emotional stress and the effects of dopamine

12 Feb 2009

From the extract report of dr.Oliver Sacks, Awakings, 1990

It is surprising to know that the level of dopamine has a significant influence for the level of rigidity in a Parkinson patient. PET scan is able to determine the precise level of dopamine in a brain. For example, when the level of emotional stress increases, there will be an obvious drop in dopamine level in a brain, but a 30 to 50% drop may not produce any clinical symptoms. However, if it is further reduce by another 20%, Parkinsonian symptoms may prompt appear. Hence, if one reaches a threshold level or borderline which caused by stress, there may be a depletion of dopamine in the brain, and this may further trigger the Parkinsonian symptoms. In other words, the symptoms may come and go in any given situation. This should not be interpreted as the symptom may just disappear like that.

Rhythms of the brain

In a real life brain networks, there is no top or bottom up process signals because the activities of the neurons can be transmitted to any level. It was reported by Gyorgy Buzsaki in his book mentioned above (2008) that the messages of the neurons between the area of the cortexes can be exchanged by oscillations, resonant loops, or transcient oscillatory coupling.

In the context of a workng memory in human brain, the nested gamma oscillations can be used for grouping cell assemblies from a theta cycles. Holding and shifting the sequences in subsequent theta cycles can serve to represent episodic memories. Repeated episodic memories in hippocampus can translate into sematic memory.