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Journal articles on the topic 'Magnocellular Processing'

Author: Grafiati

Published: 9 March 2023

Last updated: 19 July 2025

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Chieffi, Sergio. "Dysfunction of Magnocellular/dorsal Processing Stream in Schizophrenia." Current Psychiatry Research and Reviews 15, no. 1 (2019): 26–36. http://dx.doi.org/10.2174/1573400515666190119163522.

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Background: Patients with schizophrenia show not only cognitive, but also perceptual deficits. Perceptual deficits may affect different sensory modalities. Among these, the impairment of visual information processing is of particular relevance as demonstrated by the high incidence of visual disturbances. In recent years, the study of neurophysiological mechanisms that underlie visuo-perceptual, -spatial and -motor disorders in schizophrenia has increasingly attracted the interest of researchers. Objective: The study aims to review the existent literature on magnocellular/dorsal (occipitoparietal) visual processing stream impairment in schizophrenia. The impairment of relatively early stages of visual information processing was examined using experimental paradigms such as backward masking, contrast sensitivity, contour detection, and perceptual closure. The deficits of late processing stages were detected by examining visuo-spatial and -motor abilities. Results: Neurophysiological and behavioral studies support the existence of deficits in the processing of visual information along the magnocellular/dorsal pathway. These deficits appear to affect both early and late stages of visual information processing. Conclusion: The existence of disturbances in the early processing of visual information along the magnocellular/dorsal pathway is strongly supported by neurophysiological and behavioral observations. Early magnocellular dysfunction may provide a substrate for late dorsal processing impairment as well as higher-level cognition deficits.

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Carretié, Luis, Dominique Kessel, María J. García-Rubio, Tamara Giménez-Fernández, Sandra Hoyos, and María Hernández-Lorca. "Magnocellular Bias in Exogenous Attention to Biologically Salient Stimuli as Revealed by Manipulating Their Luminosity and Color." Journal of Cognitive Neuroscience 29, no. 10 (2017): 1699–711. http://dx.doi.org/10.1162/jocn_a_01148.

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Exogenous attention is a set of mechanisms that allow us to detect and reorient toward salient events—such as appetitive or aversive—that appear out of the current focus of attention. The nature of these mechanisms, particularly the involvement of the parvocellular and magnocellular visual processing systems, was explored. Thirty-four participants performed a demanding digit categorization task while salient (spiders or S) and neutral (wheels or W) stimuli were presented as distractors under two figure–ground formats: heterochromatic/isoluminant (exclusively processed by the parvocellular system, Par trials) and isochromatic/heteroluminant (preferentially processed by the magnocellular system, Mag trials). This resulted in four conditions: SPar, SMag, WPar, and WMag. Behavioral (RTs and error rates in the task) and electrophysiological (ERPs) indices of exogenous attention were analyzed. Behavior showed greater attentional capture by SMag than by SPar distractors and enhanced modulation of SMag capture as fear of spiders reported by participants increased. ERPs reflected a sequence from magnocellular dominant (P1p, ≃120 msec) to both magnocellular and parvocellular processing (N2p and P2a, ≃200 msec). Importantly, amplitudes in one N2p subcomponent were greater to SMag than to SPar and WMag distractors, indicating greater magnocellular sensitivity to saliency. Taking together, results support a magnocellular bias in exogenous attention toward distractors of any nature during initial processing, a bias that remains in later stages when biologically salient distractors are present.

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Goodbourn, Patrick T., Jenny M. Bosten, Ruth E. Hogg, Gary Bargary, Adam J. Lawrance-Owen, and J. D. Mollon. "Do different ‘magnocellular tasks’ probe the same neural substrate?" Proceedings of the Royal Society B: Biological Sciences 279, no. 1745 (2012): 4263–71. http://dx.doi.org/10.1098/rspb.2012.1430.

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The sensory abnormalities associated with disorders such as dyslexia, autism and schizophrenia have often been attributed to a generalized deficit in the visual magnocellular–dorsal stream and its auditory homologue. To probe magnocellular function, various psychophysical tasks are often employed that require the processing of rapidly changing stimuli. But is performance on these several tasks supported by a common substrate? To answer this question, we tested a cohort of 1060 individuals on four ‘magnocellular tasks’: detection of low-spatial-frequency gratings reversing in contrast at a high temporal frequency (so-called frequency-doubled gratings); detection of pulsed low-spatial-frequency gratings on a steady luminance pedestal; detection of coherent motion; and auditory discrimination of temporal order. Although all tasks showed test–retest reliability, only one pair shared more than 4 per cent of variance. Correlations within the set of ‘magnocellular tasks’ were similar to the correlations between those tasks and a ‘non-magnocellular task’, and there was little consistency between ‘magnocellular deficit’ groups comprising individuals with the lowest sensitivity for each task. Our results suggest that different ‘magnocellular tasks’ reflect different sources of variance, and thus are not general measures of ‘magnocellular function’.

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Tyler, Christopher W., and Lani Hardage. "Long-Range Twinkle Induction: An Achromatic Rebound Effect in the Magnocellular Processing System?" Perception 27, no. 2 (1998): 203–14. http://dx.doi.org/10.1068/p270203.

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After viewing a blank region surrounded by a dynamic noise stimulus, viewers report the perception of prolonged dynamic twinkle in the unstimulated blank region. This twinkle aftereffect may be induced over long ranges in the visual field, up to 10° from the edge of the noise in central vision. Our previous studies of the properties of this aftereffect suggested mediation by the magnocellular processing system. We therefore evaluated the properties predicted by the magnocellular hypothesis by varying the coloring, the temporal and the spatial frequency of the stimulus. No aftereffect could be induced by an equiluminant color stimulus or by luminance noise below the temporal frequency of 5 Hz. The aftereffect obtained by luminance noise above 5 Hz was stronger for larger inducing elements. These results are consistent with known properties of the magnocellular processing system.

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Vidal-López, Joaquín, and Juan Antonio Romera-Vivancos. "Is Manipulation of Color Effective in Study of the Global Precedence Effect?" Perceptual and Motor Skills 108, no. 2 (2009): 631–35. http://dx.doi.org/10.2466/pms.108.2.631-635.

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This article evaluates the use of color manipulation in studying the effect of global precedence and the possible involvement of the magnocellular processing system. The analysis shows variations of color used in three studies produced changes on the global precedence effect, but findings based on this technique present some methodological problems and have little theoretical support from the magnocellular processing-system perspective. For this reason, more research is required to develop knowledge about the origin of these variations in global precedence.

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Cornelissen, P. L., P. C. Hansen, and J. F. Stein. "Integration of Impaired Visual as Well as Impaired Phonological Information Can Cause Reading Errors." Perception 26, no. 1_suppl (1997): 116. http://dx.doi.org/10.1068/v970019.

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Developmental dyslexia is a common problem amongst school children (5% – 10% are afflicted), yet controversy surrounds the explanation for its cause. Fluent reading requires rapid association of visual with phonological information—therefore problems with either visual or phonological processing could cause reading difficulties. It is known that dyslexics’ speech perception is often impaired, giving rise to ‘fuzzy’ or ‘underspecified’ phonological representations. This leads, in turn, to difficulties with letter-to-sound mapping during reading. Dyslexic individuals also find it unusually difficult to detect flickering or moving visual stimuli, consistent with impaired processing in the magnocellular visual stream. This raises the question of whether dyslexics' reading problems may be caused not only by abnormal phonological processing but also by magnocellular impairment. We suggest that, when children read, impaired magnocellular function may degrade information about where letters are positioned with respect to each other. We predicted that this might cause reading errors which contain sounds not represented in the printed word. We call these orthographically inconsistent nonsense errors ‘letter’ errors. To test this idea we assessed magnocellular function in 58 children by using a coherent-motion detection task. We then gave these children a single-word reading task and found that the likelihood of them making ‘letter’ errors was best explained by independent contributions from motion detection (ie magnocellular function) and phonological awareness (assessed by a spoonerism task). This result held even when chronological age, reading ability, and IQ were controlled for. These findings suggest that, when visual and phonological information is integrated during reading, impairments in both domains may indeed affect how children read.

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Spear, P. D., R. J. Moore, C. B. Kim, J. T. Xue, and N. Tumosa. "Effects of aging on the primate visual system: spatial and temporal processing by lateral geniculate neurons in young adult and old rhesus monkeys." Journal of Neurophysiology 72, no. 1 (1994): 402–20. http://dx.doi.org/10.1152/jn.1994.72.1.402.

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1. Visual abilities decline during normal aging, and many of these declines are due to neural changes in the retina or central visual pathways. We have begun studies of the primate visual system to investigate the location and nature of these changes as well as to answer general questions about the effects of aging on neural function. We began with the dorsal lateral geniculate nucleus (LGN) because it is the main structure through which visual information passes on the way to cortex and because the parallel parvocellular and magnocellular pathways, which may be affected differently by aging, are anatomically distinct there. 2. Single -cell recordings were made in the LGN of young adult (5–16 yr) and old (25–28 yr) rhesus monkeys. We made quantitative measures of a wide variety of response properties for a large number of parvocellular (n = 257) and magnocellular (n = 113) neurons in the two groups of animals. As a result, in addition to studying the effects of aging, we were able to make quantitative comparisons between parvocellular and magnocellular neurons using larger samples than have been studied previously and for some properties that have not been studied before. 3. We found that magnocellular neurons have significantly higher maximal response rates and signal -to -noise ratios than parvocellular neurons. However, response latencies to visual stimulation were similar for neurons in the two types of layers. In agreement with previous studies, magnocellular neurons had higher maximal contrast sensitivity and higher contrast gain than parvocellular neurons. However, the sensitivity difference occurred because nearly all of the neurons with low sensitivities (< 10) were in the parvocellular layers, not because neurons in the magnocellular layers had the highest sensitivities. 4. Neurons with the smallest receptive-field centers, the highest spatial-frequency resolutions, and the highest optimal spatial frequencies were found in the parvocellular layers. However, the overall distributions of each of these properties overlapped substantially for neurons in the two types of layers, and the mean values were not significantly different. The mean high temporal-frequency cutoff was significantly higher for magnocellular than parvocellular neurons, but the difference was small (only 3 Hz), and it occurred because many parvocellular neurons had lower cutoffs than any seen in the magnocellular layers, not because magnocellular neurons had the highest temporal-frequency cutoffs. Parvocellular neurons also had narrower temporal-frequency tuning than magnocellular neurons. However, there was no significant difference in optimal temporal frequency.(ABSTRACT TRUNCATED AT 400 WORDS)

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Marosi, C., Z. Fodor, and G. Csukly. "Consequence of the magnocellular dysfunction on processing facial affect recognition in Schizophrenia." European Psychiatry 65, S1 (2022): S153. http://dx.doi.org/10.1192/j.eurpsy.2022.411.

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Introduction Magnocellular deficit in visual perception and impaired emotion recognition are core features of schizophrenia, however their relationship and the neurobiological underpinnings are still unclear. Objectives The aim of our research was to investigate the oscillatory background of perception and emotion recognition in schizophrenia and to examine the relationship between these processes. Methods Thirty-nine subjects with schizophrenia and forty healthy controls subjects were enrolled in the study; the two study groups did not differ in age, gender and education. In the visual paradigm the participants viewed magnocellular biased low-spatial frequency (LSF) and parvocellular biased high-spatial frequency (HSF) Gabor-patches and in the second paradigm happy, sad and neutral faces were presented, while 128-channel EEG was recorded. Results Significantly weaker theta (4-7 Hz) event related synchronisation (ERS) was observed in patients compared to controls in the LSF condition, whereas in the HSF condition there was no difference between the two groups. Event related changes in theta amplitude were also found to be significantly weaker in patients compared to healthy controls in the emotion recognition task, which difference was disappeared after correction for ERS to LSF condition. In the correlational analysis theta activity in the magnocellular biased stimuli correlated significantly with theta activity in the emotion recognition task, while theta to parvocellular biased stimuli showed no similar correlation with emotion recognition. Conclusions In schizophrenia, emotion recognition impairments are closely related to the dysfunction of the magnocellular system, which supports the bottom-up model of schizophrenia. Disclosure No significant relationships.

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DELORD, SANDRINE, MARIA GIOVANNA DUCATO, DELPHINE PINS, et al. "Psychophysical assessment of magno- and parvocellular function in schizophrenia." Visual Neuroscience 23, no. 3-4 (2006): 645–50. http://dx.doi.org/10.1017/s0952523806233017.

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Recently developed psychophysical techniques permit the biasing of the processing of the stimulus by early visual channels so that responses reflect characteristics of either magno- or parvocellular pathways (Pokorny & Smith, 1997). We used such techniques to test psychophysically whether the global magnocellular dysfunction reported in schizophrenia also affects early processes. Seven schizophrenic patients and 19 normal controls participated. The task was a four-alternative forced-choice luminance discrimination, using a 2 × 2 configuration of four 1-deg squares. Target luminance threshold was determined in three conditions: the stimulus, including the target, was pulsed for 17 ms (pulse paradigm); the target was presented on a steady background of four squares (steady paradigm), or the target was presented alone (no background paradigm). We replicated previous results demonstrating magnocellular and parvocellular signatures in control participants. No evidence for an early magnocellular deficit could be detected as the thresholds of all schizophrenic observers were higher both in the steady paradigm (presumed magnocellular mediation) and in the pulse paradigm (presumed parvocellular mediation). Magnocellular dysfunction, if present in schizophrenia, must concern more integrated processes, possibly at levels at which parvocellular and magnocellular paths interact.

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Kim, Dongsoo, Glenn Wylie, Roey Pasternak, Pamela D. Butler, and Daniel C. Javitt. "Magnocellular contributions to impaired motion processing in schizophrenia." Schizophrenia Research 82, no. 1 (2006): 1–8. http://dx.doi.org/10.1016/j.schres.2005.10.008.

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CHASE, CHRIS, and ANNETTE R. JENNER. "Magnocellular Visual Deficits Affect Temporal Processing of Dyslexics." Annals of the New York Academy of Sciences 682, no. 1 Temporal Info (1993): 326–29. http://dx.doi.org/10.1111/j.1749-6632.1993.tb22983.x.

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Sullivan, W. E. "Classification of response patterns in cochlear nucleus of barn owl: correlation with functional response properties." Journal of Neurophysiology 53, no. 1 (1985): 201–16. http://dx.doi.org/10.1152/jn.1985.53.1.201.

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Response patterns of neurons in the cochlear nuclei of the barn owl (Tyto alba) were studied by obtaining poststimulus time histograms (PSTHs) and interspike interval histograms for the response to short tone bursts at the neuron's characteristic frequency. The observed response patterns can be classified according to the scheme developed for neurons of the mammalian cochlear nuclear complex (22). Neurons of the magnocellular cochlear nucleus (n. magnocellularis), which respond in a phase-locked manner to sinusoidal signals and do not show large increases in spike discharge rate with changes in stimulus intensity (26), have "primarylike" (PSTH) discharge patterns and broad interspike interval histograms. This indicates that magnocellular neurons have irregular firing patterns, with the timing of individual spikes being dependent on the phase of the stimulus waveform. Neurons of the angular cochlear nucleus (n. angularis), which show little or no phase-locking and large increases in spike rate with increasing intensity (26), had almost exclusively "transient chopper" discharge patterns. The interspike interval histograms of these angular units are sharp, indicating that their discharge is very regular. At the onset of the response where the chopper pattern is observed, both discharge regularity and rate-intensity sensitivity are at their maximum levels. Several "onset" units were isolated in the angular cochlear nucleus, but no "pauser" or "buildup" units were seen. Also, all of the units in the angular nucleus had monotonic rate-intensity functions. Thus no neural response patterns typical of mammalian dorsal cochlear nucleus units were observed. The relationship of response pattern type to neural function is discussed in relation to the acoustic cues used by the owl for two-dimensional sound localization. The primarylike, phase-locked discharge of magnocellular units is undoubtedly involved in the analysis of interaural differences in stimulus phase, which the owl uses for horizontal localization. There is strong evidence suggesting that the angular nucleus is involved in processing stimulus intensity information, which is important for determining sound elevation (due to asymmetries in vertical directionality of the owl's external ears). The predominant chopper patterns seen in the angular nucleus suggest that in the owl, this response type is correlated with stimulus intensity processing. Similarities in both anatomy and physiology suggest that the magnocellular nucleus is analogous to the spherical cell or bushy cell population of the anterior division of the mammalian anteroventral cochlear nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)

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Michimata, Chikashi, Matia Okubo, and Yosuke Mugishima. "Effects of Background Color on the Global and Local Processing of Hierarchically Organized Stimuli." Journal of Cognitive Neuroscience 11, no. 1 (1999): 1–8. http://dx.doi.org/10.1162/089892999563201.

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Recent studies have shown that (1) the global precedence effects in processing the hierarchically organized stimulus can be attenuated by eliminating the low spatial frequencies contained in the stimulus and (2) the human magnocellular pathway is responsible for processing low spatial frequencies and the pathway can be attenuated by imposing a red background on the stimulus. In the present study, a reaction-time experiment was conducted to examine the effect of background color of the stimulus to the processing of the hierarchically organized stimulus. The result showed that although the control condition (a green background) produced a prototypical asymmetric global interference, a red background that was equiluminant to the green background produced a symmetrical interference. It was concluded that the human magnocellular pathway is at least partially responsible in producing the global precedence effects.

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DOWNIE, ANDREA L. S., LORNA S. JAKOBSON, VIRGINIA FRISK, and IRENE USHYCKY. "Periventricular brain injury, visual motion processing, and reading and spelling abilities in children who were extremely low birthweight." Journal of the International Neuropsychological Society 9, no. 3 (2003): 440–49. http://dx.doi.org/10.1017/s1355617703930098.

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Among children born at extremely low birthweight (ELBW: <1000 g at birth) there is an association between the presence of periventricular brain injury (PVBI) and lowered performance on tests of reading and spelling ability. The present study was designed to determine if this association might be related to underlying dysfunction in the subcortical magnocellular visual pathway or its cortical targets in the dorsal stream, a prediction motivated by the magnocellular theory of dyslexia. Thirty-five ELBW children were divided into two groups based upon the presence or absence of PVBI (no PVBI, n = 11; PVBI, n = 24). The performance of these two groups was compared to that of a group of healthy full term children (n = 12) on a motion-defined form recognition task believed to tap into the functioning of the magnocellular pathway and/or the dorsal stream. ELBW children did, in fact, show a striking impairment on this task, with 71% of the sample performing at a level more than three standard deviations below the mean of full term controls. Surprisingly, their difficulties were not found to be related to either the presence of brain injury (verified by neonatal cranial ultrasound) or to problems with reading or spelling. An association was documented, however, between difficulties with motion processing and performance on several subtests of the Performance IQ scale of the Wechsler Intelligence Scale for Children–Third Edition. This latter finding is consistent with our earlier suggestion that magnocellular pathway/dorsal stream dysfunction may underlie problems with visuospatial and visuomotor performance in this population. (JINS, 2003, 9, 440–449.)

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Jason, M. J., and M. W. Levine. "The highs and lows of magnocellular and parvocellular processing." Journal of Vision 4, no. 8 (2004): 515. http://dx.doi.org/10.1167/4.8.515.

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Stuart, Geoffrey W., Mark Edwards, and Michael L. Cook. "Colour Inputs to Random-Dot Stereopsis." Perception 21, no. 6 (1992): 717–29. http://dx.doi.org/10.1068/p210717.

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Recently it has been claimed by Livingstone and Hubel that, of three anatomically and functionally distinct visual channels (the magnocellular, parvocellular interblob, and blob channels), only the magnocellular channel is involved in the processing of stereoscopic depth. Since the magnocellular system shows little overt colour opponency, the reported loss of the ability to resolve random-dot stereograms defined only by colour contrast seems consistent with this view. However, Julesz observed that reversed-contrast stereograms could be fused if correlated colour information was added. In the present study, ‘noise’ (non-corresponding) pixels were injected into random-dot stereograms in order to increase fusion time. All six subjects tested were able to achieve stereopsis in less than three minutes when there was only correspondence in colour and not in luminance, and three when luminance contrast was completely reversed. This ability depends on information about the direction of colour contrast, not just the presence of chromatic borders. When luminance and chromatic contrast are defined in terms of signal-to-noise ratios at the photoreceptor mosaic, chromatic information plays at least as important a role in stereopsis as does luminance information, suggesting that the magnocellular channel is not uniquely involved.

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Vidyasagar, Trichur R. "Attentional Gating in Primary Visual Cortex: A Physiological Basis for Dyslexia." Perception 34, no. 8 (2005): 903–11. http://dx.doi.org/10.1068/p5332.

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The visual magnocellular pathway is known to play a central part in visuospatial attention and in directing attention to specific parts of the visual world in serial search. It is proposed that, in the case of reading, this mechanism is trained to perform a sequential gating of visual information coming into the primary visual cortex to enable further orderly processing by the ventral stream. This scheme, taken together with the potential for plasticity between the different afferent channels in the case of a relative impairment of the magnocellular system, can provide some limited rationale for the beneficial effects that have been claimed for the use of coloured overlays and glasses.

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Clarke, Stephanie. "Vision et langage: quelle importance du traitement en parallèle?" Travaux neuchâtelois de linguistique, no. 33 (December 1, 2000): 67–81. http://dx.doi.org/10.26034/tranel.2000.2681.

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The visual system of man and of non-human primates is organised in a way which favours parallel processing. Different aspects of visual information, such as colour, shape or motion are processed independantly. Focal hemispheric lesions can thus cause very selective deficits. The parvo- and magnocellular pathways, specialised in the processing of psychophysically different visual stimuli, have separate representations at the cortical level. Two main pathways are involved in visual recognition and in visuo-spatial functions respectively. Lesions that occur in the adult and remain restricted to one or the other pathway are accompanied with distinct types of visual agnosia. Early occurring deficit in magnocellular processing was proposed to play a role in developmental dyslexia. Models of reading based on observations in normal subjects and the occurrence of different types of alexia following brain damage suggest that several neural pathways are involved in reading. Although these pathways have not been yet identified anatomically, recent experimental work demonstrated the largely parallel connections between structures known to be involved in reading.

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Kristensen, Stephanie, Frank E. Garcea, Bradford Z. Mahon, and Jorge Almeida. "Temporal Frequency Tuning Reveals Interactions between the Dorsal and Ventral Visual Streams." Journal of Cognitive Neuroscience 28, no. 9 (2016): 1295–302. http://dx.doi.org/10.1162/jocn_a_00969.

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Visual processing of complex objects is supported by the ventral visual pathway in the service of object identification and by the dorsal visual pathway in the service of object-directed reaching and grasping. Here, we address how these two streams interact during tool processing, by exploiting the known asymmetry in projections of subcortical magnocellular and parvocellular inputs to the dorsal and ventral streams. The ventral visual pathway receives both parvocellular and magnocellular input, whereas the dorsal visual pathway receives largely magnocellular input. We used fMRI to measure tool preferences in parietal cortex when the images were presented at either high or low temporal frequencies, exploiting the fact that parvocellular channels project principally to the ventral but not dorsal visual pathway. We reason that regions of parietal cortex that exhibit tool preferences for stimuli presented at frequencies characteristic of the parvocellular pathway receive their inputs from the ventral stream. We found that the left inferior parietal lobule, in the vicinity of the supramarginal gyrus, exhibited tool preferences for images presented at low temporal frequencies, whereas superior and posterior parietal regions exhibited tool preferences for images present at high temporal frequencies. These data indicate that object identity, processed within the ventral stream, is communicated to the left inferior parietal lobule and may there combine with inputs from the dorsal visual pathway to allow for functionally appropriate object manipulation.

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Carther-Krone, Tiffany A., and Jonathan J. Marotta. "The influence of magnocellular and parvocellular visual information on global processing in White and Asian populations." PLOS ONE 17, no. 7 (2022): e0270422. http://dx.doi.org/10.1371/journal.pone.0270422.

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Humans have the remarkable ability to efficiently group elements of a scene together to form a global whole. However, cross-cultural comparisons show that East Asian individuals process scenes more globally than White individuals. This experiment presents new insights into global processing, revealing the relative contributions of two types of visual cells in mediating global and local visual processing in these two groups. Participants completed the Navon hierarchical letters task under divided-attention conditions, indicating whether a target letter “H” was present in the stimuli. Stimuli were either ‘unbiased’, displayed as black letters on a grey screen, or biased to predominantly process low spatial frequency information using psychophysical thresholds that converted unbiased stimuli into achromatic magnocellular-biased stimuli and red-green isoluminant parvocellular-biased stimuli. White participants processed stimuli more globally than Asian participants when low spatial frequency information was conveyed via the parvocellular pathway, while Asian participants showed a global processing advantage when low spatial frequency information was conveyed via the magnocellular pathway, and to a lesser extent through the parvocellular pathway. These findings suggest that the means by which a global processing bias is achieved depends on the subcortical pathway through which visual information is transmitted, and provides a deeper understanding of the relationship between global/local processing, subcortical pathways and spatial frequencies.

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Roth, Elizabeth Cowin, and Joseph B. Hellige. "Spatial Processing and Hemispheric Asymmetry: Contributions of the Transient/Magnocellular Visual System." Journal of Cognitive Neuroscience 10, no. 4 (1998): 472–84. http://dx.doi.org/10.1162/089892998562889.

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Right-handed observers were presented with stimuli consisting of a line and two horizontally separated dots. A categorical spatial task required observers to indicate whether the dots were above or below the line, and a coordinate spatial task required observers to indicate whether the line could fit into the space between the two dots. For the coordinate task, reaction time was faster when the stimuli were presented to the left visual field (right hemisphere) than when the stimuli were presented to the right visual field (left hemisphere). The opposite hemispheric asymmetry was obtained for the categorical task. In addition, coordinate spatial processing took longer with stimuli presented on a red background than with stimuli presented on a green background. The opposite trend characterized categorical spatial processing. Because the color red attenuates processing in the transient/magnocellular visual pathway, these results suggest that coordinate spatial processing is more dependent on the transient/magnocellular pathway than is categorical spatial processing. However, manipulations of color condition had no effect on visual field (hemispheric) asymmetries, suggesting that the two hemispheres rely on the same visual information and on the same computational mechanisms as each other—although they do not always use that information with equal efficiency.

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McAnany, J. J., and M. W. Levine. "Magnocellular- and parvocellular-pathway processing in a novel visual illusion." Journal of Vision 5, no. 8 (2010): 56. http://dx.doi.org/10.1167/5.8.56.

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Martinez, A., S. A. Hillyard, S. Bickel, E. C. Dias, P. D. Butler, and D. C. Javitt. "Consequences of Magnocellular Dysfunction on Processing Attended Information in Schizophrenia." Cerebral Cortex 22, no. 6 (2011): 1282–93. http://dx.doi.org/10.1093/cercor/bhr195.

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Grose-Fifer, Jill, Danielle Mascarelli, Elvira Kirilko, Kevin Constante, Amy Medina, and Danielle diFilipo. "Magnocellular and parvocellular pathway contributions to face processing in adolescents." Journal of Vision 15, no. 12 (2015): 163. http://dx.doi.org/10.1167/15.12.163.

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Brown, Alyse C., Jessica Peters, Carl Parsons, David P. Crewther, and Sheila G. Crewther. "Less Efficient Magnocellular Processing: A Common Deficit in Neurodevelopmental Disorders." Journal of Vision 19, no. 10 (2019): 48a. http://dx.doi.org/10.1167/19.10.48a.

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Vahine, Theodora, Stephanie Mathey, Jean-Noel Foulin, and Sandrine Delord. "Dissociation between magnocellular and parvocellular processing in visual word recognition." Journal of Vision 16, no. 12 (2016): 1417. http://dx.doi.org/10.1167/16.12.1417.

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Cushing, Cody A., Hee Yeon Im, Reginald B. Adams Jr, Noreen Ward, and Kestutis Kveraga. "Magnocellular and parvocellular pathway contributions to facial threat cue processing." Social Cognitive and Affective Neuroscience 14, no. 2 (2019): 151–62. http://dx.doi.org/10.1093/scan/nsz003.

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Denison, Rachel N., and Michael A. Silver. "Distinct Contributions of the Magnocellular and Parvocellular Visual Streams to Perceptual Selection." Journal of Cognitive Neuroscience 24, no. 1 (2012): 246–59. http://dx.doi.org/10.1162/jocn_a_00121.

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During binocular rivalry, conflicting images presented to the two eyes compete for perceptual dominance, but the neural basis of this competition is disputed. In interocular switch rivalry, rival images periodically exchanged between the two eyes generate one of two types of perceptual alternation: (1) a fast, regular alternation between the images that is time-locked to the stimulus switches and has been proposed to arise from competition at lower levels of the visual processing hierarchy or (2) a slow, irregular alternation spanning multiple stimulus switches that has been associated with higher levels of the visual system. The existence of these two types of perceptual alternation has been influential in establishing the view that rivalry may be resolved at multiple hierarchical levels of the visual system. We varied the spatial, temporal, and luminance properties of interocular switch rivalry gratings and found, instead, an association between fast, regular perceptual alternations and processing by the magnocellular stream and between slow, irregular alternations and processing by the parvocellular stream. The magnocellular and parvocellular streams are two early visual pathways that are specialized for the processing of motion and form, respectively. These results provide a new framework for understanding the neural substrates of binocular rivalry that emphasizes the importance of parallel visual processing streams, and not only hierarchical organization, in the perceptual resolution of ambiguities in the visual environment.

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Viret, Anne-Claire, Céline Cavézian, Olivier Coubard, et al. "Optic Neuritis: From Magnocellular to Cognitive Residual Dysfunction." Behavioural Neurology 27, no. 3 (2013): 277–83. http://dx.doi.org/10.1155/2013/142680.

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Optic Neuritis (ON) has been associated to both parvocellular dysfunction and to an alteration of the magnocellular pathway. After objective visual field and acuity recovery, ON patients may complain about their vision suggesting a residual subclinical deficit. To better characterize visual abnormalities, 8 patients recovering from a first ON episode as well as 16 healthy controls performed a simple detection task and a more complex categorization task of images presented in low spatial frequencies (to target the magnocellular system) or in high spatial frequencies (to target the parvocellular system) or of non-filtered images. When completing the tasks with their (previously) pathologic eye, optic neuritis patients showed lower accuracy compared to controls or to their healthy eye for low spatial frequency images only. Conjointly, the longest reaction times were observed with the previously pathologic eye regardless the type of images and to a greater extent in the categorization task than in the detection task. Such data suggest two distinct, although associated, types of residual dysfunction in ON: a magnocellular pathway alteration and a more general (magno and parvocellular) visual dysfunction that could implicate the cognitive levels of visual processing.

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Castellotti, Serena, and Maria Michela Del Viva. "Neural Substrates for Early Data Reduction in Fast Vision: A Psychophysical Investigation." Brain Sciences 14, no. 8 (2024): 753. http://dx.doi.org/10.3390/brainsci14080753.

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To ensure survival, the visual system must rapidly extract the most important elements from a large stream of information. This necessity clashes with the computational limitations of the human brain, so a strong early data reduction is required to efficiently process information in fast vision. A theoretical early vision model, recently developed to preserve maximum information using minimal computational resources, allows efficient image data reduction by extracting simplified sketches containing only optimally informative, salient features. Here, we investigate the neural substrates of this mechanism for optimal encoding of information, possibly located in early visual structures. We adopted a flicker adaptation paradigm, which has been demonstrated to specifically impair the contrast sensitivity of the magnocellular pathway. We compared flicker-induced contrast threshold changes in three different tasks. The results indicate that, after adapting to a uniform flickering field, thresholds for image discrimination using briefly presented sketches increase. Similar threshold elevations occur for motion discrimination, a task typically targeting the magnocellular system. Instead, contrast thresholds for orientation discrimination, a task typically targeting the parvocellular system, do not change with flicker adaptation. The computation performed by this early data reduction mechanism seems thus consistent with magnocellular processing.

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Grosser, George S., and Carol S. Spafford. "Reply to Stuart and Lovegrove's Question, “Visual Processing Deficits in Dyslexia: Receptors or Neural Mechanisms?”." Perceptual and Motor Skills 75, no. 1 (1992): 115–20. http://dx.doi.org/10.2466/pms.1992.75.1.115.

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Recently Stuart and Lovegrove questioned the receptor hypothesis of Grosser and Spafford which these authors used to account for the findings that dyslexic individuals have superior peripheral color discrimination to normal readers but also have poorer peripheral brightness discrimination than normal readers. Stuart and Lovegrove hypothesized that dyslexics instead have an impaired transient visual system. The receptor hypothesis is an attempt by Grosser and Spafford to link the functioning of the rods and cones to transient and sustained visual system functioning in a more specific manner than has been tried heretofore by suggesting that, while the parvocellular system is almost entirely fed by cones, both kinds of receptors drive magnocellular cells (but with the rapid onset of early transient system responding being due to the highly light sensitive rods). The rods are proposed to be the receptors initiating the rapid onset of responding in the magnocellular, transient pathway. In dyslexic individuals, they maintain, there are relatively fewer rods to provide for the rapid onset of transient system responses, resulting in a diminished capacity of the transient system to inhibit sustained system activity (as occurs with normal readers). Their receptor hypothesis supplements the concept of transient-vs-sustained system differences.

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Yeshurun, Yaffa, and Gilad Sabo. "Differential effects of transient attention on inferred parvocellular and magnocellular processing." Vision Research 74 (December 2012): 21–29. http://dx.doi.org/10.1016/j.visres.2012.06.006.

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Yeshurun, Y. "Differential effects of transient attention on inferred parvocellular and magnocellular processing." Journal of Vision 13, no. 9 (2013): 475. http://dx.doi.org/10.1167/13.9.475.

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McCleery, Joseph P., Elizabeth Allman, Leslie J. Carver, and Karen R. Dobkins. "Abnormal Magnocellular Pathway Visual Processing in Infants at Risk for Autism." Biological Psychiatry 62, no. 9 (2007): 1007–14. http://dx.doi.org/10.1016/j.biopsych.2007.02.009.

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Barnes, James, Lisa Hinkley, Stuart Masters, and Laura Boubert. "Visual Memory Transformations in Dyslexia." Perceptual and Motor Skills 104, no. 3 (2007): 881–91. http://dx.doi.org/10.2466/pms.104.3.881-891.

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Representational Momentum refers to observers' distortion of recognition memory for pictures that imply motion because of an automatic mental process which extrapolates along the implied trajectory of the picture. Neuroimaging evidence suggests that activity in the magnocellular visual pathway is necessary for representational momentum to occur. It has been proposed that individuals with dyslexia have a magnocellular deficit, so it was hypothesised that these individuals would show reduced or absent representational momentum. In this study, 30 adults with dyslexia and 30 age-matched controls were compared on two tasks, one linear and one rotation, which had previously elicited the representational momentum effect. Analysis indicated significant differences in the performance of the two groups, with the dyslexia group having a reduced susceptibility to representational momentum in both linear and rotational directions. The findings highlight that deficits in temporal spatial processing may contribute to the perceptual profile of dyslexia.

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Hellige, Joseph. "Hemispheric asymmetry for visual information processing." Acta Neurobiologiae Experimentalis 56, no. 1 (1996): 485–97. http://dx.doi.org/10.55782/ane-1996-1151.

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The left and right hemispheres of humans do not handle all aspects of visual information processing with equal ability. This is illustrated by a review of research concerning the processing of global versus local stimulus properties, low versus high spatial frequencies, and coordinate versus categorical spatial relationships. In general, the right hemisphere is dominant for processing global aspects of visual stimuli that are carried by low spatial frequencies, for the processing of coordinate spatial relationships and, perhaps, for extracting information from the magnocellular visual pathway. In something of a complementary manner, the left hemisphere is dominant for processing local aspects of visual stimuli that are carried by high spatial frequencies and, perhaps, for processing categorical spatial relationships and for extracting information from the parvocellular visual pathway. Consideration is given to developmental mechanisms that may underlie the emergence of hemispheric asymmetry for these interrelated aspects of visual information processing.

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Paolini, Antonio G., and John S. McKenzie. "Effects of inactivation of the magnocellular preoptic nucleus of olfactory bulb processing." NeuroReport 8, no. 4 (1997): 929–35. http://dx.doi.org/10.1097/00001756-199703030-00023.

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Vaziri-Pashkam, Maryam, JohnMark Taylor, and Yaoda Xu. "Spatial Frequency Tolerant Visual Object Representations in the Human Ventral and Dorsal Visual Processing Pathways." Journal of Cognitive Neuroscience 31, no. 1 (2019): 49–63. http://dx.doi.org/10.1162/jocn_a_01335.

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Primate ventral and dorsal visual pathways both contain visual object representations. Dorsal regions receive more input from magnocellular system while ventral regions receive inputs from both magnocellular and parvocellular systems. Due to potential differences in the spatial sensitivites of manocellular and parvocellular systems, object representations in ventral and dorsal regions may differ in how they represent visual input from different spatial scales. To test this prediction, we asked observers to view blocks of images from six object categories, shown in full spectrum, high spatial frequency (SF), or low SF. We found robust object category decoding in all SF conditions as well as SF decoding in nearly all the early visual, ventral, and dorsal regions examined. Cross-SF decoding further revealed that object category representations in all regions exhibited substantial tolerance across the SF components. No difference between ventral and dorsal regions was found in their preference for the different SF components. Further comparisons revealed that, whereas differences in the SF component separated object category representations in early visual areas, such a separation was much smaller in downstream ventral and dorsal regions. In those regions, variations among the object categories played a more significant role in shaping the visual representational structures. Our findings show that ventral and dorsal regions are similar in how they represent visual input from different spatial scales and argue against a dissociation of these regions based on differential sensitivity to different SFs.

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Pavan, Andrea, Seyma Koc Yilmaz, Hulusi Kafaligonul, Luca Battaglini, and Steven P. Blurton. "Motion processing impaired by transient spatial attention: Potential implications for the magnocellular pathway." Vision Research 199 (October 2022): 108080. http://dx.doi.org/10.1016/j.visres.2022.108080.

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Solan, Harold A., John F. Shelley-Tremblay, Peter C. Hansen, and Steven Larson. "Is There a Common Linkage Among Reading Comprehension, Visual Attention, and Magnocellular Processing?" Journal of Learning Disabilities 40, no. 3 (2007): 270–78. http://dx.doi.org/10.1177/00222194070400030701.

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Beaudot, W. H. A. "Dynamics in Parvocellular and Magnocellular Pathways: Consequences for Luminance and Colour Processing Streams." Perception 25, no. 1_suppl (1996): 9. http://dx.doi.org/10.1068/v96l0710.

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An achromatic neuromorphic model of the vertebrate retina has already accounted for X and Y pathways (Beaudot and Hérault, 1994 Perception23 Supplement, 25) and has shown a temporal ‘coarse-to-fine’ processing of spatial information (Beaudot et al, 1995 Perception24 Supplement, 93). This model has been extended to colour vision. By taking into account the chromatic sensitivities of cones, functional properties of the parvocellular pathway are modelled. Approximating the responses of colour-opponent cells, the model provides a spatial multiplexing of luminance and chrominance information: sustained responses show spatial band-pass behaviour to luminance variations and low-pass behaviour to equiluminant colour changes. In addition the spatiotemporal inseparability for luminance in the parvocellular model leads to a temporal multiplexing of spatial luminance information: at higher temporal frequencies the spatial filtering is low-pass, conveying only luminance information. Demultiplexing this mixed information suggests interactions between retinal channels. By locally combining additive and subtractive mechanisms between opposite parvocellular pathways (eg G+/ R−± R+/ G−), and an inhibition from the magnocellular pathway, the existence of at least three functional subchannels is predicted: (i) a transient, spatially low-pass channel, (ii) a sustained, spatially band-pass channel, dedicated to the analysis of luminance information in a spatiotemporally separable way (eg moving shadows and static textures), and (iii) a spatiotemporally low-pass, colour-opponent channel leading to colour induction, which is little affected by the presence of shadows and is more representative of objects. This hypothesis of spatiotemporal demultiplexing of luminance and chrominance information, which should presumably occur at an early cortical level, is in accordance with the multiple-processing-streams organisation of the primate visual system.

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Zeev-Wolf, Maor, and Yuri Rassovsky. "Testing the magnocellular-pathway advantage in facial expressions processing for consistency over time." Neuropsychologia 138 (February 2020): 107352. http://dx.doi.org/10.1016/j.neuropsychologia.2020.107352.

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Lalor, Edmund C., Pierfilippo De Sanctis, Menahem I. Krakowski, and John J. Foxe. "Visual sensory processing deficits in schizophrenia: Is there anything to the magnocellular account?" Schizophrenia Research 139, no. 1-3 (2012): 246–52. http://dx.doi.org/10.1016/j.schres.2012.05.022.

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Delorme, A., G. Richard, and M. Fabre-Thorpe. "Rapid processing of complex natural scenes: A role for the magnocellular visual pathways?" Neurocomputing 26-27 (June 1999): 663–70. http://dx.doi.org/10.1016/s0925-2312(98)00158-1.

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Johannes, Sönke, Clifton L. Kussmaul, Thomas F. Münte, and George R. Mangun. "Developmental dyslexia: Passive visual stimulation provides no evidence for a magnocellular processing defect." Neuropsychologia 34, no. 11 (1996): 1123–27. http://dx.doi.org/10.1016/0028-3932(96)00026-7.

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Landry, M., D. Roche, E. Angelova, and A. Calas. "Expression of galanin in hypothalamic magnocellular neurones of lactating rats: co-existence with vasopressin and oxytocin." Journal of Endocrinology 155, no. 3 (1997): 467–81. http://dx.doi.org/10.1677/joe.0.1550467.

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Lactation is a physiological condition known to upregulate the expression of the hypothalamic neurohormones, oxytocin and vasopressin, in the rat supraoptic and paraventricular nuclei. Other neuropeptides such as galanin are co-localized in the same magnocellular neurones and their expression has been demonstrated to be regulated by different experimental and physiological conditions. In the present study, we investigated the possible changes in galanin expression during lactation, using in situ hybridization and immunohistochemistry separately or in combination. Galanin messenger RNA concentrations decreased on day 3 of lactation in both the supraoptic and paraventricular nuclei and remained low on day 7 of lactation, but no differences were observed between control and 14-day lactating rats. In parallel, immunopositive cell bodies were almost undetectable on day 7 of lactation and immunoreactivity remained weak after 14 days of lactation, whereas galanin immunoreactive profiles in the supraoptic nucleus were more numerous than in the control group. Moreover, the subcellular distribution of immunostaining changed on day 14 of lactation. Galanin immunoreactivity was confined around the nucleus in the control females, but it became weaker and more homogenously distributed throughout the cytoplasm in the lactating rats. Electron microscopy using a pre-embedding technique confirmed that galanin immunoreactivity was no longer restricted to the Golgi complex, but was apparent throughout in the cytoplasm. Multiple labellings showed galanin and galanin messenger RNA to be co-localized with oxytocin messenger RNA in neurones of the dorsomedial part of the supraoptic nucleus during lactation. Some of those doubly labelled cells also expressed vasopressin messenger RNA in the same conditions as revealed by a triple-labelling procedure. As these co-localizations have not been observed in female control rats, lactation provided an example of a physiological condition inducing oxytocin and galanin co-synthesis in a subpopulation of magnocellular neurones. In conclusion, we have demonstrated plasticity of galanin expression during lactation in the hypothalamic magnocellular neurones. This plasticity could be caused by changes in galanin expression or in galanin processing in magnocellular neurones.

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Serniclaes, Willy. "Allophonic perception in developmental dyslexia." Written Language and Literacy 9, no. 1 (2006): 135–52. http://dx.doi.org/10.1075/wll.9.1.09ser.

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Current theories on dyslexia refer either to phonological or perceptual factors. The phonological theory explains dyslexia by a deficit in phonological awareness which would affect the build-up of grapheme–phoneme correspondences. This is challenged by the magnocellular theory which ascribes dyslexia to a deficit in temporal processing of auditory and visual signals. However, the auditory deficit in dyslexia is not specifically temporal. Further, the perceptual deficit is not merely sensory but cognitive in nature as evidenced by both weaker discrimination of phonological contrasts and stronger discrimination of differences within phonological categories. This reflects a deficit in “Categorical Perception” which is also sometimes associated with a weaker precision of the perceptual boundary between phonemes (“Boundary Precision” deficit). Categorical deficits are more reliable than magnocellular ones and might be no less reliable than those in phonemic awareness. The categorical deficit suggests that dyslexic children perceive speech with allophonic rather than phonemic units, which has straightforward consequences for the acquisition of phoneme–grapheme correspondences and might also explain the other phonological troubles associated with dyslexia.

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HANSEN, BRUCE C., THEODORE JACQUES, AARON P. JOHNSON, and DAVE ELLEMBERG. "From spatial frequency contrast to edge preponderance: the differential modulation of early visual evoked potentials by natural scene stimuli." Visual Neuroscience 28, no. 3 (2011): 221–37. http://dx.doi.org/10.1017/s095252381100006x.

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AbstractThe contrast response function of early visual evoked potentials elicited by sinusoidal gratings is known to exhibit characteristic potentials closely associated with the processes of parvocellular and magnocellular pathways. Specifically, the N1 component has been linked with parvocellular processes, while the P1 component has been linked with magnocellular processes. However, little is known regarding the response properties of the N1 and P1 components during the processing and encoding of complex (i.e., broadband) stimuli such as natural scenes. Here, we examine how established physical characteristics of natural scene imagery modulate the N1 and P1 components in humans by providing a systematic investigation of component modulation as visual stimuli are gradually built up from simple sinusoidal gratings to highly complex natural scene imagery. The results suggest that the relative dominance in signal output of the N1 and P1 components is dependent on spatial frequency (SF) luminance contrast for simple stimuli up to natural scene imagery possessing few edges. However, such a dependency shifts to a dominant N1 signal for natural scenes possessing abundant edge content and operates independently of SF luminance contrast.

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Werth, Reinhard. "Is Developmental Dyslexia Due to a Visual and Not a Phonological Impairment?" Brain Sciences 11, no. 10 (2021): 1313. http://dx.doi.org/10.3390/brainsci11101313.

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It is a widely held belief that developmental dyslexia (DD) is a phonological disorder in which readers have difficulty associating graphemes with their corresponding phonemes. In contrast, the magnocellular theory of dyslexia assumes that DD is a visual disorder caused by dysfunctional magnocellular neural pathways. The review explores arguments for and against these theories. Recent results have shown that DD is caused by (1) a reduced ability to simultaneously recognize sequences of letters that make up words, (2) longer fixation times required to simultaneously recognize strings of letters, and (3) amplitudes of saccades that do not match the number of simultaneously recognized letters. It was shown that pseudowords that could not be recognized simultaneously were recognized almost without errors when the fixation time was extended. However, there is an individual maximum number of letters that each reader with DD can recognize simultaneously. Findings on the neurobiological basis of temporal summation have shown that a necessary prolongation of fixation times is due to impaired processing mechanisms of the visual system, presumably involving magnocells and parvocells. An area in the mid-fusiform gyrus also appears to play a significant role in the ability to simultaneously recognize words and pseudowords. The results also contradict the assumption that DD is due to a lack of eye movement control. The present research does not support the assumption that DD is caused by a phonological disorder but shows that DD is due to a visual processing dysfunction.

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Maunsell, J. H., and J. R. Gibson. "Visual response latencies in striate cortex of the macaque monkey." Journal of Neurophysiology 68, no. 4 (1992): 1332–44. http://dx.doi.org/10.1152/jn.1992.68.4.1332.

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1. Many lines of evidence suggest that signals relayed by the magnocellular and parvocellular subdivisions of the primate lateral geniculate nucleus (LGN) maintain their segregation in cortical processing. We have examined two response properties of units in the striate cortex of macaque monkeys, latency and transience, with the goal of assessing whether they might be used to infer specific geniculate contributions. Recordings were made from 298 isolated units and 1,129 multiunit sites in the striate cortex in four monkeys. Excitotoxin lesions that selectively affected one or the other LGN subdivision were made in three animals to demonstrate directly the magnocellular and parvocellular contributions. An additional 435 single units and 551 multiunit sites were recorded after the ablations. 2. Most units in striate cortex had visual response latencies in the range of 30-50 ms under the stimulus conditions used. The earliest neuronal responses in striate cortex differed appreciably between individuals. The shortest latency recorded in the four animals ranged from 20 to 31 ms. Comparable values were obtained from both single unit and multiunit sites. After lesions were made in the magnocellular subdivision of the LGN in two animals, the shortest response latencies were 7 and 10 ms later than before the ablations. A larger lesion in the parvocellular subdivision of another animal produced no such shift. Thus it appears that the first 7-10 ms of cortical activation can be attributed to activation relayed by the magnocellular layers of the LGN. 3. The units with the shortest latencies were all found in layers 4C or 6 and their responses were among the most transient in striate cortex. Furthermore, their responses all showed a pronounced periodicity at a frequency of 50-100 Hz. This periodicity was stimulus locked, and the responses of all short-latency units oscillated in phase. 4. An index of response transience was computed for the units recorded in striate cortex. The distribution of this index was unimodal and gave no suggestion of distinct contributions from the geniculate subdivisions. Magnocellular and the parvocellular lesions affected the overall transience of responses in striate cortex. The changes, however, were very small; extremely transient responses and extremely sustained responses survived both types of lesions. 5. A characteristic profile was observed in the response latencies in superficial layers. Latencies appeared to increase monotonically from layer 4 toward the surface of cortex, with the most superficial neurons not becoming active until 15 ms after responses were observed in layer 4C.(ABSTRACT TRUNCATED AT 400 WORDS)

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