FoundationalConceptsNeuroscience

of incident light. Short-wavelength visible light activates primarily S cones, with M and L cones activated to a lesser extent; ...

Two fully functional variants of the L opsin gene have been found in humans, giving rise to two L cone opsin photoreceptor prote ...

men. Thus, in any large group of individuals, there may be quite a few men (and a small number of women) who are color anomalous ...

ceptor proteins are sensitive to low levels of light and have little or no input into color perception. They operate at night or ...

200-+- g^1 100-4 (thouands per square mm) 8 1 Photoreceptor cell density 11109 8765432103123 45 6 7 8 9 1011 Distance from fovea ...

where there are no rods and no cones—no photoreceptors at all. This is the place where the axons from the neurons in the retina ...

around, we are still not aware there is a blind spot. Because our eyes and body are constantly moving, again, the visual system ...

inner segments contain nuclei, mitochondria, and other structures necessary for the functioning of the cell. This is a profound ...

gins the cascade of events leading to a neural signal. Figure 14.5. Diagram of a rhodopsin molecule in a lipid bilayer membrane, ...

VV Lo Retinal Our body cannot make retinal from scratch; it’s made from closely related molecules that we eat: vitamin A and car ...

double bond where the kink is and straightens out, into a form called the all-trans isomer of retinal. This process is called li ...

phodiesterase and activates it. The phosphodiesterase then interacts with cGMP (cyclic guanosine monophosphate), hydrolyzing it ...

reflects a substantial integration of information between the pho- toreceptors and the ganglion cells. Two other major cell type ...

Figure 14.6. Drawing by Ramon y Cajal of the cell layers in a vertebrate retina. The top of this drawing is the part of the reti ...

ning with the photoreceptor, bipolar, and ganglion cells in the retina —is the receptive field. Because of the light-focusing pr ...

Lateral geniculate nuclei Figure 14.7. Coronal section showing location of the lateral geniculate nuclei. The LGN cells send axo ...

lobe called visual area 1, or V1. Cells in V1 send axons to other nearby regions of the cerebral cortex called V2, V3, V4, and V ...

Figure 14.8. Lateral view of brain showing locations of several visual areas in the posterior cortex. Much of what has been lear ...

cortex make connections to neurons in V1, damage to V1 produces a substantial disruption to the flow of visual information in th ...

even a complete loss of ability to recognize faces. This is a very specific symptom; other aspects of visual perception remain i ...