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Aug 19, 2023 · The blind spot. All the nerve impulses generated in the retina travel back to the brain by way of the axons in the optic nerve (above). At the point on the retina where the approximately 1 million axons converge on the optic nerve, there are no rods or cones. This spot, called the blind spot, is thus insensitive to light. Figure 15.9.3.2 Blind spot
Jul 16, 2020 · It takes many cells — and finally the brain — to make sense of it all. As light enters our eyes, it first heads through a tough outer tissue called the cornea. This protects the delicate inner eye from everything the world might throw at it. Light passes right through the cornea and into a transparent, flexible tissue called the lens.
Vision. Trace the path of light as is passes through the eye to the retina, and describe which structures are responsible for refracting the light rays. Trace the signal pathway from the retina through the optic nerve, optic chiasm, optic tract, and to the various parts of the brain. Explain how the optical system of the eye creates an image on ...
- Anatomy of The Eye and Vision
- Structure and Function of The Eye
- Photoreceptors
- Retinal Processing
- The Biochemical Level of Transduction
- Visual Field Processing
- Central Processing
- Visual Field Processing and Lateral Geniculate Nucleus
- Inferior and Superior Colliculus
- Visual Processing and The Brain
The innermost layer of the eye is the neural tunic, or retina, which contains the nervous tissue responsible for photoreception. The eye is also divided into two cavities: the anterior cavity and the posterior cavity. The anterior cavity is the space between the cornea and lens, including the iris and ciliary body. It is filled with a watery fluid ...
The photoreceptors of the eye, where transduction of light into nervous impulses occurs, are located in the innermost part of the retina. This means that light will have to pass through several ocular structures to reach its receptor, as seen in figure 2b. The cornea, the front transparent layer of the eye, and the crystalline lens, a transparent c...
Photoreceptors have two parts, the inner segment and the outer segment, shown in figure 3. The inner segment contains the nucleus and other common organelles of a cell, whereas the outer segment is a specialized region in which photoreception takes place. There are two types of photoreceptors—rods and cones—which differ in the shape of their outer ...
Visual signals leave the cones and rods, travel to the bipolar cells, and then to ganglion cells. A large degree of processing of visual information occurs in the retina itself, before visual information is sent to the brain. Photoreceptors in the retina undergo tonic activity, meaning they are constitutively active, even when not stimulated by lig...
Rods and cones transduce the signal of light into a nerve impulse. Both rods and cones contain photopigments. In vertebrates, the main photopigment, rhodopsin, has two parts. An opsin, which is a membrane protein, and retinal—a molecule that absorbs light. When light hits a photoreceptor, it causes a conformation change in the retinal, altering its...
The following video explains where light from locations of our visual field will act on the retinea 0:20-1:50. It then explores how signals generated by those lights will be integrated or segregated depending on what part of the retina they came from 1:51-4:09. The important structures to remember are the optic chiasm (where the optics nerves cross...
The myelinated axons of ganglion cells make up the optic nerves. Within the nerves, different axons carry different qualities of the visual signal. Some axons constitute the magnocellular (big cell) pathway, which carries information about form, movement, depth, and differences in brightness. Other axons constitute the parvocellular (small cell) pa...
The lateral geniculate nucleus (LGN) (also called the lateral geniculate body or lateral geniculate complex) is a relay center in the thalamus for the visual pathway. It receives a major sensory input from the retina. The LGN is the main central connection for the optic nerve to the occipital lobe. Each LGN has six layers of neurons (grey matter) a...
Neurons of the inferior colliculus project to the thalamus, which then sends auditory information to the cerebrum for the conscious perception of sound. The superior colliculus is the superior pair and combines sensory information about visual space, auditory space, and somatosensory space. Activity in the superior colliculusis related to orienting...
There are two main regions that surround the primary visual cortex in the occipital lobe that are usually referred to as areas V2 and V3 (the primary visual cortex is area V1). These surrounding areas are the visual association cortex. The visual association regions develop more complex visual perceptions by adding colour and motion information. Th...
This creates a “blind spot” in the retina, and a corresponding blind spot in our visual field. Note that the photoreceptors in the retina (rods and cones) are located behind the axons, RGCs, bipolar cells, and retinal blood vessels. A significant amount of light is absorbed by these structures before the light reaches the photoreceptor cells.
Oct 31, 2023 · Figure 36.14.1: Rhodopsin: (a) Rhodopsin, the photoreceptor in vertebrates, has two parts: the trans-membrane protein opsin and retinal. When light strikes the retinal, it changes shape from (b) a cis to a trans form. The signal is passed to a G-protein called transducin, triggering a series of downstream events.
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Vision. Vision is the special sense of sight that is based on the transduction of light stimuli received through the eyes. The eyes are located within either orbit in the skull. The bony orbits surround the eyeballs, protecting them and anchoring the soft tissues of the eye (Figure 15.5.1). The eyelids, with lashes at their leading edges, help ...
