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The Biological Bases of Photoreception in the Process of Image Vision
Published in Agnieszka Wolska, Dariusz Sawicki, Małgorzata Tafil-Klawe, Visual and Non-Visual Effects of Light, 2020
Agnieszka Wolska, Dariusz Sawicki, Małgorzata Tafil-Klawe
Phototransduction – the process of the translation of photon energy into electrical signals – occurs in photoreceptors located in the retina. Rods (one class of photoreceptors) are active in dim light, whereas cones (another class of photoreceptors) function in brighter light. Photons of light are absorbed by the visual pigments of molecules in the photoreceptor cells. The pigment molecule is formed by retinal (vitamin A1 aldehyde) and a large membrane protein, called opsin (rhodopsin in rods). Absorption of light causes biochemical and electrophysiological processes in the cells of the retina. The complex organization of the retina suggests the different cells’ participation in various physiological regulatory processes in the visual system. Visual information is carried from the retina to the other structures of the central nervous system by patterns of action potentials in the axons of the retinal ganglion cells forming the optic nerve. This group of ganglion cells are the important part of image vision. “The visual brain” is specialized in analyzing object form, color, location, and motion.
Modeling Neuroretinal Development and Disease in Stem Cells
Published in Deepak A. Lamba, Patient-Specific Stem Cells, 2017
The retina is the main light-sensing region of the eye. The light sensing is carried out by a group of cells lining the back of the retina called the photoreceptors. The cells are involved in the conversion of the light signal into a chemical signal by the process of phototransduction, which is passed onto the downstream inner retinal neurons. The retina has three main cellular layers: the outer nuclear layer where the photoreceptors reside; the inner nuclear layers, which contain the main excitatory inner neurons called the bipolar cells along with two types of inhibitory interneurons called the horizontal and amacrine cells; and finally, the ganglion cell layer, which contains the retinal ganglion cells (RGCs) whose axons project to the central visual cortical areas (Figure 11.1). As stated previously, photoreceptors are the light-sensing cells of the retina. There are two main types of photoreceptors in the vertebrate retina, the rod and the cone. Cone photoreceptors are born earlier than the rods and are critical for high acuity vision and crowd the central part of the retina. One of the earliest photoreceptor genes expressed is cone–rod homeobox gene (Crx) (Furukawa et al., 1997). Following specification, the photoreceptors take up either a rod or a cone fate. The cone photoreceptors subsequently decide between short and medium wavelengths (and long wavelength in Old World primates like humans) (Hunt et al., 1998).
AI’s Humanoid Appearance Can Affect Human Perceptions of Its Emotional Capability: Evidence from Self-Reported Data in the U.S
Published in International Journal of Human–Computer Interaction, 2023
Quan-Hoang Vuong, Viet-Phuong La, Minh-Hoang Nguyen, Ruining Jin, Minh-Khanh La, Tam-Tri Le
Regarding sensory perception information input, it should be mentioned that our capability to comprehend the world around us, navigate the surrounding environment, and make judgments depend heavily on vision (Senior, 2010). In fact, the majority of human sense receptors are located in the eyes (Nahai, 2018). In the retina’s photoreceptors, 11-cis-retinal (C20H28O – a photosensitive derivative of vitamin A) is isomerized to all-trans-retinal when interacting with a photon. This is the step of activating the photoreceptor within the visual cycle, which starts the processing of visual information. Signals from the eye are then transmitted into the brain to be processed further for meaning generation. It is suggested that losing vision frightens people significantly more than losing either of their other senses (Hutmacher, 2019). For a human to see is not at all straightforward since it involves a sophisticated process orchestrated by hundreds of millions of cells. Phototransduction is the process of converting light into electrical signals in the retina, which contains five primary neuronal types for light collection and conversion (Hussey et al., 2022). In a sense, what we visually perceive as reality is based on how light signals are interpreted in our brains through biological pathways.
Comparison of Static and Ambulatory Measurements of Illuminance and Spectral Composition That Can Be Used for Assessing Light Exposure in Real Working Environments
Published in LEUKOS, 2019
Mathias Adamsson, Thorbjörn Laike, Takeshi Morita
The methods used for measuring and estimating the lighting in an environment are becoming increasingly important considering the growing knowledge about the non-image-forming effects of light (Lucas et al. 2014). The spectral composition of the exposing light radiation is an important parameter to consider when investigating non-image-forming effects. Rods, cones, and intrinsically photosensitive retinal ganglion cells, containing the photo pigment melanopsin, differentially contribute to the phototransduction over a wide range of intensities (Gooley et al. 2010, 2012; Lall et al. 2010). Furthermore, the photosensitivity function for the melanopsin pigment is shifted toward the short wavelength part of the spectrum, with a maximum sensitivity at approximately 480 nm (Bailes and Lucas 2013; Zaidi et al. 2007). Two action spectra for human melatonin suppression have reported a peak sensitivity at wavelengths between 459 and 477 nm (Brainard et al. 2001; Thapan et al. 2001). On the other hand, in humans short, middle, and long wavelength cone opsins have a maximum sensitivity at approximately 420, 535, and 565 nm, respectively, and the rod opsin is most sensitive to light radiation at approximately 500 nm (Lucas et al. 2014).