Contents

Methylphenidate (MPH) decreased the amount of glucose needed by the brain to perform a cognitive task [2]. Positron emission tomography (PET) imaging documented that a cognitive task significantly increased whole brain metabolism, however the increase in whole brain metabolism was significantly smaller when the cognitive task was preceded by MPH, than when preceded by placebo [2]. Compared to placebo, MPH reduced (focused) the use of attentional resources in the human brain that are necessary to achieve similar levels of performance (as measured by money made during the task) [2]. In contrast to the mathematical task condition, there was no MPH difference in brain metabolism in the neutral non-task condition [2]. In the MPH condition, since the brain required about 50 % less increase in glucose to perform the task at the same level of performance, this suggests that one of the mechanisms of action of MPH is to focus activation and make the brain more efficient [2]. The global effects in metabolism that were observed with MPH while performing the task may reflect downstream effects of increasing signal-to-noise in regions processing the task into regions whose background activity covary with that of regions activated by the task [1]. The MPH-induced attenuation of brain metabolism was correlated with performance on the task, and so one could speculate that the ability of MPH to decrease the activity in the default network, and to decrease mind-wandering, which may account for its beneficial effects [2]. Another interesting possibility is that stimulants might enhance working memory ability through better coordination of information processing across the nodes of widely distributed, yet functionally connected networks [3].

Acronyms

MPH

methylphenidate

PET

positron emission tomography

References