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Journalism of Courage
Researchers have discovered a potential 8220;switch8221; in the human brain which prompts us to change our behaviour instantly as per the situation.
Investigators at the University of Michigan and Eli Lilly measured levels of a neurotransmitter called acetylcholine,which is involved in attention and memory,while rats monitored a screen for a signal.
8220;In other words,the increase in acetylcholine seemed to activate or 8216;switch on8217; the response to the signal,and to be unnecessary if that response was already activated,8221; said Cindy Lustig,one of the study8217;s senior authors.
Researchers repeated the study in humans using functional magnetic resonance imaging fMRI,which measures brain activity,and also found a short increase in right prefrontal cortex activity for the first signal in a series.
To connect the findings between rats and humans,they measured changes in oxygen levels,similar to the changes that produce the FMRI signal,in the brains of rats performing the task.
They again found a response in the right prefrontal cortex that only occurred for the first signal in a series. A follow-up experiment showed that direct stimulation of brain
tissue using drugs that target acetylcholine receptors could likewise produce these changes in brain oxygen.
Together,the studies8217; results provide some of the most direct evidence,so far,linking a specific neurotransmitter response to changes in brain activity in humans. The findings could guide the development of better treatments for disorders in which people have difficulty switching out of current behaviours and activating new ones.
Repetitive behaviours associated with obsessive-compulsive disorder and autism are the most obvious examples,and related mechanisms may underlie problems with preservative behaviour in schizophrenia,dementia and ageing.The findings appear in the Journal of Neuroscience.
