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The visual system is the physiological basis of visual perception (the ability to detect and process light).The system detects, transduces and interprets information concerning light within the visible range to construct an image and build a mental model of the surrounding environment.
The retina is where a group of light-sensing cells called photoreceptors are located. There are two types of photoreceptors: rods and cones. Rods are sensitive to dim light, and cones are better able to transduce bright light. Photoreceptors connect to bipolar cells, which induce action potentials in retinal ganglion cells.
Visual phototransduction is the sensory transduction process of the visual system by which light is detected by photoreceptor cells (rods and cones) in the vertebrate retina.A photon is absorbed by a retinal chromophore (each bound to an opsin), which initiates a signal cascade through several intermediate cells, then through the retinal ganglion cells (RGCs) comprising the optic nerve.
The mechanoreception of sound requires a specific set of receptor cells called hair cells that allow for gradient signals to pass onto spatial ganglia where the signal will be sent to the brain to be processed. Since this is mechanoreception, different from chemoreception, adaptation of sound from surroundings highly depends on the physical ...
Brain cells make up the functional tissue of the brain. The rest of the brain tissue is the structural stroma that includes connective tissue such as the meninges , blood vessels , and ducts. The two main types of cells in the brain are neurons , also known as nerve cells, and glial cells , also known as neuroglia. [ 1 ]
Richard Caton discovered electrical activity in the cerebral hemispheres of rabbits and monkeys and presented his findings in 1875. [4] Adolf Beck published in 1890 his observations of spontaneous electrical activity of the brain of rabbits and dogs that included rhythmic oscillations altered by light, detected with electrodes directly placed on the surface of the brain. [5]
Brain tissue in its natural state is too soft to work with, but it can be hardened by immersion in alcohol or other fixatives, and then sliced apart for examination of the interior. Visually, the interior of the brain consists of areas of so-called grey matter, with a dark color, separated by areas of white matter, with a lighter color. Further ...
Consistent light exposure has a greater effect than intermittent exposure. [14] In rats, constant light eventually disrupts the cycle to the point that memory and stress coping may be impaired. [15] The intensity and the wavelength of light influence entrainment. [2] Dim light can affect entrainment relative to darkness. [16]