MODULE 3
THE DORSAL COLUMN - MEDIAL LEMNISCUS (DC-ML) PATHWAY
THE SOMATIC SENSORY CORTEX
Third order neurons, conveying somatic sensory information, pass through the internal capsule to terminate in the postcentral gyrus, in a region termed the primary somatic sensory cortex of S-I. This region corresponds to Brodmann's areas 3a, 3b, 1 and 2. From here, sensory information is relayed to two other regions - the secondary somatic sensory area (S-II) and the posterior parietal cortex (Brodmann's areas 5 and 7). Blumenfeld describes this briefly on page 270; see the section in Fitzgerald starting on page 317, or the one in Haines starting on page 271 for more detailed information. In Kandel read the section starting on page 452 and view Figure 23-1.
All we want to stress here is that S1 has a precise somatotopic organization, as shown in Figure 3-9. S2 is also said to be somatotopically organized, but the details are less clear.
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