A study by UC Davis researchers appearing in the journal Science on December 12, reports the discovery of a new mechanism of attention in the human brain. Previous studies in animals implicated changes in the state of a portion of the brainstem, called the locus ceruleus (LC), in shifts from distractible to attentive states.Cool that they are now able to figure out how drugs work by using fMRIs of the brain. Hopefully this research will lead to even better cognitive enhancers.
By administering a drug that modifies the state of the LC, which was visualized using functional magnetic resonance (fMRI) brain imaging techniques, the researchers were able to shift volunteers into a more attentive state in which they showed enhanced coordinated brain activity and performance on a test of attention control.
The drug modafinil is approved by the Food and Drug Administration (FDA) for treating narcolepsy, shift-work related sleep disorders and obstructive sleep apnea, and indicated for conditions including ADHD, Parkinson's disease and depression. But how it works has not been well understood until now.
"We have shown that the way modafinil works is by quieting activity in the LC and increasing its connections with the frontal cortex," said Cameron Carter, a UC Davis professor of psychiatry and behavioral sciences and senior author of the study.
"Now that we know how it works, we can develop better cognitive enhancers that can treat more people suffering from a wider variety of neurodevelopmental disorders, like ADHD, autism and schizophrenia," he said.
Previous studies in primates showed that, when not performing a complex task, neurons in the prefrontal cortex fire often and seemingly at random. During the performance of a focused task, however, that area of the brain is quiet and the cells fire only in concert with actions associated with the task. These modes are called exploration and exploitative, respectively.
"We found that modafinil shifts the human brain into exploitation mode and study subjects perform better on tasks," Minzenberg said.
"This is a proof-of-concept study supporting the use of fMRI to study drug effects on the brain as a way of gaining insight into how the drugs work," he said.
via Science Daily