Perception of pain is a subjective experience that includes both sensory and emotionnal components. This emotional component of pain is capable of significantly altering the pain sensation but its processing remains distinct from the sensation of a noxious stimulus. The processing of the sensory component of pain primarily occurs in the somatosensory cortex, while the processing of the emotional component occurs in amygdala and anterior cingulate cortex. The conscious experience of a noxious stimulus induces glutamatergic synaptic plasticity in amygdala and anterior cingulate cortex, which parallels the aversive behavior of the organism apart from the sensation of the stimuli. In particular, this pain induced synaptic plasticity involves mechanisms such as the enhancement of glutamate release, enhancement of glutamate receptor-mediated responses, synaptic trafficking of AMPA receptors, and structural changes in the syanpases1. Modifications of the synpases in the areas responsible for emotional component of pain as well as motor cortex have been proposed to have significant clinical applications in chronic pain treatments.2,3 In particular, neuropathic pain, a type of chronic pain caused by damaged or dysfunctional nervous tissue, is not effectively treated with current systemic medication. Recent research suggests that the noninvasive pain management procedures such as transcranial direct current stimulation (tDCS) and repeated transcranial magnetic stimulation (rTMS) can produce long lasting analgesic effects in patients suffering from phantom pain.4

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Pain-induce synaptic plasticity in anterior cingulate cortex (H. Park)
1.1 The LTP in ACC and chronic pain
1.1a Pain induced glutamatergic synaptic plasticity
1.2 PKMζ and AMPA receptor mediated EPSP in ACC
1.3 Blockade of PKMζ and erasure of LTP in ACC
1.4 Blockade of PKMζ and modality specific analgesic effects

Neuropathic pain and treatment (S. Park)
1. Causes
2. Mechanisms
3. Noninvasive pain treatment approach





References
1. Bie B, Brown DL, Naquib M. Synaptic plasticity and pain aversion. Eur J Pharmacol. (2011). 667(1-3):26-31
2. Li, XY. Ko, HG. Chen, T. Collingridge, GL. Kaang, BK. Zhuo, M. Erasing injury-related cortical synaptic potentiation as a new treatment for chronic pain. Journal of Molecular
Medicine. (2011). 89 (9): 847-855.
3. Leung, A. Donohue, M. Xu, R. Lee, R. Lefaucheur, JP. Khedr, EM. Saitoh, Y. Andre-Obadia, N. Rollnik, J. Wallace, M. Chen, R. RTMS for suppressing neuropathic pain: a meta
analysis. Journal of Pain. (2009). 10 (12): 1205-1216.
4. Ahmed, MA. Mohamed, SA. Sayed, D. Long-term antalgic effects of repetitive transcranial magnetic stimulation of motor cortex and serum beta-endorphin in patients with
phantom pain. Neurological Research. (2011). 33 (9): 953-958.