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In the human genome, which, according to January 2013 estimates, has about 20,848 protein coding genes [32] in total, there are 497 nuclear genes encoding cytoplasmic tRNA molecules, and 324 tRNA-derived pseudogenes—tRNA genes thought to be no longer functional [33] (although pseudo tRNAs have been shown to be involved in antibiotic ...
In neuroanatomy, the optic chiasm, or optic chiasma (/ ɒ p t ɪ k k aɪ æ z əm /; from Greek χίασμα 'crossing', from Ancient Greek χιάζω 'to mark with an X'), is the part of the brain where the optic nerves cross. It is located at the bottom of the brain immediately inferior to the hypothalamus. [1]
the eye on the opposite side (the contralateral eye) sends information to layers 1, 4 and 6. This description applies to the LGN of many primates, but not all. The sequence of layers receiving information from the ipsilateral and contralateral (opposite side of the head) eyes is different in the tarsier . [ 10 ]
There are about 0.7 to 1.5 million retinal ganglion cells in the human retina. [2] With about 4.6 million cone cells and 92 million rod cells, or 96.6 million photoreceptors per retina, [3] on average each retinal ganglion cell receives inputs from about 100 rods and cones.
Bird, reptilian, and monotreme cone cells. The difference in the signals received from the three cone types allows the brain to perceive a continuous range of colors through the opponent process of color vision. Rod cells have a peak sensitivity at 498 nm, roughly halfway between the peak sensitivities of the S and M cones.
There is a traditional view that visual processing follows a feedforward system where there is a one-way process by which light is sent from the retina to higher cortical areas, however, there is increasing evidence that visual pathways operate bidirectionally, with both feedforward and feedback mechanisms in place that transmit information to ...
The cells of the brain include neurons and supportive glial cells. There are more than 86 billion neurons in the brain, and a more or less equal number of other cells. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response to nerve impulses.
Illustration of the distribution of cone cells in the fovea of an individual with normal color vision (left), and a color blind (protanopic) retina. Note that the center of the fovea holds very few blue-sensitive cones. Distribution of rods and cones along a line passing through the fovea and the blind spot of a human eye [7]