Somatic Structures: a variety of “somatosensory receptors” scattered throughout the body can become activated by (sensory) input. The sensory information is then further processed as it progresses, via ascending sensory pathways, to the cerebral cortex. (Patestas, 137)
Somatosensory information (is) initially processed in the "primary somatosensory cortex," then conveyed to the "secondary somatosensory cortex." Further processing occurs in the “association cortex” of the “parietal lobes.” (Blumenfeld, 282) When I touch you on the shoulder, touch receptors in your skin detect the pressure and send a message to your “primary somatosensory cortex.” You feel the touch. Similarly when you touch different textures, a neighboring area, the secondary somatosensory cortex, is activated. Another brain region, the “insula,” maps internal feelings from your body. Streams of sensation (flow in from) from receptor cells in your "heart," "lungs," "liver," "bones," "joints," "ligaments," "muscles," etc. (RamachandranTTB, 97)
Primary Somatosensory Cortex (S1): a region of the "parietal lobe" that governs the sense of touch. (Kandel, 110) Responsible for processing tactile inputs. (Hawkins, 117) A narrow strip that runs from ear to ear across the crown of the head. 'Relational words' are represented near here. This makes sense since the somatosensory cortex is involved in representations of space. (Goldberg, 95) Human beings 'primary touch map.’ (Blakeslee, 19) Each (neuron) in the somatosensory cortex has its territory on the body’s surface to which it responds. This is called the (neuron’s) “receptive field.” A map of the entire body surface exists in the brain. (Doidge, 27) Involved in sensation for the opposite side of the body. (Blumenfeld, 28) The main function of the (primary somatosensory cortex) is to construct and use highly specific feature detectors, such as those for orientation, motion, and faces. (Koch, 22) Also referred to as 'somatosensory cortex,' 'sensory cortex,' 'primary sensory cortex,' 'primary touch cortex,' 'touch cortex,' 'primary touch map' and 'Brodmann Area 3.'
Secondary Somatosensory Cortex (S2): a brain region that discriminates higher levels of shape, texture, and motion analysis than the primary (somatosensory cortex). Contains "mirror neurons." (Blakeslee, 214) Editor’s note - includes part of “Brodmann area” 40 and 43.
Tertiary Somatosensory Cortex: function is “stereognosis.” (Blumenfeld, 31)