Aspirin inhibits prostaglandin synthesis nsaid ii

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Aspirin inhibits prostaglandin synthesis (NSAID) II. Somatosensory Networks in the Brain The Dorsal Column Medial Lemniscus and A nterolateral Spinothalamic Pathways for somatosensation Somatosensory Cortex Central Sulcus Primary somatosensory cortex – Post Central Gyrus Somatotopic (homunculus) The larger the area, the greater the acuity of processing more connections Input contralateral 3 different areas of Brodmann's areas (BA) 3, 1, 2 BA 3a: muscle sense (position and movement of muscles) BA 3b: fast and slow adapting skin receptors (“Is something there?” / “is it still there?”) fast – adapting: loses sensation quickly BA 1: fast adapting skin receptors BA 2: deep pressure and joint sense Motor Cortex – Pre Central Gyrus SS2 – mainly input from SS1 somatotopic, input from BOTH sides of the body (bilateral) as you come closer to the midline, the sides of your body will have a more similar response to external stimuli Somatosensory Feature Detection Neurons Orientation sensitive neuron Direction sensitive neuron Somatosensory Agnosias
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Astereognosia: inability to recognize objects by touch pure cases are rare – other sensory deficits are usually present damage to sensory apparatus Asomatognosia: failure to recognize parts of one's own body the case of the man who fell out of bed Anosagnosia: lack of awareness of paralysis of a limb (“denial”) Misoplegia: “dislike” of a limb November 28, 2012: Somatosensory (cont.) III. Control of Pain Peripheral vs. Central (Descending) Control of Pain Peripheral Pain Control S – small nerve fiber (pain fibers) – send excitatory signal to pain projection neuron (opens pain gate) inhibit inhibitory neuron L – large nerve fiber (normal mechanoreceptors) – send excitatory signal to pain projection neuron (closes pain gate) excite inhibitory neuron I – inhibitory neuron inhibits connection between small and large nerve fibers onto the pain projection neuron activated when you're not feeling anything P – pain projection neuron System is called “Pain gate”: no input, gate closed The Periaquductral gray in midbrain Central (Descending) Analgesia Circuit 1. Opiates inhibit the activity of PAG. This stops the inhibition on the second projection neurons. 2. Activity of axons that descend from the PAG excites raphe nucleus neurons whose axons descend in the dorsal columns of the spinal chord. 3. The descending of the dorsal column axons excites spinal interneuron that block incoming pain signals. IV. The Effect of Loss of a Body Part on Somatosensory Cortex Training Effect Before differential stimulation – cortical map of digits average number of receptive fields is equal in all the fingers Several months, stimulated several digits After differential stimulation a larger number of receptive fields is identified in the fingers of stimulated digits
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  • Fall '12
  • PaulLipton
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