Neuroscientists seem to have made an important move forwards in their understanding of stress and the brain's role in mitigating its impact. They say they discovered 'thin" and 'mushroom like' nerve cells that are responsible for learning and memory. More importantly they say it's possible for these cells to alter what is remembered after the fact, so that painful or traumatic memories are lessened.
There appears to be a particular protein produced to help the brain adjust for stressful experiences, lessening the effect and the way the memory is stored. Thus mice lacking this particular protein were found to be less out going and tended to try to hide in the dark, in what researchers concluded was a more cautious response to an unpleasant memory.
Dr Pawlak, from the University Department of Cell Physiology and Pharmacology, said:
"Every day stress "reshapes" the brain - nerve cells change their morphology, the number of connections with other cells and the way they communicate with other neurons. In most cases these responses are adaptive and beneficial - " they help the brain to cope with stress and shape adequate behavioural reaction. However, upon severe stress things can get out of control, the brain "buffering" capacity is exhausted and the nerve cells in the hippocampus - " an area of the brain responsible for learning and memory - start to withdraw their processes, don't effectively communicate with other cells and show signs of disease."The Mushroom spines help us remember things we once learned - but bad memories can be over inhibitive. Very stressful experiences would be better if forgotten quickly or clear memories of them may cause anxiety disorders. There is a constant work in process inside the brain that tries to balance what we should remember and what should be clouded or forgotten.
Dr Pawlak said :
"One strategy that brain cells particularly like to use to cope with stress is changing the shape of tiny processes they normally employ to exchange information with other neurons, called dendritic spines. Spines can be as small as 1/1000 of a millimeter and have various shapes. Some spines (called "thin" spines) are like children - very mobile and inquisitive, constantly change shape and "conversation" partners - " they help us learn new things. Once spines learn, they change into mature "couch potatoes" - " they are mushroom-shaped, have stable connections, do not change partners and do not like to move".
The work was published in Proceedings of the National Academy of Sciences (PNAS), and is likely to be important for understanding stress-related psychiatric diseases in humans. The work was supported by a Marie Curie Excellence Grant from the European Commission. Dr Robert Pawlak, lecturer in Neuroscience at the University of Leicester, said the discovery had identified that production of the protein by the brain may assist individuals from experiencing "too much anxiety" and help the brain to better cope with various adverse life events.
Dr Robert Pawlak continues :
"We have identified a protein that the brain produces in response to stress in order to reduce the number of mushroom spines and therefore reduce future anxiety associated with stressful events. This protein, lipocalin-2, is normally not produced, but its fabrication dramatically increases in response to stress in the hippocampus. When we added lipocalin-2 to neurons in culture the way it occurs on stress, neurons started losing their "memory spines" -" the mature, mushroom-shaped ones.
"We therefore asked -" what if we remove lipocalin-2 from the brain and subject mice to stress? Would that affect the way they react? To this end we used mice in which the lipocalin-2 gene was disrupted and found that, on stress, they were more anxious than normal mice. For example, they were less "outgoing" and preferred hiding in dark, enclosed spaces instead of exploring the neighborhood normally. We found that in these mice mushroom spines were more readily formed in the brain after stress and therefore they had stronger memories of the stressful event.
The Identification of lipocalin-2 as a new player the brain uses to help us cope with stress is an important step towards decoding molecular mechanisms of stress that, if not functioning correctly may lead to stress-related psychiatric diseases.
"Stress-related psychological and mental disturbances are extremely common and affect more than 30% of the population. We are keen to investigate whether the mechanisms discovered by us apply to humans and could help inform clinical strategies to deal with anxiety disorders and depression".
Rupert Shepherd reporting for Medical News Today.com