This short chapter covers where body sensation finally arrives in the cerebral cortex: the somatosensory areas, how they are wired, how the body is mapped on them, and what their lesions do. Long questions rarely come from it; expect a short note on the sensory cortex and the sensory homunculus, and quick viva questions on the areas and their lesions.
Topics, in the book’s order
- Somatosensory cortex · pp. 1033–1035 · asked twice
When you’ve read them: Quiz 123 · Sensory Cortex, 14 questions.
After this chapter you should be able to
- name the cortical sensory areas and say what each one does
- describe how the sensory areas are connected with the thalamus, with each other and with the motor cortex
- state what a lesion of each sensory area does
- describe how the body is laid out in the sensory homunculus, and why some parts get more cortex
Viva checklist
- The somatosensory areas, and where each lies
- Which areas your book calls primary, and which secondary
- The Brodmann areas of SI, and the two parts of area 3
- The thalamic input to SI, to SII and to area 5
- Which part of SI answers skin stimuli, which deep, and which both
- Where the face, hand and leg lie in the homunculus
- Why the lips and fingers get the largest areas
- What columnar organization means, with the 3a and 3b example
- Which sensations a cortical lesion hits most, which least, and which it almost abolishes
- The deficit from a lesion of area 1, and of area 5
- The effect of an SII lesion
- Hemineglect and constructional apraxia: which cortex, which hemisphere