Editing Working memory (section)

=== Effects of stress on neurophysiology ===
Working memory is [[effects of stress on memory|impaired by acute and chronic psychological stress]]. This phenomenon was first discovered in animal studies by Arnsten and colleagues,<ref>{{cite journal | vauthors = Arnsten AF | title = The biology of being frazzled | journal = Science | volume = 280 | issue = 5370 | pages = 1711–1712 | date = June 1998 | pmid = 9660710 | doi = 10.1126/science.280.5370.1711 | s2cid = 25842149 }}</ref> who have shown that stress-induced [[catecholamine]] release in PFC rapidly decreases PFC neuronal firing and impairs working memory performance through feedforward, intracellular signaling pathways that open potassium channels to rapidly weaken prefrontal network connections.<ref>{{cite journal | vauthors = Arnsten AF | title = Stress signalling pathways that impair prefrontal cortex structure and function | journal = Nature Reviews. Neuroscience | volume = 10 | issue = 6 | pages = 410–422 | date = June 2009 | pmid = 19455173 | pmc = 2907136 | doi = 10.1038/nrn2648 }}</ref> This process of rapid changes in network strength is called Dynamic Network Connectivity,<ref>{{cite journal |last1=Arnsten |first1=Amy F.T. |last2=Paspalas |first2=Constantinos D. |last3=Gamo |first3=Nao J. |last4=Yang |first4=Yang |last5=Wang |first5=Min |title=Dynamic Network Connectivity: A new form of neuroplasticity |journal=Trends in Cognitive Sciences |date=August 2010 |volume=14 |issue=8 |pages=365–375 |doi=10.1016/j.tics.2010.05.003 |pmid=20554470 |pmc=2914830 }}</ref> and can be seen in human brain imaging when cortical functional connectivity rapidly changes in response to a stressor.<ref>{{cite journal |last1=Hermans |first1=Erno J. |last2=van Marle |first2=Hein J. F. |last3=Ossewaarde |first3=Lindsey |last4=Henckens |first4=Marloes J. A. G. |last5=Qin |first5=Shaozheng |last6=van Kesteren |first6=Marlieke T. R. |last7=Schoots |first7=Vincent C. |last8=Cousijn |first8=Helena |last9=Rijpkema |first9=Mark |last10=Oostenveld |first10=Robert |last11=Fernández |first11=Guillén |title=Stress-Related Noradrenergic Activity Prompts Large-Scale Neural Network Reconfiguration |journal=Science |date=25 November 2011 |volume=334 |issue=6059 |pages=1151–1153 |doi=10.1126/science.1209603 |pmid=22116887 |bibcode=2011Sci...334.1151H }}</ref> Exposure to chronic stress leads to more profound working memory deficits and additional architectural changes in PFC, including dendritic atrophy and spine loss,<ref>{{cite journal | vauthors = Radley JJ, Rocher AB, Miller M, Janssen WG, Liston C, Hof PR, McEwen BS, Morrison JH | display-authors = 6 | title = Repeated stress induces dendritic spine loss in the rat medial prefrontal cortex | journal = Cerebral Cortex | volume = 16 | issue = 3 | pages = 313–320 | date = March 2006 | pmid = 15901656 | doi = 10.1093/cercor/bhi104 | doi-access = free }}</ref> which can be prevented by inhibition of protein kinase C signaling.<ref>{{cite journal | vauthors = Hains AB, Vu MA, Maciejewski PK, van Dyck CH, Gottron M, Arnsten AF | title = Inhibition of protein kinase C signaling protects prefrontal cortex dendritic spines and cognition from the effects of chronic stress | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 106 | issue = 42 | pages = 17957–17962 | date = October 2009 | pmid = 19805148 | pmc = 2742406 | doi = 10.1073/pnas.0908563106 | doi-access = free | bibcode = 2009PNAS..10617957H | author-link4 = Christopher H. van Dyck }}</ref> [[fMRI]] research has extended this research to humans, and confirms that reduced working memory caused by acute stress links to reduced activation of the PFC, and stress increased levels of [[catecholamine]]s.<ref>{{cite journal | vauthors = Qin S, Hermans EJ, van Marle HJ, Luo J, Fernández G | title = Acute psychological stress reduces working memory-related activity in the dorsolateral prefrontal cortex | journal = Biological Psychiatry | volume = 66 | issue = 1 | pages = 25–32 | date = July 2009 | pmid = 19403118 | doi = 10.1016/j.biopsych.2009.03.006 | s2cid = 22601360 }}</ref> Imaging studies of medical students undergoing stressful exams have also shown weakened PFC functional connectivity, consistent with the animal studies.<ref>{{cite journal | vauthors = Liston C, McEwen BS, Casey BJ | title = Psychosocial stress reversibly disrupts prefrontal processing and attentional control | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 106 | issue = 3 | pages = 912–917 | date = January 2009 | pmid = 19139412 | pmc = 2621252 | doi = 10.1073/pnas.0807041106 | doi-access = free | bibcode = 2009PNAS..106..912L }}</ref> The marked effects of stress on PFC structure and function may help to explain how stress can cause or exacerbate mental illness.
The more stress in one's life, the lower the efficiency of working memory in performing simple cognitive tasks. Students who performed exercises that reduced the intrusion of negative thoughts showed an increase in their working memory capacity. Mood states (positive or negative) can have an influence on the neurotransmitter dopamine, which in turn can affect problem solving.<ref>{{cite book| vauthors = Revlin R |title=Human Cognition : Theory and Practice.|year=2007|publisher=Worth Pub|location=New York, NY|isbn=978-0-7167-5667-5|page=147|edition=International}}</ref>