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Prepare for an upcoming quiz on the van Gammeren et al. paper and Cranial Nerves and Somatic & Autonomic Motor Systems lecture. Topics include sensory physiology, ascending pathways, somatotopy, and the homunculus. Lab review and storytime included.
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10 October 2008 1) Turn in Take-Home Quiz on van Gammeren et al. paper. 2) Take in-class quiz on Cranial Nerves and Somatic & Autonomic Motor Systems Lecture: Chapter 7 Sensory Physiology Ascending pathways for touch, proprioception, temperature, and pain. Somatotopy and the homunculus. Lab next week: Sensory physiology (no advance preparation necessary.)
Review of last lecture topics: Aspects of a stimulus that must be encoded using only action potentials What? (modality & labeled line) Where? (location enhanced by lateral inhibition) How long? (duration, onset/offset.. Adaptation) How strong? (intensity)
Figure 7.16 How does sensory information from the skinreach the somatosensory cortex?
Figure 7.14 =Post-central gyrus
Figure 7.19 Anterolateral (spinothalamic) tract 1st order synapses onto 2nd order in spinal cord, 2nd order axon decussates in spinal cord, travels to thalamus in contralateral anterolateral tract, synpases onto 3rd order neuron in thalamus, which sends its axon to SSC. Dorsal column-medial lemniscal tract 1st order axons ascend in ipsilateral dorsal columns to synapses onto 2nd order in dorsal column nuclei of brainstem, 2nd order axon decussates in brainstem, travel to thalamus to synpases onto 3rd order neuron, which sends it axons to SSC.
Figure 7.20 Somatotopy in the SSC (post-central gyrus.) Homunculus: representation of body in the SSC;somatic sensations from adjacent parts of the body are processed by adjacent regions of SSC, with those body regions more densely innervated by sensory receptors occupying more cortical tissue.
