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CHAPTER 4 : MECHANISM OF PERCEPTION (:<3: 2 Major somatosensory…

- - - - Cutaneous receptors (ADAM)
        Free nerve ending
        
        simplest neuron endings with no specialiezed structure
        
        sensitive to temprature change and pain
        
        Pacinian corpuscles
        
        largest and deepest
        
        adapt rapidly
        -respond to sudden displacement of skin , not constant preassure
        
        Merkel's disks
        
        adapt slowly
        
        respond to gradual skin indentation
        
        When constant preassure is applied to the skin , burst of friring in all receptors which correspond to the sensation of touch
        -stereognosis : identification of objects by touch
        1.Stimuli to the skin changes chemistry of the receptor
        2.changes permeability of receptor cell membrane to ions
        3.sends a neural signal
- - - - :check: Secondary somatosensory cortex
        
        is just ventral to the primary
        
        :check: Association cortex (posterior parietal lobe)
    - - :<3: Astereognosia
        
        Inability to recognize objects by touch
        
        Rare
        
        :<3: Asomatognosia
        
        Inability to recognize parts of your own body.
        
        Usually only affects the left side of the body after damage to the right posterior parietal lobe.
        
        E.g: ,A limb, may be expressed verbally or as a pattern of neglect. The limb may also be attributed to another person, a delusion known as somatoparaphrenia.