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Journal articles on the topic 'Parvocellular Pathway'

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Published: 2 June 2025

Last updated: 19 July 2025

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TING, CHRISTOPHER HIAN-ANN. "MAGNOCELLULAR PATHWAY FOR ROTATION INVARIANT NEOCOGNITRON." International Journal of Neural Systems 04, no. 01 (1993): 43–54. http://dx.doi.org/10.1142/s0129065793000067.

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In the mammalian visual system, magnocellular pathway and parvocellular pathway cooperatively process visual information in parallel. The magnocellular pathway is more global and less particular about the details while the parvocellular pathway recognizes objects based on the local features. In many aspects, Neocognitron may be regarded as the artificial analogue of the parvocellular pathway. It is interesting then to model the magnocellular pathway. In order to achieve "rotation invariance" for Neocognitron, we propose a neural network model after the magnocellular pathway and expand its roles to include surmising the orientation of the input pattern prior to recognition. With the incorporation of the magnocellular pathway, a basic shift in the original paradigm has taken place. A pattern is now said to be recognized when and only when one of the winners of the magnocellular pathway is validified by the parvocellular pathway. We have implemented the magnocellular pathway coupled with Neocognitron parallel on transputers; our simulation programme is now able to recognize numerals in arbitrary orientation.

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Momose, K. "Relationship between the Binary Kernels of Visually Evoked Potentials and the Visual Responses on the Magnocellular and Parvocellular Pathways." Methods of Information in Medicine 46, no. 02 (2007): 169–73. http://dx.doi.org/10.1055/s-0038-1625401.

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Summary Objectives : To investigate the nonlinear characteristics of visual evoked potentials (VEPs), and their correlation with the visual responses on parvocellular and magnocellular pathways. First and second-order kernels of the VEPs elicited by several checkerboard patterns were estimated, and their relations to the visual pathway responses were investigated. Methods : VEPs elicited by checkerboard pattern (0.5, 1.0, 2.0 and 4.0 c/d) alternating based on pseudorandom binary sequence were measured, and thei binary kernels were calculated. First and second-order binary kernels were compared with amplitudes o the steady-state VEPs (S-VEPs) to pattern reversal stimulation with a constant temporal frequency (4, 8, 12, 16, and 32 Hz). Results : Positive peak latencies at 150 ms (P150) of second-order first and second slices were correlated with S-VEP amplitude for higher temporal frequencies, indicating that the first and second slices reflect the response of the magnocellular. However, for second and third slices, their amplitudes were partially correlated with 4-16 Hz S-VEP, and this indicated that the second slice contains both magno- and parvocellular pathway responses. P150 latencies of third slices were correlated with S-VEP for lower temporal frequencies, indicating that third slice reflects the response of the parvocellular pathway. Conclusions : The lower slices of second-order binary kernels reflect the response of the magnocellular pathway and the higher slices reflect those on the parvocellular pathway in the human visual system of VEPs.

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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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Farrag, A. F., E. M. Khedr, and W. Abel-Naser. "Impaired parvocellular pathway in dyslexic children." European Journal of Neurology 9, no. 4 (2002): 359–63. http://dx.doi.org/10.1046/j.1468-1331.2002.00410.x.

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Valberg, Arne, and Inger Rudvin. "Possible contributions of magnocellular- and parvocellular-pathway cells to transient VEPs." Visual Neuroscience 14, no. 1 (1997): 1–11. http://dx.doi.org/10.1017/s0952523800008701.

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AbstractWe have measured transient visual evoked potentials (VEPs) to low-contrast luminance stimuli favoring responses of magnocellular pathway cells and to low-contrast red-green stimuli favoring parvocellular cells. Stimuli were square-wave alternating, 3-deg homogeneous disks. Low-contrast stimuli modulated in luminance elicited relatively simple responses. For some observers, a negativity was present that saturated at low contrast. This may be the signature of inputs from magnocellular channels to the visual cortex. The slope of the contrast—response curve for low-contrast stimuli was about the same for all subjects. For medium contrasts, these contrast—response curves displayed an abrupt increase of slope. The shallower slope may reflect the responsivity of magnocellular-pathway inputs to the cortex, whereas the steeper slope may be caused by additional parvocellular activation.Contrast-response curves for the most sensitive waveforms of the isoluminant green—red modulation also showed two branches, although not as clearly as for luminance. This may indicate parvocellular-mediated activity for small chromatic differences, and a combination of parvocellular and magnocellular inputs for larger contrasts. Curves of time-to-peak response as a function of contrast often changed their monotonous behavior near the kink of the corresponding contrast—response curve, thus supporting the notion of a contribution from several mechanisms to the main waveforms.

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McKendrick, AM, and GP Sampson. "Low Spatial Frequency Contrast Sensitivity Deficits in Migraine are not Visual Pathway Selective." Cephalalgia 29, no. 5 (2009): 539–49. http://dx.doi.org/10.1111/j.1468-2982.2008.01817.x.

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Some people who experience migraine demonstrate reduced visual contrast sensitivity that is measurable between migraines. Contrast sensitivity loss to low spatial frequency gratings has been previously attributed to possible impairment of magnocellular pathway function. This study measured contrast sensitivity using low spatial frequency targets (0.25–4 c/deg) where the adaptation aspects of the stimuli were designed to preferentially assess either magnocellular or parvocellular pathway function (steady and pulsed pedestal technique). Twelve people with migraine with measured visual field abnormalities and 17 controls participated. Subjects were tested foveally and at 10° eccentricity. Foveally, there was no significant difference in group mean contrast sensitivity. At 10°, the migraine group demonstrated reduced contrast sensitivity for both the stimuli designed to assess magnocellular and parvocellular function ( P < 0.05). The functional deficits measured in this study infer that abnormalities of the low spatial frequency sensitive channels of both pathways contribute to contrast sensitivity deficits in people with migraine.

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Breitmeyer, Bruno G. "Contributions of magno- and parvocellular channels to conscious and non-conscious vision." Philosophical Transactions of the Royal Society B: Biological Sciences 369, no. 1641 (2014): 20130213. http://dx.doi.org/10.1098/rstb.2013.0213.

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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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YANG, CHIA-YEN, JEN-CHUEN HSIEH, and YIN CHANG. "Foveal evoked magneto-encephalography features related to the parvocellular pathway." Visual Neuroscience 25, no. 2 (2008): 179–85. http://dx.doi.org/10.1017/s0952523808080413.

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AbstractThe aim of this study was to use non-invasive magneto-encephalographic techniques, together with visual stimulus paradigms that can psychophysically separate the M- and P-pathways, to examine the physiological relations of the pathways at the fovea with (1) the magneto-encephalography components M70 and M100 (in latency and amplitude), and (2) the cortical oscillatory activities (alpha, beta, and gamma), respectively. The checkerboard stimuli accompanied with different spatial frequencies (SFs) (0.5 or 4 cycles per degree) were presented (within 2° of the retinal center) to six healthy subjects by using steady-pedestal and pulse paradigms, which could activate distinct populations of M- and P-neurons. SF analyzed brain responses in each paradigm. The results show a consistent trend in M70 and M100 with increased latencies and amplitudes in response to the high SF. Mean while, the beta to gamma activities are apparently enhanced by the stimulus of high SF, especially under pulse paradigm (p = 0.03). In this study, we suggest that M70 can be a good clue to characterize the P-pathway. Moreover, in the frequency analysis, the beta oscillations may serve for more detailed visual information, while the gamma oscillations seem to reflect the signal processing in the P-pathway and with sensitivity to the fovea.

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Edwards, Mark, Stephanie C. Goodhew, and David R. Badcock. "Using perceptual tasks to selectively measure magnocellular and parvocellular performance: Rationale and a user’s guide." Psychonomic Bulletin & Review 28, no. 4 (2021): 1029–50. http://dx.doi.org/10.3758/s13423-020-01874-w.

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AbstractThe visual system uses parallel pathways to process information. However, an ongoing debate centers on the extent to which the pathways from the retina, via the Lateral Geniculate nucleus to the visual cortex, process distinct aspects of the visual scene and, if they do, can stimuli in the laboratory be used to selectively drive them. These questions are important for a number of reasons, including that some pathologies are thought to be associated with impaired functioning of one of these pathways and certain cognitive functions have been preferentially linked to specific pathways. Here we examine the two main pathways that have been the focus of this debate: the magnocellular and parvocellular pathways. Specifically, we review the results of electrophysiological and lesion studies that have investigated their properties and conclude that while there is substantial overlap in the type of information that they process, it is possible to identify aspects of visual information that are predominantly processed by either the magnocellular or parvocellular pathway. We then discuss the types of visual stimuli that can be used to preferentially drive these pathways.

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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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Patel, Roma P., Jerry Lin, and S. Khizer Khaderi. "Beyond Gaming." International Journal of Gaming and Computer-Mediated Simulations 6, no. 1 (2014): 41–49. http://dx.doi.org/10.4018/ijgcms.2014010103.

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The interest around the utilization of video games as a component of rehabilitative therapy has dramatically increased over the past decade. Research efforts have confirmed the positive effects of repetitive gaming in improving visual outcomes; however, there is limited knowledge on the mechanism of action delivered by repetitive gaming. Utilizing knowledge of the visual system, including targeting specific cells in the retina with visual stimuli, the authors captured the training effects of gaming to augment pre-selected skills. Specifically, the authors embedded a homerun derby style baseball game with a contrast threshold test, to stimulate parvocellular retinal ganglion cells. Parvocellular cells are the first line of the ventral, or “what” pathway of visual processing. Repetitive stimulation of the parvocellular system shows promising preliminary results in improving batting performance.

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Graves, Roger E. "Luminance and color effects on localization of briefly flashed visual stimuli." Visual Neuroscience 13, no. 3 (1996): 567–73. http://dx.doi.org/10.1017/s0952523800008245.

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AbstractVisual localization was studied by flashing small stimuli on a green background and requiring observers to press keys to indicate whether the stimulus appeared to the left or right of fixation. The results suggest that, for small (0.25 deg) briefly flashed (17 ms) stimuli at an eccentric location (10 deg), color contrast is not useable and localization presumably must rely on the magnocellular pathway. When stimulus size and duration were increased at 10-deg eccentricity, isochromatic stimuli could be localized at less than 10% luminance contrast (again suggesting use of the magnocellular high sensitivity luminance-contrast system), but isoluminant color-contrast stimuli could also be localized (suggesting use of the color-contrast sensitive parvocellular system). Thus, the results indicate that, dependent on stimulus conditions, both magnocellular and parvocellular pathways were utilized by normal observers in this localization task.

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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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Ávila, Francisco J. "Visual Neuroplasticity: Modulating Cortical Excitability with Flickering Light Stimulation." Journal of Imaging 11, no. 7 (2025): 237. https://doi.org/10.3390/jimaging11070237.

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The balance between cortical excitation and inhibition (E/I balance) in the cerebral cortex is critical for cognitive processing and neuroplasticity. Modulation of this balance has been linked to a wide range of neuropsychiatric and neurodegenerative disorders. The human visual system has well-differentiated magnocellular (M) and parvocellular (P) pathways, which provide a useful model to study cortical excitability using non-invasive visual flicker stimulation. We present an Arduino-driven non-image forming system to deliver controlled flickering light stimuli at different frequencies and wavelengths. By triggering the critical flicker fusion (CFF) frequency, we attempt to modulate the M-pathway activity and attenuate P-pathway responses, in parallel with induced optical scattering. EEG recordings were used to monitor cortical excitability and oscillatory dynamics during visual stimulation. Visual stimulation in the CFF, combined with induced optical scattering, selectively enhanced magnocellular activity and suppressed parvocellular input. EEG analysis showed a modulation of cortical oscillations, especially in the high frequency beta and gamma range. Our results support the hypothesis that visual flicker in the CFF, in addition to spatial degradation, initiates detectable neuroplasticity and regulates cortical excitation and inhibition. These findings suggest new avenues for therapeutic manipulation through visual pathways in diseases such as Alzheimer’s disease, epilepsy, severe depression, and schizophrenia.

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Collins, Elliot, Erez Freud, Jana M. Kainerstorfer, Jiaming Cao, and Marlene Behrmann. "Temporal Dynamics of Shape Processing Differentiate Contributions of Dorsal and Ventral Visual Pathways." Journal of Cognitive Neuroscience 31, no. 6 (2019): 821–36. http://dx.doi.org/10.1162/jocn_a_01391.

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Although shape perception is primarily considered a function of the ventral visual pathway, previous research has shown that both dorsal and ventral pathways represent shape information. Here, we examine whether the shape-selective electrophysiological signals observed in dorsal cortex are a product of the connectivity to ventral cortex or are independently computed. We conducted multiple EEG studies in which we manipulated the input parameters of the stimuli so as to bias processing to either the dorsal or ventral visual pathway. Participants viewed displays of common objects with shape information parametrically degraded across five levels. We measured shape sensitivity by regressing the amplitude of the evoked signal against the degree of stimulus scrambling. Experiment 1, which included grayscale versions of the stimuli, served as a benchmark establishing the temporal pattern of shape processing during typical object perception. These stimuli evoked broad and sustained patterns of shape sensitivity beginning as early as 50 msec after stimulus onset. In Experiments 2 and 3, we calibrated the stimuli such that visual information was delivered primarily through parvocellular inputs, which mainly project to the ventral pathway, or through koniocellular inputs, which mainly project to the dorsal pathway. In the second and third experiments, shape sensitivity was observed, but in distinct spatio-temporal configurations from each other and from that elicited by grayscale inputs. Of particular interest, in the koniocellular condition, shape selectivity emerged earlier than in the parvocellular condition. These findings support the conclusion of distinct dorsal pathway computations of object shape, independent from the ventral pathway.

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Troscianko, Tom, Jules Davidoff, Glyn Humphreys, et al. "Human colour discrimination based on a non-parvocellular pathway." Current Biology 6, no. 2 (1996): 200–210. http://dx.doi.org/10.1016/s0960-9822(02)00453-0.

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JAEKL, PHILIP M., and LAURENCE R. HARRIS. "Sounds can affect visual perception mediated primarily by the parvocellular pathway." Visual Neuroscience 26, no. 5-6 (2009): 477–86. http://dx.doi.org/10.1017/s0952523809990289.

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AbstractWe investigated the effect of auditory–visual sensory integration on visual tasks that were predominantly dependent on parvocellular processing. These tasks were (i) detecting metacontrast-masked targets and (ii) discriminating orientation differences between high spatial frequency Gabor patch stimuli. Sounds that contained no information relevant to either task were presented before, synchronized with, or after the visual targets, and the results were compared to conditions with no sound. Both tasks used a two-alternative forced choice technique. For detecting metacontrast-masked targets, one interval contained the visual target and both (or neither) intervals contained a sound. Sound–target synchrony within 50 ms lowered luminance thresholds for detecting the presence of a target compared to when no sound occurred or when sound onset preceded target onset. Threshold angles for discriminating the orientation of a Gabor patch consistently increased in the presence of a sound. These results are compatible with sound-induced activity in the parvocellular visual pathway increasing the visibility of flashed targets and hindering orientation discrimination.

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Cole, Geoff G., Robert W. Kentridge, and Charles A. Heywood. "Object Onset and Parvocellular Guidance of Attentional Allocation." Psychological Science 16, no. 4 (2005): 270–74. http://dx.doi.org/10.1111/j.0956-7976.2005.01527.x.

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The parvocellular visual pathway in the primate brain is known to be involved with the processing of color. However, a subject of debate is whether an abrupt change in color, conveyed via this pathway, is capable of automatically attracting attention. It has been shown that the appearance of new objects defined solely by color is indeed capable of modulating attention. However, given evidence suggesting that the visual system is particularly sensitive to new onsets, it is unclear to what extent such results reflect effects of color change per se, rather than effects of object onset. We assessed attentional capture by color change that occurred as a result of either new objects appearing or already-present “old” objects changing color. Results showed that although new object onsets accrued attention, changing the color of old objects did not. We conclude that abrupt color change per se is not sufficient to capture attention.

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Mackay, A. M. "Adjustments to Stimulation Frequency and Duration of STEP VEPs in Paediatric CVI." International Journal of Medical Science and Clinical Invention 10, no. 07 (2023): 6801–3. http://dx.doi.org/10.18535/ijmsci/v10i7.02.

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Recent research has demonstrated that the agreement between VEP and subjective VA is influenced by both technical and clinical factors [1-3]. In normal visual development, spatial resolution threshold is limited by the density of retinal bipolar cells [4] which initiate three distinct functional pathways; magnocellular, parvocellular, and koniocellular [5]. Ophthalmological conditions during development with pathology before the LGN and resulting in moderate or severe visual impairment [6] may preferentially preserve the magnocellular pathway making steady state VEPs the ideal assessment.

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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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Zhuang, Xiaohua, Joel Pokorny, and Dingcai Cao. "Flicker Adaptation Desensitizes the Magnocellular but Not the Parvocellular Pathway." Investigative Opthalmology & Visual Science 56, no. 5 (2015): 2901. http://dx.doi.org/10.1167/iovs.14-16067.

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Zhuang, X., D. Cao, and J. Pokorny. "Flicker adaptation desensitizes the magnocellular but not the parvocellular pathway." Journal of Vision 14, no. 10 (2014): 791. http://dx.doi.org/10.1167/14.10.791.

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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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McAnany, J. Jason, and Michael W. Levine. "Magnocellular and parvocellular visual pathway contributions to visual field anisotropies." Vision Research 47, no. 17 (2007): 2327–36. http://dx.doi.org/10.1016/j.visres.2007.05.013.

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Zele, Andrew J., Joanne M. Wood, and Cameron C. Girgenti. "Magnocellular and parvocellular pathway mediated luminance contrast discrimination in amblyopia." Vision Research 50, no. 10 (2010): 969–76. http://dx.doi.org/10.1016/j.visres.2010.03.002.

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Pokorny, Joel, and Vivianne C. Smith. "Psychophysical signatures associated with magnocellular and parvocellular pathway contrast gain." Journal of the Optical Society of America A 14, no. 9 (1997): 2477. http://dx.doi.org/10.1364/josaa.14.002477.

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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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West, Greg L., Adam K. Anderson, Jeffrey S. Bedwell, and Jay Pratt. "Red Diffuse Light Suppresses the Accelerated Perception of Fear." Psychological Science 21, no. 7 (2010): 992–99. http://dx.doi.org/10.1177/0956797610371966.

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Prioritization of affective events may occur via two parallel pathways originating from the retina—a parvocellular (P) pathway projecting to ventral-stream structures responsible for object recognition or a faster and phylogenetically older magnocellular (M) pathway projecting to dorsal-stream structures responsible for localization and action. It has previously been demonstrated that retinal exposure to red diffuse light suppresses M-cell neural activity. We tested whether the fast propagation along the dorsal-action pathway drives an accelerated conduction of fear-based content. Using a visual prior-entry procedure, we assessed accelerated stimulus perception while either suppressing the M pathway with red diffuse light or leaving it unaffected with green diffuse light. We show that the encoding of fearful faces is accelerated, but not when M-channel activity is suppressed, revealing a dissociation that implicates a privileged neural link between emotion and action that begins at the retina.

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Brown, James M., and Benjamin A. Guenther. "Magnocellular and Parvocellular Pathway Influences on Location-Based Inhibition-Of-Return." Perception 41, no. 3 (2012): 319–38. http://dx.doi.org/10.1068/p7133.

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Snippe, Herman P. "Psychophysical signatures associated with magnocellular and parvocellular pathway contrast gain: comment." Journal of the Optical Society of America A 15, no. 9 (1998): 2440. http://dx.doi.org/10.1364/josaa.15.002440.

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Jusuf, Patricia R., Paul R. Martin, and Ulrike Grünert. "Synaptic connectivity in the midget-parvocellular pathway of primate central retina." Journal of Comparative Neurology 494, no. 2 (2005): 260–74. http://dx.doi.org/10.1002/cne.20804.

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Taylor, J. Eric T., Davood G. Gozli, David Chan, Greg Huffman, and Jay Pratt. "A touchy subject: advancing the modulated visual pathways account of altered vision near the hand." Translational Neuroscience 6, no. 1 (2015): 1–7. http://dx.doi.org/10.1515/tnsci-2015-0001.

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AbstractA growing body of evidence demonstrates that human vision operates differently in the space near and on the hands; for example, early findings in this literature reported that rapid onsets are detected faster near the hands, and that objects are searched more thoroughly. These and many other effects were attributed to enhanced attention via the recruitment of bimodal visual-tactile neurons representing the hand and near-hand space. However, recent research supports an alternative account: stimuli near the hands are preferentially processed by the action-oriented magnocellular visual pathway at the expense of processing in the parvocellular pathway. This Modulated Visual Pathways (MVP) account of altered vision near the hands describes a hand position-dependent trade-off between the two main retinal-cortical visual pathways between the eye and brain. The MVP account explains past findings and makes new predictions regarding near-hand vision supported by new research.

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KÉRI, SZABOLCS, and GYÖRGY BENEDEK. "Visual contrast sensitivity alterations in inferred magnocellular pathways and anomalous perceptual experiences in people at high-risk for psychosis." Visual Neuroscience 24, no. 2 (2007): 183–89. http://dx.doi.org/10.1017/s0952523807070253.

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Evidence suggests that patients with schizophrenia show impaired performances on tests assessing the magnocellular (M) visual pathway. The aim of this study was to investigate M pathway functioning in persons at high-risk of psychosis. Sixteen high-risk persons at the prodromal phase of psychosis and 20 healthy controls participated. Two types of contrast sensitivity measurements were used, during which participants were asked to detect a briefly presented target Gabor patch. In the pulsed-pedestal paradigm, the luminance of the background field was decreased to saturate M pathways and to bias information processing to parvocellular (P) pathways. In the steady-pedestal paradigm, the luminance of the background field was constant and briefly presented targets were processed by the M pathway. Anomalous perceptual experiences were assessed using the Structured Interview for Assessing Perceptual Anomalies (SIAPA). Results revealed that the high-risk persons showed elevated contrast sensitivity during the M pathway test, and normal sensitivity during the P pathway test. The visual SIAPA scores showed significant positive correlations with the M pathway sensitivity values. These results suggest that the high-risk mental state is associated with hyper-reactive M pathways, which may be responsible for some anomalous perceptual experiences, including abnormal intensity of environmental stimuli, feelings of being flooded and inundated, and inability to focus attention to relevant details.

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Shuai, Liu, Zou Leilei, Wen Wen, et al. "Binocular treatment in adult amblyopia is based on parvocellular or magnocellular pathway." European Journal of Ophthalmology 30, no. 4 (2019): 658–67. http://dx.doi.org/10.1177/1120672119841216.

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Introduction: Amblyopia is speculated to be an untreatable disease in the patient, who is beyond the critical period of vision; however, currently, it is treatable in adults. Purpose: This study aimed to elucidate whether the treatment is useful in both anisometropic amblyopia and strabismic amblyopia. In addition, the differences were detected between anisometropic amblyopia and strabismic amblyopia after the same perceptual treatment and whether the suppression in anisometropic amblyopia or strabismic amblyopia could be decreased before and after the treatment. Methods: A binocular perceptual learning was applied for the treatment, the suppression was measured, and the patients were followed up for 2 months after training. Anisometropic amblyopia and strabismic amblyopia groups were subjected to the assessment of stereo, visual acuity, contrast sensitivity, and suppression before and after the training. Results: After 6 weeks of “Diploma Gabor Orientation Coherence” training, in the anisometropic amblyopia group, the outcomes of visual acuity (t = 3.114, p = 0.026) and contrast sensitivity (t = 7.786, p = 0.001) were increased significantly. While in the strabismic amblyopia group, the outcomes of stereo (t = 2.987, p = 0.040) and contrast sensitivity (t = 3.638, p = 0.022) were increased significantly. Conclusion: After Diploma Gabor Orientation Coherence training in the same frequency and in the same duration, the anisometropic amblyopia group got an improvement in visual acuity, but the strabismic amblyopia group got an improvement in stereo. As there are evidences to show that anisometropic amblyopia and strabismic amblyopia were injured in different pathways, we think the diverse results might come from the different pathway injury in anisometropic amblyopia and strabismic amblyopia.

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Fujita, Takako, Takao Yamasaki, Yoko Kamio, Shinichi Hirose, and Shozo Tobimatsu. "Parvocellular pathway impairment in autism spectrum disorder: Evidence from visual evoked potentials." Research in Autism Spectrum Disorders 5, no. 1 (2011): 277–85. http://dx.doi.org/10.1016/j.rasd.2010.04.009.

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Telkes, Ildiko, Sammy C. S. Lee, Patricia R. Jusuf, and Ulrike Grünert. "The midget-parvocellular pathway of marmoset retina: A quantitative light microscopic study." Journal of Comparative Neurology 510, no. 5 (2008): 539–49. http://dx.doi.org/10.1002/cne.21813.

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PALLETT, PAMELA M., and KAREN R. DOBKINS. "Development of face discrimination abilities, and relationship to magnocellular pathway development, between childhood and adulthood." Visual Neuroscience 30, no. 5-6 (2013): 251–62. http://dx.doi.org/10.1017/s0952523813000217.

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AbstractThe current study tested the development of face and object processing in young children (mean age = 5.24 years), adolescents (mean age = 15.8 years), and adults (mean age = 21.1 years) using stimuli that were equated for low-level visual characteristics (luminance, contrast, and spatial frequency make-up) and methods that equate for difficulty across ages. We also tested sensitivity to luminance and chromatic contrast (i.e., thought to be mediated primarily by the subcortical Magnocellular (M) and Parvocellular (P) pathways, respectively) to determine whether age-related improvements in face or object discrimination were driven by age-related changes in the M and/or P pathways. Results showed a selective age-related improvement in face sensitivity and a relationship between age-related increases in face sensitivity and luminance contrast sensitivity. These results add to the mounting evidence that the M pathway may influence face processing.

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Zhuang, Xiaohua, Tam Tran, Doris Jin, Riya Philip, and Chaorong Wu. "Aging effects on contrast sensitivity in visual pathways: A pilot study on flicker adaptation." PLOS ONE 16, no. 12 (2021): e0261927. http://dx.doi.org/10.1371/journal.pone.0261927.

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Contrast sensitivity is reduced in older adults and is often measured at an overall perceptual level. Recent human psychophysical studies have provided paradigms to measure contrast sensitivity independently in the magnocellular (MC) and parvocellular (PC) visual pathways and have reported desensitization in the MC pathway after flicker adaptation. The current study investigates the influence of aging on contrast sensitivity and on the desensitization effect in the two visual pathways. The steady- and pulsed-pedestal paradigms were used to measure contrast sensitivity under two adaptation conditions in 45 observers. In the non-flicker adaptation condition, observers adapted to a pedestal array of four 1°×1° squares presented with a steady luminance; in the flicker adaptation condition, observers adapted to a square-wave modulated luminance flicker of 7.5 Hz and 50% contrast. Results showed significant age-related contrast sensitivity reductions in the MC and PC pathways, with a significantly larger decrease of contrast sensitivity for individuals older than 50 years of age in the MC pathway but not in the PC pathway. These results are consistent with the hypothesis that sensitivity reduction observed at the overall perceptual level likely comes from both the MC and PC visual pathways, with a more dramatic reduction resulting from the MC pathway for adults >50 years of age. In addition, a similar desensitization effect from flicker adaptation was observed in the MC pathway for all ages, which suggests that aging may not affect the process of visual adaptation to rapid luminance flicker.

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Wilson, James R., Donna M. Forestner, and Ryan P. Cramer. "Quantitative analyses of synaptic contacts of interneurons in the dorsal lateral geniculate nucleus of the squirrel monkey." Visual Neuroscience 13, no. 6 (1996): 1129–42. http://dx.doi.org/10.1017/s095252380000777x.

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AbstractThree interneurons were recorded from and then injected with horseradish peroxidase in the parvocellular laminae of the squirrel monkey's (Saimiri sciureus) dorsal lateral geniculate nucleus. They were then examined using the electron microscope for their synaptic contacts, both the afferent contacts onto their dendrites and their presynaptic dendritic contacts onto presumptive projection (relay) neuron dendrites. The somata of these interneurons were small (mean = 178 μm2), but the dendritic trees were large compared with those of projection neurons. All three interneurons had similar synaptic patterns onto their dendrites with about equal numbers of retinal, cortical, and GABAergic contacts. The distribution of these contacts was more uniform compared with the same types of contacts made onto projection neurons. The presynaptic dendrites were observed to contact only the dendrites of presumptive projection neurons, and these contacts were nearly all in the form of geniculate triads. None of the three interneurons displayed an axon. The receptive fields of these interneurons were similar to those of projection cells, but were larger and had center-response signs that were the opposite of the projection neurons around them (e.g. OFF center for the dorsal part of the parvocellular mass where ON-center projection neurons reside). The squirrel monkey data provides additional evidence that one aspect of the laminar pattern observed in the parvocellular pathway of the primate's dLGN might be related to a segregation of projection neurons of one center-response sign with interneurons of the opposite center-response sign.

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Troy, J. B., and B. B. Lee. "Steady discharges of macaque retinal ganglion cells." Visual Neuroscience 11, no. 1 (1994): 111–18. http://dx.doi.org/10.1017/s0952523800011159.

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AbstractSteady discharges were collected from ganglion cells of the magnocellular (MC) and parvocellular (PC) pathways of the macaque while their receptive fields were uniformly illuminated with a 4.7-deg steady yellow light of photopic illuminance. The mean rates, coefficients of variation, interval distributions, serial correlation coefficients, and power spectra of these discharges were determined. The results presented permit one to estimate the noise power in the discharges of macaque ganglion cells and hence determine how visual signals of different amplitudes will be affected by the noise resident in their discharges.Although there was some small serial correlation in the discharges of both MC- and PC-pathway cells, their discharges can be considered to result from renewal processes with reasonable accuracy. As with the discharges of cat ganglion cells, macaque ganglion cell discharges can be considered to have approximately gamma-distributed intervals. Steady discharges of MC- and PC-pathway cells show considerable overlap in their statistics, although small but significant differences are present.

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LUTZE, MARGARET, JOEL POKORNY, and VIVIANNE C. SMITH. "Achromatic parvocellular contrast gain in normal and color defective observers: Implications for the evolution of color vision." Visual Neuroscience 23, no. 3-4 (2006): 611–16. http://dx.doi.org/10.1017/s0952523806233078.

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The PC pathway conveys both chromatic and achromatic information, with PC neurons being more responsive to chromatic (L−M) than to achromatic (L+M) stimuli. In considering the evolution of color vision, it has been suggested that the dynamic range of chromatic PC-pathway processing is tuned to the chromatic content of the natural environment. Anomalous trichromats, with reduced separation of their L- and M-cone spectral sensitivities, have diminished chromatic input to PC-pathway cells. Dichromats, with absent L or M cones, should have no chromatic input to PC-pathway cells. Therefore, the PC-pathway dynamic range of color defectives should be released from any constraint imposed by the chromatic environment. Here we ask whether this results in compensatory enhancement of achromatic PC-pathway processing in color defectives. This study employed a psychophysical method designed to isolate PC-pathway processing using achromatic stimuli. In a pulsed-pedestal condition, a four-square stimulus array appeared within a uniform surround. During a trial, one of the test squares differed from the other three, and the observer's task was to choose the square that was different. A four-alternative, forced-choice method was used to determine thresholds as a function of the contrast of the four-square array to the surround. Seven color defective and four normal observers participated. Results showed no systematic differences between normals and color defectives. There was no enhancement of achromatic processing as compensation for reduced chromatic processing in the PC-pathway system in color defectives. From physiological recordings, PC-pathway achromatic contrast gains of dichromatic and trichromatic New World primates and trichromatic Old World macaques have also been shown to be similar to each other. Our study and the animal studies imply that PC-pathway contrast gain parameters were regulated by factors other than the environmental chromaticity gamut, and may have arisen in a nontrichromatic common ancestor to both Old and New World primates.

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LENEMAN, MICHAL, LORI BUCHANAN, and JOANNE ROVET. "Where and what visuospatial processing in adolescents with congenital hypothyroidism." Journal of the International Neuropsychological Society 7, no. 5 (2001): 556–62. http://dx.doi.org/10.1017/s1355617701755038.

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Visuospatial processing is accomplished in distinct neuroanatomic pathways. One such pathway, known as the where pathway, involves a dorsal route through magnocellular thalamic cells to occipital and parietal cortices and conveys location and motion information. A second pathway, known as the what pathway, involves a ventral route through parvocellular thalamic cells to occipital and temporal cortices and conveys color and form information. The where pathway is thought to be responsible for processing spatial relationships while the what pathway is responsible for object identification. Children with early-treated congenital hypothyroidism (CH) who exhibit selective visuospatial deficits may provide a good model to study the differential development of these pathways. Because children with CH lacked thyroid hormone at a time when needed by developing brain regions such as the parietal cortex, these children may be affected to a greater degree on tasks tapping where but not what pathway processing. We tested this hypothesis via retrospective analysis of their performance on 6 spatial tasks. Compared were 49 adolescents with CH and 49 matched control participants. On the basis of confirmatory factor analysis, tasks were assigned to either where or what pathway groupings. A repeated measures ANOVA showed the CH group was impaired relative to a normal comparison group only on where pathway tasks. Regression analyses indicated that severity of early hypothyroidism was the strongest predictor of where pathway processing but had no effect on what pathway tasks. It is concluded that thyroid hormone is required during late gestation and early life for the normal development of the where aspects of visuospatial processing. (JINS, 2001, 7, 556–562.)

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ALLISON, JOHN D., PETER MELZER, YUCHUAN DING, A. B. BONDS, and VIVIEN A. CASAGRANDE. "Differential contributions of magnocellular and parvocellular pathways to the contrast response of neurons in bush baby primary visual cortex (V1)." Visual Neuroscience 17, no. 1 (2000): 71–76. http://dx.doi.org/10.1017/s095252380017107x.

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How neurons in the primary visual cortex (V1) of primates process parallel inputs from the magnocellular (M) and parvocellular (P) layers of the lateral geniculate nucleus (LGN) is not completely understood. To investigate whether signals from the two pathways are integrated in the cortex, we recorded contrast-response functions (CRFs) from 20 bush baby V1 neurons before, during, and after pharmacologically inactivating neural activity in either the contralateral LGN M or P layers. Inactivating the M layer reduced the responses of V1 neurons (n = 10) to all stimulus contrasts and significantly elevated (t = 8.15, P < 0.01) their average contrast threshold from 8.04 (± 4.1)% contrast to 22.46 (± 6.28)% contrast. M layer inactivation also significantly reduced (t = 4.06, P < 0.01) the average peak response amplitude. Inactivating the P layer did not elevate the average contrast threshold of V1 neurons (n = 10), but significantly reduced (t = 4.34, P < 0.01) their average peak response amplitude. These data demonstrate that input from the M pathway can account for the responses of V1 neurons to low stimulus contrasts and also contributes to responses to high stimulus contrasts. The P pathway appears to influence mainly the responses of V1 neurons to high stimulus contrasts. None of the cells in our sample, which included cells in all output layers of V1, appeared to receive input from only one pathway. These findings support the view that many V1 neurons integrate information about stimulus contrast carried by the LGN M and P pathways.

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RUDVIN, INGER, ARNE VALBERG, and BJØRG ELISABETH KILAVIK. "Visual evoked potentials and magnocellular and parvocellular segregation." Visual Neuroscience 17, no. 4 (2000): 579–90. http://dx.doi.org/10.1017/s0952523800174085.

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We have measured visual evoked potentials (VEPs) to luminance-modulated, square-wave alternating, 3-deg homogeneous disks for stimulus frequencies ranging from 1 Hz to 16.7 Hz. The aim of the study was to determine the range of frequencies at which we could reproduce the two-branched contrast-response (C-R) curves we had seen at 1 Hz (Valberg & Rudvin, 1997) and which we interpreted as magnocellular (MC) and parvocellular (PC) segregation. Low-contrast stimuli elicited relatively simple responses to luminance increments resulting in waveforms that may be the signatures of inputs from magnocellular channels to the visual cortex. At all frequencies, the C-R curves of the main waveforms were characterized by a steep slope at low contrasts and a leveling off at 10%–20% Michelson contrast. This was typically followed by an abrupt increase in slope at higher contrasts, giving a distinctive two-branched C-R curve. On the assumption that the low-contrast, high-gain branch reflects the responsivity of magnocellular-pathway inputs to the cortex, the high-contrast branch may be attributed to additional parvocellular activation. While a two-branched curve was maintained for frequencies up to 8 Hz, the high-contrast response was significantly compromised at 16.7 Hz, revealing a differential low-pass filtering. A model decomposing the measured VEP response into two separate C-R curves yielded a difference in sensitivity of the putative MC- and PC-mediated response that, when plotted as a function of frequency, followed a trend similar to that found for single cells. Due to temporal overlap of responses, the MC and PC contributions to the waveforms were hard to distinguish in the transient VEP. However, curves of time-to-peak (delay) as a function of contrast often went through a minimum before the high-contrast gain increase of the corresponding C-R curve, supporting the notion of a recruitment of new cell ensembles in the transition from low to high contrasts.

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Ostadimoghaddam, H., Rad D. Sobhani, A. Esmaeili, et al. "An Investigation of the Visual Function of Dyslexic Children." International Journal of Ophthalmology & Eye Science 3, no. 5 (2015): 110–13. https://doi.org/10.19070/2332-290X-1500022.

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Background: Dyslexia is the most common learning disability, accounts for 5 to 17% of the school-aged children. Dyslexia is defined as an impairment in which the child faces difficulties learning, reading and writing relative to IQ. Objective: The aim of this study was to investigate the central and peripheral visual function in a group of dyslexic children who write from right to left direction. Materials/Patients and Methods: Twenty dyslexic eyes and 20 normal eyes were examined in this study. The visual examinations consisted of measuring distant and near visual acuity, refraction and visual field evaluation using an Octopus 101 automated perimeter. Foveal sensitivity was also measured with static perimetry, and then kinetic perimetry in two target brightness levels: 15 and 20 dB and data were analyzed by SPSS 17 statistical software. Results: Dyslexic and normal children of the study population aged from 7 to 10 years with mean age of 8.5. Mean visible surface area at brightness levels of 15 and 20 dB was significantly different between two groups (p<0.001, p=0.001). In addition, inferior hemifield had the most noticeable differences between groups compared to other hemifields. No significant difference was noted between two groups for other examinations such as visual acuity at distance and near, refractive errors and static foveal sensitivity. Conclusions: Visible surface area was defected in dyslexic children; however, the foveal function was similar to normal individuals. These results support the hypothesis of an impairment of the magnocellular function in dyslexia, whereas the parvocellular pathway is intact.

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Brigell, Mitchell, Antonio Strafella, Lucio Parmeggiani, Paul J. Demarco, and Gastone G. Celesia. "The effects of luminance and chromatic background flicker on the human visual evoked potential." Visual Neuroscience 13, no. 2 (1996): 265–75. http://dx.doi.org/10.1017/s0952523800007501.

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AbstractPrevious studies report that background luminance flicker, which is asynchronous with signal averaging, reduces the amplitude and increases the latency of the pattern-onset visual evoked potential (VEP). This effect has been attributed to saturation of the magnocellular (m-) pathway by the flicker stimulus. In the current study, we evaluate this hypothesis and further characterize this effect. We found that flicker had similar effects on the pattern-onset and pattern-reversal VEP, suggesting that the reversal and onset responses have similar generators. Chromatic flicker decreased latency of the chromatic VEP whereas luminance flicker increased peak latency to luminance targets. This result indicates that luminance flicker saturates a rapidly conducting m-pathway whereas chromatic flicker saturates a more slowly conducting parvocellular (p-) pathway. Finally, evoked potentials to chromatic and luminance stimuli were recorded from 34 electrodes over the scalp in the presence of static and asynchronously modulated backgrounds. An equivalent dipole model was used to assess occipital, parietal, and temporal lobe components of the surface response topography. Results showed that chromatic flicker reduced activity to a greater extent in the ventral visual pathway whereas luminance flicker reduced activity to a greater extent in the dorsal visual pathway to parietal lobe. We conclude that the VEP to isoluminant color and luminance stimuli contains both m- and p-pathway components. Asynchronous flicker can be used to selectively reduce the contribution of these pathways to the surface recorded VEP. Our results provide evidence of parallel pathways in the human visual system, with a dorsal luminance channel projecting predominantly to the posterior parietal lobe and a ventral color channel projecting predominantly to inferior temporal lobe.

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Kageyama, Kazunori, Komaki Hanada, Yasumasa Iwasaki, and Toshihiro Suda. "Regulation and role of suppressor of cytokine signaling-3 in hypothalamic 4B cells." Journal of Endocrinology 201, no. 3 (2009): 369–76. http://dx.doi.org/10.1677/joe-08-0506.

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Corticotropin-releasing factor (CRF) plays a central role in regulating stress responses. In the hypothalamic paraventricular nucleus (PVN), CRF, produced in response to stress, stimulates the release of ACTH from the anterior pituitary. ACTH then stimulates the release of glucocorticoids from the adrenal glands; circulating glucocorticoids are critical for recovery from stress conditions. Cytokines are also implicated in the regulation of CRF expression. Among them, interleukin (IL)-6 plays a role in the regulation of CRF. Factors other than glucocorticoids are likely to be involved in limiting the stimulation of CRF during stress. Suppressor of cytokine signaling (SOCS)-3 acts as a potent negative regulator of cytokine signaling. Little is known about the ability of the inhibitory signaling pathways to limit activation of the CRF gene in parvocellular PVN neurons. Hypothalamic 4B cells are useful for exploring the mechanisms, because these cells show characteristics of the parvocellular neurons of the PVN. In the present study, we examined whether SOCS-3 is regulated by IL-6 and cAMP in hypothalamic 4B cells. We also explored the involvement of SOCS-3 in the regulation of CRF gene expression. SOCS-3 was found to be regulated by IL-6 and via the cAMP/protein kinase A pathway in the hypothalamic cells. SOCS-3 knockdown increased IL-6- or forskolin-induced CRF gene transcription and mRNA levels. Therefore, SOCS-3, induced by a cAMP stimulant and IL-6, would be involved in the negative regulation of CRF gene expression in hypothalamic cells.

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Plainis, Sotiris, and Ian J. Murray. "Magnocellular Channel Subserves the Human Contrast-Sensitivity Function." Perception 34, no. 8 (2005): 933–40. http://dx.doi.org/10.1068/p5451.

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There is evidence that the human contrast-sensitivity function (CSF) is mediated by the spatiotemporal characteristics of magno and parvo neurons early in the visual pathway. In this study we use a measure of contrast gain derived from simple reaction times, to investigate the neural substrates of suprathreshold performance. The results reveal the activity of two mechanisms having distinctly different contrast-gain characteristics. Comparing these to neurophysiological data, we find that the magnocellular system dominates close-to-threshold detection and probably forms the basis of the achromatic CSF, whereas the parvocellular system dominates detection at higher contrasts, when the magnocellular system saturates.

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Martínez-Cañada, Pablo, Christian Morillas, and Francisco Pelayo. "A Neuronal Network Model of the Primate Visual System: Color Mechanisms in the Retina, LGN and V1." International Journal of Neural Systems 29, no. 02 (2019): 1850036. http://dx.doi.org/10.1142/s0129065718500363.

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Color plays a key role in human vision but the neural machinery that underlies the transformation from stimulus to perception is not well understood. Here, we implemented a two-dimensional network model of the first stages in the primate parvocellular pathway (retina, lateral geniculate nucleus and layer 4C[Formula: see text] in V1) consisting of conductance-based point neurons. Model parameters were tuned based on physiological and anatomical data from the primate foveal and parafoveal vision, the most relevant visual field areas for color vision. We exhaustively benchmarked the model against well-established chromatic and achromatic visual stimuli, showing spatial and temporal responses of the model to disk- and ring-shaped light flashes, spatially uniform squares and sine-wave gratings of varying spatial frequency. The spatiotemporal patterns of parvocellular cells and cortical cells are consistent with their classification into chromatically single-opponent and double-opponent groups, and nonopponent cells selective for luminance stimuli. The model was implemented in the widely used neural simulation tool NEST and released as open source software. The aim of our modeling is to provide a biologically realistic framework within which a broad range of neuronal interactions can be examined at several different levels, with a focus on understanding how color information is processed.

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