Education & Certifications

  • B.S.N, Medical University of South Carolina, Nursing (2008)
  • Ph.D., Medical University of South Carolina, Neuroscience (2007)
  • B.E., Vanderbilt University, Biomedical Engineering, Psychology (2002)


Professional Interests

I have an interest in the development of neuroscience technologies for clinical use. My primary areas of research are neuroimaging and brain stimulation. I am currently involved in several projects:

1) Characterizing Chronic Low Back Pain

Low back pain is one of the most common types of chronic pain. Individuals with low back pain experience a range of symptoms that limit various aspects of daily life. Research from our lab found brain regions in structural MRI scans that differ between healthy research volunteers and research participants with chronic low back pain. Additional research using pain questionnaires, sensory testing, and MRI scanning is intended to further understand the neurobiology of low back pain. Such an understanding can advance the diagnosis and treatment of low back pain.

2) Characterizing Pain Processing with Long-Term Opioid Use

Opioids are a large class of medications used primarily for treating pain. While opioids can be quite effective for pain with short-term use, the effects with long-term use are less clear. Patients with chronic pain or in methadone maintenance programs may use opioid medications for a long period of time. Research using pain questionnaires, sensory testing, and MRI scanning is intended to further understand pain processing with long-term opioid use. Such an understanding can inform the use of opioids for treating pain.

3) Non-Invasive Brain Stimulation for Reducing Pain

There are many new types of non-invasive stimulation, such as Transcranial Magnetic Stimulation (TMS) and Transcranial Direct Current Stimulation (tDCS). Such stimulation is generally safe for research to study brain function, and TMS is even FDA approved as a therapy for depression. Research is intended to understand if non-invasive stimulation can alter pain in patients, such as volunteers with chronic low back pain or with complex regional pain syndrome.


All Publications

  • Intermittent "Real-time" fMRI Feedback Is Superior to Continuous Presentation for a Motor Imagery Task: A Pilot Study JOURNAL OF NEUROIMAGING Johnson, K. A., Hartwell, K., LeMatty, T., Borckardt, J., Morgan, P. S., Govindarajan, K., Brady, K., George, M. S. 2012; 22 (1): 58-66


    Real-time functional MRI feedback (RTfMRIf) is a developing technique, with unanswered methodological questions. Given a delay of seconds between neural activity and the measurable hemodynamic response, one issue is the optimal method for presentation of neurofeedback to subjects. The primary objective of this preliminary study was to compare the methods of continuous and intermittent presentation of neural feedback on targeted brain activity.Thirteen participants performed a motor imagery task and were instructed to increase activation in an individually defined region of left premotor cortex using RTfMRIf. The fMRI signal change was compared between real and false feedback for scans with either continuous or intermittent feedback presentation.More individuals were able to increase their fMRI signal with intermittent feedback, while some individuals had decreased signal with continuous feedback. The evaluation of feedback itself activated an extensive amount of brain regions, and false feedback resulted in brain activation outside of the individually defined region of interest.As implemented in this study, intermittent presentation of feedback is more effective than continuous presentation in promoting self-modulation of brain activity. Furthermore, it appears that the process of evaluating feedback involves many brain regions that can be isolated using intermittent presentation.

    View details for DOI 10.1111/j.1552-6569.2010.00529.x

    View details for Web of Science ID 000299158500011

    View details for PubMedID 20977537

  • Neural correlates of craving and resisting craving for tobacco in nicotine dependent smokers ADDICTION BIOLOGY Hartwell, K. J., Johnson, K. A., Li, X., Myrick, H., LeMatty, T., George, M. S., Brady, K. T. 2011; 16 (4): 654-666


    Craving is a significant factor which can lead to relapse during smoking quit attempts. Attempts to resist urges to smoke during cue-elicited craving have been shown to activate regions in the brain associated with decision-making, anxiety regulation and visual processing. In this study, 32 treatment-seeking, nicotine-dependent smokers viewed blocks of smoking and neutral cues alternating with rest periods during magnetic resonance imaging scanning in a 3T Siemens scanner (Siemens AG, Erlangen, Bavaria, Germany). While viewing cues or control images, participants were instructed either to 'allow yourself to crave' or 'resist craving.' Data were analyzed with FSL 4.1.5, focused on the smoking cues versus neutral cues contrast, using cluster thresholding (Z > 2.3 and corrected cluster threshold of P = 0.05) at the individual and group levels. During the Crave condition, activation was seen on the left anterior cingulated cortex (LACC), medial prefrontal cortex, left middle cingulate gyrus, bilateral posterior cingulated gyrus and bilateral precuneus, areas associated with attention, decision-making and episodic memory. The LACC and areas of the prefrontal cortex associated with higher executive functioning were activated during the Resist condition. No clear distinctions between group crave and resist analyses as a whole were seen without taking into account specific strategies used to resist the urge to smoke, supporting the idea that craving is associated with some degree of resisting the urge to smoke, and trying to resist is almost always accompanied by some degree of craving. Different strategies for resisting, such as distraction, activated different regions. Understanding the underlying neurobiology of resisting craving to smoke may identify new foci for treatments.

    View details for DOI 10.1111/j.1369-1600.2011.00340.x

    View details for Web of Science ID 000295015400013

    View details for PubMedID 21790899

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