm; P < 0.003). Overall, neonatal astigmatism was reduced with blue light. CONCLUSIONS Illuminants rich in blue light can protect against myopic eye growth when the eye is exposed to slow changes in luminance contrast as might occur with near work.
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113
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Hagmann CE, Potter MC. Ultrafast scene detection and recognition with limited visual information. VISUAL COGNITION 2016; 24:2-14. [PMID: 28255263 DOI: 10.1080/13506285.2016.1170745] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Humans can detect target color pictures of scenes depicting concepts like picnic or harbor in sequences of six or twelve pictures presented as briefly as 13 ms, even when the target is named after the sequence (Potter, Wyble, Hagmann, & McCourt, 2014). Such rapid detection suggests that feedforward processing alone enabled detection without recurrent cortical feedback. There is debate about whether coarse, global, low spatial frequencies (LSFs) provide predictive information to high cortical levels through the rapid magnocellular (M) projection of the visual path, enabling top-down prediction of possible object identities. To test the "Fast M" hypothesis, we compared detection of a named target across five stimulus conditions: unaltered color, blurred color, grayscale, thresholded monochrome, and LSF pictures. The pictures were presented for 13-80 ms in six-picture rapid serial visual presentation (RSVP) sequences. Blurred, monochrome, and LSF pictures were detected less accurately than normal color or grayscale pictures. When the target was named before the sequence, all picture types except LSF resulted in above-chance detection at all durations. Crucially, when the name was given only after the sequence, performance dropped and the monochrome and LSF pictures (but not the blurred pictures) were at or near chance. Thus, without advance information, monochrome and LSF pictures were rarely understood. The results offer only limited support for the Fast M hypothesis, suggesting instead that feedforward processing is able to activate conceptual representations without complementary reentrant processing.
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114
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Gardiner SK, Swanson WH, Demirel S. The Effect of Limiting the Range of Perimetric Sensitivities on Pointwise Assessment of Visual Field Progression in Glaucoma. Invest Ophthalmol Vis Sci 2016; 57:288-94. [PMID: 26824408 PMCID: PMC4736987 DOI: 10.1167/iovs.15-18000] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 12/22/2015] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Automated perimetry does not produce reliable estimates of true psychophysical threshold in glaucomatous visual fields when the perimetric threshold falls below 15 to 19 dB. It may be possible to truncate testing at such locations and not use stimuli with very high contrast. However, this can only be recommended if it does not harm the ability to monitor change. This study examined the effect of applying such a cutoff by censoring sensitivities in two existing longitudinal datasets. METHODS Series of six visual fields were taken from participants with glaucoma or high-risk ocular hypertension in the Portland Progression Project (P3) and Rotterdam Eye Study (RES). Pointwise linear regression was used to find "progressing" locations, defined as a slope ≤ -1 dB/y with P < 1%. An eye was labeled progressing if ≥3 locations were progressing. This was repeated after setting any sensitivities below the cutoff value C (CdB) to instead equal that value for different integer values of CdB. RESULTS In the P3 cohort tested using Swedish Interactive Testing Algorithm (SITA) Standard, censoring below 15 to 19 dB did not reduce the number of eyes flagged as progressing. For the RES cohort tested using the Full Threshold algorithm, censoring below 10 dB did not reduce the number of eyes flagged as progressing, but a modest reduction was seen for CdB between 10 dB and 15 to 19 dB. CONCLUSIONS The proportion of eyes flagged as progressing was not decreased by censoring unreliable sensitivities. Restricting the range of contrast used in clinical perimetry may be possible without hampering the ability to monitor glaucomatous visual field progression.
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Affiliation(s)
- Stuart K. Gardiner
- Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States
| | - William H. Swanson
- School of Optometry, Indiana University, Bloomington, Indiana, United States
| | - Shaban Demirel
- Devers Eye Institute Legacy Research Institute, Portland, Oregon, United States
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115
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Paracchini S, Diaz R, Stein J. Advances in Dyslexia Genetics—New Insights Into the Role of Brain Asymmetries. ADVANCES IN GENETICS 2016; 96:53-97. [DOI: 10.1016/bs.adgen.2016.08.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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116
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Lee JS, Park G, Song MJ, Choi KH, Lee SH. Early visual processing for low spatial frequency fearful face is correlated with cortical volume in patients with schizophrenia. Neuropsychiatr Dis Treat 2016; 12:1-14. [PMID: 26730192 PMCID: PMC4694689 DOI: 10.2147/ndt.s97089] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Patients with schizophrenia present with dysfunction of the magnocellular pathway, which might impair their early visual processing. We explored the relationship between functional abnormality of early visual processing and brain volumetric changes in schizophrenia. Eighteen patients and 16 healthy controls underwent electroencephalographic recordings and high-resolution magnetic resonance imaging. During electroencephalographic recordings, participants passively viewed neutral or fearful faces with broad, high, or low spatial frequency characteristics. Voxel-based morphometry was performed to investigate brain volume correlates of visual processing deficits. Event related potential analysis suggested that patients with schizophrenia had relatively impaired P100 processing of low spatial frequency fearful face stimuli compared with healthy controls; patients' gray-matter volumes in the dorsolateral and medial prefrontal cortices positively correlated with this amplitude. In addition, patients' gray-matter volume in the right cuneus positively correlated with the P100 amplitude in the left hemisphere for the high spatial frequency neutral face condition and that in the left dorsolateral prefrontal cortex negatively correlated with the negative score of the Positive and Negative Syndrome Scale. No significant correlations were observed in healthy controls. This study suggests that the cuneus and prefrontal cortex are significantly involved with the early visual processing of magnocellular input in patients with schizophrenia.
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Affiliation(s)
- Jung Suk Lee
- Department of Psychiatry, National Health Insurance Service Ilsan Hospital, Goyang, Republic of Korea
| | - Gewnhi Park
- Department of Psychology, Azusa Pacific University, Azusa, CA, USA
| | - Myeong Ju Song
- Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Republic of Korea
| | - Kee-Hong Choi
- Department of Psychology, Korea University, Seoul, Republic of Korea
| | - Seung-Hwan Lee
- Clinical Emotion and Cognition Research Laboratory, Goyang, Republic of Korea; Department of Psychiatry, Inje University, Ilsan-Paik Hospital, Goyang, Republic of Korea
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Abstract
The thalamus is the heavily interconnected partner of the neocortex. All areas of the neocortex receive afferent input from and send efferent projections to specific thalamic nuclei. Through these connections, the thalamus serves to provide the cortex with sensory input, and to facilitate interareal cortical communication and motor and cognitive functions. In the visual system, the lateral geniculate nucleus (LGN) of the dorsal thalamus is the gateway through which visual information reaches the cerebral cortex. Visual processing in the LGN includes spatial and temporal influences on visual signals that serve to adjust response gain, transform the temporal structure of retinal activity patterns, and increase the signal-to-noise ratio of the retinal signal while preserving its basic content. This review examines recent advances in our understanding of LGN function and circuit organization and places these findings in a historical context.
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Affiliation(s)
- W Martin Usrey
- Center for Neuroscience and Department of Neurobiology, Physiology & Behavior, University of California, Davis, California 95618
| | - Henry J Alitto
- Center for Neuroscience and Department of Neurobiology, Physiology & Behavior, University of California, Davis, California 95618
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118
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Monocular and binocular mechanisms mediating flicker adaptation. Vision Res 2015; 117:41-8. [PMID: 26505684 DOI: 10.1016/j.visres.2015.08.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/11/2015] [Accepted: 08/13/2015] [Indexed: 11/21/2022]
Abstract
Flicker adaptation reduces subsequent temporal contrast sensitivity. Recent studies show that this adaptation likely results from neural changes in the magnocellular visual pathway, but whether this adaptation occurs at a monocular or a binocular level, or both, is unclear. Here, two experiments address this question. The first experiment exploits the observation that flicker adaptation is stronger at higher than lower temporal frequencies. Observers' two eyes adapted to 3Hz flicker with an incremental pulse at 1/4 duty cycle, either in-phase or out-of-phase in the two eyes. At the binocular level, the flicker rate was 6Hz in the out-of-phase condition if the two eyes' pulse trains sum. Similar sensitivity reduction was found in both phase conditions, as expected for independent monocular adapting mechanisms. The second experiment tested for interocular transfer of adaptation between eyes. Results showed that (1) flicker adaptation was strongest with adapting and test fields in only the same eye, (2) adaptation can be partially transferred interocularly with adaptation in only the opposite eye, and (3) adaptation was weakened when both eyes were adapted simultaneously at different contrasts, compared to test-eye adaptation alone. Taken together, the findings are consistent with mechanisms of flicker adaptation at both the monocular and binocular level.
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119
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Tsukamoto Y, Omi N. OFF bipolar cells in macaque retina: type-specific connectivity in the outer and inner synaptic layers. Front Neuroanat 2015; 9:122. [PMID: 26500507 PMCID: PMC4594025 DOI: 10.3389/fnana.2015.00122] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/29/2015] [Indexed: 11/13/2022] Open
Abstract
OFF bipolar cells in the macaque retina were recently classified into five types: flat midget bipolar (FMB) and diffuse bipolar (DB) 1, 2, 3a, and 3b. We examined all parallel pathways from cone photoreceptors via OFF bipolar cells to parasol and midget ganglion cells by serial section transmission electron microscopy. Basal contacts of OFF bipolar cells to cone pedicles were previously categorized as triad-associated (TA) and non-TA (NTA). The latter was further divided into two groups located in the middle and marginal areas of the pedicle at the present eccentricity of 15°. We then mapped the distributions of all three basal contacts of the five OFF bipolar cell types in the same area of cone pedicles. TA contacts were more numerous than NTA contacts in FMB (93%), DB1 (67%), and DB3a (81%) cells, but less in DB2 (30%) and DB3b (21%) cells. Cluster analysis of these contact parameters reconfirmed five distinct OFF bipolar cell types and showed these positional configurations of basal synapses to be cell type-specific. This architecture is thought to provide a spatial framework for the interstitial diffusion and local uptake of the neurotransmitter (glutamate) that spills over from ribbon synapses. All five OFF bipolar cell types formed ribbon-synaptic contacts to both parasol and midget ganglion cells. DB2 and 3a, DB1 and 3b, and FMB predominantly, moderately, and negligibly contacted parasol ganglion cells, respectively. FMB almost exclusively contacted midget ganglion cells, to which DB1 provided dominant output (58%), and DB2, 3a, and 3b provided between 3% and 10% of their output. Consequently, the cone signal sampling routes of a midget ganglion cell consisted of two substructures: the narrow (mainly 2-3 cones) FMB pathway and the wide (mainly 10 cones) DB pathway, where connection strength was four-fold greater in the FMB than DB pathway. The narrow and strong FMB pathway may confer the highest spatial resolution and sporadically may include blue cone signals.
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Affiliation(s)
- Yoshihiko Tsukamoto
- Studio Retina, Satonaka Nishinomiya, Japan ; Department of Biology, Hyogo College of Medicine Nishinomiya, Japan
| | - Naoko Omi
- Studio Retina, Satonaka Nishinomiya, Japan
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120
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Gori S, Seitz AR, Ronconi L, Franceschini S, Facoetti A. Multiple Causal Links Between Magnocellular-Dorsal Pathway Deficit and Developmental Dyslexia. Cereb Cortex 2015; 26:4356-4369. [PMID: 26400914 DOI: 10.1093/cercor/bhv206] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Although impaired auditory-phonological processing is the most popular explanation of developmental dyslexia (DD), the literature shows that the combination of several causes rather than a single factor contributes to DD. Functioning of the visual magnocellular-dorsal (MD) pathway, which plays a key role in motion perception, is a much debated, but heavily suspected factor contributing to DD. Here, we employ a comprehensive approach that incorporates all the accepted methods required to test the relationship between the MD pathway dysfunction and DD. The results of 4 experiments show that (1) Motion perception is impaired in children with dyslexia in comparison both with age-match and with reading-level controls; (2) pre-reading visual motion perception-independently from auditory-phonological skill-predicts future reading development, and (3) targeted MD trainings-not involving any auditory-phonological stimulation-leads to improved reading skill in children and adults with DD. Our findings demonstrate, for the first time, a causal relationship between MD deficits and DD, virtually closing a 30-year long debate. Since MD dysfunction can be diagnosed much earlier than reading and language disorders, our findings pave the way for low resource-intensive, early prevention programs that could drastically reduce the incidence of DD.
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Affiliation(s)
- Simone Gori
- Department of Human and Social Sciences, University of Bergamo, Bergamo 24129, Italy Child Psychopathology Unit, Scientific Institute "E. Medea", Bosisio Parini, Lecco 23842, Italy
| | - Aaron R Seitz
- Department of Psychology, University of California - Riverside, Riverside, CA, USA
| | - Luca Ronconi
- Child Psychopathology Unit, Scientific Institute "E. Medea", Bosisio Parini, Lecco 23842, Italy Developmental and Cognitive Neuroscience Lab, Department of General Psychology, University of Padua, Padova 35131, Italy
| | - Sandro Franceschini
- Child Psychopathology Unit, Scientific Institute "E. Medea", Bosisio Parini, Lecco 23842, Italy Developmental and Cognitive Neuroscience Lab, Department of General Psychology, University of Padua, Padova 35131, Italy
| | - Andrea Facoetti
- Child Psychopathology Unit, Scientific Institute "E. Medea", Bosisio Parini, Lecco 23842, Italy Developmental and Cognitive Neuroscience Lab, Department of General Psychology, University of Padua, Padova 35131, Italy
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121
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Masking with faces in central visual field under a variety of temporal schedules. Vision Res 2015; 116:1-12. [PMID: 26381296 DOI: 10.1016/j.visres.2015.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 11/20/2022]
Abstract
With a few exceptions, previous studies have explored masking using either a backward mask or a common onset trailing mask, but not both. In a series of experiments, we demonstrate the use of faces in central visual field as a viable method to study the relationship between these two types of mask schedule. We tested observers in a two alternative forced choice face identification task, where both target and mask comprised synthetic faces, and show that a simple model can successfully predict masking across a variety of masking schedules ranging from a backward mask to a common onset trailing mask and a number of intermediate variations. Our data are well accounted for by a window of sensitivity to mask interference that is centered at around 100 ms.
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122
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Contrast adaptation is spatial frequency specific in mouse primary visual cortex. Neuroscience 2015; 310:198-205. [PMID: 26386296 DOI: 10.1016/j.neuroscience.2015.09.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 11/20/2022]
Abstract
Contrast adaptation, generated by prolonged viewing of a high contrast spatial pattern, is known to reduce perceptual sensitivity to subsequently presented stimuli of similar spatial frequency (SF). Neural correlates of this pattern-specific contrast adaptation have been described in several classic studies in cat primary visual cortex (V1). These results have also recently been extended to mice, which is a genetically manipulable animal model. Here we attempt to parse the potential mechanisms contributing to this phenomenon by determining whether the SF specificity of contrast adaptation observed in mouse V1 neurons depends on the spike rate elicited by the adapting gratings. We found that adapting stimuli that drove a neuron more strongly generally produced more adaptation, implicating an intrinsic or fatigue-like process. Importantly, we also observed that slightly stronger contrast adaptation was produced when the adapting SF matched the test SF even when matched and nonmatched adapting gratings elicited similar spike rates indicating extrinsic or network processes contribute as well.
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123
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Anderson AJ, Jiao J, Bui BV. Efficiently Measuring Magnocellular and Parvocellular Function in Human Clinical Studies. Transl Vis Sci Technol 2015; 4:1. [PMID: 26346944 DOI: 10.1167/tvst.4.5.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 07/12/2015] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Pokorny and Smith (J Opt Soc Am A Opt Image Sci Vis. 1997;14:2477-2486) described a laboratory method to behaviorally measure magnocellular and parvocellular pathway sensitivity. We investigated whether their method may be more efficiently applied to clinical populations by reducing adaptation times. METHODS We measured contrast detection thresholds to a 30-ms increment on a 30 cd/m2 background every 2 seconds after a 1-minute preadaptation to either a bright (90 cd/m2) or dim (3 cd/m2) luminance, in four observers. We also measured increment thresholds atop a steady 60 cd/m2 luminous pedestal (30 cd/m2 above the background) that remained on for 80 seconds, and tracked thresholds for 60 seconds after pedestal offset. We also assessed the minimum number of stimulus presentations required to reliably estimate thresholds using our four alternative forced choice (4-AFC) zippy estimation by sequential testing (ZEST) procedure. RESULTS Detection thresholds between the bright and dim preadaptation conditions were identical within seconds after the offset of the preadaptation luminance. Thresholds on the steady luminance pedestal reached stable values within approximately 10 seconds from pedestal onset, and recovered within 2 seconds of pedestal offset. Analysis of the 4-AFC ZEST procedure found little decrease in threshold variability after approximately 14 stimulus presentations. CONCLUSIONS Preadaptation and stimulus adaptation times may be reduced dramatically from those described by Pokorny and Smith, without altering thresholds. TRANSLATIONAL RELEVANCE Experimental time with clinical populations often is limited. Increasing the efficiency of the method of Pokorny and Smith allows for either shorter test sessions, or for a more extensive range of experimental parameters to be explored in disease.
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Affiliation(s)
- Andrew J Anderson
- Department of Optometry and Vision Sciences The University of Melbourne, Parkville, Australia
| | - Julie Jiao
- Department of Optometry and Vision Sciences The University of Melbourne, Parkville, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences The University of Melbourne, Parkville, Australia
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124
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Abstract
When the human primary visual cortex (V1) is damaged, the dominant geniculo-striate pathway can no longer convey visual information to the occipital cortex. However, many patients with such damage retain some residual visual function that must rely on an alternative pathway directly to extrastriate occipital regions. This residual vision is most robust for moving stimuli, suggesting a role for motion area hMT+. However, residual vision also requires high-contrast stimuli, which is inconsistent with hMT+ sensitivity to contrast in which even low-contrast levels elicit near-maximal neural activation. We sought to investigate this discrepancy by measuring behavioral and neural responses to increasing contrast in patients with V1 damage. Eight patients underwent behavioral testing and functional magnetic resonance imaging to record contrast sensitivity in hMT+ of their damaged hemisphere, using Gabor stimuli with a spatial frequency of 1 cycle/°. The responses from hMT+ of the blind hemisphere were compared with hMT+ and V1 responses in the sighted hemisphere of patients and a group of age-matched controls. Unlike hMT+, neural responses in V1 tend to increase linearly with increasing contrast, likely reflecting a dominant parvocellular channel input. Across all patients, the responses in hMT+ of the blind hemisphere no longer showed early saturation but increased linearly with contrast. Given the spatiotemporal parameters used in this study and the known direct subcortical projections from the koniocellular layers of the lateral geniculate nucleus to hMT+, we propose that this altered contrast sensitivity in hMT+ could be consistent with input from the koniocellular pathway.
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125
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Skottun BC. On the use of spatial frequency to isolate contributions from the magnocellular and parvocellular systems and the dorsal and ventral cortical streams. Neurosci Biobehav Rev 2015; 56:266-75. [PMID: 26188134 DOI: 10.1016/j.neubiorev.2015.07.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 07/05/2015] [Accepted: 07/06/2015] [Indexed: 10/23/2022]
Abstract
Many authors have claimed that suprathreshold achromatic stimuli of low and high spatial frequency can be used to separate responses from different entities in the visual system. Most prominently, it has been proposed that such stimuli can differentiate responses from the magnocellular and parvocellular systems. As is reviewed here, investigators who have examined stimulus specificity of neurons in these systems have found little difference between magno- and parvocellular cells. It has also been proposed that spatial frequency can be used to selectively activate the "magnocellular-dorsal stream". The present review indicates that cells in Area MT of the dorsal stream do prefer very low spatial frequencies. However, the review also shows that cells in Area V4 of the ventral stream respond, not only to relatively high spatial frequencies, but also to low frequency stimuli. Thus, low spatial frequencies cannot be relied upon to selectively activate the dorsal stream.
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126
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Can Variability of Pattern ERG Signal Help to Detect Retinal Ganglion Cells Dysfunction in Glaucomatous Eyes? BIOMED RESEARCH INTERNATIONAL 2015; 2015:571314. [PMID: 26167489 PMCID: PMC4475748 DOI: 10.1155/2015/571314] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 12/30/2014] [Accepted: 01/01/2015] [Indexed: 11/29/2022]
Abstract
Objective. To evaluate variability of steady-state pattern electroretinogram (SS-PERG) signal in normal, suspected, and glaucomatous eyes. Methods. Twenty-one subjects with suspected glaucoma due to disc abnormalities (GS), 37 patients with early glaucoma (EG), and 24 normal control (NC) were tested with spectral-domain optical coherence tomography (SD-OCT), standard automated perimetry (SAP), and SS-PERG. Mean deviation (MD), pattern standard deviation (PSD), retinal nerve fiber layer (RNFL), and ganglionar complex cells (GCC) were evaluated. The SS-PERG was recorded five consecutive times and the amplitude and phase of second harmonic were measured. PERG amplitude and coefficient of variation of phase (CVphase) were recorded, and correlation with structural and functional parameters of disease, by means of one-way ANOVA and Pearson's correlation, was analysed. Results. PERG amplitude was reduced, as expression of retinal ganglion cells (RGCs) dysfunction, in EG patients and GS subjects compared to NC patients (P < 0.0001). CVphase was significantly increased in EG patients and GS subjects, compared to healthy (P < 0.0001), and it was also correlated with PSD (P = 0.0009), GCC (P = 0.028), and RNFL (P = 0.0078) only in EG patients. Conclusions. Increased intrasession variability of phase in suspected glaucomatous eyes may be a sign of RGCs dysfunction.
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127
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Jiang Y, Yampolsky D, Purushothaman G, Casagrande VA. Perceptual decision related activity in the lateral geniculate nucleus. J Neurophysiol 2015; 114:717-35. [PMID: 26019309 DOI: 10.1152/jn.00068.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 05/26/2015] [Indexed: 12/24/2022] Open
Abstract
Fundamental to neuroscience is the understanding of how the language of neurons relates to behavior. In the lateral geniculate nucleus (LGN), cells show distinct properties such as selectivity for particular wavelengths, increments or decrements in contrast, or preference for fine detail versus rapid motion. No studies, however, have measured how LGN cells respond when an animal is challenged to make a perceptual decision using information within the receptive fields of those LGN cells. In this study we measured neural activity in the macaque LGN during a two-alternative, forced-choice (2AFC) contrast detection task or during a passive fixation task and found that a small proportion (13.5%) of single LGN parvocellular (P) and magnocellular (M) neurons matched the psychophysical performance of the monkey. The majority of LGN neurons measured in both tasks were not as sensitive as the monkey. The covariation between neural response and behavior (quantified as choice probability) was significantly above chance during active detection, even when there was no external stimulus. Interneuronal correlations and task-related gain modulations were negligible under the same condition. A bottom-up pooling model that used sensory neural responses to compute perceptual choices in the absence of interneuronal correlations could fully explain these results at the level of the LGN, supporting the hypothesis that the perceptual decision pool consists of multiple sensory neurons and that response fluctuations in these neurons can influence perception.
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Affiliation(s)
- Yaoguang Jiang
- Department of Psychology, Vanderbilt University, Nashville, Tennessee
| | - Dmitry Yampolsky
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee; and
| | - Gopathy Purushothaman
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee; and
| | - Vivien A Casagrande
- Department of Psychology, Vanderbilt University, Nashville, Tennessee; Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee; and Department of Ophthalmology and Visual Sciences, Vanderbilt University, Nashville, Tennessee
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128
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Contrast Sensitivity in Patients with Schizophrenia of Different Durations of Illness. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/s11055-015-0103-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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129
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Gardiner SK, Demirel S, Goren D, Mansberger SL, Swanson WH. The Effect of Stimulus Size on the Reliable Stimulus Range of Perimetry. Transl Vis Sci Technol 2015; 4:10. [DOI: 10.1167/tvst.4.2.10] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 02/17/2015] [Indexed: 11/24/2022] Open
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130
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Trapp S, Bar M. Prediction, context, and competition in visual recognition. Ann N Y Acad Sci 2015; 1339:190-8. [DOI: 10.1111/nyas.12680] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Sabrina Trapp
- Max Planck Institute for Human Cognitive and Brain Sciences; Leipzig Germany
| | - Moshe Bar
- Gonda Center for Brain Research, Bar-Ilan University; Ramat Gan Israel
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131
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Alterations induced by bangerter filters on the visual field: a frequency doubling technology and standard automated perimetry study. J Ophthalmol 2015; 2015:909848. [PMID: 25688299 PMCID: PMC4320864 DOI: 10.1155/2015/909848] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 12/15/2014] [Accepted: 12/30/2014] [Indexed: 12/02/2022] Open
Abstract
Purpose. To investigate the effects of Bangerter filters on the visual field in healthy and in amblyopic patients. Materials and Methods. Fifteen normal adults and fifteen anisometropic amblyopia patients were analysed with standard automated perimetry (SAP) and frequency doubling technology (FDT) at baseline and with filters 0.8 and 0.1.
Results. With 0.1 filter in SAP there was an increase of MD compared with controls (−10.24 ± 1.09 dB) in either the amblyopic (−11.34 ± 2.06 dB; P < 0.050) or sound eyes (−11.34 ± 1.66 dB; P < 0.030). With filters 0.8 the PSD was increased in the amblyopic eyes (2.09 ± 0.70 dB; P < 0.007) and in the sound eyes (1.92 ± 0.29 dB; P < 0.004) compared with controls. The FDT-PSD values in the control group were increased with the interposition of the filters compared to baseline (0.8; P < 0.0004 and 0.1; P < 0.0010). We did not find significant differences of the baseline PSD between amblyopic eyes (3.80 ± 2.21 dB) and the sound eyes (4.33 ± 1.31 dB) and when comparing the filters 0.8 (4.55 ± 1.50 versus 4.53 ± 1.76 dB) and 0.1 (4.66 ± 1.80 versus 5.10 ± 2.04 dB). Conclusions. The use of Bangerter filters leads to a reduction of the functionality of the magno- and parvocellular pathway.
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132
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Alitto HJ, Usrey WM. Surround suppression and temporal processing of visual signals. J Neurophysiol 2015; 113:2605-17. [PMID: 25652919 DOI: 10.1152/jn.00480.2014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 02/03/2015] [Indexed: 11/22/2022] Open
Abstract
Extraclassical surround suppression strongly modulates responses of neurons in the retina, lateral geniculate nucleus (LGN), and primary visual cortex. Although a great deal is known about the spatial properties of extraclassical suppression and the role it serves in stimulus size tuning, relatively little is known about how extraclassical suppression shapes visual processing in the temporal domain. We recorded the spiking activity of retinal ganglion cells and LGN neurons in the cat to test the hypothesis that extraclassical suppression influences temporal features of visual responses in the early visual system. Our results demonstrate that extraclassical suppression not only shifts the distribution of interspike intervals in a manner that decreases the efficacy of neuronal communication, it also decreases the reliability of neuronal responses to visual stimuli and it decreases the duration of visual responses, an effect that underlies a rightward shift in the temporal frequency tuning of LGN neurons. Taken together, these results reveal a dynamic relationship between extraclassical suppression and the temporal features of neuronal responses.
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Affiliation(s)
- Henry J Alitto
- Center for Neuroscience, University of California-Davis, Davis, California; Department of Neurobiology, Physiology, and Behavior, University of California-Davis, Davis, California; and
| | - W Martin Usrey
- Center for Neuroscience, University of California-Davis, Davis, California; Department of Neurobiology, Physiology, and Behavior, University of California-Davis, Davis, California; and Department of Neurology, University of California-Davis, Sacramento, California
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133
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Risuenho BBO, Miquilini L, Lacerda EMCB, Silveira LCL, Souza GS. Cortical responses elicited by luminance and compound stimuli modulated by pseudo-random sequences: comparison between normal trichromats and congenital red-green color blinds. Front Psychol 2015; 6:53. [PMID: 25674074 PMCID: PMC4309178 DOI: 10.3389/fpsyg.2015.00053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 01/12/2015] [Indexed: 11/17/2022] Open
Abstract
Conventional pattern-reversal visual evoked cortical potential (VECP) shows positivity for luminance and chromatic equiluminant stimuli while conventional pattern-onset VECP shows positivity for luminance pattern-onset and negativity for chromatic pattern-onset. We evaluated how the presentation mode affects VECPs elicited by luminance and compound (luminance plus chromatic) pseudo-random stimulation. Eleven normal trichromats and 17 red-green color-blinds were studied. Pattern-reversal and pattern-onset luminance and compound (luminance plus red-green) gratings were temporally modulated by m-sequence. We used a cross-correlation routine to extract the first order kernel (K1) and the first and second slices of the second order kernel (K2.1 and K2.2, respectively) from the VECP response. We integrated the amplitude of VECP components as a function of time in order to estimate its magnitude for each stimulus condition. We also used a normalized cross-correlation method in order to test the similarity of the VECP components. The VECP components varied with the presentation mode and the presence of red-green contrast in the stimuli. In trichromats, for compound conditions, pattern-onset K1, K2.1, and K2.2, and pattern-reversal K2.1 and K2.2 had negative-dominated waveforms at 100 ms. Small negativity or small positivity were observed in dichromats. Trichromats had larger VECP magnitude than color-blinds for compound pattern-onset K1 (with large variability across subjects), compound pattern-onset and pattern-reversal K2.1, and compound pattern-reversal K2.2. Trichromats and color-blinds had similar VECP amplitude for compound pattern-reversal K1 and compound pattern-onset K2.2, as well as for all luminance conditions. The cross-correlation analysis showed high similarity between waveforms of compound pattern-onset K2.1 and pattern-reversal K2.2 as well as pattern-reversal K2.1 and K2.2. We suggest that compound pattern-reversal K2.1 is an appropriate response to study red-green color-opponent activity.
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Affiliation(s)
| | - Letícia Miquilini
- Instituto de Ciências Biológicas - Universidade Federal do Pará Belém, Brazil
| | | | - Luiz Carlos L Silveira
- Instituto de Ciências Biológicas - Universidade Federal do Pará Belém, Brazil ; Núcleo de Medicina Tropical - Universidade Federal do Pará Belém, Brazil ; Universidade Ceuma São Luís, Brazil
| | - Givago S Souza
- Instituto de Ciências Biológicas - Universidade Federal do Pará Belém, Brazil ; Núcleo de Medicina Tropical - Universidade Federal do Pará Belém, Brazil
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Souza GS, Malone FL, Crawford TL, Miquilini L, Salomão RC, Guimarães DL, Ventura DF, Fitzgerald MEC, Silveira LCL. Low number of luminance levels in the luminance noise increases color discrimination thresholds estimated with pseudoisochromatic stimuli. Front Psychol 2015; 5:1291. [PMID: 25566106 PMCID: PMC4274881 DOI: 10.3389/fpsyg.2014.01291] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 10/24/2014] [Indexed: 11/13/2022] Open
Abstract
In pseudoisochromatic stimuli the presence of spatial and luminance noise forces the subject to discriminate the target from the background solely on the basis of chromaticity difference. Color-blind subjects may show difficulty to identify the target due to the elimination of borders and brightness clues caused by the luminance and spatial noise. Few studies have fully described the features of pseudoisochromatic stimuli. Fewer investigators have focused their studies in the effects of specific pseudoisochromatic parameters on color discrimination. We used the Cambridge Color Test (CCT) to investigate the influence on color discrimination thresholds due to the number of luminance levels present in the luminance noise. The CCT default has six luminance steps; however, in our investigation a total of eight different conditions were tested from 2 to 16 luminance steps. It was found that the CCT provided very robust values for color discrimination thresholds, which were degraded only for very small number of luminance steps. When the number of steps was increased, the color discrimination thresholds improved from 2 to 6 luminance steps and gradually reached a plateau for 10 or more luminance steps. The area of color discrimination ellipses as a function of luminance steps matches the relative proportion of ineffective contrasts between mosaic patches as a function of luminance steps, assuming that contrast becomes ineffective for values 18.6% or less. The lower number of color and luminance interactions in these conditions could explain the measured increase of color discrimination thresholds. The primary conclusion from this investigation was that results from pseudoisochromatic tests should have their parameters described in more detail. This type of description would allow a better understanding of the results provided, interpretations, and therefore cross study comparison of results obtained from different laboratories.
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Affiliation(s)
- Givago S Souza
- Instituto de Ciências Biológicas, Universidade Federal do Pará Belém, Brazil ; Núcleo de Medicina Tropical, Universidade Federal do Pará Belém, Brazil
| | | | - Teera L Crawford
- College of Medicine, University of Tennessee Health Science Center Memphis, TN, USA
| | - Letícia Miquilini
- Instituto de Ciências Biológicas, Universidade Federal do Pará Belém, Brazil
| | - Raílson C Salomão
- Instituto de Ciências Biológicas, Universidade Federal do Pará Belém, Brazil
| | - Diego L Guimarães
- Instituto de Ciências Biológicas, Universidade Federal do Pará Belém, Brazil
| | - Dora F Ventura
- Instituto de Psicologia, Universidade de São Paulo São Paulo, Brazil
| | - Malinda E C Fitzgerald
- Department of Biology, University of Memphis Memphis, TN, USA ; Department of Anatomy and Neurobiology, University of Tennessee Health Science Center Memphis, TN, USA
| | - Luiz Carlos L Silveira
- Instituto de Ciências Biológicas, Universidade Federal do Pará Belém, Brazil ; Núcleo de Medicina Tropical, Universidade Federal do Pará Belém, Brazil
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135
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Finlay BL, Charvet CJ, Bastille I, Cheung DT, Muniz JAPC, de Lima Silveira LC. Scaling the primate lateral geniculate nucleus: niche and neurodevelopment in the regulation of magnocellular and parvocellular cell number and nucleus volume. J Comp Neurol 2014; 522:1839-57. [PMID: 24222647 DOI: 10.1002/cne.23505] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 11/03/2013] [Accepted: 11/07/2013] [Indexed: 12/28/2022]
Abstract
New stereological assessments of lateral geniculate nucleus (LGN) neuron numbers and volumes in five New World primates (Cebus apella, Saguinus midas niger, Alouatta caraya, Aotus azarae, and Callicebus moloch) and compiled LGN volumes for an additional 26 mammals were analyzed for a better understanding of visual system evolution. Both the magnocellular (M)- and the parvocellular (P)-cell populations scale allometrically with brain volume in primates, P cells with a significantly higher slope such that, for every increase in M neuron number, P neuron numbers more than double (ln scale; y = 0.89x + 2.42R(2) = 0.664). In diurnal primates, the ratio of P to M cells was slightly but significantly higher than in nocturnal primates. For all mammals, including primates, LGN volume was unrelated to nocturnal or diurnal niche but showed marked differences in slope and intercept depending on taxonomic group. The allometric scaling of M and P cells can be related to the order of neurogenesis, with late-generated P cells increasing with positive allometry compared with the earlier-generated M cells. This developmental regularity links relative foveal representation to relative isocortex enlargement, which is also generated late. The small increase in the P/M cell ratio in diurnal primates may result from increased developmental neuron loss in the M-cell population as it competes for limited termination zones in primary visual cortex.
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Affiliation(s)
- Barbara L Finlay
- Behavioral and Evolutionary Neuroscience Group, Department of Psychology, Cornell University, Ithaca, New York, 14853
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136
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Duszyk A, Bierzyńska M, Radzikowska Z, Milanowski P, Kuś R, Suffczyński P, Michalska M, Łabęcki M, Zwoliński P, Durka P. Towards an optimization of stimulus parameters for brain-computer interfaces based on steady state visual evoked potentials. PLoS One 2014; 9:e112099. [PMID: 25398134 PMCID: PMC4232393 DOI: 10.1371/journal.pone.0112099] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 10/12/2014] [Indexed: 11/29/2022] Open
Abstract
Efforts to construct an effective brain-computer interface (BCI) system based on Steady State Visual Evoked Potentials (SSVEP) commonly focus on sophisticated mathematical methods for data analysis. The role of different stimulus features in evoking strong SSVEP is less often considered and the knowledge on the optimal stimulus properties is still fragmentary. The goal of this study was to provide insight into the influence of stimulus characteristics on the magnitude of SSVEP response. Five stimuli parameters were tested: size, distance, colour, shape, and presence of a fixation point in the middle of each flickering field. The stimuli were presented on four squares on LCD screen, with each square highlighted by LEDs flickering with different frequencies. Brighter colours and larger dimensions of flickering fields resulted in a significantly stronger SSVEP response. The distance between stimulation fields and the presence or absence of the fixation point had no significant effect on the response. Contrary to a popular belief, these results suggest that absence of the fixation point does not reduce the magnitude of SSVEP response. However, some parameters of the stimuli such as colour and the size of the flickering field play an important role in evoking SSVEP response, which indicates that stimuli rendering is an important factor in building effective SSVEP based BCI systems.
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Affiliation(s)
- Anna Duszyk
- University of Social Sciences and Humanities, Warsaw, Poland
| | | | | | | | - Rafał Kuś
- University of Warsaw, Faculty of Physics, Warsaw, Poland
| | | | | | - Maciej Łabęcki
- University of Warsaw, Faculty of Physics, Warsaw, Poland
| | - Piotr Zwoliński
- Warsaw Memorial Child Hospital, Department of Neurosurgery, Warsaw, Poland
| | - Piotr Durka
- University of Warsaw, Faculty of Physics, Warsaw, Poland
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137
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Skottun BC. The magnocellular system versus the dorsal stream. Front Hum Neurosci 2014; 8:786. [PMID: 25339887 PMCID: PMC4186266 DOI: 10.3389/fnhum.2014.00786] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 09/16/2014] [Indexed: 12/03/2022] Open
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138
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Tapia E, Beck DM. Probing feedforward and feedback contributions to awareness with visual masking and transcranial magnetic stimulation. Front Psychol 2014; 5:1173. [PMID: 25374548 PMCID: PMC4204434 DOI: 10.3389/fpsyg.2014.01173] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 09/26/2014] [Indexed: 11/13/2022] Open
Abstract
A number of influential theories posit that visual awareness relies not only on the initial, stimulus-driven (i.e., feedforward) sweep of activation but also on recurrent feedback activity within and between brain regions. These theories of awareness draw heavily on data from masking paradigms in which visibility of one stimulus is reduced due to the presence of another stimulus. More recently transcranial magnetic stimulation (TMS) has been used to study the temporal dynamics of visual awareness. TMS over occipital cortex affects performance on visual tasks at distinct time points and in a manner that is comparable to visual masking. We draw parallels between these two methods and examine evidence for the neural mechanisms by which visual masking and TMS suppress stimulus visibility. Specifically, both methods have been proposed to affect feedforward as well as feedback signals when applied at distinct time windows relative to stimulus onset and as a result modify visual awareness. Most recent empirical evidence, moreover, suggests that while visual masking and TMS impact stimulus visibility comparably, the processes these methods affect may not be as similar as previously thought. In addition to reviewing both masking and TMS studies that examine feedforward and feedback processes in vision, we raise questions to guide future studies and further probe the necessary conditions for visual awareness.
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Affiliation(s)
- Evelina Tapia
- Beckman Institute, University of Illinois Urbana-Champaign Urbana, IL USA
| | - Diane M Beck
- Beckman Institute, University of Illinois Urbana-Champaign Urbana, IL USA ; Department of Psychology, University of Illinois Urbana-Champaign Urbana, IL, USA
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139
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Gori S, Mascheretti S, Giora E, Ronconi L, Ruffino M, Quadrelli E, Facoetti A, Marino C. The DCDC2 Intron 2 Deletion Impairs Illusory Motion Perception Unveiling the Selective Role of Magnocellular-Dorsal Stream in Reading (Dis)ability. Cereb Cortex 2014; 25:1685-95. [PMID: 25270309 DOI: 10.1093/cercor/bhu234] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Simone Gori
- Developmental and Cognitive Neuroscience Lab, Department of General Psychology, University of Padua, 35131 Padua, Italy Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, 23842 Bosisio Parini, Lecco, Italy
| | - Sara Mascheretti
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, 23842 Bosisio Parini, Lecco, Italy
| | - Enrico Giora
- Faculty of Psychology, "Vita-Salute" San Raffaele University, 20132 Milan, Italy
| | - Luca Ronconi
- Developmental and Cognitive Neuroscience Lab, Department of General Psychology, University of Padua, 35131 Padua, Italy Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, 23842 Bosisio Parini, Lecco, Italy
| | - Milena Ruffino
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, 23842 Bosisio Parini, Lecco, Italy
| | - Ermanno Quadrelli
- Department of Psychology, University of Milan-Bicocca, 20126 Milan, Italy
| | - Andrea Facoetti
- Developmental and Cognitive Neuroscience Lab, Department of General Psychology, University of Padua, 35131 Padua, Italy Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, 23842 Bosisio Parini, Lecco, Italy
| | - Cecilia Marino
- Child Psychopathology Unit, Scientific Institute, IRCCS Eugenio Medea, 23842 Bosisio Parini, Lecco, Italy Centre de Recherche de L'Institut Universitaire en Santé Mentale de Québec, Québec, QC, Canada G1J 2G3 Département de Psychiatrie et Neurosciences, Faculté de Médecine, Université Laval, Québec, QC, Canada G1V 0A6
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140
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Swanson WH, Horner DG, Dul MW, Malinovsky VE. Choice of Stimulus Range and Size Can Reduce Test-Retest Variability in Glaucomatous Visual Field Defects. Transl Vis Sci Technol 2014; 3:6. [PMID: 25371855 DOI: 10.1167/tvst.3.5.6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 07/20/2014] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To develop guidelines for engineering perimetric stimuli to reduce test-retest variability in glaucomatous defects. METHODS Perimetric testing was performed on one eye for 62 patients with glaucoma and 41 age-similar controls on size III and frequency-doubling perimetry and three custom tests with Gaussian blob and Gabor sinusoid stimuli. Stimulus range was controlled by values for ceiling (maximum sensitivity) and floor (minimum sensitivity). Bland-Altman analysis was used to derive 95% limits of agreement on test and retest, and bootstrap analysis was used to test the hypotheses about peak variability. RESULTS Limits of agreement for the three custom stimuli were similar in width (0.72 to 0.79 log units) and peak variability (0.22 to 0.29 log units) for a stimulus range of 1.7 log units. The width of the limits of agreement for size III decreased from 1.78 to 1.37 to 0.99 log units for stimulus ranges of 3.9, 2.7, and 1.7 log units, respectively (F = 3.23, P < 0.001); peak variability was 0.99, 0.54, and 0.34 log units, respectively (P < 0.01). For a stimulus range of 1.3 log units, limits of agreement were narrowest with Gabor and widest with size III stimuli, and peak variability was lower (P < 0.01) with Gabor (0.18 log units) and frequency-doubling perimetry (0.24 log units) than with size III stimuli (0.38 log units). CONCLUSIONS Test-retest variability in glaucomatous visual field defects was substantially reduced by engineering the stimuli. TRANSLATIONAL RELEVANCE The guidelines should allow developers to choose from a wide range of stimuli.
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141
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Yan T, Wang B, Geng Y, Yan Y, Mu N, Wu J, Guo Q, Tang X, Zeng Y, Peng Y. Contrast response functions with wide-view stimuli in the human visual cortex. Perception 2014; 43:677-93. [PMID: 25223111 DOI: 10.1068/p7640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In this manuscript, using a novel wide-view visual presentation system that we developed for vision research and functional magnetic resonance imaging (fMRI), we studied contrast response functions in regions of the brain that are central and peripheral to the entire set of visual areas (V1, V2, V3, V3A, MT+), regions that have not been all investigated in previous vision research. Under the stimulus conditions which were 0-20 deg, 20-40 deg, and 40-60 deg eccentricity black-and-white checkerboard patterns, we measured the blood oxygenation level-dependent fMRI contrast response at five contrast levels (6, 12, 24, 48, and 96%) in the visual areas. On the basis of these data, the central and pericentral visual areas had low-contrast gain, whereas the peripheral visual areas had high-contrast gain. In addition, our results showed that the signals fundamentally shift during visual processing through posterior visual cortical areas (V1, V2, and V3) to superior visual cortical areas (V3A and MT+).
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142
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Pietersen ANJ, Cheong SK, Solomon SG, Tailby C, Martin PR. Temporal response properties of koniocellular (blue-on and blue-off) cells in marmoset lateral geniculate nucleus. J Neurophysiol 2014; 112:1421-38. [DOI: 10.1152/jn.00077.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Visual perception requires integrating signals arriving at different times from parallel visual streams. For example, signals carried on the phasic-magnocellular (MC) pathway reach the cerebral cortex pathways some tens of milliseconds before signals traveling on the tonic-parvocellular (PC) pathway. Visual latencies of cells in the koniocellular (KC) pathway have not been specifically studied in simian primates. Here we compared MC and PC cells to “blue-on” (BON) and “blue-off” (BOF) KC cells; these cells carry visual signals originating in short-wavelength-sensitive (S) cones. We made extracellular recordings in the lateral geniculate nucleus (LGN) of anesthetized marmosets. We found that BON visual latencies are 10–20 ms longer than those of PC or MC cells. A small number of recorded BOF cells ( n = 7) had latencies 10–20 ms longer than those of BON cells. Within all cell groups, latencies of foveal receptive fields (<10° eccentricity) were longer (by 3–8 ms) than latencies of peripheral receptive fields (>10°). Latencies of yellow-off inputs to BON cells lagged the blue-on inputs by up to 30 ms, but no differences in visual latency were seen on comparing marmosets expressing dichromatic (“red-green color-blind”) or trichromatic color vision phenotype. We conclude that S-cone signals leaving the LGN on KC pathways are delayed with respect to signals traveling on PC and MC pathways. Cortical circuits serving color vision must therefore integrate across delays in (red-green) chromatic signals carried by PC cells and (blue-yellow) signals carried by KC cells.
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Affiliation(s)
- A. N. J. Pietersen
- Australian Research Council Centre of Excellence for Integrative Brain Function, University of Sydney, Sydney, Australia
- Save Sight Institute, University of Sydney, Sydney, Australia
| | - S. K. Cheong
- Australian Research Council Centre of Excellence for Integrative Brain Function, University of Sydney, Sydney, Australia
- Save Sight Institute, University of Sydney, Sydney, Australia
| | - S. G. Solomon
- School of Medical Sciences, University of Sydney, Sydney, Australia
- Department of Experimental Psychology, University College London, London, United Kingdom; and
| | - C. Tailby
- School of Medical Sciences, University of Sydney, Sydney, Australia
- Florey Institute of Neuroscience and Mental Health, Heidelberg, Australia
| | - P. R. Martin
- Australian Research Council Centre of Excellence for Integrative Brain Function, University of Sydney, Sydney, Australia
- Save Sight Institute, University of Sydney, Sydney, Australia
- School of Medical Sciences, University of Sydney, Sydney, Australia
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143
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Kaposvári P, Bognár A, Csibri P, Utassy G, Sáry G. Fusion and fission in the visual pathways. Physiol Res 2014; 63:625-35. [PMID: 24908093 DOI: 10.33549/physiolres.932691] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Inconsistent information from different modalities can be delusive for perception. This phenomenon can be observed with simultaneously presented inconsistent numbers of brief flashes and short tones. The conflict of bimodal information is reflected in double flash or fission, and flash fusion illusions, respectively. The temporal resolution of the vision system plays a fundamental role in the development of these illusions. As the parallel, dorsal and ventral pathways have different temporal resolution we presume that these pathways play different roles in the illusions. We used pathway-optimized stimuli to induce the illusions on separately driven visual streams. Our results show that both pathways support the double flash illusion, while the presence of the fusion illusion depends on the activated pathway. The dorsal pathway, which has better temporal resolution, does not support fusion, while the ventral pathway which has worse temporal resolution shows fusion strongly.
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Affiliation(s)
- P Kaposvári
- Department of Physiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
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144
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Jaekl P, Pérez-Bellido A, Soto-Faraco S. On the 'visual' in 'audio-visual integration': a hypothesis concerning visual pathways. Exp Brain Res 2014; 232:1631-8. [PMID: 24699769 DOI: 10.1007/s00221-014-3927-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 03/19/2014] [Indexed: 11/28/2022]
Abstract
Crossmodal interaction conferring enhancement in sensory processing is nowadays widely accepted. Such benefit is often exemplified by neural response amplification reported in physiological studies conducted with animals, which parallel behavioural demonstrations of sound-driven improvement in visual tasks in humans. Yet, a good deal of controversy still surrounds the nature and interpretation of these human psychophysical studies. Here, we consider the interpretation of crossmodal enhancement findings under the light of the functional as well as anatomical specialization of magno- and parvocellular visual pathways, whose paramount relevance has been well established in visual research but often overlooked in crossmodal research. We contend that a more explicit consideration of this important visual division may resolve some current controversies and help optimize the design of future crossmodal research.
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Affiliation(s)
- Philip Jaekl
- Department of Brain and Cognitive Sciences, Center for Visual Science, University of Rochester, Rochester, NY, USA,
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145
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Breitmeyer BG. Contributions of magno- and parvocellular channels to conscious and non-conscious vision. Philos Trans R Soc Lond B Biol Sci 2014; 369:20130213. [PMID: 24639584 DOI: 10.1098/rstb.2013.0213] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The dorsal and ventral cortical pathways, driven predominantly by magnocellular (M) and parvocellular (P) inputs, respectively, assume leading roles in models of visual information processing. Although in prior proposals, the dorsal and ventral pathways support non-conscious and conscious vision, respectively, recent modelling and empirical developments indicate that each pathway plays important roles in both non-conscious and conscious vision. In these models, the ventral P-pathway consists of one subpathway processing an object's contour features, e.g. curvature, the other processing its surface attributes, e.g. colour. Masked priming studies have shown that feed-forward activity in the ventral P-pathway on its own supports non-conscious processing of contour and surface features. The dorsal M-pathway activity contributes directly to conscious vision of motion and indirectly to object vision by projecting to prefrontal cortex, which in turn injects top-down neural activity into the ventral P-pathway and there 'ignites' feed-forward-re-entrant loops deemed necessary for conscious vision. Moreover, an object's shape or contour remains invisible without the prior conscious registration of its surface properties, which for that reason are taken to comprise fundamental visual qualia. Besides suggesting avenues for future research, these developments bear on several recent and past philosophical issues.
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Affiliation(s)
- Bruno G Breitmeyer
- Department of Psychology and Center for Neuro-Engineering and Cognitive Science, University of Houston, , Houston, TX 77204-5022, USA
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146
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Gardiner SK, Swanson WH, Goren D, Mansberger SL, Demirel S. Assessment of the reliability of standard automated perimetry in regions of glaucomatous damage. Ophthalmology 2014; 121:1359-69. [PMID: 24629617 DOI: 10.1016/j.ophtha.2014.01.020] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 01/14/2014] [Accepted: 01/16/2014] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Visual field testing uses high-contrast stimuli in areas of severe visual field loss. However, retinal ganglion cells saturate with high-contrast stimuli, suggesting that the probability of detecting perimetric stimuli may not increase indefinitely as contrast increases. Driven by this concept, this study examines the lower limit of perimetric sensitivity for reliable testing by standard automated perimetry. DESIGN Evaluation of a diagnostic test. PARTICIPANTS A total of 34 participants with moderate to severe glaucoma; mean deviation at their last clinic visit averaged -10.90 dB (range, -20.94 to -3.38 dB). A total of 75 of the 136 locations tested had a perimetric sensitivity of ≤ 19 dB. METHODS Frequency-of-seeing curves were constructed at 4 nonadjacent visual field locations by the Method of Constant Stimuli (MOCS), using 35 stimulus presentations at each of 7 contrasts. Locations were chosen a priori and included at least 2 with glaucomatous damage but a sensitivity of ≥ 6 dB. Cumulative Gaussian curves were fit to the data, first assuming a 5% false-negative rate and subsequently allowing the asymptotic maximum response probability to be a free parameter. MAIN OUTCOME MEASURES The strength of the relation (R(2)) between perimetric sensitivity (mean of last 2 clinic visits) and MOCS sensitivity (from the experiment) for all locations with perimetric sensitivity within ± 4 dB of each selected value, at 0.5 dB intervals. RESULTS Bins centered at sensitivities ≥ 19 dB always had R(2) >0.1. All bins centered at sensitivities ≤ 15 dB had R(2) <0.1, an indication that sensitivities are unreliable. No consistent conclusions could be drawn between 15 and 19 dB. At 57 of the 81 locations with perimetric sensitivity <19 dB, including 49 of the 63 locations ≤ 15 dB, the fitted asymptotic maximum response probability was <80%, consistent with the hypothesis of response saturation. At 29 of these locations the asymptotic maximum was <50%, and so contrast sensitivity (50% response rate) is undefined. CONCLUSIONS Clinical visual field testing may be unreliable when visual field locations have sensitivity below approximately 15 to 19 dB because of a reduction in the asymptotic maximum response probability. Researchers and clinicians may have difficulty detecting worsening sensitivity in these visual field locations, and this difficulty may occur commonly in patients with glaucoma with moderate to severe glaucomatous visual field loss.
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Affiliation(s)
| | - William H Swanson
- Optometry and Vision Science, Indiana University, Bloomington, Indiana
| | - Deborah Goren
- Devers Eye Institute, Legacy Research Institute, Portland, Oregon
| | | | - Shaban Demirel
- Devers Eye Institute, Legacy Research Institute, Portland, Oregon
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147
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Abstract
The propagation of visual signals from individual cone photoreceptors through parallel neural circuits was examined in the primate retina. Targeted stimulation of individual cones was combined with simultaneous recording from multiple retinal ganglion cells of identified types. The visual signal initiated by an individual cone produced strong responses with different kinetics in three of the four numerically dominant ganglion cell types. The magnitude and kinetics of light responses in each ganglion cell varied nonlinearly with stimulus strength but in a manner that was independent of the cone of origin after accounting for the overall input strength of each cone. Based on this property of independence, the receptive field profile of an individual ganglion cell could be well estimated from responses to stimulation of each cone individually. Together, these findings provide a quantitative account of how elementary visual inputs form the ganglion cell receptive field.
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148
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Distribution and specificity of S-cone (“blue cone”) signals in subcortical visual pathways. Vis Neurosci 2014; 31:177-87. [DOI: 10.1017/s0952523813000631] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractWe review here the distribution of S-cone signals and properties of S-cone recipient receptive fields in subcortical pathways. Nearly everything we know about S-cone signals in the subcortical visual system comes from the study of visual systems in cats and primates (monkeys); in this review, we concentrate on results from macaque and marmoset monkeys. We discuss segregation of S-cone recipient (blue-on and blue-off) receptive fields in the dorsal lateral geniculate nucleus and describe their receptive field properties. We treat in some detail the question of detecting weak S-cone signals as an introduction for newcomers to the field. Finally, we briefly consider the question on how S-cone signals are distributed among nongeniculate targets.
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149
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Shoshina II, Shelepin YE, Semenova NB. Frequency-contrast sensitivity of visual stimulus perception in patients with schizophrenia treated with atypical and typical antipsychotics. ACTA ACUST UNITED AC 2014. [DOI: 10.1134/s0362119714010150] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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150
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Silveira VDA, Souza GDS, Gomes BD, Rodrigues AR, Silveira LCDL. Joint entropy for space and spatial frequency domains estimated from psychometric functions of achromatic discrimination. PLoS One 2014; 9:e86579. [PMID: 24466158 PMCID: PMC3900586 DOI: 10.1371/journal.pone.0086579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 12/12/2013] [Indexed: 11/18/2022] Open
Abstract
We used psychometric functions to estimate the joint entropy for space discrimination and spatial frequency discrimination. Space discrimination was taken as discrimination of spatial extent. Seven subjects were tested. Gábor functions comprising unidimensionalsinusoidal gratings (0.4, 2, and 10 cpd) and bidimensionalGaussian envelopes (1°) were used as reference stimuli. The experiment comprised the comparison between reference and test stimulithat differed in grating's spatial frequency or envelope's standard deviation. We tested 21 different envelope's standard deviations around the reference standard deviation to study spatial extent discrimination and 19 different grating's spatial frequencies around the reference spatial frequency to study spatial frequency discrimination. Two series of psychometric functions were obtained for 2%, 5%, 10%, and 100% stimulus contrast. The psychometric function data points for spatial extent discrimination or spatial frequency discrimination were fitted with Gaussian functions using the least square method, and the spatial extent and spatial frequency entropies were estimated from the standard deviation of these Gaussian functions. Then, joint entropy was obtained by multiplying the square root of space extent entropy times the spatial frequency entropy. We compared our results to the theoretical minimum for unidimensional Gábor functions, 1/4π or 0.0796. At low and intermediate spatial frequencies and high contrasts, joint entropy reached levels below the theoretical minimum, suggesting non-linear interactions between two or more visual mechanisms. We concluded that non-linear interactions of visual pathways, such as the M and P pathways, could explain joint entropy values below the theoretical minimum at low and intermediate spatial frequencies and high contrasts. These non-linear interactions might be at work at intermediate and high contrasts at all spatial frequencies once there was a substantial decrease in joint entropy for these stimulus conditions when contrast was raised.
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Affiliation(s)
| | - Givago da Silva Souza
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil
- Núcleo de Medicina Tropical, Universidade Federal do Pará, Belém, Pará, Brazil
| | - Bruno Duarte Gomes
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil
| | | | - Luiz Carlos de Lima Silveira
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Pará, Brazil
- Núcleo de Medicina Tropical, Universidade Federal do Pará, Belém, Pará, Brazil
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