fMRI study uncovers mechanism for drug cravings

This article at Medical Xpress caught my interest because I’ve been reading Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100 by Michio Kaku, which spends a fair amount of time talking about fMRI.

“An fMRI machine uses “echoes” created by radio waves to peer inside living tissue. This allows us to pinpoint the location of the various signals, giving us spectacular 3-D images of inside the brain…

The fMRI scans allows scientists to locate the presence of oxygen contained within hemoglobin in the blood. Since oxygenated hemoglobin contains the energy that fuels cell activity, detecting the flow of this oxygen allows one to trace the flow of thoughts in the brain.

…fMRI scans can even detect the motion of thoughts in the living brain to a resolution of .1 millimeter, or smaller than the head of a pin, which corresponds to perhaps a few thousand neurons. An fMRI can thus give three-dimensional pictures of the energy flow inside the thinking brain to astonishing accuracy…”

According to the Medical Xpress article:

“Cues such as the sight of drugs can induce cravings and lead to drug-seeking behaviors and drug use. But cravings are also influenced by other factors, such as drug availability and self-control. To investigate the neural mechanisms involved in cue-induced cravings the researchers studied the brain activity of a group of 10 smokers, following exposure to cigarette cues under two different conditions of cigarette availability. In one experiment cigarettes were available immediately and in the other they were not. The researchers combined a technique called transcranial magnetic stimulation (TMS) with functional magnetic resonance imaging (fMRI).

The results demonstrate that in smokers the orbitofrontal cortex (OFC) tracks the level of craving while the dorsolateral prefrontal cortex (DPFC) is responsible for integrating drug cues and drug availability. Moreover, the DPFC has the ability to suppress activity in the OFC when the cigarette is unavailable. When the DPFC was inactivated using TMS, both craving and craving-related signals in the OFC became independent of drug availability.”

Cool stuff.

Article referenced: Takuya Hayashi, Ji Hyun Ko, Antonio P. Strafella, Alain Dagher; “Dorsolateral prefrontal and orbitofrontal cortex interactions during self-control of cigarette craving.” PNAS, January 2013, DOI:10.1073/pnas.1212185110

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