Which sense does not go through the thalamus?<span>One, this is the only sense that does not travel to the thalamus before accessing the fore brain. The thalamus, if you remember, is the relay center for all sensory signals. Nearly all receptors send signals through the thalamus first, which then sends the signals to the proper areas of the brain for perception</span>
        
             
        
        
        
Normal colour vision (trichromacy) refers to vision that uses all three types of light cones. People with defected trichromatic vision will be colour blind to some extent and these conditions are called anomalous trichromacy. Three types anomalous trichromacy ( one type of cone perceives light slightly) :
1.	Protanomaly – phenotype: reduced sensitivity to red light
2.	Deuteranomaly  - phenotype:  reduced sensitivity to green light
3.	Tritanomaly – phenotype: reduced sensitivity to blue  
People can also have color blindess as the result of mutation, when loss of function of one cone occurs. This condition is called dichromacy. If there is complete color blindness or monochromacy, the person can’t distinguish any color from grey.
Color blindness is an inherited genetic disorder resulted from mutations on the X chromosome.