Understanding central mechanisms of acupuncture analgesia using dynamic quantitative sensory testing: a review.

We discuss the emerging translational tools for the study of acupuncture analgesia with a focus on psychophysical methods. The gap between animal mechanistic studies and human clinical trials of acupuncture analgesia calls for effective translational tools that bridge neurophysiological data with meaningful clinical outcomes. Temporal summation (TS) and conditioned pain modulation (CPM) are two promising tools yet to be widely utilized. These psychophysical measures capture the state of the ascending facilitation and the descending inhibition of nociceptive transmission, respectively. We review the basic concepts and current methodologies underlying these measures in clinical pain research, and illustrate their application to research on acupuncture analgesia. Finally, we highlight the strengths and limitations of these research methods and make recommendations on future directions. The appropriate addition of TS and CPM to our current research armamentarium will facilitate our efforts to elucidate the central analgesic mechanisms of acupuncture in clinical populations.

Volitional reduction of anterior cingulate cortex activity produces decreased cue craving in smoking cessation: a preliminary real-time fMRI study.

Numerous research groups are now using analysis of blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) results and relaying back information about regional activity in their brains to participants in the scanner in 'real time'. In this study, we explored the feasibility of self-regulation of frontal cortical activation using real-time fMRI (rtfMRI) neurofeedback in nicotine-dependent cigarette smokers during exposure to smoking cues. Ten cigarette smokers were shown smoking-related visual cues in a 3 Tesla MRI scanner to induce their nicotine craving. Participants were instructed to modify their craving using rtfMRI feedback with two different approaches. In a 'reduce craving' paradigm, participants were instructed to 'reduce' their craving, and decrease the anterior cingulate cortex (ACC) activity. In a separate 'increase resistance' paradigm, participants were asked to increase their resistance to craving and to increase middle prefrontal cortex (mPFC) activity. We found that participants were able to significantly reduce the BOLD signal in the ACC during the 'reduce craving' task (P=0.028). There was a significant correlation between decreased ACC activation and reduced craving ratings during the 'reduce craving' session (P=0.011). In contrast, there was no modulation of the BOLD signal in mPFC during the 'increase resistance' session. These preliminary results suggest that some smokers may be able to use neurofeedback via rtfMRI to voluntarily regulate ACC activation and temporarily reduce smoking cue-induced craving. Further research is needed to determine the optimal parameters of neurofeedback rtfMRI, and whether it might eventually become a therapeutic tool for nicotine dependence.

Intermittent "real-time" fMRI feedback is superior to continuous presentation for a motor imagery task: a pilot study.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Cerebral activation patterns related to initiation and inhibition of hand movement.

Sequential ordering of purposeful movements includes distinct transitions between muscle contraction and relaxation. To explore cerebral activation patterns underlying such movement initiation and inhibition, we applied functional magnetic resonance imaging to test the effects of (1) ballistic movement (dominated by initiation), (2) movement with stepwise interruption (dominated by inhibition) and (3) smooth movements. Right-hand movements were performed by 21 healthy participants. In the basal ganglia, ballistic movements evoked putamen activation, indicating its specific contribution to initiation. Stepwise interrupted movement induced increased activation of the caudate nucleus, globus pallidus and subthalamic nucleus whereas, at the cortical level, supplementary motor area activation increased. This indicates a specific basal ganglia-thalamocortical circuit involved in motor inhibition.

Environmental exposure to polychlorinated biphenyls among raccoons (Procyon lotor) at the paducah gaseous diffusion plant, Western Kentucky, USA.

An investigation involving raccoons (Procyon lotor) as a sentinel species at the Paducah Gaseous Diffusion Plant (PGDP) in Western Kentucky (USA) delineated the extent of exposure to polychlorinated biphenyls (PCBs) and PCB spatial distribution. Raccoon exposure to PCBs was demonstrated through analysis of subcutaneous fat, abdominal fat, liver, and brain tissues from raccoons collected at the PGDP but also was clearly evident in raccoons from a reference area situated along the Ohio River (USA). Raccoons with the highest tissue PCB concentrations appeared to be those inhabiting areas nearest the plant itself and most likely those that ventured into the plants interior. Male raccoons at the PGDP had similar concentrations of total PCBs in subcutaneous fat (1.86 +/- 0.64 microg/g) as males from the reference site (1.41 +/- 0.35 microg/g), but females had higher PCB body burdens than those at the reference site (9.90 +/- 6.13 microg/g vs 0.75 +/- 0.40 microg/g). Gross measurements of exposure to radiation-producing materials revealed that counts per minute exceeded background in 61% of PGDP raccoons compared with 27% at the reference site and five raccoons at the PGDP had beta counts that were more than twice the background. Differences among trapping success, growth rates, and serum chemistry parameters were noted but may have been related to habitat and other environmental and population density factors.