Navigation Links
Why serotonin can cause depression and anxiety
Date:2/4/2008

Mood disorders could be caused by a loss of our inherent, reflexive avoidance of aversive events, according to a study published in PLoS Computational Biology. Researchers from UCL in London and Columbia University in New York used computational modeling techniques to integrate what appeared to be blatant contradictions between serotonins roles in different states of health.

Serotonin appears to be one of the major players in mood and a variety of other disorders. But exactly how remains an open question. Imagine walking past a dark alleyway in a dangerous part of some city; although it might be a shortcut, most people wouldnt consider taking it. In healthy subjects, serotonin appears important for this automatic avoidance.

It has long been suggested that over-activity of the serotonin system may relate to mood disorders such as depression and anxiety, as these seem characterized by too much withdrawal and avoidance. However, the new modeling study simply suggests that we think about what happens when these reflexes failsuddenly you have to think hard to avoid things that used to be avoided reflexively You might for example consider walking down the dangerous alley, be robbed and thus be reminded and taught by additional experience that dark alleys are to be avoided.

In this study Prof. Peter Dayan and Dr. Quentin Huys built a reinforcement learning model of reflexive choices. Agents take actions and as a result of these move through a set of states, some of which are rewarded or punished. As agents progress through this space, they learn the value of each statehow much punishment or reward is to be expected from this state onwards.

It turns out that adding to the agents behavioural repertoire a simple reflex, which guides the agent away from an action with potential for poor consequences, does two things: it increases the rewards reaped overall, but, because bad states are now not explored any more, it also prevents them from learning exactly how bad these bad states are. When serotonin drops, say in depression or anxiety, agents have no more recourse to the reflexive avoidance and have to rely on what they learned. Because they have not learned how bad the bad states are, they start exploring states that dont look too bad to them, but in reality are much worse. Serotonin enhancing drugs, such as Prozac, are then suggested to reinstate the reflexive avoidance, and thus to redress the balance.

This study gives insight into some puzzling findingsfor example, it argues that the association of depression with aggression may have to do with a lack of reflexive avoidance of it. In addition, stress not only causes depression, but people with depression experience more stressors. Again, this may be related to a dysfunctional reflexive avoidance system. The study, however, vastly oversimplifies a number of issues, such as the flexibility of reflexive actions, and the effect of non-reflexive action choice. These provide interesting avenues for further research, and may in fact give some insight into the co-morbidity of different mood disorders.


'/>"/>

Contact: Mary Kohut
Press@plos.org
415-568-3457
Public Library of Science
Source:Eurekalert

Related biology news :

1. Women more depressed and men more impulsive with reduced serotonin functioning
2. deCODE discovers cause of major subtype of glaucoma
3. Study begins to reveal clues to the cause and progression of sepsis
4. Bleeding, not inflammation, is major cause of early lung infection death
5. Gamma globulin effective in treating eye infections caused by adenoviruses
6. Hidden interactions between predators and prey: evolution causes cryptic dynamics in ecology
7. Spaceflight shown to alter ability of bacteria to cause disease
8. Grubs passion for plastic causes water loss
9. Human embryonic stem cells remain embryonic because of epigenetic factors
10. Salmonid hatcheries cause stunning loss of reproduction
11. Researchers find evidence linking stress caused by the Sept. 11 disaster with low birth weights
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/18/2017)... Inc., a global expert in SoC-based imaging and computing solutions, has ... features the company,s hybrid codec technology. A demonstration utilizing TeraFaces ® ... be showcased during the upcoming Medtec Japan at Tokyo Big Sight ... Las Vegas Convention Center April 24-27. ... Click here for an image of the ...
(Date:4/11/2017)... 11, 2017 Crossmatch®, a globally-recognized leader ... today announced that it has been awarded a ... Activity (IARPA) to develop next-generation Presentation Attack Detection ... "Innovation has been a driving force within Crossmatch ... allow us to innovate and develop new technologies ...
(Date:4/6/2017)... Forecasts by Product Type (EAC), Biometrics, Card-Based ... & Logistics, Government & Public Sector, Utilities / Energy ... Nuclear Power), Industrial, Retail, Business Organisation (BFSI), Hospitality & ... for a definitive report on the $27.9bn Access Control ... ...
Breaking Biology News(10 mins):
(Date:8/16/2017)... WAKEFIELD, Mass. , Aug. 16, 2017  This year,s edition of ... global leader in life sciences workforce solutions, has made the list for ... Inc. 5000 recognizes the nation,s fastest-growing private companies based on a set ... Fast 50, which includes the fastest-growing companies in the Bay ... Inc. 5000 ...
(Date:8/15/2017)... 2017 After spending the past two years building a ... collection, GeneFo now offers this platform to healthcare stakeholders (hospitals, foundations, ... adherence, and data collection vis a vis their members, under their ... launch of this offer. ... ...
(Date:8/15/2017)... ... August 15, 2017 , ... ... accelerate pharmaceutical and biotherapeutics development, announces the launch of the new NHS ... to gain kinetic binding data for a wide range of molecules, including small ...
(Date:8/15/2017)... , ... August 15, 2017 , ... Any expert in ... has compromised these disciplines for more than half a century. Despite their essential ... It is widely known that molecular tags developed for this purpose also tag ...
Breaking Biology Technology: