Research suggesting conscious control over brain region activation? Has there been any research proving, disproving, or exploring the concept of conscious activation of specific brain regions?

To elaborate on this:

I've read that performing processing tasks causes the brain to reinforce that type/kind of processing or thinking.  For example, visualizing performing a task fires the same neurons as actually performing the task.

Thus, has there been research into the idea that mental models and biofeedback mechanisms can result in conscious control over the activation of particular brain regions?

For example, with biofeedback and practice, can I consciously, measurably, and significantly increase activity (blood flow, electrical activity, etc) in the frontal lobe?
Yes! Recent work using fMRI has shown that subjects can indeed control localized brain regions through practice [1]. Some regions that have been tested include the rostal ACC [2] responsible for pain perception, PPA responsible for representing locations, and FFA responsible for representing faces. Repeated experiments seem to suggest the phenomenon is robust, and that the technique may not be particular to regulating any specific brain region but could work on many brain regions given the proper experimental design.
Typically, these experiments work by utilizing real-time fMRI, a technique that allows real-time biofeedback of brain activation to be presented to a subject in an fMRI scanner. In these experiments, a subject may specifically be instructed to &quot;up-regulate&quot; or &quot;down-regulate&quot; activation in a brain region by performing a specific task. For instance, a subject can &quot;up-regulate&quot; activation in the fusiform face area (FFA) by mentally picturing faces. Consequently, feedback is presented to the subject (e.g., as a 'thermometer') indicating level of activation of the FFA.
Interestingly, subjects become better at up-regulating or down-regulating activation in specific brain regions by attending to feedback-- even moreso than subjects who do not receive biofeedback. This is reflected both in the fMRI images and subjective reports from the subjects. This technique has potential implications for rehabilitation, e.g. giving chronic pain patients another tool to cope with their disorder.
The technique has even been used to up-regulate abstract, distributed patterns across the brain. For instance, Stephen LaConte and colleagues have used a machine learning technique called support-vector machines to classify abstract patterns such as 'craving' or 'not craving', represented as a distributed pattern of brain activity. Using real-time fMRI, smokers have been able to learn to control their cravings through instruction and biofeedback.
I believe similar findings have been shown using EEG as well, though I am not as familiar with the literature. However, there is evidence that subjects using an EEG brain-computer interface to control an on-screen keyboard become better with practice, which suggests that they are able to manipulate their brain patterns in order to perform the task.
References

de Charms et al. (2004). Learned regulation of spatially localized brain activation using
real-time fMRI. NeuroImage, 21, 436-443. Retrieved from http://www.christofflab.ca/pdfs/deCharms_2004_Neuroimage.pdf

de Charms et al. (2005). Control over brain activation and pain learned
by using real-time functional MRI. PNAS, 102,
18626–18631. Retrieved from http://www.stanford.edu/~fumiko/publications.files/Hoeft(Maeda)_2005PNASdeCharms.pdf