Visual Centers in the Brain

Berlucchi, Giovanni; Brindley, G. S.; Brooks, Barbara A.; Creutzfeldt, O. D.; Dodt, E.; Doty, Robert W.; Freund, H.-J.; Gross, C. G.; Jeffreys, D. Aled; Kuhnt, U.; Mackay, D. M.; Marg, Elwin; Negrão, Núbio; Rizzolatti, Giacomo; Sprague, James M.; Székely, George; Szentágothai, J; Whitteridge, D.; Jung, R.

doi:10.1007/978-3-642-65495-4

Cited by 2 publications

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“…The differentiation is poor in the superficial layers but appears to increase in the middle and deep layers. This could be due to the long-range horizontal connections between the columns in the superficial layers, that has been shown previously in cats and monkeys (Berlucchi et al, 1973;Fisken et al, 1975;Gilbert, 1983). These horizontal connections are both inhibitory and faciliatory in nature.…”

Section: Vaso Produced Better Differentiation Between Stimulated and ...mentioning

confidence: 60%

Layer Dependence of Monocular and Binocular Responses in Human Ocular Dominance Columns at 7T using VASO and BOLD

Akbari

Gati

Zeman³

et al. 2023

Preprint

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The neurons located in the striate cortex (V1) preferentially respond to the input from one eye or another, forming a fingerprint-like pattern of ocular dominance columns (ODCs). At this mesoscopic scale, accessible by ultra-high field fMRI, V1 is supplied/drained by a network of surface (pial) vessels that connect to descending/ascending tangential vessels that penetrate the cortex and supply/drain a capillary bed whose density is also layer dependent. In this study, we measured the layer dependence of monocular and binocular responses of ocular dominance columns in V1 at 7T using Blood Oxygenation Level Dependent (BOLD) and VAscular Space Occupancy (VASO) contrasts. Our results indicate that the microvascular blood volume changes that give rise to VASO are well confined to the site of neural activity across the layers of the cortex and between the columns. Pial veins dominate the BOLD response and mix the signal between columns. When the GRE BOLD response was examined in only the VASO-specific voxels (thus eliminating the pial vein signal), the laminar profile was very similar to VASO, however, the columnar response was still blurred. Caution needs to be exercised in the interpretation of signal changes in BOLD at the mesoscale both in terms of feedforward/feedback effects and inhibitory and excitatory effects.

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Section: Vaso Produced Better Differentiation Between Stimulated and ...mentioning

confidence: 60%

Layer Dependence of Monocular and Binocular Responses in Human Ocular Dominance Columns at 7T using VASO and BOLD

Akbari

Gati

Zeman³

et al. 2023

Preprint

View full text Add to dashboard Cite

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Light Pollution, Circadian Photoreception, and Melatonin in Vertebrates

et al. 2019

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Artificial light at night (ALAN) is increasing exponentially worldwide, accelerated by the transition to new efficient lighting technologies. However, ALAN and resulting light pollution can cause unintended physiological consequences. In vertebrates, production of melatonin—the “hormone of darkness” and a key player in circadian regulation—can be suppressed by ALAN. In this paper, we provide an overview of research on melatonin and ALAN in vertebrates. We discuss how ALAN disrupts natural photic environments, its effect on melatonin and circadian rhythms, and different photoreceptor systems across vertebrate taxa. We then present the results of a systematic review in which we identified studies on melatonin under typical light-polluted conditions in fishes, amphibians, reptiles, birds, and mammals, including humans. Melatonin is suppressed by extremely low light intensities in many vertebrates, ranging from 0.01–0.03 lx for fishes and rodents to 6 lx for sensitive humans. Even lower, wavelength-dependent intensities are implied by some studies and require rigorous testing in ecological contexts. In many studies, melatonin suppression occurs at the minimum light levels tested, and, in better-studied groups, melatonin suppression is reported to occur at lower light levels. We identify major research gaps and conclude that, for most groups, crucial information is lacking. No studies were identified for amphibians and reptiles and long-term impacts of low-level ALAN exposure are unknown. Given the high sensitivity of vertebrate melatonin production to ALAN and the paucity of available information, it is crucial to research impacts of ALAN further in order to inform effective mitigation strategies for human health and the wellbeing and fitness of vertebrates in natural ecosystems.

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Visual Centers in the Brain

Cited by 2 publications

References 0 publications

Layer Dependence of Monocular and Binocular Responses in Human Ocular Dominance Columns at 7T using VASO and BOLD

Layer Dependence of Monocular and Binocular Responses in Human Ocular Dominance Columns at 7T using VASO and BOLD

Light Pollution, Circadian Photoreception, and Melatonin in Vertebrates

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